drivers/iio/imu/bmi323/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
  15 struct 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  */
  25 static 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
  52 static 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
  64 static const struct regmap_bus bmi323_regmap_bus = {
  65         .read = bmi323_regmap_i2c_read,
  66         .write = bmi323_regmap_i2c_write,
  67 };
  68
  69 static 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
  76 static 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
  96 static 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 };
 114 MODULE_DEVICE_TABLE(acpi, bmi323_acpi_match);
 115
 116 static const struct i2c_device_id bmi323_i2c_ids[] = {
 117         { "bmi323" },
 118         { }
 119 };
 120 MODULE_DEVICE_TABLE(i2c, bmi323_i2c_ids);
 121
 122 static const struct of_device_id bmi323_of_i2c_match[] = {
 123         { .compatible = "bosch,bmi323" },
 124         { }
 125 };
 126 MODULE_DEVICE_TABLE(of, bmi323_of_i2c_match);
 127
 128 static 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 };
 138 module_i2c_driver(bmi323_i2c_driver);
 139
 140 MODULE_DESCRIPTION("Bosch BMI323 IMU driver");
 141 MODULE_AUTHOR("Jagath Jog J <jagathjog1996@gmail.com>");
 142 MODULE_LICENSE("GPL");
 143 MODULE_IMPORT_NS("IIO_BMI323");