bmi323_i2c.c

  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 const 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		.pm = pm_ptr(&bmi323_core_pm_ops),
132		.of_match_table = bmi323_of_i2c_match,
133		.acpi_match_table = bmi323_acpi_match,
134	},
135	.probe = bmi323_i2c_probe,
136	.id_table = bmi323_i2c_ids,
137};
138module_i2c_driver(bmi323_i2c_driver);
139
140MODULE_DESCRIPTION("Bosch BMI323 IMU driver");
141MODULE_AUTHOR("Jagath Jog J <jagathjog1996@gmail.com>");
142MODULE_LICENSE("GPL");
143MODULE_IMPORT_NS("IIO_BMI323");