1 // SPDX-License-Identifier: GPL-2.0-only
3  * Loongson-2K/Loongson LS7A I2C controller mode driver
6  * Copyright (C) 2014-2017 Lemote, Inc.
7  * Copyright (C) 2018-2022 Loongson Technology Corporation Limited.
18 #include <linux/i2c.h>
29 /* I2C Registers */
30 #define I2C_LS2X_PRER_LO	0x0 /* Freq Division Low Byte Register */
31 #define I2C_LS2X_PRER_HI	0x1 /* Freq Division High Byte Register */
48 #define LS2X_SR_BUSY		BIT(6) /* Bus busy state */
54 #define LS2X_CTR_EN		BIT(7) /* 0: I2c frequency setting 1: Normal */
55 #define LS2X_CTR_IEN		BIT(6) /* Enable i2c interrupt */
63 /* The default bus frequency, which is an empirical value */
75  * This gets called whenever an I2C interrupt occurs.
81 	if (!(readb(priv->base + I2C_LS2X_SR) & LS2X_SR_IF))  in ls2x_i2c_isr()
84 	writeb(LS2X_CR_IACK, priv->base + I2C_LS2X_CR);  in ls2x_i2c_isr()
85 	complete(&priv->cmd_complete);  in ls2x_i2c_isr()
90  * The ls2x i2c controller supports standard mode and fast mode, so the
91  * maximum bus frequency is '400kHz'.
92  * The bus frequency is set to the empirical value of '33KHz' by default,
99 	struct i2c_timings *t = &priv->i2c_t;  in ls2x_i2c_adjust_bus_speed()
100 	struct device *dev = priv->adapter.dev.parent;  in ls2x_i2c_adjust_bus_speed()
105 	if (acpi_speed || t->bus_freq_hz)  in ls2x_i2c_adjust_bus_speed()
106 		t->bus_freq_hz = max(t->bus_freq_hz, acpi_speed);  in ls2x_i2c_adjust_bus_speed()
108 		t->bus_freq_hz = LS2X_I2C_FREQ_STD;  in ls2x_i2c_adjust_bus_speed()
113 	 * So set the I2C frequency with a sequential writeb() instead of writew().  in ls2x_i2c_adjust_bus_speed()
115 	val = LS2X_I2C_PCLK_FREQ / (5 * t->bus_freq_hz) - 1;  in ls2x_i2c_adjust_bus_speed()
116 	writeb(FIELD_GET(GENMASK(7, 0), val), priv->base + I2C_LS2X_PRER_LO);  in ls2x_i2c_adjust_bus_speed()
117 	writeb(FIELD_GET(GENMASK(15, 8), val), priv->base + I2C_LS2X_PRER_HI);  in ls2x_i2c_adjust_bus_speed()
122 	/* Set i2c frequency setting mode and disable interrupts. */  in ls2x_i2c_init()
123 	writeb(readb(priv->base + I2C_LS2X_CTR) & ~CTR_FREQ_MASK,  in ls2x_i2c_init()
124 	       priv->base + I2C_LS2X_CTR);  in ls2x_i2c_init()
128 	/* Set i2c normal operating mode and enable interrupts. */  in ls2x_i2c_init()
129 	writeb(readb(priv->base + I2C_LS2X_CTR) | CTR_READY_MASK,  in ls2x_i2c_init()
130 	       priv->base + I2C_LS2X_CTR);  in ls2x_i2c_init()
138 	writeb(txdata, priv->base + I2C_LS2X_CR);  in ls2x_i2c_xfer_byte()
140 	time_left = wait_for_completion_timeout(&priv->cmd_complete,  in ls2x_i2c_xfer_byte()
141 						priv->adapter.timeout);  in ls2x_i2c_xfer_byte()
143 		return -ETIMEDOUT;  in ls2x_i2c_xfer_byte()
145 	rxdata = readb(priv->base + I2C_LS2X_SR);  in ls2x_i2c_xfer_byte()
162 		return -EAGAIN;  in ls2x_i2c_send_byte()
165 		return -ENXIO;  in ls2x_i2c_send_byte()
174 	writeb(LS2X_CR_STOP, priv->base + I2C_LS2X_CR);  in ls2x_i2c_stop()
175 	return readb_poll_timeout(priv->base + I2C_LS2X_SR, value,  in ls2x_i2c_stop()
177 				  jiffies_to_usecs(priv->adapter.timeout));  in ls2x_i2c_stop()
182 	reinit_completion(&priv->cmd_complete);  in ls2x_i2c_start()
184 	writeb(i2c_8bit_addr_from_msg(msgs), priv->base + I2C_LS2X_TXR);  in ls2x_i2c_start()
191 	u8 rxdata, *buf = msg->buf;  in ls2x_i2c_rx()
192 	u16 len = msg->len;  in ls2x_i2c_rx()
199 	while (len--) {  in ls2x_i2c_rx()
206 		*buf++ = readb(priv->base + I2C_LS2X_RXR);  in ls2x_i2c_rx()
215 	u8 *buf = msg->buf;  in ls2x_i2c_tx()
216 	u16 len = msg->len;  in ls2x_i2c_tx()
223 	while (len--) {  in ls2x_i2c_tx()
224 		writeb(*buf++, priv->base + I2C_LS2X_TXR);  in ls2x_i2c_tx()
239 	if (msg->flags & I2C_M_RD)  in ls2x_i2c_xfer_one()
246 		if (ret == -ETIMEDOUT)  in ls2x_i2c_xfer_one()
269 		ret = ls2x_i2c_xfer_one(priv, msg, msg == emsg - 1);  in ls2x_i2c_xfer()
292 	struct device *dev = &pdev->dev;  in ls2x_i2c_probe()
296 		return -ENOMEM;  in ls2x_i2c_probe()
299 	priv->base = devm_platform_ioremap_resource(pdev, 0);  in ls2x_i2c_probe()
300 	if (IS_ERR(priv->base))  in ls2x_i2c_probe()
301 		return PTR_ERR(priv->base);  in ls2x_i2c_probe()
307 	/* Add the i2c adapter */  in ls2x_i2c_probe()
308 	adap = &priv->adapter;  in ls2x_i2c_probe()
309 	adap->retries = 5;  in ls2x_i2c_probe()
310 	adap->nr = pdev->id;  in ls2x_i2c_probe()
311 	adap->dev.parent = dev;  in ls2x_i2c_probe()
312 	adap->owner = THIS_MODULE;  in ls2x_i2c_probe()
313 	adap->algo = &ls2x_i2c_algo;  in ls2x_i2c_probe()
314 	adap->timeout = msecs_to_jiffies(100);  in ls2x_i2c_probe()
315 	device_set_node(&adap->dev, dev_fwnode(dev));  in ls2x_i2c_probe()
317 	strscpy(adap->name, pdev->name, sizeof(adap->name));  in ls2x_i2c_probe()
318 	init_completion(&priv->cmd_complete);  in ls2x_i2c_probe()
323 	ret = devm_request_irq(dev, irq, ls2x_i2c_isr, IRQF_SHARED, "ls2x-i2c",  in ls2x_i2c_probe()
336 	writeb(readb(priv->base + I2C_LS2X_CTR) & ~LS2X_CTR_IEN,  in ls2x_i2c_suspend()
337 	       priv->base + I2C_LS2X_CTR);  in ls2x_i2c_suspend()
352 	{ .compatible = "loongson,ls2k-i2c" },
353 	{ .compatible = "loongson,ls7a-i2c" },
367 		.name	= "ls2x-i2c",
375 MODULE_DESCRIPTION("Loongson LS2X I2C Bus driver");