1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles 4 * (C) 2007 EADS Astrium 5 * 6 * This driver is based on the lm75 and other lm_sensors/hwmon drivers 7 * 8 * Written by Steve Hardy <shardy@redhat.com> 9 * 10 * ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com> 11 * 12 * For further information, see the Documentation/hwmon/ads7828.rst file. 13 */ 14 15 #include <linux/err.h> 16 #include <linux/hwmon.h> 17 #include <linux/hwmon-sysfs.h> 18 #include <linux/i2c.h> 19 #include <linux/init.h> 20 #include <linux/module.h> 21 #include <linux/of.h> 22 #include <linux/platform_data/ads7828.h> 23 #include <linux/regmap.h> 24 #include <linux/slab.h> 25 #include <linux/regulator/consumer.h> 26 27 /* The ADS7828 registers */ 28 #define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */ 29 #define ADS7828_CMD_PD1 0x04 /* Internal vref OFF && A/D ON */ 30 #define ADS7828_CMD_PD3 0x0C /* Internal vref ON && A/D ON */ 31 #define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */ 32 #define ADS7828_EXT_VREF_MV_MIN 50 /* External vref min value 0.05V */ 33 #define ADS7828_EXT_VREF_MV_MAX 5250 /* External vref max value 5.25V */ 34 35 /* List of supported devices */ 36 enum ads7828_chips { ads7828, ads7830 }; 37 38 /* Client specific data */ 39 struct ads7828_data { 40 struct regmap *regmap; 41 u8 cmd_byte; /* Command byte without channel bits */ 42 unsigned int lsb_resol; /* Resolution of the ADC sample LSB */ 43 }; 44 45 /* Command byte C2,C1,C0 - see datasheet */ 46 static inline u8 ads7828_cmd_byte(u8 cmd, int ch) 47 { 48 return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4); 49 } 50 51 /* sysfs callback function */ 52 static ssize_t ads7828_in_show(struct device *dev, 53 struct device_attribute *da, char *buf) 54 { 55 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 56 struct ads7828_data *data = dev_get_drvdata(dev); 57 u8 cmd = ads7828_cmd_byte(data->cmd_byte, attr->index); 58 unsigned int regval; 59 int err; 60 61 err = regmap_read(data->regmap, cmd, ®val); 62 if (err < 0) 63 return err; 64 65 return sprintf(buf, "%d\n", 66 DIV_ROUND_CLOSEST(regval * data->lsb_resol, 1000)); 67 } 68 69 static SENSOR_DEVICE_ATTR_RO(in0_input, ads7828_in, 0); 70 static SENSOR_DEVICE_ATTR_RO(in1_input, ads7828_in, 1); 71 static SENSOR_DEVICE_ATTR_RO(in2_input, ads7828_in, 2); 72 static SENSOR_DEVICE_ATTR_RO(in3_input, ads7828_in, 3); 73 static SENSOR_DEVICE_ATTR_RO(in4_input, ads7828_in, 4); 74 static SENSOR_DEVICE_ATTR_RO(in5_input, ads7828_in, 5); 75 static SENSOR_DEVICE_ATTR_RO(in6_input, ads7828_in, 6); 76 static SENSOR_DEVICE_ATTR_RO(in7_input, ads7828_in, 7); 77 78 static struct attribute *ads7828_attrs[] = { 79 &sensor_dev_attr_in0_input.dev_attr.attr, 80 &sensor_dev_attr_in1_input.dev_attr.attr, 81 &sensor_dev_attr_in2_input.dev_attr.attr, 82 &sensor_dev_attr_in3_input.dev_attr.attr, 83 &sensor_dev_attr_in4_input.dev_attr.attr, 84 &sensor_dev_attr_in5_input.dev_attr.attr, 85 &sensor_dev_attr_in6_input.dev_attr.attr, 86 &sensor_dev_attr_in7_input.dev_attr.attr, 87 NULL 88 }; 89 90 ATTRIBUTE_GROUPS(ads7828); 91 92 static const struct regmap_config ads2828_regmap_config = { 93 .reg_bits = 8, 94 .val_bits = 16, 95 }; 96 97 static const struct regmap_config ads2830_regmap_config = { 98 .reg_bits = 8, 99 .val_bits = 8, 100 }; 101 102 static int ads7828_probe(struct i2c_client *client) 103 { 104 struct device *dev = &client->dev; 105 struct ads7828_platform_data *pdata = dev_get_platdata(dev); 106 struct ads7828_data *data; 107 struct device *hwmon_dev; 108 unsigned int vref_mv = ADS7828_INT_VREF_MV; 109 unsigned int vref_uv; 110 bool diff_input = false; 111 bool ext_vref = false; 112 unsigned int regval; 113 enum ads7828_chips chip; 114 struct regulator *reg; 115 116 data = devm_kzalloc(dev, sizeof(struct ads7828_data), GFP_KERNEL); 117 if (!data) 118 return -ENOMEM; 119 120 if (pdata) { 121 diff_input = pdata->diff_input; 122 ext_vref = pdata->ext_vref; 123 if (ext_vref && pdata->vref_mv) 124 vref_mv = pdata->vref_mv; 125 } else if (dev->of_node) { 126 diff_input = of_property_read_bool(dev->of_node, 127 "ti,differential-input"); 128 reg = devm_regulator_get_optional(dev, "vref"); 129 if (!IS_ERR(reg)) { 130 vref_uv = regulator_get_voltage(reg); 131 vref_mv = DIV_ROUND_CLOSEST(vref_uv, 1000); 132 if (vref_mv < ADS7828_EXT_VREF_MV_MIN || 133 vref_mv > ADS7828_EXT_VREF_MV_MAX) 134 return -EINVAL; 135 ext_vref = true; 136 } 137 } 138 139 chip = (uintptr_t)i2c_get_match_data(client); 140 141 /* Bound Vref with min/max values */ 142 vref_mv = clamp_val(vref_mv, ADS7828_EXT_VREF_MV_MIN, 143 ADS7828_EXT_VREF_MV_MAX); 144 145 /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */ 146 if (chip == ads7828) { 147 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 4096); 148 data->regmap = devm_regmap_init_i2c(client, 149 &ads2828_regmap_config); 150 } else { 151 data->lsb_resol = DIV_ROUND_CLOSEST(vref_mv * 1000, 256); 152 data->regmap = devm_regmap_init_i2c(client, 153 &ads2830_regmap_config); 154 } 155 156 if (IS_ERR(data->regmap)) 157 return PTR_ERR(data->regmap); 158 159 data->cmd_byte = ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3; 160 if (!diff_input) 161 data->cmd_byte |= ADS7828_CMD_SD_SE; 162 163 /* 164 * Datasheet specifies internal reference voltage is disabled by 165 * default. The internal reference voltage needs to be enabled and 166 * voltage needs to settle before getting valid ADC data. So perform a 167 * dummy read to enable the internal reference voltage. 168 */ 169 if (!ext_vref) 170 regmap_read(data->regmap, data->cmd_byte, ®val); 171 172 hwmon_dev = devm_hwmon_device_register_with_groups(dev, client->name, 173 data, 174 ads7828_groups); 175 return PTR_ERR_OR_ZERO(hwmon_dev); 176 } 177 178 static const struct i2c_device_id ads7828_device_ids[] = { 179 { "ads7828", ads7828 }, 180 { "ads7830", ads7830 }, 181 { } 182 }; 183 MODULE_DEVICE_TABLE(i2c, ads7828_device_ids); 184 185 static const struct of_device_id __maybe_unused ads7828_of_match[] = { 186 { 187 .compatible = "ti,ads7828", 188 .data = (void *)ads7828 189 }, 190 { 191 .compatible = "ti,ads7830", 192 .data = (void *)ads7830 193 }, 194 { }, 195 }; 196 MODULE_DEVICE_TABLE(of, ads7828_of_match); 197 198 static struct i2c_driver ads7828_driver = { 199 .driver = { 200 .name = "ads7828", 201 .of_match_table = of_match_ptr(ads7828_of_match), 202 }, 203 204 .id_table = ads7828_device_ids, 205 .probe = ads7828_probe, 206 }; 207 208 module_i2c_driver(ads7828_driver); 209 210 MODULE_LICENSE("GPL"); 211 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>"); 212 MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles"); 213