1 // SPDX-License-Identifier: GPL-2.0-only 2 3 /* 4 * Copyright (c) Rajat Khandelwal <rajat.khandelwal@linux.intel.com> 5 * 6 * Maxim MAX30208 digital temperature sensor with 0.1°C accuracy 7 * (7-bit I2C slave address (0x50 - 0x53)) 8 */ 9 10 #include <linux/bitops.h> 11 #include <linux/delay.h> 12 #include <linux/iio/iio.h> 13 #include <linux/i2c.h> 14 #include <linux/module.h> 15 #include <linux/types.h> 16 17 #define MAX30208_STATUS 0x00 18 #define MAX30208_STATUS_TEMP_RDY BIT(0) 19 #define MAX30208_INT_ENABLE 0x01 20 #define MAX30208_INT_ENABLE_TEMP_RDY BIT(0) 21 22 #define MAX30208_FIFO_OVF_CNTR 0x06 23 #define MAX30208_FIFO_DATA_CNTR 0x07 24 #define MAX30208_FIFO_DATA 0x08 25 26 #define MAX30208_FIFO_CONFIG 0x0a 27 #define MAX30208_FIFO_CONFIG_RO BIT(1) 28 29 #define MAX30208_SYSTEM_CTRL 0x0c 30 #define MAX30208_SYSTEM_CTRL_RESET 0x01 31 32 #define MAX30208_TEMP_SENSOR_SETUP 0x14 33 #define MAX30208_TEMP_SENSOR_SETUP_CONV BIT(0) 34 35 struct max30208_data { 36 struct i2c_client *client; 37 struct iio_dev *indio_dev; 38 struct mutex lock; /* Lock to prevent concurrent reads of temperature readings */ 39 }; 40 41 static const struct iio_chan_spec max30208_channels[] = { 42 { 43 .type = IIO_TEMP, 44 .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) | BIT(IIO_CHAN_INFO_SCALE), 45 }, 46 }; 47 48 /** 49 * max30208_request() - Request a reading 50 * @data: Struct comprising member elements of the device 51 * 52 * Requests a reading from the device and waits until the conversion is ready. 53 */ 54 static int max30208_request(struct max30208_data *data) 55 { 56 /* 57 * Sensor can take up to 500 ms to respond so execute a total of 58 * 10 retries to give the device sufficient time. 59 */ 60 int retries = 10; 61 u8 regval; 62 int ret; 63 64 ret = i2c_smbus_read_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP); 65 if (ret < 0) 66 return ret; 67 68 regval = ret | MAX30208_TEMP_SENSOR_SETUP_CONV; 69 70 ret = i2c_smbus_write_byte_data(data->client, MAX30208_TEMP_SENSOR_SETUP, regval); 71 if (ret) 72 return ret; 73 74 while (retries--) { 75 ret = i2c_smbus_read_byte_data(data->client, MAX30208_STATUS); 76 if (ret < 0) 77 return ret; 78 79 if (ret & MAX30208_STATUS_TEMP_RDY) 80 return 0; 81 82 msleep(50); 83 } 84 dev_err(&data->client->dev, "Temperature conversion failed\n"); 85 86 return -ETIMEDOUT; 87 } 88 89 static int max30208_update_temp(struct max30208_data *data) 90 { 91 u8 data_count; 92 int ret; 93 94 mutex_lock(&data->lock); 95 96 ret = max30208_request(data); 97 if (ret) 98 goto unlock; 99 100 ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_OVF_CNTR); 101 if (ret < 0) 102 goto unlock; 103 else if (!ret) { 104 ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_DATA_CNTR); 105 if (ret < 0) 106 goto unlock; 107 108 data_count = ret; 109 } else 110 data_count = 1; 111 112 while (data_count) { 113 ret = i2c_smbus_read_word_swapped(data->client, MAX30208_FIFO_DATA); 114 if (ret < 0) 115 goto unlock; 116 117 data_count--; 118 } 119 120 unlock: 121 mutex_unlock(&data->lock); 122 return ret; 123 } 124 125 /** 126 * max30208_config_setup() - Set up FIFO configuration register 127 * @data: Struct comprising member elements of the device 128 * 129 * Sets the rollover bit to '1' to enable overwriting FIFO during overflow. 130 */ 131 static int max30208_config_setup(struct max30208_data *data) 132 { 133 u8 regval; 134 int ret; 135 136 ret = i2c_smbus_read_byte_data(data->client, MAX30208_FIFO_CONFIG); 137 if (ret < 0) 138 return ret; 139 140 regval = ret | MAX30208_FIFO_CONFIG_RO; 141 142 ret = i2c_smbus_write_byte_data(data->client, MAX30208_FIFO_CONFIG, regval); 143 if (ret) 144 return ret; 145 146 return 0; 147 } 148 149 static int max30208_read(struct iio_dev *indio_dev, 150 struct iio_chan_spec const *chan, 151 int *val, int *val2, long mask) 152 { 153 struct max30208_data *data = iio_priv(indio_dev); 154 int ret; 155 156 switch (mask) { 157 case IIO_CHAN_INFO_RAW: 158 ret = max30208_update_temp(data); 159 if (ret < 0) 160 return ret; 161 162 *val = sign_extend32(ret, 15); 163 return IIO_VAL_INT; 164 165 case IIO_CHAN_INFO_SCALE: 166 *val = 5; 167 return IIO_VAL_INT; 168 169 default: 170 return -EINVAL; 171 } 172 } 173 174 static const struct iio_info max30208_info = { 175 .read_raw = max30208_read, 176 }; 177 178 static int max30208_probe(struct i2c_client *i2c) 179 { 180 struct device *dev = &i2c->dev; 181 struct max30208_data *data; 182 struct iio_dev *indio_dev; 183 int ret; 184 185 indio_dev = devm_iio_device_alloc(dev, sizeof(*data)); 186 if (!indio_dev) 187 return -ENOMEM; 188 189 data = iio_priv(indio_dev); 190 data->client = i2c; 191 mutex_init(&data->lock); 192 193 indio_dev->name = "max30208"; 194 indio_dev->channels = max30208_channels; 195 indio_dev->num_channels = ARRAY_SIZE(max30208_channels); 196 indio_dev->info = &max30208_info; 197 indio_dev->modes = INDIO_DIRECT_MODE; 198 199 ret = i2c_smbus_write_byte_data(data->client, MAX30208_SYSTEM_CTRL, 200 MAX30208_SYSTEM_CTRL_RESET); 201 if (ret) { 202 dev_err(dev, "Failure in performing reset\n"); 203 return ret; 204 } 205 206 msleep(50); 207 208 ret = max30208_config_setup(data); 209 if (ret) 210 return ret; 211 212 ret = devm_iio_device_register(dev, indio_dev); 213 if (ret) { 214 dev_err(dev, "Failed to register IIO device\n"); 215 return ret; 216 } 217 218 return 0; 219 } 220 221 static const struct i2c_device_id max30208_id_table[] = { 222 { "max30208" }, 223 { } 224 }; 225 MODULE_DEVICE_TABLE(i2c, max30208_id_table); 226 227 static const struct acpi_device_id max30208_acpi_match[] = { 228 { "MAX30208" }, 229 { } 230 }; 231 MODULE_DEVICE_TABLE(acpi, max30208_acpi_match); 232 233 static const struct of_device_id max30208_of_match[] = { 234 { .compatible = "maxim,max30208" }, 235 { } 236 }; 237 MODULE_DEVICE_TABLE(of, max30208_of_match); 238 239 static struct i2c_driver max30208_driver = { 240 .driver = { 241 .name = "max30208", 242 .of_match_table = max30208_of_match, 243 .acpi_match_table = max30208_acpi_match, 244 }, 245 .probe = max30208_probe, 246 .id_table = max30208_id_table, 247 }; 248 module_i2c_driver(max30208_driver); 249 250 MODULE_AUTHOR("Rajat Khandelwal <rajat.khandelwal@linux.intel.com>"); 251 MODULE_DESCRIPTION("Maxim MAX30208 digital temperature sensor"); 252 MODULE_LICENSE("GPL"); 253