1 /* 2 * MXC6255 - MEMSIC orientation sensing accelerometer 3 * 4 * Copyright (c) 2015, Intel Corporation. 5 * 6 * This file is subject to the terms and conditions of version 2 of 7 * the GNU General Public License. See the file COPYING in the main 8 * directory of this archive for more details. 9 * 10 * IIO driver for MXC6255 (7-bit I2C slave address 0x15). 11 */ 12 13 #include <linux/module.h> 14 #include <linux/i2c.h> 15 #include <linux/init.h> 16 #include <linux/iio/iio.h> 17 #include <linux/delay.h> 18 #include <linux/acpi.h> 19 #include <linux/regmap.h> 20 #include <linux/iio/sysfs.h> 21 22 #define MXC6255_DRV_NAME "mxc6255" 23 #define MXC6255_REGMAP_NAME "mxc6255_regmap" 24 25 #define MXC6255_REG_XOUT 0x00 26 #define MXC6255_REG_YOUT 0x01 27 #define MXC6255_REG_CHIP_ID 0x08 28 29 #define MXC6255_CHIP_ID 0x05 30 31 /* 32 * MXC6255 has only one measurement range: +/- 2G. 33 * The acceleration output is an 8-bit value. 34 * 35 * Scale is calculated as follows: 36 * (2 + 2) * 9.80665 / (2^8 - 1) = 0.153829 37 * 38 * Scale value for +/- 2G measurement range 39 */ 40 #define MXC6255_SCALE 153829 41 42 enum mxc6255_axis { 43 AXIS_X, 44 AXIS_Y, 45 }; 46 47 struct mxc6255_data { 48 struct i2c_client *client; 49 struct regmap *regmap; 50 }; 51 52 static int mxc6255_read_raw(struct iio_dev *indio_dev, 53 struct iio_chan_spec const *chan, 54 int *val, int *val2, long mask) 55 { 56 struct mxc6255_data *data = iio_priv(indio_dev); 57 unsigned int reg; 58 int ret; 59 60 switch (mask) { 61 case IIO_CHAN_INFO_RAW: 62 ret = regmap_read(data->regmap, chan->address, ®); 63 if (ret < 0) { 64 dev_err(&data->client->dev, 65 "Error reading reg %lu\n", chan->address); 66 return ret; 67 } 68 69 *val = sign_extend32(reg, 7); 70 return IIO_VAL_INT; 71 case IIO_CHAN_INFO_SCALE: 72 *val = 0; 73 *val2 = MXC6255_SCALE; 74 return IIO_VAL_INT_PLUS_MICRO; 75 default: 76 return -EINVAL; 77 } 78 } 79 80 static const struct iio_info mxc6255_info = { 81 .driver_module = THIS_MODULE, 82 .read_raw = mxc6255_read_raw, 83 }; 84 85 #define MXC6255_CHANNEL(_axis, reg) { \ 86 .type = IIO_ACCEL, \ 87 .modified = 1, \ 88 .channel2 = IIO_MOD_##_axis, \ 89 .address = reg, \ 90 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \ 91 .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE), \ 92 } 93 94 static const struct iio_chan_spec mxc6255_channels[] = { 95 MXC6255_CHANNEL(X, MXC6255_REG_XOUT), 96 MXC6255_CHANNEL(Y, MXC6255_REG_YOUT), 97 }; 98 99 static bool mxc6255_is_readable_reg(struct device *dev, unsigned int reg) 100 { 101 switch (reg) { 102 case MXC6255_REG_XOUT: 103 case MXC6255_REG_YOUT: 104 case MXC6255_REG_CHIP_ID: 105 return true; 106 default: 107 return false; 108 } 109 } 110 111 static const struct regmap_config mxc6255_regmap_config = { 112 .name = MXC6255_REGMAP_NAME, 113 114 .reg_bits = 8, 115 .val_bits = 8, 116 117 .readable_reg = mxc6255_is_readable_reg, 118 }; 119 120 static int mxc6255_probe(struct i2c_client *client, 121 const struct i2c_device_id *id) 122 { 123 struct mxc6255_data *data; 124 struct iio_dev *indio_dev; 125 struct regmap *regmap; 126 unsigned int chip_id; 127 int ret; 128 129 indio_dev = devm_iio_device_alloc(&client->dev, sizeof(*data)); 130 if (!indio_dev) 131 return -ENOMEM; 132 133 regmap = devm_regmap_init_i2c(client, &mxc6255_regmap_config); 134 if (IS_ERR(regmap)) { 135 dev_err(&client->dev, "Error initializing regmap\n"); 136 return PTR_ERR(regmap); 137 } 138 139 data = iio_priv(indio_dev); 140 i2c_set_clientdata(client, indio_dev); 141 data->client = client; 142 data->regmap = regmap; 143 144 indio_dev->name = MXC6255_DRV_NAME; 145 indio_dev->dev.parent = &client->dev; 146 indio_dev->channels = mxc6255_channels; 147 indio_dev->num_channels = ARRAY_SIZE(mxc6255_channels); 148 indio_dev->modes = INDIO_DIRECT_MODE; 149 indio_dev->info = &mxc6255_info; 150 151 ret = regmap_read(data->regmap, MXC6255_REG_CHIP_ID, &chip_id); 152 if (ret < 0) { 153 dev_err(&client->dev, "Error reading chip id %d\n", ret); 154 return ret; 155 } 156 157 if ((chip_id & 0x1f) != MXC6255_CHIP_ID) { 158 dev_err(&client->dev, "Invalid chip id %x\n", chip_id); 159 return -ENODEV; 160 } 161 162 dev_dbg(&client->dev, "Chip id %x\n", chip_id); 163 164 ret = devm_iio_device_register(&client->dev, indio_dev); 165 if (ret < 0) { 166 dev_err(&client->dev, "Could not register IIO device\n"); 167 return ret; 168 } 169 170 return 0; 171 } 172 173 static const struct acpi_device_id mxc6255_acpi_match[] = { 174 {"MXC6225", 0}, 175 {"MXC6255", 0}, 176 { } 177 }; 178 MODULE_DEVICE_TABLE(acpi, mxc6255_acpi_match); 179 180 static const struct i2c_device_id mxc6255_id[] = { 181 {"mxc6225", 0}, 182 {"mxc6255", 0}, 183 { } 184 }; 185 MODULE_DEVICE_TABLE(i2c, mxc6255_id); 186 187 static struct i2c_driver mxc6255_driver = { 188 .driver = { 189 .name = MXC6255_DRV_NAME, 190 .acpi_match_table = ACPI_PTR(mxc6255_acpi_match), 191 }, 192 .probe = mxc6255_probe, 193 .id_table = mxc6255_id, 194 }; 195 196 module_i2c_driver(mxc6255_driver); 197 198 MODULE_AUTHOR("Teodora Baluta <teodora.baluta@intel.com>"); 199 MODULE_DESCRIPTION("MEMSIC MXC6255 orientation sensing accelerometer driver"); 200 MODULE_LICENSE("GPL v2"); 201