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(client->adapter, msgs, 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(tps6594_i2c_crc_table, crc_data, 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(tps6594_i2c_crc_table, crc_data, sizeof(crc_data), CRC8_INIT_VALUE);
 99
100	return tps6594_i2c_transfer(client->adapter, &msg, 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 + i, 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(client->adapter, msgs, 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 + i, bytes[i + 2]);
161
162		return ret;
163	}
164
165	/* Setup buffer: page byte is not sent */
166	buf = kzalloc(--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(client->adapter, &msg, 1);
181
182	kfree(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, sizeof(*tps), GFP_KERNEL);
210	if (!tps)
211		return -ENOMEM;
212
213	i2c_set_clientdata(client, 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(tps->regmap))
221		return dev_err_probe(dev, PTR_ERR(tps->regmap), "Failed to init regmap\n");
222
223	match = of_match_device(tps6594_i2c_of_match_table, dev);
224	if (!match)
225		return dev_err_probe(dev, -EINVAL, "Failed to find matching chip ID\n");
226	tps->chip_id = (unsigned long)match->data;
227
228	crc8_populate_msb(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");