nrf52/src/ble_phy.c

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *  http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

#include <stdint.h>
#include <string.h>
#include <assert.h>
#include "syscfg/syscfg.h"
#include "os/os.h"
#include "ble/xcvr.h"
#include "nimble/ble.h"
#include "nimble/nimble_opt.h"
#include "nimble/nimble_npl.h"
#include "controller/ble_phy.h"
#include "controller/ble_phy_trace.h"
#include "controller/ble_ll.h"
#include "nrfx.h"
#if MYNEWT
#include "mcu/nrf52_clock.h"
#include "mcu/cmsis_nvic.h"
#include "hal/hal_gpio.h"
#else
#include "core_cm4.h"
#endif

/*
 * NOTE: This code uses a couple of PPI channels so care should be taken when
 *       using PPI somewhere else.
 *
 * Pre-programmed channels: CH20, CH21, CH23, CH25, CH31
 * Regular channels: CH4, CH5 and optionally CH17, CH18, CH19
 *  - CH4 = cancel wfr timer on address match
 *  - CH5 = disable radio on wfr timer expiry
 *  - CH17 = (optional) gpio debug for radio ramp-up
 *  - CH18 = (optional) gpio debug for wfr timer RX enabled
 *  - CH19 = (optional) gpio debug for wfr timer radio disabled
 *
 */

/* XXX: 4) Make sure RF is higher priority interrupt than schedule */

/*
 * XXX: Maximum possible transmit time is 1 msec for a 60ppm crystal
 * and 16ms for a 30ppm crystal! We need to limit PDU size based on
 * crystal accuracy. Look at this in the spec.
 */

/* XXX: private header file? */
extern uint8_t g_nrf_num_irks;
extern uint32_t g_nrf_irk_list[];

/* To disable all radio interrupts */
#define NRF_RADIO_IRQ_MASK_ALL  (0x34FF)

/*
 * We configure the nrf with a 1 byte S0 field, 8 bit length field, and
 * zero bit S1 field. The preamble is 8 bits long.
 */
#define NRF_LFLEN_BITS          (8)
#define NRF_S0LEN               (1)
#define NRF_S1LEN_BITS          (0)
#define NRF_CILEN_BITS          (2)
#define NRF_TERMLEN_BITS        (3)

/* Maximum length of frames */
#define NRF_MAXLEN              (255)
#define NRF_BALEN               (3)     /* For base address of 3 bytes */

/* Maximum tx power */
#define NRF_TX_PWR_MAX_DBM      (4)
#define NRF_TX_PWR_MIN_DBM      (-40)

/* NRF_RADIO->PCNF0 configuration values */
#define NRF_PCNF0               (NRF_LFLEN_BITS << RADIO_PCNF0_LFLEN_Pos) | \
                                (RADIO_PCNF0_S1INCL_Msk) | \
                                (NRF_S0LEN << RADIO_PCNF0_S0LEN_Pos) | \
                                (NRF_S1LEN_BITS << RADIO_PCNF0_S1LEN_Pos)
#define NRF_PCNF0_1M            (NRF_PCNF0) | \
                                (RADIO_PCNF0_PLEN_8bit << RADIO_PCNF0_PLEN_Pos)
#define NRF_PCNF0_2M            (NRF_PCNF0) | \
                                (RADIO_PCNF0_PLEN_16bit << RADIO_PCNF0_PLEN_Pos)
#define NRF_PCNF0_CODED         (NRF_PCNF0) | \
                                (RADIO_PCNF0_PLEN_LongRange << RADIO_PCNF0_PLEN_Pos) | \
                                (NRF_CILEN_BITS << RADIO_PCNF0_CILEN_Pos) | \
                                (NRF_TERMLEN_BITS << RADIO_PCNF0_TERMLEN_Pos)

/* BLE PHY data structure */
struct ble_phy_obj
{
    uint8_t phy_stats_initialized;
    int8_t  phy_txpwr_dbm;
    uint8_t phy_chan;
    uint8_t phy_state;
    uint8_t phy_transition;
    uint8_t phy_transition_late;
    uint8_t phy_rx_started;
    uint8_t phy_encrypted;
    uint8_t phy_privacy;
    uint8_t phy_tx_pyld_len;
    uint8_t phy_txtorx_phy_mode;
    uint8_t phy_cur_phy_mode;
    uint8_t phy_bcc_offset;
    uint32_t phy_aar_scratch;
    uint32_t phy_access_address;
    struct ble_mbuf_hdr rxhdr;
    void *txend_arg;
    ble_phy_tx_end_func txend_cb;
    uint32_t phy_start_cputime;
};
struct ble_phy_obj g_ble_phy_data;

/* XXX: if 27 byte packets desired we can make this smaller */
/* Global transmit/receive buffer */
static uint32_t g_ble_phy_tx_buf[(BLE_PHY_MAX_PDU_LEN + 3) / 4];
static uint32_t g_ble_phy_rx_buf[(BLE_PHY_MAX_PDU_LEN + 3) / 4];

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION) == 1)
/* Make sure word-aligned for faster copies */
static uint32_t g_ble_phy_enc_buf[(BLE_PHY_MAX_PDU_LEN + 3) / 4];
#endif

/* RF center frequency for each channel index (offset from 2400 MHz) */
static const uint8_t g_ble_phy_chan_freq[BLE_PHY_NUM_CHANS] = {
     4,  6,  8, 10, 12, 14, 16, 18, 20, 22, /* 0-9 */
    24, 28, 30, 32, 34, 36, 38, 40, 42, 44, /* 10-19 */
    46, 48, 50, 52, 54, 56, 58, 60, 62, 64, /* 20-29 */
    66, 68, 70, 72, 74, 76, 78,  2, 26, 80, /* 30-39 */
};

#if (BLE_LL_BT5_PHY_SUPPORTED == 1)
/* packet start offsets (in usecs) */
static const uint16_t g_ble_phy_mode_pkt_start_off[BLE_PHY_NUM_MODE] = { 376, 40, 24, 376 };
#endif

/* Various radio timings */
/* Radio ramp-up times in usecs (fast mode) */
#define BLE_PHY_T_TXENFAST      (XCVR_TX_RADIO_RAMPUP_USECS)
#define BLE_PHY_T_RXENFAST      (XCVR_RX_RADIO_RAMPUP_USECS)
/* delay between EVENTS_READY and start of tx */
static const uint8_t g_ble_phy_t_txdelay[BLE_PHY_NUM_MODE] = { 5, 4, 3, 5 };
/* delay between EVENTS_END and end of txd packet */
static const uint8_t g_ble_phy_t_txenddelay[BLE_PHY_NUM_MODE] = { 9, 4, 3, 3 };
/* delay between rxd access address (w/ TERM1 for coded) and EVENTS_ADDRESS */
static const uint8_t g_ble_phy_t_rxaddrdelay[BLE_PHY_NUM_MODE] = { 17, 6, 2, 17 };
/* delay between end of rxd packet and EVENTS_END */
static const uint8_t g_ble_phy_t_rxenddelay[BLE_PHY_NUM_MODE] = { 27, 6, 2, 22 };

/* Statistics */
STATS_SECT_START(ble_phy_stats)
    STATS_SECT_ENTRY(phy_isrs)
    STATS_SECT_ENTRY(tx_good)
    STATS_SECT_ENTRY(tx_fail)
    STATS_SECT_ENTRY(tx_late)
    STATS_SECT_ENTRY(tx_bytes)
    STATS_SECT_ENTRY(rx_starts)
    STATS_SECT_ENTRY(rx_aborts)
    STATS_SECT_ENTRY(rx_valid)
    STATS_SECT_ENTRY(rx_crc_err)
    STATS_SECT_ENTRY(rx_late)
    STATS_SECT_ENTRY(radio_state_errs)
    STATS_SECT_ENTRY(rx_hw_err)
    STATS_SECT_ENTRY(tx_hw_err)
STATS_SECT_END
STATS_SECT_DECL(ble_phy_stats) ble_phy_stats;

STATS_NAME_START(ble_phy_stats)
    STATS_NAME(ble_phy_stats, phy_isrs)
    STATS_NAME(ble_phy_stats, tx_good)
    STATS_NAME(ble_phy_stats, tx_fail)
    STATS_NAME(ble_phy_stats, tx_late)
    STATS_NAME(ble_phy_stats, tx_bytes)
    STATS_NAME(ble_phy_stats, rx_starts)
    STATS_NAME(ble_phy_stats, rx_aborts)
    STATS_NAME(ble_phy_stats, rx_valid)
    STATS_NAME(ble_phy_stats, rx_crc_err)
    STATS_NAME(ble_phy_stats, rx_late)
    STATS_NAME(ble_phy_stats, radio_state_errs)
    STATS_NAME(ble_phy_stats, rx_hw_err)
    STATS_NAME(ble_phy_stats, tx_hw_err)
STATS_NAME_END(ble_phy_stats)

/*
 * NOTE:
 * Tested the following to see what would happen:
 *  -> NVIC has radio irq enabled (interrupt # 1, mask 0x2).
 *  -> Set up nrf to receive. Clear ADDRESS event register.
 *  -> Enable ADDRESS interrupt on nrf5 by writing to INTENSET.
 *  -> Enable RX.
 *  -> Disable interrupts globally using OS_ENTER_CRITICAL().
 *  -> Wait until a packet is received and the ADDRESS event occurs.
 *  -> Call ble_phy_disable().
 *
 *  At this point I wanted to see the state of the cortex NVIC. The IRQ
 *  pending bit was TRUE for the radio interrupt (as expected) as we never
 *  serviced the radio interrupt (interrupts were disabled).
 *
 *  What was unexpected was this: without clearing the pending IRQ in the NVIC,
 *  when radio interrupts were re-enabled (address event bit in INTENSET set to
 *  1) and the radio ADDRESS event register read 1 (it was never cleared after
 *  the first address event), the radio did not enter the ISR! I would have
 *  expected that if the following were true, an interrupt would occur:
 *      -> NVIC ISER bit set to TRUE
 *      -> NVIC ISPR bit reads TRUE, meaning interrupt is pending.
 *      -> Radio peripheral interrupts are enabled for some event (or events).
 *      -> Corresponding event register(s) in radio peripheral read 1.
 *
 *  Not sure what the end result of all this is. We will clear the pending
 *  bit in the NVIC just to be sure when we disable the PHY.
 */

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION) == 1)

/*
 * Per nordic, the number of bytes needed for scratch is 16 + MAX_PKT_SIZE.
 * However, when I used a smaller size it still overwrote the scratchpad. Until
 * I figure this out I am just going to allocate 67 words so we have enough
 * space for 267 bytes of scratch. I used 268 bytes since not sure if this
 * needs to be aligned and burning a byte is no big deal.
 */
//#define NRF_ENC_SCRATCH_WORDS (((MYNEWT_VAL(BLE_LL_MAX_PKT_SIZE) + 16) + 3) / 4)
#define NRF_ENC_SCRATCH_WORDS   (67)

uint32_t g_nrf_encrypt_scratchpad[NRF_ENC_SCRATCH_WORDS];

struct nrf_ccm_data
{
    uint8_t key[16];
    uint64_t pkt_counter;
    uint8_t dir_bit;
    uint8_t iv[8];
} __attribute__((packed));

struct nrf_ccm_data g_nrf_ccm_data;
#endif

#ifdef NRF52
static void
ble_phy_apply_errata_102_106_107(void)
{
    /* [102] RADIO: PAYLOAD/END events delayed or not triggered after ADDRESS
     * [106] RADIO: Higher CRC error rates for some access addresses
     * [107] RADIO: Immediate address match for access addresses containing MSBs 0x00
     */
    *(volatile uint32_t *)0x40001774 = ((*(volatile uint32_t *)0x40001774) &
                         0xfffffffe) | 0x01000000;
}
#endif

#if (BLE_LL_BT5_PHY_SUPPORTED == 1)

/* Packet start offset (in usecs). This is the preamble plus access address.
 * For LE Coded PHY this also includes CI and TERM1. */
uint32_t
ble_phy_mode_pdu_start_off(int phy_mode)
{
    return g_ble_phy_mode_pkt_start_off[phy_mode];
}

#if NRF52840_XXAA
static inline bool
ble_phy_mode_is_coded(uint8_t phy_mode)
{
    return (phy_mode == BLE_PHY_MODE_CODED_125KBPS) ||
           (phy_mode == BLE_PHY_MODE_CODED_500KBPS);
}

static void
ble_phy_apply_nrf52840_errata(uint8_t new_phy_mode)
{
    bool new_coded = ble_phy_mode_is_coded(new_phy_mode);
    bool cur_coded = ble_phy_mode_is_coded(g_ble_phy_data.phy_cur_phy_mode);

    /*
     * Workarounds should be applied only when switching to/from LE Coded PHY
     * so no need to apply them every time.
     *
     * nRF52840 Engineering A Errata v1.2
     * [164] RADIO: Low sensitivity in long range mode
     *
     * nRF52840 Rev 1 Errata
     * [191] RADIO: High packet error rate in BLE Long Range mode
     */
    if (new_coded == cur_coded) {
        return;
    }

    if (new_coded) {
#if MYNEWT_VAL(BLE_PHY_NRF52840_ERRATA_164)
        /* [164] */
        *(volatile uint32_t *)0x4000173C |= 0x80000000;
        *(volatile uint32_t *)0x4000173C =
                        ((*(volatile uint32_t *)0x4000173C & 0xFFFFFF00) | 0x5C);
#endif
#if MYNEWT_VAL(BLE_PHY_NRF52840_ERRATA_191)
        /* [191] */
        *(volatile uint32_t *) 0x40001740 =
                        ((*((volatile uint32_t *) 0x40001740)) & 0x7FFF00FF) |
                        0x80000000 | (((uint32_t)(196)) << 8);
#endif
    } else {
#if MYNEWT_VAL(BLE_PHY_NRF52840_ERRATA_164)
        /* [164] */
        *(volatile uint32_t *)0x4000173C &= ~0x80000000;
#endif
#if MYNEWT_VAL(BLE_PHY_NRF52840_ERRATA_191)
        /* [191] */
        *(volatile uint32_t *) 0x40001740 =
                        ((*((volatile uint32_t *) 0x40001740)) & 0x7FFFFFFF);
#endif
    }
}
#endif

void
ble_phy_mode_set(uint8_t new_phy_mode, uint8_t txtorx_phy_mode)
{
    if (new_phy_mode == g_ble_phy_data.phy_cur_phy_mode) {
        g_ble_phy_data.phy_txtorx_phy_mode = txtorx_phy_mode;
        return;
    }

#if NRF52840_XXAA
    ble_phy_apply_nrf52840_errata(new_phy_mode);
#endif

    switch (new_phy_mode) {
    case BLE_PHY_MODE_1M:
        NRF_RADIO->MODE = RADIO_MODE_MODE_Ble_1Mbit;
        NRF_RADIO->PCNF0 = NRF_PCNF0_1M;
        break;
#if MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_2M_PHY)
    case BLE_PHY_MODE_2M:
        NRF_RADIO->MODE = RADIO_MODE_MODE_Ble_2Mbit;
        NRF_RADIO->PCNF0 = NRF_PCNF0_2M;
        break;
#endif
#if MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_CODED_PHY)
    case BLE_PHY_MODE_CODED_125KBPS:
        NRF_RADIO->MODE = RADIO_MODE_MODE_Ble_LR125Kbit;
        NRF_RADIO->PCNF0 = NRF_PCNF0_CODED;
        break;
    case BLE_PHY_MODE_CODED_500KBPS:
        NRF_RADIO->MODE = RADIO_MODE_MODE_Ble_LR500Kbit;
        NRF_RADIO->PCNF0 = NRF_PCNF0_CODED;
        break;
#endif
    default:
        assert(0);
    }

    g_ble_phy_data.phy_cur_phy_mode = new_phy_mode;
    g_ble_phy_data.phy_txtorx_phy_mode = txtorx_phy_mode;
}
#endif

int
ble_phy_get_cur_phy(void)
{
#if (BLE_LL_BT5_PHY_SUPPORTED == 1)
    switch (g_ble_phy_data.phy_cur_phy_mode) {
        case BLE_PHY_MODE_1M:
            return BLE_PHY_1M;
        case BLE_PHY_MODE_2M:
            return BLE_PHY_2M;
        case BLE_PHY_MODE_CODED_125KBPS:
        case BLE_PHY_MODE_CODED_500KBPS:
            return BLE_PHY_CODED;
        default:
            assert(0);
            return -1;
    }
#else
    return BLE_PHY_1M;
#endif
}

/**
 * Copies the data from the phy receive buffer into a mbuf chain.
 *
 * @param dptr Pointer to receive buffer
 * @param rxpdu Pointer to already allocated mbuf chain
 *
 * NOTE: the packet header already has the total mbuf length in it. The
 * lengths of the individual mbufs are not set prior to calling.
 *
 */
void
ble_phy_rxpdu_copy(uint8_t *dptr, struct os_mbuf *rxpdu)
{
    uint16_t rem_bytes;
    uint16_t mb_bytes;
    uint16_t copylen;
    uint32_t *dst;
    uint32_t *src;
    struct os_mbuf *m;
    struct ble_mbuf_hdr *ble_hdr;
    struct os_mbuf_pkthdr *pkthdr;

    /* Better be aligned */
    assert(((uint32_t)dptr & 3) == 0);

    pkthdr = OS_MBUF_PKTHDR(rxpdu);
    rem_bytes = pkthdr->omp_len;

    /* Fill in the mbuf pkthdr first. */
    dst = (uint32_t *)(rxpdu->om_data);
    src = (uint32_t *)dptr;

    mb_bytes = (rxpdu->om_omp->omp_databuf_len - rxpdu->om_pkthdr_len - 4);
    copylen = min(mb_bytes, rem_bytes);
    copylen &= 0xFFFC;
    rem_bytes -= copylen;
    mb_bytes -= copylen;
    rxpdu->om_len = copylen;
    while (copylen > 0) {
        *dst = *src;
        ++dst;
        ++src;
        copylen -= 4;
    }

    /* Copy remaining bytes */
    m = rxpdu;
    while (rem_bytes > 0) {
        /* If there are enough bytes in the mbuf, copy them and leave */
        if (rem_bytes <= mb_bytes) {
            memcpy(m->om_data + m->om_len, src, rem_bytes);
            m->om_len += rem_bytes;
            break;
        }

        m = SLIST_NEXT(m, om_next);
        assert(m != NULL);

        mb_bytes = m->om_omp->omp_databuf_len;
        copylen = min(mb_bytes, rem_bytes);
        copylen &= 0xFFFC;
        rem_bytes -= copylen;
        mb_bytes -= copylen;
        m->om_len = copylen;
        dst = (uint32_t *)m->om_data;
        while (copylen > 0) {
            *dst = *src;
            ++dst;
            ++src;
            copylen -= 4;
        }
    }

    /* Copy ble header */
    ble_hdr = BLE_MBUF_HDR_PTR(rxpdu);
    memcpy(ble_hdr, &g_ble_phy_data.rxhdr, sizeof(struct ble_mbuf_hdr));
}

/**
 * Called when we want to wait if the radio is in either the rx or tx
 * disable states. We want to wait until that state is over before doing
 * anything to the radio
 */
static void
nrf_wait_disabled(void)
{
    uint32_t state;

    state = NRF_RADIO->STATE;
    if (state != RADIO_STATE_STATE_Disabled) {
        if ((state == RADIO_STATE_STATE_RxDisable) ||
            (state == RADIO_STATE_STATE_TxDisable)) {
            /* This will end within a short time (6 usecs). Just poll */
            while (NRF_RADIO->STATE == state) {
                /* If this fails, something is really wrong. Should last
                 * no more than 6 usecs */
            }
        }
    }
}

/**
 *
 *
 */
static int
ble_phy_set_start_time(uint32_t cputime, uint8_t rem_usecs, bool tx)
{
    uint32_t next_cc;
    uint32_t cur_cc;
    uint32_t cntr;
    uint32_t delta;

    /*
     * We need to adjust start time to include radio ramp-up and TX pipeline
     * delay (the latter only if applicable, so only for TX).
     *
     * Radio ramp-up time is 40 usecs and TX delay is 3 or 5 usecs depending on
     * phy, thus we'll offset RTC by 2 full ticks (61 usecs) and then compensate
     * using TIMER0 with 1 usec precision.
     */

    cputime -= 2;
    rem_usecs += 61;
    if (tx) {
        rem_usecs -= BLE_PHY_T_TXENFAST;
        rem_usecs -= g_ble_phy_t_txdelay[g_ble_phy_data.phy_cur_phy_mode];
    } else {
        rem_usecs -= BLE_PHY_T_RXENFAST;
    }

    /*
     * rem_usecs will be no more than 2 ticks, but if it is more than single
     * tick then we should better count one more low-power tick rather than
     * 30 high-power usecs. Also make sure we don't set TIMER0 CC to 0 as the
     * compare won't occur.
     */

    if (rem_usecs > 30) {
        cputime++;
        rem_usecs -= 30;
    }

    /*
     * Can we set the RTC compare to start TIMER0? We can do it if:
     *      a) Current compare value is not N+1 or N+2 ticks from current
     *      counter.
     *      b) The value we want to set is not at least N+2 from current
     *      counter.
     *
     * NOTE: since the counter can tick 1 while we do these calculations we
     * need to account for it.
     */
    next_cc = cputime & 0xffffff;
    cur_cc = NRF_RTC0->CC[0];
    cntr = NRF_RTC0->COUNTER;

    delta = (cur_cc - cntr) & 0xffffff;
    if ((delta <= 3) && (delta != 0)) {
        return -1;
    }
    delta = (next_cc - cntr) & 0xffffff;
    if ((delta & 0x800000) || (delta < 3)) {
        return -1;
    }

    /* Clear and set TIMER0 to fire off at proper time */
    NRF_TIMER0->TASKS_CLEAR = 1;
    NRF_TIMER0->CC[0] = rem_usecs;
    NRF_TIMER0->EVENTS_COMPARE[0] = 0;

    /* Set RTC compare to start TIMER0 */
    NRF_RTC0->EVENTS_COMPARE[0] = 0;
    NRF_RTC0->CC[0] = next_cc;
    NRF_RTC0->EVTENSET = RTC_EVTENSET_COMPARE0_Msk;

    /* Enable PPI */
    NRF_PPI->CHENSET = PPI_CHEN_CH31_Msk;

    /* Store the cputime at which we set the RTC */
    g_ble_phy_data.phy_start_cputime = cputime;

    return 0;
}

static int
ble_phy_set_start_now(void)
{
    uint32_t cntr;

    /* Read current RTC0 state */
    cntr = NRF_RTC0->COUNTER;

    /*
     * Set TIMER0 to fire immediately. We can't set CC to 0 as compare will not
     * occur in such case.
     */
    NRF_TIMER0->TASKS_CLEAR = 1;
    NRF_TIMER0->CC[0] = 1;
    NRF_TIMER0->EVENTS_COMPARE[0] = 0;

    /*
     * Set RTC compare to start TIMER0. We need to set it to at least N+2 ticks
     * from current value to guarantee triggering compare event, but let's set
     * it to N+3 to account for possible extra tick on RTC0 during these
     * operations.
     */
    NRF_RTC0->EVENTS_COMPARE[0] = 0;
    NRF_RTC0->CC[0] = cntr + 3;
    NRF_RTC0->EVTENSET = RTC_EVTENSET_COMPARE0_Msk;

    /* Enable PPI */
    NRF_PPI->CHENSET = PPI_CHEN_CH31_Msk;

    /*
     * Store the cputime at which we set the RTC
     *
     * XXX Compare event may be triggered on previous CC value (if it was set to
     * less than N+2) so in rare cases actual start time may be 2 ticks earlier
     * than what we expect. Since this is only used on RX, it may cause AUX scan
     * to be scheduled 1 or 2 ticks too late so we'll miss it - it's acceptable
     * for now.
     */
    g_ble_phy_data.phy_start_cputime = cntr + 3;

    return 0;
}

/**
 * Function is used to set PPI so that we can time out waiting for a reception
 * to occur. This happens for two reasons: we have sent a packet and we are
 * waiting for a respons (txrx should be set to ENABLE_TXRX) or we are
 * starting a connection event and we are a slave and we are waiting for the
 * master to send us a packet (txrx should be set to ENABLE_RX).
 *
 * NOTE: when waiting for a txrx turn-around, wfr_usecs is not used as there
 * is no additional time to wait; we know when we should receive the address of
 * the received frame.
 *
 * @param txrx Flag denoting if this wfr is a txrx turn-around or not.
 * @param tx_phy_mode phy mode for last TX (only valid for TX->RX)
 * @param wfr_usecs Amount of usecs to wait.
 */
void
ble_phy_wfr_enable(int txrx, uint8_t tx_phy_mode, uint32_t wfr_usecs)
{
    uint32_t end_time;
    uint8_t phy;

    phy = g_ble_phy_data.phy_cur_phy_mode;

    if (txrx == BLE_PHY_WFR_ENABLE_TXRX) {
        /* RX shall start exactly T_IFS after TX end captured in CC[2] */
        end_time = NRF_TIMER0->CC[2] + BLE_LL_IFS;
        /* Adjust for delay between EVENT_END and actual TX end time */
        end_time += g_ble_phy_t_txenddelay[tx_phy_mode];
        /* Wait a bit longer due to allowed active clock accuracy */
        end_time += 2;
        /*
         * It's possible that we'll capture PDU start time at the end of timer
         * cycle and since wfr expires at the beginning of calculated timer
         * cycle it can be almost 1 usec too early. Let's compensate for this
         * by waiting 1 usec more.
         */
        end_time += 1;
#if MYNEWT_VAL(BLE_PHY_CODED_RX_IFS_EXTRA_MARGIN) > 0
        if ((phy == BLE_PHY_MODE_CODED_125KBPS) ||
                                    (phy == BLE_PHY_MODE_CODED_500KBPS)) {
            /*
             * Some controllers exceed T_IFS when transmitting on coded phy
             * so let's wait a bit longer to be able to talk to them if this
             * workaround is enabled.
             */
            end_time += MYNEWT_VAL(BLE_PHY_CODED_RX_IFS_EXTRA_MARGIN);
        }
#endif
    } else {
        /*
         * RX shall start no later than wfr_usecs after RX enabled.
         * CC[0] is the time of RXEN so adjust for radio ram-up.
         * Do not add jitter since this is already covered by LL.
         */
        end_time = NRF_TIMER0->CC[0] + BLE_PHY_T_RXENFAST + wfr_usecs;
    }

    /*
     * Note: on LE Coded EVENT_ADDRESS is fired after TERM1 is received, so
     *       we are actually calculating relative to start of packet payload
     *       which is fine.
     */

    /* Adjust for receiving access address since this triggers EVENT_ADDRESS */
    end_time += ble_phy_mode_pdu_start_off(phy);
    /* Adjust for delay between actual access address RX and EVENT_ADDRESS */
    end_time += g_ble_phy_t_rxaddrdelay[phy];

    /* wfr_secs is the time from rxen until timeout */
    NRF_TIMER0->CC[3] = end_time;
    NRF_TIMER0->EVENTS_COMPARE[3] = 0;

    /* Enable wait for response PPI */
    NRF_PPI->CHENSET = (PPI_CHEN_CH4_Msk | PPI_CHEN_CH5_Msk);

    /* Enable the disabled interrupt so we time out on events compare */
    NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk;

    /*
     * It may happen that if CPU is halted for a brief moment (e.g. during flash
     * erase or write), TIMER0 already counted past CC[3] and thus wfr will not
     * fire as expected. In case this happened, let's just disable PPIs for wfr
     * and trigger wfr manually (i.e. disable radio).
     *
     * Note that the same applies to RX start time set in CC[0] but since it
     * should fire earlier than wfr, fixing wfr is enough.
     *
     * CC[1] is only used as a reference on RX start, we do not need it here so
     * it can be used to read TIMER0 counter.
     */
    NRF_TIMER0->TASKS_CAPTURE[1] = 1;
    if (NRF_TIMER0->CC[1] > NRF_TIMER0->CC[3]) {
        NRF_PPI->CHENCLR = PPI_CHEN_CH4_Msk | PPI_CHEN_CH5_Msk;
        NRF_RADIO->TASKS_DISABLE = 1;
    }
}

#if MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION)
static uint32_t
ble_phy_get_ccm_datarate(void)
{
#if BLE_LL_BT5_PHY_SUPPORTED
    switch (g_ble_phy_data.phy_cur_phy_mode) {
    case BLE_PHY_MODE_1M:
        return CCM_MODE_DATARATE_1Mbit << CCM_MODE_DATARATE_Pos;
    case BLE_PHY_MODE_2M:
        return CCM_MODE_DATARATE_2Mbit << CCM_MODE_DATARATE_Pos;
#if MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_CODED_PHY)
    case BLE_PHY_MODE_CODED_125KBPS:
        return CCM_MODE_DATARATE_125Kbps << CCM_MODE_DATARATE_Pos;
    case BLE_PHY_MODE_CODED_500KBPS:
        return CCM_MODE_DATARATE_500Kbps << CCM_MODE_DATARATE_Pos;
#endif
    }

    assert(0);
    return 0;
#else
    return CCM_MODE_DATARATE_1Mbit << CCM_MODE_DATARATE_Pos;
#endif
}
#endif

/**
 * Setup transceiver for receive.
 */
static void
ble_phy_rx_xcvr_setup(void)
{
    uint8_t *dptr;

    dptr = (uint8_t *)&g_ble_phy_rx_buf[0];
    dptr += 3;

#if MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION)
    if (g_ble_phy_data.phy_encrypted) {
        NRF_RADIO->PACKETPTR = (uint32_t)&g_ble_phy_enc_buf[0];
        NRF_CCM->INPTR = (uint32_t)&g_ble_phy_enc_buf[0];
        NRF_CCM->OUTPTR = (uint32_t)dptr;
        NRF_CCM->SCRATCHPTR = (uint32_t)&g_nrf_encrypt_scratchpad[0];
        NRF_CCM->MODE = CCM_MODE_LENGTH_Msk | CCM_MODE_MODE_Decryption |
                                                    ble_phy_get_ccm_datarate();
        NRF_CCM->CNFPTR = (uint32_t)&g_nrf_ccm_data;
        NRF_CCM->SHORTS = 0;
        NRF_CCM->EVENTS_ERROR = 0;
        NRF_CCM->EVENTS_ENDCRYPT = 0;
        NRF_CCM->TASKS_KSGEN = 1;
        NRF_PPI->CHENSET = PPI_CHEN_CH25_Msk;
    } else {
        NRF_RADIO->PACKETPTR = (uint32_t)dptr;
    }
#else
    NRF_RADIO->PACKETPTR = (uint32_t)dptr;
#endif

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_PRIVACY) == 1)
    if (g_ble_phy_data.phy_privacy) {
        NRF_AAR->ENABLE = AAR_ENABLE_ENABLE_Enabled;
        NRF_AAR->IRKPTR = (uint32_t)&g_nrf_irk_list[0];
        NRF_AAR->SCRATCHPTR = (uint32_t)&g_ble_phy_data.phy_aar_scratch;
        NRF_AAR->EVENTS_END = 0;
        NRF_AAR->EVENTS_RESOLVED = 0;
        NRF_AAR->EVENTS_NOTRESOLVED = 0;
    } else {
        if (g_ble_phy_data.phy_encrypted == 0) {
            NRF_AAR->ENABLE = AAR_ENABLE_ENABLE_Disabled;
        }
    }
#endif

    /* Turn off trigger TXEN on output compare match and AAR on bcmatch */
    NRF_PPI->CHENCLR = PPI_CHEN_CH20_Msk | PPI_CHEN_CH23_Msk;

    /* Reset the rx started flag. Used for the wait for response */
    g_ble_phy_data.phy_rx_started = 0;
    g_ble_phy_data.phy_state = BLE_PHY_STATE_RX;

#if BLE_LL_BT5_PHY_SUPPORTED
    /*
     * On Coded PHY there are CI and TERM1 fields before PDU starts so we need
     * to take this into account when setting up BCC.
     */
    if (g_ble_phy_data.phy_cur_phy_mode == BLE_PHY_MODE_CODED_125KBPS ||
            g_ble_phy_data.phy_cur_phy_mode == BLE_PHY_MODE_CODED_500KBPS) {
        g_ble_phy_data.phy_bcc_offset = 5;
    } else {
        g_ble_phy_data.phy_bcc_offset = 0;
    }
#else
    g_ble_phy_data.phy_bcc_offset = 0;
#endif

    /* I want to know when 1st byte received (after address) */
    NRF_RADIO->BCC = 8 + g_ble_phy_data.phy_bcc_offset; /* in bits */
    NRF_RADIO->EVENTS_ADDRESS = 0;
    NRF_RADIO->EVENTS_DEVMATCH = 0;
    NRF_RADIO->EVENTS_BCMATCH = 0;
    NRF_RADIO->EVENTS_RSSIEND = 0;
    NRF_RADIO->EVENTS_CRCOK = 0;
    NRF_RADIO->SHORTS = RADIO_SHORTS_END_DISABLE_Msk |
                        RADIO_SHORTS_READY_START_Msk |
                        RADIO_SHORTS_ADDRESS_BCSTART_Msk |
                        RADIO_SHORTS_ADDRESS_RSSISTART_Msk |
                        RADIO_SHORTS_DISABLED_RSSISTOP_Msk;

    NRF_RADIO->INTENSET = RADIO_INTENSET_ADDRESS_Msk;
}

/**
 * Called from interrupt context when the transmit ends
 *
 */
static void
ble_phy_tx_end_isr(void)
{
#if (BLE_LL_BT5_PHY_SUPPORTED == 1)
    int phy;
#endif
    uint8_t tx_phy_mode;
    uint8_t was_encrypted;
    uint8_t transition;
    uint32_t rx_time;
    uint32_t wfr_time;

    /* Store PHY on which we've just transmitted smth */
    tx_phy_mode = g_ble_phy_data.phy_cur_phy_mode;

    /* If this transmission was encrypted we need to remember it */
    was_encrypted = g_ble_phy_data.phy_encrypted;
    (void)was_encrypted;

    /* Better be in TX state! */
    assert(g_ble_phy_data.phy_state == BLE_PHY_STATE_TX);

    /* Clear events and clear interrupt on disabled event */
    NRF_RADIO->EVENTS_DISABLED = 0;
    NRF_RADIO->INTENCLR = RADIO_INTENCLR_DISABLED_Msk;
    NRF_RADIO->EVENTS_END = 0;
    wfr_time = NRF_RADIO->SHORTS;
    (void)wfr_time;

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION) == 1)
    /*
     * XXX: not sure what to do. We had a HW error during transmission.
     * For now I just count a stat but continue on like all is good.
     */
    if (was_encrypted) {
        if (NRF_CCM->EVENTS_ERROR) {
            STATS_INC(ble_phy_stats, tx_hw_err);
            NRF_CCM->EVENTS_ERROR = 0;
        }
    }
#endif

    /* Call transmit end callback */
    if (g_ble_phy_data.txend_cb) {
        g_ble_phy_data.txend_cb(g_ble_phy_data.txend_arg);
    }

    transition = g_ble_phy_data.phy_transition;
    if (transition == BLE_PHY_TRANSITION_TX_RX) {

#if (BLE_LL_BT5_PHY_SUPPORTED == 1)
        /* See if a new phy has been specified for tx to rx transition */
        phy = g_ble_phy_data.phy_txtorx_phy_mode;
        if (phy != g_ble_phy_data.phy_cur_phy_mode) {
            ble_phy_mode_set(phy, phy);
        }
#endif

        /* Packet pointer needs to be reset. */
        ble_phy_rx_xcvr_setup();

        ble_phy_wfr_enable(BLE_PHY_WFR_ENABLE_TXRX, tx_phy_mode, 0);

        /* Schedule RX exactly T_IFS after TX end captured in CC[2] */
        rx_time = NRF_TIMER0->CC[2] + BLE_LL_IFS;
        /* Adjust for delay between EVENT_END and actual TX end time */
        rx_time += g_ble_phy_t_txenddelay[tx_phy_mode];
        /* Adjust for radio ramp-up */
        rx_time -= BLE_PHY_T_RXENFAST;
        /* Start listening a bit earlier due to allowed active clock accuracy */
        rx_time -= 2;

        NRF_TIMER0->CC[0] = rx_time;
        NRF_TIMER0->EVENTS_COMPARE[0] = 0;
        NRF_PPI->CHENSET = PPI_CHEN_CH21_Msk;
    } else {
        /*
         * XXX: not sure we need to stop the timer here all the time. Or that
         * it should be stopped here.
         */
        NRF_TIMER0->TASKS_STOP = 1;
        NRF_TIMER0->TASKS_SHUTDOWN = 1;
        NRF_PPI->CHENCLR = PPI_CHEN_CH4_Msk | PPI_CHEN_CH5_Msk |
                           PPI_CHEN_CH20_Msk | PPI_CHEN_CH31_Msk;
        assert(transition == BLE_PHY_TRANSITION_NONE);
    }
}

static inline uint8_t
ble_phy_get_cur_rx_phy_mode(void)
{
    uint8_t phy;

    phy = g_ble_phy_data.phy_cur_phy_mode;

#if MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_CODED_PHY)
    /*
     * For Coded PHY mode can be set to either codings since actual coding is
     * set in packet header. However, here we need actual coding of received
     * packet as this determines pipeline delays so need to figure this out
     * using CI field.
     */
    if ((phy == BLE_PHY_MODE_CODED_125KBPS) ||
                                    (phy == BLE_PHY_MODE_CODED_500KBPS)) {
        phy = NRF_RADIO->PDUSTAT & RADIO_PDUSTAT_CISTAT_Msk ?
                                   BLE_PHY_MODE_CODED_500KBPS :
                                   BLE_PHY_MODE_CODED_125KBPS;
    }
#endif

    return phy;
}

static void
ble_phy_rx_end_isr(void)
{
    int rc;
    uint8_t *dptr;
    uint8_t crcok;
    uint32_t tx_time;
    struct ble_mbuf_hdr *ble_hdr;

    /* Clear events and clear interrupt */
    NRF_RADIO->EVENTS_END = 0;
    NRF_RADIO->INTENCLR = RADIO_INTENCLR_END_Msk;

    /* Disable automatic RXEN */
    NRF_PPI->CHENCLR = PPI_CHEN_CH21_Msk;

    /* Set RSSI and CRC status flag in header */
    ble_hdr = &g_ble_phy_data.rxhdr;
    assert(NRF_RADIO->EVENTS_RSSIEND != 0);
    ble_hdr->rxinfo.rssi = -1 * NRF_RADIO->RSSISAMPLE;

    dptr = (uint8_t *)&g_ble_phy_rx_buf[0];
    dptr += 3;

    /* Count PHY crc errors and valid packets */
    crcok = NRF_RADIO->EVENTS_CRCOK;
    if (!crcok) {
        STATS_INC(ble_phy_stats, rx_crc_err);
    } else {
        STATS_INC(ble_phy_stats, rx_valid);
        ble_hdr->rxinfo.flags |= BLE_MBUF_HDR_F_CRC_OK;
#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION) == 1)
        if (g_ble_phy_data.phy_encrypted) {
            /* Only set MIC failure flag if frame is not zero length */
            if ((dptr[1] != 0) && (NRF_CCM->MICSTATUS == 0)) {
                ble_hdr->rxinfo.flags |= BLE_MBUF_HDR_F_MIC_FAILURE;
            }

            /*
             * XXX: not sure how to deal with this. This should not
             * be a MIC failure but we should not hand it up. I guess
             * this is just some form of rx error and that is how we
             * handle it? For now, just set CRC error flags
             */
            if (NRF_CCM->EVENTS_ERROR) {
                STATS_INC(ble_phy_stats, rx_hw_err);
                ble_hdr->rxinfo.flags &= ~BLE_MBUF_HDR_F_CRC_OK;
            }

            /*
             * XXX: This is a total hack work-around for now but I dont
             * know what else to do. If ENDCRYPT is not set and we are
             * encrypted we need to not trust this frame and drop it.
             */
            if (NRF_CCM->EVENTS_ENDCRYPT == 0) {
                STATS_INC(ble_phy_stats, rx_hw_err);
                ble_hdr->rxinfo.flags &= ~BLE_MBUF_HDR_F_CRC_OK;
            }
        }
#endif
    }

    /*
     * Let's schedule TX now and we will just cancel it after processing RXed
     * packet if we don't need TX.
     *
     * We need this to initiate connection in case AUX_CONNECT_REQ was sent on
     * LE Coded S8. In this case the time we process RXed packet is roughly the
     * same as the limit when we need to have TX scheduled (i.e. TIMER0 and PPI
     * armed) so we may simply miss the slot and set the timer in the past.
     *
     * When TX is scheduled in advance, we may event process packet a bit longer
     * during radio ramp-up - this gives us extra 40 usecs which is more than
     * enough.
     */

    /* Schedule TX exactly T_IFS after RX end captured in CC[2] */
    tx_time = NRF_TIMER0->CC[2] + BLE_LL_IFS;
    /* Adjust for delay between actual RX end time and EVENT_END */
    tx_time -= g_ble_phy_t_rxenddelay[ble_hdr->rxinfo.phy_mode];
    /* Adjust for radio ramp-up */
    tx_time -= BLE_PHY_T_TXENFAST;
    /* Adjust for delay between EVENT_READY and actual TX start time */
    /* XXX: we may have asymmetric phy so next phy may be different... */
    tx_time -= g_ble_phy_t_txdelay[g_ble_phy_data.phy_cur_phy_mode];

    NRF_TIMER0->CC[0] = tx_time;
    NRF_TIMER0->EVENTS_COMPARE[0] = 0;
    NRF_PPI->CHENSET = PPI_CHEN_CH20_Msk;

    /*
     * XXX: Hack warning!
     *
     * It may happen (during flash erase) that CPU is stopped for a moment and
     * TIMER0 already counted past CC[0]. In such case we will be stuck waiting
     * for TX to start since EVENTS_COMPARE[0] will not happen any time soon.
     * For now let's set a flag denoting that we are late in RX-TX transition so
     * ble_phy_tx() will fail - this allows everything to cleanup nicely without
     * the need for extra handling in many places.
     *
     * Note: CC[3] is used only for wfr which we do not need here.
     */
    NRF_TIMER0->TASKS_CAPTURE[3] = 1;
    if (NRF_TIMER0->CC[3] > NRF_TIMER0->CC[0]) {
        NRF_PPI->CHENCLR = PPI_CHEN_CH20_Msk;
        g_ble_phy_data.phy_transition_late = 1;
    }

    /*
     * XXX: This is a horrible ugly hack to deal with the RAM S1 byte
     * that is not sent over the air but is present here. Simply move the
     * data pointer to deal with it. Fix this later.
     */
    dptr[2] = dptr[1];
    dptr[1] = dptr[0];
    rc = ble_ll_rx_end(dptr + 1, ble_hdr);
    if (rc < 0) {
        ble_phy_disable();
    }
}

static bool
ble_phy_rx_start_isr(void)
{
    int rc;
    uint32_t state;
    uint32_t usecs;
    uint32_t pdu_usecs;
    uint32_t ticks;
    struct ble_mbuf_hdr *ble_hdr;
    uint8_t *dptr;

    dptr = (uint8_t *)&g_ble_phy_rx_buf[0];

    /* Clear events and clear interrupt */
    NRF_RADIO->EVENTS_ADDRESS = 0;

    /* Clear wfr timer channels and DISABLED interrupt */
    NRF_RADIO->INTENCLR = RADIO_INTENCLR_DISABLED_Msk | RADIO_INTENCLR_ADDRESS_Msk;
    NRF_PPI->CHENCLR = PPI_CHEN_CH4_Msk | PPI_CHEN_CH5_Msk;

    /* Initialize the ble mbuf header */
    ble_hdr = &g_ble_phy_data.rxhdr;
    ble_hdr->rxinfo.flags = ble_ll_state_get();
    ble_hdr->rxinfo.channel = g_ble_phy_data.phy_chan;
    ble_hdr->rxinfo.handle = 0;
    ble_hdr->rxinfo.phy = ble_phy_get_cur_phy();
    ble_hdr->rxinfo.phy_mode = ble_phy_get_cur_rx_phy_mode();
#if MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_EXT_ADV)
    ble_hdr->rxinfo.user_data = NULL;
#endif

    /*
     * Calculate accurate packets start time (with remainder)
     *
     * We may start receiving packet somewhere during preamble in which case
     * it is possible that actual transmission started before TIMER0 was
     * running - need to take this into account.
     */
    ble_hdr->beg_cputime = g_ble_phy_data.phy_start_cputime;

    usecs = NRF_TIMER0->CC[1];
    pdu_usecs = ble_phy_mode_pdu_start_off(ble_hdr->rxinfo.phy_mode) +
                g_ble_phy_t_rxaddrdelay[ble_hdr->rxinfo.phy_mode];
    if (usecs < pdu_usecs) {
        g_ble_phy_data.phy_start_cputime--;
        usecs += 30;
    }
    usecs -= pdu_usecs;

    ticks = os_cputime_usecs_to_ticks(usecs);
    usecs -= os_cputime_ticks_to_usecs(ticks);
    if (usecs == 31) {
        usecs = 0;
        ++ticks;
    }

    ble_hdr->beg_cputime += ticks;
    ble_hdr->rem_usecs = usecs;

    /* XXX: I wonder if we always have the 1st byte. If we need to wait for
     * rx chain delay, it could be 18 usecs from address interrupt. The
       nrf52 may be able to get here early. */
    /* Wait to get 1st byte of frame */
    while (1) {
        state = NRF_RADIO->STATE;
        if (NRF_RADIO->EVENTS_BCMATCH != 0) {
            break;
        }

        /*
         * If state is disabled, we should have the BCMATCH. If not,
         * something is wrong!
         */
        if (state == RADIO_STATE_STATE_Disabled) {
            NRF_RADIO->INTENCLR = NRF_RADIO_IRQ_MASK_ALL;
            NRF_RADIO->SHORTS = 0;
            return false;
        }
    }

    /* Call Link Layer receive start function */
    rc = ble_ll_rx_start(dptr + 3,
                         g_ble_phy_data.phy_chan,
                         &g_ble_phy_data.rxhdr);
    if (rc >= 0) {
        /* Set rx started flag and enable rx end ISR */
        g_ble_phy_data.phy_rx_started = 1;
        NRF_RADIO->INTENSET = RADIO_INTENSET_END_Msk;

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_PRIVACY) == 1)
        /* Must start aar if we need to  */
        if (g_ble_phy_data.phy_privacy) {
            NRF_RADIO->EVENTS_BCMATCH = 0;
            NRF_PPI->CHENSET = PPI_CHEN_CH23_Msk;

            /*
             * Setup AAR to resolve AdvA and trigger it after complete address
             * is received, i.e. after PDU header and AdvA is received.
             *
             * AdvA starts at 4th octet in receive buffer, after S0, len and S1
             * fields.
             *
             * In case of extended advertising AdvA is located after extended
             * header (+2 octets).
             */
            if (BLE_MBUF_HDR_EXT_ADV(&g_ble_phy_data.rxhdr)) {
                NRF_AAR->ADDRPTR = (uint32_t)(dptr + 5);
                NRF_RADIO->BCC = (BLE_DEV_ADDR_LEN + BLE_LL_PDU_HDR_LEN + 2) * 8 +
                                 g_ble_phy_data.phy_bcc_offset;
            } else {
                NRF_AAR->ADDRPTR = (uint32_t)(dptr + 3);
                NRF_RADIO->BCC = (BLE_DEV_ADDR_LEN + BLE_LL_PDU_HDR_LEN) * 8 +
                                 g_ble_phy_data.phy_bcc_offset;
            }
        }
#endif
    } else {
        /* Disable PHY */
        ble_phy_disable();
        STATS_INC(ble_phy_stats, rx_aborts);
    }

    /* Count rx starts */
    STATS_INC(ble_phy_stats, rx_starts);

    return true;
}

static void
ble_phy_isr(void)
{
    uint32_t irq_en;

    os_trace_isr_enter();

    /* Read irq register to determine which interrupts are enabled */
    irq_en = NRF_RADIO->INTENCLR;

    /*
     * NOTE: order of checking is important! Possible, if things get delayed,
     * we have both an ADDRESS and DISABLED interrupt in rx state. If we get
     * an address, we disable the DISABLED interrupt.
     */

    /* We get this if we have started to receive a frame */
    if ((irq_en & RADIO_INTENCLR_ADDRESS_Msk) && NRF_RADIO->EVENTS_ADDRESS) {
        /*
         * wfr timer is calculated to expire at the exact time we should start
         * receiving a packet (with 1 usec precision) so it is possible  it will
         * fire at the same time as EVENT_ADDRESS. If this happens, radio will
         * be disabled while we are waiting for EVENT_BCCMATCH after 1st byte
         * of payload is received and ble_phy_rx_start_isr() will fail. In this
         * case we should not clear DISABLED irq mask so it will be handled as
         * regular radio disabled event below. In other case radio was disabled
         * on purpose and there's nothing more to handle so we can clear mask.
         */
        if (ble_phy_rx_start_isr()) {
            irq_en &= ~RADIO_INTENCLR_DISABLED_Msk;
        }
    }

    /* Check for disabled event. This only happens for transmits now */
    if ((irq_en & RADIO_INTENCLR_DISABLED_Msk) && NRF_RADIO->EVENTS_DISABLED) {
        if (g_ble_phy_data.phy_state == BLE_PHY_STATE_RX) {
            NRF_RADIO->EVENTS_DISABLED = 0;
            ble_ll_wfr_timer_exp(NULL);
        } else if (g_ble_phy_data.phy_state == BLE_PHY_STATE_IDLE) {
            assert(0);
        } else {
            ble_phy_tx_end_isr();
        }
    }

    /* Receive packet end (we dont enable this for transmit) */
    if ((irq_en & RADIO_INTENCLR_END_Msk) && NRF_RADIO->EVENTS_END) {
        ble_phy_rx_end_isr();
    }

    g_ble_phy_data.phy_transition_late = 0;

    /* Ensures IRQ is cleared */
    irq_en = NRF_RADIO->SHORTS;

    /* Count # of interrupts */
    STATS_INC(ble_phy_stats, phy_isrs);

    os_trace_isr_exit();
}

#if MYNEWT_VAL(BLE_PHY_DBG_TIME_TXRXEN_READY_PIN) >= 0 || \
        MYNEWT_VAL(BLE_PHY_DBG_TIME_ADDRESS_END_PIN) >= 0 || \
        MYNEWT_VAL(BLE_PHY_DBG_TIME_WFR_PIN) >= 0
static inline void
ble_phy_dbg_time_setup_gpiote(int index, int pin)
{
    NRF_GPIO_Type *port;

#if NRF52840_XXAA
    port = pin > 31 ? NRF_P1 : NRF_P0;
    pin &= 0x1f;
#else
    port = NRF_P0;
#endif

    /* Configure GPIO directly to avoid dependency to hal_gpio (for porting) */
    port->DIRSET = (1 << pin);
    port->OUTCLR = (1 << pin);

    NRF_GPIOTE->CONFIG[index] =
                        (GPIOTE_CONFIG_MODE_Task << GPIOTE_CONFIG_MODE_Pos) |
                        ((pin & 0x1F) << GPIOTE_CONFIG_PSEL_Pos) |
#if NRF52840_XXAA
                        ((port == NRF_P1) << GPIOTE_CONFIG_PORT_Pos);
#else
                        0;
#endif
}
#endif

static void
ble_phy_dbg_time_setup(void)
{
    int gpiote_idx __attribute__((unused)) = 8;

    /*
     * We setup GPIOTE starting from last configuration index to minimize risk
     * of conflict with GPIO setup via hal. It's not great solution, but since
     * this is just debugging code we can live with this.
     */

#if MYNEWT_VAL(BLE_PHY_DBG_TIME_TXRXEN_READY_PIN) >= 0
    ble_phy_dbg_time_setup_gpiote(--gpiote_idx,
                              MYNEWT_VAL(BLE_PHY_DBG_TIME_TXRXEN_READY_PIN));

    NRF_PPI->CH[17].EEP = (uint32_t)&(NRF_RADIO->EVENTS_READY);
    NRF_PPI->CH[17].TEP = (uint32_t)&(NRF_GPIOTE->TASKS_CLR[gpiote_idx]);
    NRF_PPI->CHENSET = PPI_CHEN_CH17_Msk;

    /* CH[20] and PPI CH[21] are on to trigger TASKS_TXEN or TASKS_RXEN */
    NRF_PPI->FORK[20].TEP = (uint32_t)&(NRF_GPIOTE->TASKS_SET[gpiote_idx]);
    NRF_PPI->FORK[21].TEP = (uint32_t)&(NRF_GPIOTE->TASKS_SET[gpiote_idx]);
#endif

#if MYNEWT_VAL(BLE_PHY_DBG_TIME_ADDRESS_END_PIN) >= 0
    ble_phy_dbg_time_setup_gpiote(--gpiote_idx,
                              MYNEWT_VAL(BLE_PHY_DBG_TIME_ADDRESS_END_PIN));

    /* CH[26] and CH[27] are always on for EVENT_ADDRESS and EVENT_END */
    NRF_PPI->FORK[26].TEP = (uint32_t)&(NRF_GPIOTE->TASKS_SET[gpiote_idx]);
    NRF_PPI->FORK[27].TEP = (uint32_t)&(NRF_GPIOTE->TASKS_CLR[gpiote_idx]);
#endif

#if MYNEWT_VAL(BLE_PHY_DBG_TIME_WFR_PIN) >= 0
    ble_phy_dbg_time_setup_gpiote(--gpiote_idx,
                              MYNEWT_VAL(BLE_PHY_DBG_TIME_WFR_PIN));

#if NRF52840_XXAA
    NRF_PPI->CH[18].EEP = (uint32_t)&(NRF_RADIO->EVENTS_RXREADY);
#else
    NRF_PPI->CH[18].EEP = (uint32_t)&(NRF_RADIO->EVENTS_READY);
#endif
    NRF_PPI->CH[18].TEP = (uint32_t)&(NRF_GPIOTE->TASKS_SET[gpiote_idx]);
    NRF_PPI->CH[19].EEP = (uint32_t)&(NRF_RADIO->EVENTS_DISABLED);
    NRF_PPI->CH[19].TEP = (uint32_t)&(NRF_GPIOTE->TASKS_CLR[gpiote_idx]);
    NRF_PPI->CHENSET = PPI_CHEN_CH18_Msk | PPI_CHEN_CH19_Msk;

    /* CH[4] and CH[5] are always on for wfr */
    NRF_PPI->FORK[4].TEP = (uint32_t)&(NRF_GPIOTE->TASKS_CLR[gpiote_idx]);
    NRF_PPI->FORK[5].TEP = (uint32_t)&(NRF_GPIOTE->TASKS_CLR[gpiote_idx]);
#endif
}

/**
 * ble phy init
 *
 * Initialize the PHY.
 *
 * @return int 0: success; PHY error code otherwise
 */
int
ble_phy_init(void)
{
    int rc;

    /* Default phy to use is 1M */
    g_ble_phy_data.phy_cur_phy_mode = BLE_PHY_MODE_1M;
    g_ble_phy_data.phy_txtorx_phy_mode = BLE_PHY_MODE_1M;

#if !defined(BLE_XCVR_RFCLK)
    /* BLE wants the HFXO on all the time in this case */
    ble_phy_rfclk_enable();

    /*
     * XXX: I do not think we need to wait for settling time here since
     * we will probably not use the radio for longer than the settling time
     * and it will only degrade performance. Might want to wait here though.
     */
#endif

    /* Set phy channel to an invalid channel so first set channel works */
    g_ble_phy_data.phy_chan = BLE_PHY_NUM_CHANS;

    /* Toggle peripheral power to reset (just in case) */
    NRF_RADIO->POWER = 0;
    NRF_RADIO->POWER = 1;

    /* Disable all interrupts */
    NRF_RADIO->INTENCLR = NRF_RADIO_IRQ_MASK_ALL;

    /* Set configuration registers */
    NRF_RADIO->MODE = RADIO_MODE_MODE_Ble_1Mbit;
    NRF_RADIO->PCNF0 = NRF_PCNF0;

    /* XXX: should maxlen be 251 for encryption? */
    NRF_RADIO->PCNF1 = NRF_MAXLEN |
                       (RADIO_PCNF1_ENDIAN_Little <<  RADIO_PCNF1_ENDIAN_Pos) |
                       (NRF_BALEN << RADIO_PCNF1_BALEN_Pos) |
                       RADIO_PCNF1_WHITEEN_Msk;

    /* Enable radio fast ramp-up */
    NRF_RADIO->MODECNF0 |= (RADIO_MODECNF0_RU_Fast << RADIO_MODECNF0_RU_Pos) &
                            RADIO_MODECNF0_RU_Msk;

    /* Set logical address 1 for TX and RX */
    NRF_RADIO->TXADDRESS  = 0;
    NRF_RADIO->RXADDRESSES  = (1 << 0);

    /* Configure the CRC registers */
    NRF_RADIO->CRCCNF = (RADIO_CRCCNF_SKIPADDR_Skip << RADIO_CRCCNF_SKIPADDR_Pos) | RADIO_CRCCNF_LEN_Three;

    /* Configure BLE poly */
    NRF_RADIO->CRCPOLY = 0x0000065B;

    /* Configure IFS */
    NRF_RADIO->TIFS = BLE_LL_IFS;

    /* Captures tx/rx start in timer0 cc 1 and tx/rx end in timer0 cc 2 */
    NRF_PPI->CHENSET = PPI_CHEN_CH26_Msk | PPI_CHEN_CH27_Msk;

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION) == 1)
    NRF_CCM->INTENCLR = 0xffffffff;
    NRF_CCM->SHORTS = CCM_SHORTS_ENDKSGEN_CRYPT_Msk;
    NRF_CCM->EVENTS_ERROR = 0;
    memset(g_nrf_encrypt_scratchpad, 0, sizeof(g_nrf_encrypt_scratchpad));
#endif

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_PRIVACY) == 1)
    g_ble_phy_data.phy_aar_scratch = 0;
    NRF_AAR->IRKPTR = (uint32_t)&g_nrf_irk_list[0];
    NRF_AAR->INTENCLR = 0xffffffff;
    NRF_AAR->EVENTS_END = 0;
    NRF_AAR->EVENTS_RESOLVED = 0;
    NRF_AAR->EVENTS_NOTRESOLVED = 0;
    NRF_AAR->NIRK = 0;
#endif

    /* TIMER0 setup for PHY when using RTC */
    NRF_TIMER0->TASKS_STOP = 1;
    NRF_TIMER0->TASKS_SHUTDOWN = 1;
    NRF_TIMER0->BITMODE = 3;    /* 32-bit timer */
    NRF_TIMER0->MODE = 0;       /* Timer mode */
    NRF_TIMER0->PRESCALER = 4;  /* gives us 1 MHz */

    /*
     * PPI setup.
     * Channel 4: Captures TIMER0 in CC[3] when EVENTS_ADDRESS occurs. Used
     *            to cancel the wait for response timer.
     * Channel 5: TIMER0 CC[3] to TASKS_DISABLE on radio. This is the wait
     *            for response timer.
     */
    NRF_PPI->CH[4].EEP = (uint32_t)&(NRF_RADIO->EVENTS_ADDRESS);
    NRF_PPI->CH[4].TEP = (uint32_t)&(NRF_TIMER0->TASKS_CAPTURE[3]);
    NRF_PPI->CH[5].EEP = (uint32_t)&(NRF_TIMER0->EVENTS_COMPARE[3]);
    NRF_PPI->CH[5].TEP = (uint32_t)&(NRF_RADIO->TASKS_DISABLE);

    /* Set isr in vector table and enable interrupt */
    NVIC_SetPriority(RADIO_IRQn, 0);
#if MYNEWT
    NVIC_SetVector(RADIO_IRQn, (uint32_t)ble_phy_isr);
#else
    ble_npl_hw_set_isr(RADIO_IRQn, ble_phy_isr);
#endif
    NVIC_EnableIRQ(RADIO_IRQn);

    /* Register phy statistics */
    if (!g_ble_phy_data.phy_stats_initialized) {
        rc = stats_init_and_reg(STATS_HDR(ble_phy_stats),
                                STATS_SIZE_INIT_PARMS(ble_phy_stats,
                                                      STATS_SIZE_32),
                                STATS_NAME_INIT_PARMS(ble_phy_stats),
                                "ble_phy");
        assert(rc == 0);

        g_ble_phy_data.phy_stats_initialized  = 1;
    }

    ble_phy_dbg_time_setup();

    return 0;
}

/**
 * Puts the phy into receive mode.
 *
 * @return int 0: success; BLE Phy error code otherwise
 */
int
ble_phy_rx(void)
{
    /*
     * Check radio state.
     *
     * In case radio is now disabling we'll wait for it to finish, but if for
     * any reason it's just in idle state we proceed with RX as usual since
     * nRF52 radio can ramp-up from idle state as well.
     *
     * Note that TX and RX states values are the same except for 3rd bit so we
     * can make a shortcut here when checking for idle state.
     */
    nrf_wait_disabled();
    if ((NRF_RADIO->STATE != RADIO_STATE_STATE_Disabled) &&
            ((NRF_RADIO->STATE & 0x07) != RADIO_STATE_STATE_RxIdle)) {
        ble_phy_disable();
        STATS_INC(ble_phy_stats, radio_state_errs);
        return BLE_PHY_ERR_RADIO_STATE;
    }

    /* Make sure all interrupts are disabled */
    NRF_RADIO->INTENCLR = NRF_RADIO_IRQ_MASK_ALL;

    /* Clear events prior to enabling receive */
    NRF_RADIO->EVENTS_END = 0;
    NRF_RADIO->EVENTS_DISABLED = 0;

    /* Setup for rx */
    ble_phy_rx_xcvr_setup();

    /* PPI to start radio automatically shall be set here */
    assert(NRF_PPI->CHEN & PPI_CHEN_CH21_Msk);

    return 0;
}

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION) == 1)
/**
 * Called to enable encryption at the PHY. Note that this state will persist
 * in the PHY; in other words, if you call this function you have to call
 * disable so that future PHY transmits/receives will not be encrypted.
 *
 * @param pkt_counter
 * @param iv
 * @param key
 * @param is_master
 */
void
ble_phy_encrypt_enable(uint64_t pkt_counter, uint8_t *iv, uint8_t *key,
                       uint8_t is_master)
{
    memcpy(g_nrf_ccm_data.key, key, 16);
    g_nrf_ccm_data.pkt_counter = pkt_counter;
    memcpy(g_nrf_ccm_data.iv, iv, 8);
    g_nrf_ccm_data.dir_bit = is_master;
    g_ble_phy_data.phy_encrypted = 1;
    /* Enable the module (AAR cannot be on while CCM on) */
    NRF_AAR->ENABLE = AAR_ENABLE_ENABLE_Disabled;
    NRF_CCM->ENABLE = CCM_ENABLE_ENABLE_Enabled;
}

void
ble_phy_encrypt_set_pkt_cntr(uint64_t pkt_counter, int dir)
{
    g_nrf_ccm_data.pkt_counter = pkt_counter;
    g_nrf_ccm_data.dir_bit = dir;
}

void
ble_phy_encrypt_disable(void)
{
    NRF_PPI->CHENCLR = PPI_CHEN_CH25_Msk;
    NRF_CCM->TASKS_STOP = 1;
    NRF_CCM->EVENTS_ERROR = 0;
    NRF_CCM->ENABLE = CCM_ENABLE_ENABLE_Disabled;

    g_ble_phy_data.phy_encrypted = 0;
}
#endif

void
ble_phy_set_txend_cb(ble_phy_tx_end_func txend_cb, void *arg)
{
    /* Set transmit end callback and arg */
    g_ble_phy_data.txend_cb = txend_cb;
    g_ble_phy_data.txend_arg = arg;
}

/**
 * Called to set the start time of a transmission.
 *
 * This function is called to set the start time when we are not going from
 * rx to tx automatically.
 *
 * NOTE: care must be taken when calling this function. The channel should
 * already be set.
 *
 * @param cputime   This is the tick at which the 1st bit of the preamble
 *                  should be transmitted
 * @param rem_usecs This is used only when the underlying timing uses a 32.768
 *                  kHz crystal. It is the # of usecs from the cputime tick
 *                  at which the first bit of the preamble should be
 *                  transmitted.
 * @return int
 */
int
ble_phy_tx_set_start_time(uint32_t cputime, uint8_t rem_usecs)
{
    int rc;

    ble_phy_trace_u32x2(BLE_PHY_TRACE_ID_START_TX, cputime, rem_usecs);

    /* XXX: This should not be necessary, but paranoia is good! */
    /* Clear timer0 compare to RXEN since we are transmitting */
    NRF_PPI->CHENCLR = PPI_CHEN_CH21_Msk;

    if (ble_phy_set_start_time(cputime, rem_usecs, true) != 0) {
        STATS_INC(ble_phy_stats, tx_late);
        ble_phy_disable();
        rc = BLE_PHY_ERR_TX_LATE;
    } else {
        /* Enable PPI to automatically start TXEN */
        NRF_PPI->CHENSET = PPI_CHEN_CH20_Msk;
        rc = 0;
    }
    return rc;
}

/**
 * Called to set the start time of a reception
 *
 * This function acts a bit differently than transmit. If we are late getting
 * here we will still attempt to receive.
 *
 * NOTE: care must be taken when calling this function. The channel should
 * already be set.
 *
 * @param cputime
 *
 * @return int
 */
int
ble_phy_rx_set_start_time(uint32_t cputime, uint8_t rem_usecs)
{
    bool late = false;
    int rc = 0;

    ble_phy_trace_u32x2(BLE_PHY_TRACE_ID_START_RX, cputime, rem_usecs);

    /* XXX: This should not be necessary, but paranoia is good! */
    /* Clear timer0 compare to TXEN since we are transmitting */
    NRF_PPI->CHENCLR = PPI_CHEN_CH20_Msk;

    if (ble_phy_set_start_time(cputime, rem_usecs, false) != 0) {
        STATS_INC(ble_phy_stats, rx_late);

        /* We're late so let's just try to start RX as soon as possible */
        ble_phy_set_start_now();

        late = true;
    }

    /* Enable PPI to automatically start RXEN */
    NRF_PPI->CHENSET = PPI_CHEN_CH21_Msk;

    /* Start rx */
    rc = ble_phy_rx();

    /*
     * If we enabled receiver but were late, let's return proper error code so
     * caller can handle this.
     */
    if (!rc && late) {
        rc = BLE_PHY_ERR_RX_LATE;
    }

    return rc;
}

int
ble_phy_tx(ble_phy_tx_pducb_t pducb, void *pducb_arg, uint8_t end_trans)
{
    int rc;
    uint8_t *dptr;
    uint8_t *pktptr;
    uint8_t payload_len;
    uint8_t hdr_byte;
    uint32_t state;
    uint32_t shortcuts;

    if (g_ble_phy_data.phy_transition_late) {
        ble_phy_disable();
        STATS_INC(ble_phy_stats, tx_late);
        return BLE_PHY_ERR_TX_LATE;
    }

    /*
     * This check is to make sure that the radio is not in a state where
     * it is moving to disabled state. If so, let it get there.
     */
    nrf_wait_disabled();

    /*
     * XXX: Although we may not have to do this here, I clear all the PPI
     * that should not be used when transmitting. Some of them are only enabled
     * if encryption and/or privacy is on, but I dont care. Better to be
     * paranoid, and if you are going to clear one, might as well clear them
     * all.
     */
    NRF_PPI->CHENCLR = PPI_CHEN_CH4_Msk | PPI_CHEN_CH5_Msk | PPI_CHEN_CH23_Msk |
                       PPI_CHEN_CH25_Msk;

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION) == 1)
    if (g_ble_phy_data.phy_encrypted) {
        dptr = (uint8_t *)&g_ble_phy_enc_buf[0];
        pktptr = (uint8_t *)&g_ble_phy_tx_buf[0];
        NRF_CCM->SHORTS = CCM_SHORTS_ENDKSGEN_CRYPT_Msk;
        NRF_CCM->INPTR = (uint32_t)dptr;
        NRF_CCM->OUTPTR = (uint32_t)pktptr;
        NRF_CCM->SCRATCHPTR = (uint32_t)&g_nrf_encrypt_scratchpad[0];
        NRF_CCM->EVENTS_ERROR = 0;
        NRF_CCM->MODE = CCM_MODE_LENGTH_Msk | ble_phy_get_ccm_datarate();
        NRF_CCM->CNFPTR = (uint32_t)&g_nrf_ccm_data;
    } else {
#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_PRIVACY) == 1)
        NRF_AAR->IRKPTR = (uint32_t)&g_nrf_irk_list[0];
#endif
        dptr = (uint8_t *)&g_ble_phy_tx_buf[0];
        pktptr = dptr;
    }
#else
    dptr = (uint8_t *)&g_ble_phy_tx_buf[0];
    pktptr = dptr;
#endif

    /* Set PDU payload */
    payload_len = pducb(&dptr[3], pducb_arg, &hdr_byte);

    /* RAM representation has S0, LENGTH and S1 fields. (3 bytes) */
    dptr[0] = hdr_byte;
    dptr[1] = payload_len;
    dptr[2] = 0;

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LE_ENCRYPTION) == 1)
    /* Start key-stream generation and encryption (via short) */
    if (g_ble_phy_data.phy_encrypted) {
        NRF_CCM->TASKS_KSGEN = 1;
    }
#endif

    NRF_RADIO->PACKETPTR = (uint32_t)pktptr;

    /* Clear the ready, end and disabled events */
    NRF_RADIO->EVENTS_READY = 0;
    NRF_RADIO->EVENTS_END = 0;
    NRF_RADIO->EVENTS_DISABLED = 0;

    /* Enable shortcuts for transmit start/end. */
    shortcuts = RADIO_SHORTS_END_DISABLE_Msk | RADIO_SHORTS_READY_START_Msk;
    NRF_RADIO->SHORTS = shortcuts;
    NRF_RADIO->INTENSET = RADIO_INTENSET_DISABLED_Msk;

    /* Set the PHY transition */
    g_ble_phy_data.phy_transition = end_trans;

    /* Set transmitted payload length */
    g_ble_phy_data.phy_tx_pyld_len = payload_len;

    /* If we already started transmitting, abort it! */
    state = NRF_RADIO->STATE;
    if (state != RADIO_STATE_STATE_Tx) {
        /* Set phy state to transmitting and count packet statistics */
        g_ble_phy_data.phy_state = BLE_PHY_STATE_TX;
        STATS_INC(ble_phy_stats, tx_good);
        STATS_INCN(ble_phy_stats, tx_bytes, payload_len + BLE_LL_PDU_HDR_LEN);
        rc = BLE_ERR_SUCCESS;
    } else {
        ble_phy_disable();
        STATS_INC(ble_phy_stats, tx_late);
        rc = BLE_PHY_ERR_RADIO_STATE;
    }

    return rc;
}

/**
 * ble phy txpwr set
 *
 * Set the transmit output power (in dBm).
 *
 * NOTE: If the output power specified is within the BLE limits but outside
 * the chip limits, we "rail" the power level so we dont exceed the min/max
 * chip values.
 *
 * @param dbm Power output in dBm.
 *
 * @return int 0: success; anything else is an error
 */
int
ble_phy_txpwr_set(int dbm)
{
    /* Check valid range */
    assert(dbm <= BLE_PHY_MAX_PWR_DBM);

    /* "Rail" power level if outside supported range */
    if (dbm > NRF_TX_PWR_MAX_DBM) {
        dbm = NRF_TX_PWR_MAX_DBM;
    } else {
        if (dbm < NRF_TX_PWR_MIN_DBM) {
            dbm = NRF_TX_PWR_MIN_DBM;
        }
    }

    NRF_RADIO->TXPOWER = dbm;
    g_ble_phy_data.phy_txpwr_dbm = dbm;

    return 0;
}

/**
 * ble phy txpwr round
 *
 * Get the rounded transmit output power (in dBm).
 *
 * @param dbm Power output in dBm.
 *
 * @return int Rounded power in dBm
 */
int ble_phy_txpower_round(int dbm)
{
    /* "Rail" power level if outside supported range */
    if (dbm > NRF_TX_PWR_MAX_DBM) {
        dbm = NRF_TX_PWR_MAX_DBM;
    } else {
        if (dbm < NRF_TX_PWR_MIN_DBM) {
            dbm = NRF_TX_PWR_MIN_DBM;
        }
    }

    return dbm;
}

/**
 * ble phy set access addr
 *
 * Set access address.
 *
 * @param access_addr Access address
 *
 * @return int 0: success; PHY error code otherwise
 */
int
ble_phy_set_access_addr(uint32_t access_addr)
{
    NRF_RADIO->BASE0 = (access_addr << 8);
    NRF_RADIO->PREFIX0 = (NRF_RADIO->PREFIX0 & 0xFFFFFF00) | (access_addr >> 24);

    g_ble_phy_data.phy_access_address = access_addr;

#ifdef NRF52
    ble_phy_apply_errata_102_106_107();
#endif

    return 0;
}

/**
 * ble phy txpwr get
 *
 * Get the transmit power.
 *
 * @return int  The current PHY transmit power, in dBm
 */
int
ble_phy_txpwr_get(void)
{
    return g_ble_phy_data.phy_txpwr_dbm;
}

/**
 * ble phy setchan
 *
 * Sets the logical frequency of the transceiver. The input parameter is the
 * BLE channel index (0 to 39, inclusive). The NRF frequency register works like
 * this: logical frequency = 2400 + FREQ (MHz).
 *
 * Thus, to get a logical frequency of 2402 MHz, you would program the
 * FREQUENCY register to 2.
 *
 * @param chan This is the Data Channel Index or Advertising Channel index
 *
 * @return int 0: success; PHY error code otherwise
 */
int
ble_phy_setchan(uint8_t chan, uint32_t access_addr, uint32_t crcinit)
{
    assert(chan < BLE_PHY_NUM_CHANS);

    /* Check for valid channel range */
    if (chan >= BLE_PHY_NUM_CHANS) {
        return BLE_PHY_ERR_INV_PARAM;
    }

    /* Set current access address */
    ble_phy_set_access_addr(access_addr);

    /* Configure crcinit */
    NRF_RADIO->CRCINIT = crcinit;

    /* Set the frequency and the data whitening initial value */
    g_ble_phy_data.phy_chan = chan;
    NRF_RADIO->FREQUENCY = g_ble_phy_chan_freq[chan];
    NRF_RADIO->DATAWHITEIV = chan;

    return 0;
}

/**
 * Stop the timer used to count microseconds when using RTC for cputime
 */
void
ble_phy_stop_usec_timer(void)
{
    NRF_TIMER0->TASKS_STOP = 1;
    NRF_TIMER0->TASKS_SHUTDOWN = 1;
    NRF_RTC0->EVTENCLR = RTC_EVTENSET_COMPARE0_Msk;
}

/**
 * ble phy disable irq and ppi
 *
 * This routine is to be called when reception was stopped due to either a
 * wait for response timeout or a packet being received and the phy is to be
 * restarted in receive mode. Generally, the disable routine is called to stop
 * the phy.
 */
void
ble_phy_disable_irq_and_ppi(void)
{
    NRF_RADIO->INTENCLR = NRF_RADIO_IRQ_MASK_ALL;
    NRF_RADIO->SHORTS = 0;
    NRF_RADIO->TASKS_DISABLE = 1;
    NRF_PPI->CHENCLR = PPI_CHEN_CH4_Msk | PPI_CHEN_CH5_Msk | PPI_CHEN_CH20_Msk |
          PPI_CHEN_CH21_Msk | PPI_CHEN_CH23_Msk |
          PPI_CHEN_CH25_Msk | PPI_CHEN_CH31_Msk;
    NVIC_ClearPendingIRQ(RADIO_IRQn);
    g_ble_phy_data.phy_state = BLE_PHY_STATE_IDLE;
}

void
ble_phy_restart_rx(void)
{
    ble_phy_disable_irq_and_ppi();

    ble_phy_set_start_now();
    /* Enable PPI to automatically start RXEN */
    NRF_PPI->CHENSET = PPI_CHEN_CH21_Msk;

    ble_phy_rx();
}

/**
 * ble phy disable
 *
 * Disables the PHY. This should be called when an event is over. It stops
 * the usec timer (if used), disables interrupts, disables the RADIO, disables
 * PPI and sets state to idle.
 */
void
ble_phy_disable(void)
{
    ble_phy_trace_void(BLE_PHY_TRACE_ID_DISABLE);

    ble_phy_stop_usec_timer();
    ble_phy_disable_irq_and_ppi();
}

/* Gets the current access address */
uint32_t ble_phy_access_addr_get(void)
{
    return g_ble_phy_data.phy_access_address;
}

/**
 * Return the phy state
 *
 * @return int The current PHY state.
 */
int
ble_phy_state_get(void)
{
    return g_ble_phy_data.phy_state;
}

/**
 * Called to see if a reception has started
 *
 * @return int
 */
int
ble_phy_rx_started(void)
{
    return g_ble_phy_data.phy_rx_started;
}

/**
 * Return the transceiver state
 *
 * @return int transceiver state.
 */
uint8_t
ble_phy_xcvr_state_get(void)
{
    uint32_t state;
    state = NRF_RADIO->STATE;
    return (uint8_t)state;
}

/**
 * Called to return the maximum data pdu payload length supported by the
 * phy. For this chip, if encryption is enabled, the maximum payload is 27
 * bytes.
 *
 * @return uint8_t Maximum data channel PDU payload size supported
 */
uint8_t
ble_phy_max_data_pdu_pyld(void)
{
    return BLE_LL_DATA_PDU_MAX_PYLD;
}

#if (MYNEWT_VAL(BLE_LL_CFG_FEAT_LL_PRIVACY) == 1)
void
ble_phy_resolv_list_enable(void)
{
    NRF_AAR->NIRK = (uint32_t)g_nrf_num_irks;
    g_ble_phy_data.phy_privacy = 1;
}

void
ble_phy_resolv_list_disable(void)
{
    g_ble_phy_data.phy_privacy = 0;
}
#endif

#if MYNEWT_VAL(BLE_LL_DIRECT_TEST_MODE) == 1
void ble_phy_enable_dtm(void)
{
    /* When DTM is enabled we need to disable whitening as per
     * Bluetooth v5.0 Vol 6. Part F. 4.1.1
     */
    NRF_RADIO->PCNF1 &= ~RADIO_PCNF1_WHITEEN_Msk;
}

void ble_phy_disable_dtm(void)
{
    /* Enable whitening */
    NRF_RADIO->PCNF1 |= RADIO_PCNF1_WHITEEN_Msk;
}
#endif

void
ble_phy_rfclk_enable(void)
{
#if MYNEWT
    nrf52_clock_hfxo_request();
#else
    NRF_CLOCK->TASKS_HFCLKSTART = 1;
#endif
}

void
ble_phy_rfclk_disable(void)
{
#if MYNEWT
    nrf52_clock_hfxo_release();
#else
    NRF_CLOCK->TASKS_HFCLKSTOP = 1;
#endif
}