1 /* 2 * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles 3 * (C) 2007 EADS Astrium 4 * 5 * This driver is based on the lm75 and other lm_sensors/hwmon drivers 6 * 7 * Written by Steve Hardy <shardy@redhat.com> 8 * 9 * ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com> 10 * 11 * For further information, see the Documentation/hwmon/ads7828 file. 12 * 13 * This program is free software; you can redistribute it and/or modify 14 * it under the terms of the GNU General Public License as published by 15 * the Free Software Foundation; either version 2 of the License, or 16 * (at your option) any later version. 17 * 18 * This program is distributed in the hope that it will be useful, 19 * but WITHOUT ANY WARRANTY; without even the implied warranty of 20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 21 * GNU General Public License for more details. 22 * 23 * You should have received a copy of the GNU General Public License 24 * along with this program; if not, write to the Free Software 25 * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 26 */ 27 28 #include <linux/err.h> 29 #include <linux/hwmon.h> 30 #include <linux/hwmon-sysfs.h> 31 #include <linux/i2c.h> 32 #include <linux/init.h> 33 #include <linux/jiffies.h> 34 #include <linux/module.h> 35 #include <linux/mutex.h> 36 #include <linux/platform_data/ads7828.h> 37 #include <linux/slab.h> 38 39 /* The ADS7828 registers */ 40 #define ADS7828_NCH 8 /* 8 channels supported */ 41 #define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */ 42 #define ADS7828_CMD_PD1 0x04 /* Internal vref OFF && A/D ON */ 43 #define ADS7828_CMD_PD3 0x0C /* Internal vref ON && A/D ON */ 44 #define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */ 45 #define ADS7828_EXT_VREF_MV_MIN 50 /* External vref min value 0.05V */ 46 #define ADS7828_EXT_VREF_MV_MAX 5250 /* External vref max value 5.25V */ 47 48 /* List of supported devices */ 49 enum ads7828_chips { ads7828, ads7830 }; 50 51 /* Client specific data */ 52 struct ads7828_data { 53 struct device *hwmon_dev; 54 struct mutex update_lock; /* Mutex protecting updates */ 55 unsigned long last_updated; /* Last updated time (in jiffies) */ 56 u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH samples */ 57 bool valid; /* Validity flag */ 58 bool diff_input; /* Differential input */ 59 bool ext_vref; /* External voltage reference */ 60 unsigned int vref_mv; /* voltage reference value */ 61 u8 cmd_byte; /* Command byte without channel bits */ 62 unsigned int lsb_resol; /* Resolution of the ADC sample LSB */ 63 s32 (*read_channel)(const struct i2c_client *client, u8 command); 64 }; 65 66 /* Command byte C2,C1,C0 - see datasheet */ 67 static inline u8 ads7828_cmd_byte(u8 cmd, int ch) 68 { 69 return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4); 70 } 71 72 /* Update data for the device (all 8 channels) */ 73 static struct ads7828_data *ads7828_update_device(struct device *dev) 74 { 75 struct i2c_client *client = to_i2c_client(dev); 76 struct ads7828_data *data = i2c_get_clientdata(client); 77 78 mutex_lock(&data->update_lock); 79 80 if (time_after(jiffies, data->last_updated + HZ + HZ / 2) 81 || !data->valid) { 82 unsigned int ch; 83 dev_dbg(&client->dev, "Starting ads7828 update\n"); 84 85 for (ch = 0; ch < ADS7828_NCH; ch++) { 86 u8 cmd = ads7828_cmd_byte(data->cmd_byte, ch); 87 data->adc_input[ch] = data->read_channel(client, cmd); 88 } 89 data->last_updated = jiffies; 90 data->valid = true; 91 } 92 93 mutex_unlock(&data->update_lock); 94 95 return data; 96 } 97 98 /* sysfs callback function */ 99 static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da, 100 char *buf) 101 { 102 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 103 struct ads7828_data *data = ads7828_update_device(dev); 104 unsigned int value = DIV_ROUND_CLOSEST(data->adc_input[attr->index] * 105 data->lsb_resol, 1000); 106 107 return sprintf(buf, "%d\n", value); 108 } 109 110 static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0); 111 static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1); 112 static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2); 113 static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3); 114 static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4); 115 static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5); 116 static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6); 117 static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7); 118 119 static struct attribute *ads7828_attributes[] = { 120 &sensor_dev_attr_in0_input.dev_attr.attr, 121 &sensor_dev_attr_in1_input.dev_attr.attr, 122 &sensor_dev_attr_in2_input.dev_attr.attr, 123 &sensor_dev_attr_in3_input.dev_attr.attr, 124 &sensor_dev_attr_in4_input.dev_attr.attr, 125 &sensor_dev_attr_in5_input.dev_attr.attr, 126 &sensor_dev_attr_in6_input.dev_attr.attr, 127 &sensor_dev_attr_in7_input.dev_attr.attr, 128 NULL 129 }; 130 131 static const struct attribute_group ads7828_group = { 132 .attrs = ads7828_attributes, 133 }; 134 135 static int ads7828_remove(struct i2c_client *client) 136 { 137 struct ads7828_data *data = i2c_get_clientdata(client); 138 139 hwmon_device_unregister(data->hwmon_dev); 140 sysfs_remove_group(&client->dev.kobj, &ads7828_group); 141 142 return 0; 143 } 144 145 static int ads7828_probe(struct i2c_client *client, 146 const struct i2c_device_id *id) 147 { 148 struct ads7828_platform_data *pdata = dev_get_platdata(&client->dev); 149 struct ads7828_data *data; 150 int err; 151 152 data = devm_kzalloc(&client->dev, sizeof(struct ads7828_data), 153 GFP_KERNEL); 154 if (!data) 155 return -ENOMEM; 156 157 if (pdata) { 158 data->diff_input = pdata->diff_input; 159 data->ext_vref = pdata->ext_vref; 160 if (data->ext_vref) 161 data->vref_mv = pdata->vref_mv; 162 } 163 164 /* Bound Vref with min/max values if it was provided */ 165 if (data->vref_mv) 166 data->vref_mv = clamp_val(data->vref_mv, 167 ADS7828_EXT_VREF_MV_MIN, 168 ADS7828_EXT_VREF_MV_MAX); 169 else 170 data->vref_mv = ADS7828_INT_VREF_MV; 171 172 /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */ 173 if (id->driver_data == ads7828) { 174 data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096); 175 data->read_channel = i2c_smbus_read_word_swapped; 176 } else { 177 data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 256); 178 data->read_channel = i2c_smbus_read_byte_data; 179 } 180 181 data->cmd_byte = data->ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3; 182 if (!data->diff_input) 183 data->cmd_byte |= ADS7828_CMD_SD_SE; 184 185 i2c_set_clientdata(client, data); 186 mutex_init(&data->update_lock); 187 188 err = sysfs_create_group(&client->dev.kobj, &ads7828_group); 189 if (err) 190 return err; 191 192 data->hwmon_dev = hwmon_device_register(&client->dev); 193 if (IS_ERR(data->hwmon_dev)) { 194 err = PTR_ERR(data->hwmon_dev); 195 goto error; 196 } 197 198 return 0; 199 200 error: 201 sysfs_remove_group(&client->dev.kobj, &ads7828_group); 202 return err; 203 } 204 205 static const struct i2c_device_id ads7828_device_ids[] = { 206 { "ads7828", ads7828 }, 207 { "ads7830", ads7830 }, 208 { } 209 }; 210 MODULE_DEVICE_TABLE(i2c, ads7828_device_ids); 211 212 static struct i2c_driver ads7828_driver = { 213 .driver = { 214 .name = "ads7828", 215 }, 216 217 .id_table = ads7828_device_ids, 218 .probe = ads7828_probe, 219 .remove = ads7828_remove, 220 }; 221 222 module_i2c_driver(ads7828_driver); 223 224 MODULE_LICENSE("GPL"); 225 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>"); 226 MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles"); 227