xref: /aosp_15_r20/external/coreboot/src/ec/acpi/ec.asl (revision b9411a12aaaa7e1e6a6fb7c5e057f44ee179a49c) 
1/* SPDX-License-Identifier: GPL-2.0-only */
2
3/*
4 * ACPI style embedded controller commands
5 *
6 * Controlled by the following preprocessor defines:
7 * EC_SC_IO	I/o address of the EC_SC register
8 * EC_DATA_IO	I/o address of the EC_DATA register
9 */
10
11#define EC_MUTEX	ECMX
12#define WAIT_EC_SC	WECC
13#define SEND_EC_COMMAND	SECC
14#define SEND_EC_DATA	SECD
15#define RECV_EC_DATA	RECD
16#define EC_READ		ECRD
17#define EC_WRITE	ECWR
18#define EC_SC		ECSC
19#define EC_DATA		ECDT
20
21#define EC_OBF		0x01 /* Output buffer full (EC_DATA) */
22#define EC_IBF		0x02 /* Input buffer full (EC_DATA or EC_SC) */
23
24#define EC_ERROR_MASK	0xff00
25#define EC_TIMEOUT	0x8000
26
27#define EC_READ_CMD	0x80
28#define EC_WRITE_CMD	0x81
29
30Mutex(EC_MUTEX, 1)
31
32OperationRegion(ERSC, SystemIO, EC_SC_IO, 1)
33Field(ERSC, ByteAcc, NoLock, Preserve) { EC_SC, 8 }
34OperationRegion(ERDT, SystemIO, EC_DATA_IO, 1)
35Field(ERDT, ByteAcc, NoLock, Preserve) { EC_DATA, 8 }
36
37/*
38 * Wait for a bit in the status and command (EC_SC) register
39 *
40 * The caller is responsible of acquiring the EC_MUTEX before
41 * calling this method.
42 *
43 * Arg0: Mask, Arg1: State waiting for
44 * Returns EC_TIMEOUT if timed out, 0 else
45 */
46Method (WAIT_EC_SC, 2)
47{
48	Local0 = 0x7ff /* Timeout */
49	While (((EC_SC & Arg0) != Arg1) && Local0--) {
50		Stall (10)
51	}
52	If (Local0) {
53		Return (0)
54	} Else {
55		Return (EC_TIMEOUT)
56	}
57}
58
59/*
60 * Send command byte in Arg0 to status and command (EC_SC) register
61 *
62 * The caller is responsible of acquiring the EC_MUTEX before
63 * calling this method.
64 *
65 * Returns EC_TIMEOUT if timed out, 0 else
66 */
67Method (SEND_EC_COMMAND, 1)
68{
69	Local0 = WAIT_EC_SC (EC_IBF, 0)
70	If (!Local0) {
71		EC_SC = Arg0
72	}
73	Return (Local0)
74}
75
76/*
77 * Send data byte in Arg0 to data (EC_DATA) register
78 *
79 * The caller is responsible of acquiring the EC_MUTEX before
80 * calling this method.
81 *
82 * Returns EC_TIMEOUT if timed out, 0 else
83 */
84Method (SEND_EC_DATA, 1)
85{
86	Local0 = WAIT_EC_SC (EC_IBF, 0)
87	If (!Local0) {
88		EC_DATA =  Arg0
89	}
90	Return (Local0)
91}
92
93/*
94 * Read one byte of data from data (EC_DATA) register
95 *
96 * The caller is responsible of acquiring the EC_MUTEX before
97 * calling this method.
98 *
99 * Returns EC_TIMEOUT if timed out, the read data byte else
100 */
101Method (RECV_EC_DATA)
102{
103	Local0 = WAIT_EC_SC (EC_OBF, EC_OBF)
104	If (!Local0) {
105		Return (EC_DATA)
106	} Else {
107		Return (Local0)
108	}
109}
110
111/*
112 * Read one byte from ec memory (cmd 0x80)
113 *
114 * Arg0: Address (1 byte) to read from
115 * Returns EC_TIMEOUT if timed out, the read data byte else
116 */
117Method (EC_READ, 1)
118{
119	Acquire (EC_MUTEX, 0xffff)
120	Local0 = SEND_EC_COMMAND (EC_READ_CMD)
121	If (!Local0) {
122		Local0 = SEND_EC_DATA (Arg0)
123	}
124	If (!Local0) {
125		Local0 = RECV_EC_DATA ()
126	}
127	Release (EC_MUTEX)
128
129	Return (Local0)
130}
131
132/*
133 * Write one byte to ec memory (cmd 0x81)
134 *
135 * Arg0: Address (1 byte) to write to
136 * Arg1: Byte to write
137 * Returns EC_TIMEOUT if timed out, 0 else
138 */
139Method (EC_WRITE, 2)
140{
141	Acquire (EC_MUTEX, 0xffff)
142	Local0 = SEND_EC_COMMAND (EC_WRITE_CMD)
143	If (!Local0) {
144		Local0 = SEND_EC_DATA (Arg0)
145	}
146	If (!Local0) {
147		Local0 = SEND_EC_DATA (Arg1)
148	}
149	Release (EC_MUTEX)
150
151	Return (Local0)
152}
153