1// SPDX-License-Identifier: GPL-2.0
2/*
3 * I2C access driver for TI TPS6594/TPS6593/LP8764 PMICs
4 *
5 * Copyright (C) 2023 BayLibre Incorporated - https://www.baylibre.com/
6 */
7
8#include <linux/crc8.h>
9#include <linux/i2c.h>
10#include <linux/module.h>
11#include <linux/mod_devicetable.h>
12#include <linux/of_device.h>
13#include <linux/regmap.h>
14
15#include <linux/mfd/tps6594.h>
16
17static bool enable_crc;
18module_param(enable_crc, bool, 0444);
19MODULE_PARM_DESC(enable_crc, "Enable CRC feature for I2C interface");
20
21DECLARE_CRC8_TABLE(tps6594_i2c_crc_table);
22
23static int tps6594_i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
24{
25 int ret = i2c_transfer(adap, msgs, num);
26
27 if (ret == num)
28 return 0;
29 else if (ret < 0)
30 return ret;
31 else
32 return -EIO;
33}
34
35static int tps6594_i2c_reg_read_with_crc(struct i2c_client *client, u8 page, u8 reg, u8 *val)
36{
37 struct i2c_msg msgs[2];
38 u8 buf_rx[] = { 0, 0 };
39 /* I2C address = I2C base address + Page index */
40 const u8 addr = client->addr + page;
41 /*
42 * CRC is calculated from every bit included in the protocol
43 * except the ACK bits from the target. Byte stream is:
44 * - B0: (I2C_addr_7bits << 1) | WR_bit, with WR_bit = 0
45 * - B1: reg
46 * - B2: (I2C_addr_7bits << 1) | RD_bit, with RD_bit = 1
47 * - B3: val
48 * - B4: CRC from B0-B1-B2-B3
49 */
50 u8 crc_data[] = { addr << 1, reg, addr << 1 | 1, 0 };
51 int ret;
52
53 /* Write register */
54 msgs[0].addr = addr;
55 msgs[0].flags = 0;
56 msgs[0].len = 1;
57 msgs[0].buf = &reg;
58
59 /* Read data and CRC */
60 msgs[1].addr = msgs[0].addr;
61 msgs[1].flags = I2C_M_RD;
62 msgs[1].len = 2;
63 msgs[1].buf = buf_rx;
64
65 ret = tps6594_i2c_transfer(adap: client->adapter, msgs, num: 2);
66 if (ret < 0)
67 return ret;
68
69 crc_data[sizeof(crc_data) - 1] = *val = buf_rx[0];
70 if (buf_rx[1] != crc8(table: tps6594_i2c_crc_table, pdata: crc_data, nbytes: sizeof(crc_data), CRC8_INIT_VALUE))
71 return -EIO;
72
73 return ret;
74}
75
76static int tps6594_i2c_reg_write_with_crc(struct i2c_client *client, u8 page, u8 reg, u8 val)
77{
78 struct i2c_msg msg;
79 u8 buf[] = { reg, val, 0 };
80 /* I2C address = I2C base address + Page index */
81 const u8 addr = client->addr + page;
82 /*
83 * CRC is calculated from every bit included in the protocol
84 * except the ACK bits from the target. Byte stream is:
85 * - B0: (I2C_addr_7bits << 1) | WR_bit, with WR_bit = 0
86 * - B1: reg
87 * - B2: val
88 * - B3: CRC from B0-B1-B2
89 */
90 const u8 crc_data[] = { addr << 1, reg, val };
91
92 /* Write register, data and CRC */
93 msg.addr = addr;
94 msg.flags = client->flags & I2C_M_TEN;
95 msg.len = sizeof(buf);
96 msg.buf = buf;
97
98 buf[msg.len - 1] = crc8(table: tps6594_i2c_crc_table, pdata: crc_data, nbytes: sizeof(crc_data), CRC8_INIT_VALUE);
99
100 return tps6594_i2c_transfer(adap: client->adapter, msgs: &msg, num: 1);
101}
102
103static int tps6594_i2c_read(void *context, const void *reg_buf, size_t reg_size,
104 void *val_buf, size_t val_size)
105{
106 struct i2c_client *client = context;
107 struct tps6594 *tps = i2c_get_clientdata(client);
108 struct i2c_msg msgs[2];
109 const u8 *reg_bytes = reg_buf;
110 u8 *val_bytes = val_buf;
111 const u8 page = reg_bytes[1];
112 u8 reg = reg_bytes[0];
113 int ret = 0;
114 int i;
115
116 if (tps->use_crc) {
117 /*
118 * Auto-increment feature does not support CRC protocol.
119 * Converts the bulk read operation into a series of single read operations.
120 */
121 for (i = 0 ; ret == 0 && i < val_size ; i++)
122 ret = tps6594_i2c_reg_read_with_crc(client, page, reg: reg + i, val: val_bytes + i);
123
124 return ret;
125 }
126
127 /* Write register: I2C address = I2C base address + Page index */
128 msgs[0].addr = client->addr + page;
129 msgs[0].flags = 0;
130 msgs[0].len = 1;
131 msgs[0].buf = &reg;
132
133 /* Read data */
134 msgs[1].addr = msgs[0].addr;
135 msgs[1].flags = I2C_M_RD;
136 msgs[1].len = val_size;
137 msgs[1].buf = val_bytes;
138
139 return tps6594_i2c_transfer(adap: client->adapter, msgs, num: 2);
140}
141
142static int tps6594_i2c_write(void *context, const void *data, size_t count)
143{
144 struct i2c_client *client = context;
145 struct tps6594 *tps = i2c_get_clientdata(client);
146 struct i2c_msg msg;
147 const u8 *bytes = data;
148 u8 *buf;
149 const u8 page = bytes[1];
150 const u8 reg = bytes[0];
151 int ret = 0;
152 int i;
153
154 if (tps->use_crc) {
155 /*
156 * Auto-increment feature does not support CRC protocol.
157 * Converts the bulk write operation into a series of single write operations.
158 */
159 for (i = 0 ; ret == 0 && i < count - 2 ; i++)
160 ret = tps6594_i2c_reg_write_with_crc(client, page, reg: reg + i, val: bytes[i + 2]);
161
162 return ret;
163 }
164
165 /* Setup buffer: page byte is not sent */
166 buf = kzalloc(size: --count, GFP_KERNEL);
167 if (!buf)
168 return -ENOMEM;
169
170 buf[0] = reg;
171 for (i = 0 ; i < count - 1 ; i++)
172 buf[i + 1] = bytes[i + 2];
173
174 /* Write register and data: I2C address = I2C base address + Page index */
175 msg.addr = client->addr + page;
176 msg.flags = client->flags & I2C_M_TEN;
177 msg.len = count;
178 msg.buf = buf;
179
180 ret = tps6594_i2c_transfer(adap: client->adapter, msgs: &msg, num: 1);
181
182 kfree(objp: buf);
183 return ret;
184}
185
186static const struct regmap_config tps6594_i2c_regmap_config = {
187 .reg_bits = 16,
188 .val_bits = 8,
189 .max_register = TPS6594_REG_DWD_FAIL_CNT_REG,
190 .volatile_reg = tps6594_is_volatile_reg,
191 .read = tps6594_i2c_read,
192 .write = tps6594_i2c_write,
193};
194
195static const struct of_device_id tps6594_i2c_of_match_table[] = {
196 { .compatible = "ti,tps6594-q1", .data = (void *)TPS6594, },
197 { .compatible = "ti,tps6593-q1", .data = (void *)TPS6593, },
198 { .compatible = "ti,lp8764-q1", .data = (void *)LP8764, },
199 {}
200};
201MODULE_DEVICE_TABLE(of, tps6594_i2c_of_match_table);
202
203static int tps6594_i2c_probe(struct i2c_client *client)
204{
205 struct device *dev = &client->dev;
206 struct tps6594 *tps;
207 const struct of_device_id *match;
208
209 tps = devm_kzalloc(dev, size: sizeof(*tps), GFP_KERNEL);
210 if (!tps)
211 return -ENOMEM;
212
213 i2c_set_clientdata(client, data: tps);
214
215 tps->dev = dev;
216 tps->reg = client->addr;
217 tps->irq = client->irq;
218
219 tps->regmap = devm_regmap_init(dev, NULL, client, &tps6594_i2c_regmap_config);
220 if (IS_ERR(ptr: tps->regmap))
221 return dev_err_probe(dev, err: PTR_ERR(ptr: tps->regmap), fmt: "Failed to init regmap\n");
222
223 match = of_match_device(matches: tps6594_i2c_of_match_table, dev);
224 if (!match)
225 return dev_err_probe(dev, err: -EINVAL, fmt: "Failed to find matching chip ID\n");
226 tps->chip_id = (unsigned long)match->data;
227
228 crc8_populate_msb(table: tps6594_i2c_crc_table, TPS6594_CRC8_POLYNOMIAL);
229
230 return tps6594_device_init(tps, enable_crc);
231}
232
233static struct i2c_driver tps6594_i2c_driver = {
234 .driver = {
235 .name = "tps6594",
236 .of_match_table = tps6594_i2c_of_match_table,
237 },
238 .probe = tps6594_i2c_probe,
239};
240module_i2c_driver(tps6594_i2c_driver);
241
242MODULE_AUTHOR("Julien Panis <jpanis@baylibre.com>");
243MODULE_DESCRIPTION("TPS6594 I2C Interface Driver");
244MODULE_LICENSE("GPL");
245

source code of linux/drivers/mfd/tps6594-i2c.c