1// SPDX-License-Identifier: GPL-2.0
2/*
3 * I2C driver for Bosch BMI323 6-Axis IMU.
4 *
5 * Copyright (C) 2023, Jagath Jog J <jagathjog1996@gmail.com>
6 */
7
8#include <linux/i2c.h>
9#include <linux/mod_devicetable.h>
10#include <linux/module.h>
11#include <linux/regmap.h>
12
13#include "bmi323.h"
14
15struct bmi323_i2c_priv {
16	struct i2c_client *i2c;
17	u8 i2c_rx_buffer[BMI323_FIFO_LENGTH_IN_BYTES + BMI323_I2C_DUMMY];
18};
19
20/*
21 * From BMI323 datasheet section 4: Notes on the Serial Interface Support.
22 * Each I2C register read operation requires to read two dummy bytes before
23 * the actual payload.
24 */
25static int bmi323_regmap_i2c_read(void *context, const void *reg_buf,
26				  size_t reg_size, void *val_buf,
27				  size_t val_size)
28{
29	struct bmi323_i2c_priv *priv = context;
30	struct i2c_msg msgs[2];
31	int ret;
32
33	msgs[0].addr = priv->i2c->addr;
34	msgs[0].flags = priv->i2c->flags;
35	msgs[0].len = reg_size;
36	msgs[0].buf = (u8 *)reg_buf;
37
38	msgs[1].addr = priv->i2c->addr;
39	msgs[1].len = val_size + BMI323_I2C_DUMMY;
40	msgs[1].buf = priv->i2c_rx_buffer;
41	msgs[1].flags = priv->i2c->flags | I2C_M_RD;
42
43	ret = i2c_transfer(priv->i2c->adapter, msgs, ARRAY_SIZE(msgs));
44	if (ret < 0)
45		return -EIO;
46
47	memcpy(val_buf, priv->i2c_rx_buffer + BMI323_I2C_DUMMY, val_size);
48
49	return 0;
50}
51
52static int bmi323_regmap_i2c_write(void *context, const void *data,
53				   size_t count)
54{
55	struct bmi323_i2c_priv *priv = context;
56	u8 reg;
57
58	reg = *(u8 *)data;
59	return i2c_smbus_write_i2c_block_data(priv->i2c, reg,
60					      count - sizeof(u8),
61					      data + sizeof(u8));
62}
63
64static struct regmap_bus bmi323_regmap_bus = {
65	.read = bmi323_regmap_i2c_read,
66	.write = bmi323_regmap_i2c_write,
67};
68
69static const struct regmap_config bmi323_i2c_regmap_config = {
70	.reg_bits = 8,
71	.val_bits = 16,
72	.max_register = BMI323_CFG_RES_REG,
73	.val_format_endian = REGMAP_ENDIAN_LITTLE,
74};
75
76static int bmi323_i2c_probe(struct i2c_client *i2c)
77{
78	struct device *dev = &i2c->dev;
79	struct bmi323_i2c_priv *priv;
80	struct regmap *regmap;
81
82	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
83	if (!priv)
84		return -ENOMEM;
85
86	priv->i2c = i2c;
87	regmap = devm_regmap_init(dev, &bmi323_regmap_bus, priv,
88				  &bmi323_i2c_regmap_config);
89	if (IS_ERR(regmap))
90		return dev_err_probe(dev, PTR_ERR(regmap),
91				     "Failed to initialize I2C Regmap\n");
92
93	return bmi323_core_probe(dev);
94}
95
96static const struct acpi_device_id bmi323_acpi_match[] = {
97	/*
98	 * The "BOSC0200" identifier used here is not unique to bmi323 devices.
99	 * The same "BOSC0200" identifier is found in the ACPI tables of devices
100	 * using the bmc150 chip. This creates a conflict with duplicate ACPI
101	 * identifiers which multiple drivers want to use. If a non-bmi323
102	 * device starts to load with this "BOSC0200" ACPI match here, then the
103	 * chip ID check portion should fail because the chip IDs received (via
104	 * i2c) are unique between bmc150 and bmi323 and the driver should
105	 * relinquish the device. If and when a different driver (such as
106	 * bmc150) starts to load with the "BOSC0200" ACPI match, a short reset
107	 * should ensure that the device is not in a bad state during that
108	 * driver initialization. This device reset does occur in both the
109	 * bmi323 and bmc150 init sequences.
110	 */
111	{ "BOSC0200" },
112	{ }
113};
114MODULE_DEVICE_TABLE(acpi, bmi323_acpi_match);
115
116static const struct i2c_device_id bmi323_i2c_ids[] = {
117	{ "bmi323" },
118	{ }
119};
120MODULE_DEVICE_TABLE(i2c, bmi323_i2c_ids);
121
122static const struct of_device_id bmi323_of_i2c_match[] = {
123	{ .compatible = "bosch,bmi323" },
124	{ }
125};
126MODULE_DEVICE_TABLE(of, bmi323_of_i2c_match);
127
128static struct i2c_driver bmi323_i2c_driver = {
129	.driver = {
130		.name = "bmi323",
131		.of_match_table = bmi323_of_i2c_match,
132		.acpi_match_table = bmi323_acpi_match,
133	},
134	.probe = bmi323_i2c_probe,
135	.id_table = bmi323_i2c_ids,
136};
137module_i2c_driver(bmi323_i2c_driver);
138
139MODULE_DESCRIPTION("Bosch BMI323 IMU driver");
140MODULE_AUTHOR("Jagath Jog J <jagathjog1996@gmail.com>");
141MODULE_LICENSE("GPL");
142MODULE_IMPORT_NS(IIO_BMI323);
143