1 /* 2 ads7828.c - lm_sensors driver for ads7828 12-bit 8-channel ADC 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 Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads7828.pdf 10 11 This program is free software; you can redistribute it and/or modify 12 it under the terms of the GNU General Public License as published by 13 the Free Software Foundation; either version 2 of the License, or 14 (at your option) any later version. 15 16 This program is distributed in the hope that it will be useful, 17 but WITHOUT ANY WARRANTY; without even the implied warranty of 18 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 19 GNU General Public License for more details. 20 21 You should have received a copy of the GNU General Public License 22 along with this program; if not, write to the Free Software 23 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. 24 */ 25 26 #include <linux/module.h> 27 #include <linux/init.h> 28 #include <linux/slab.h> 29 #include <linux/jiffies.h> 30 #include <linux/i2c.h> 31 #include <linux/hwmon.h> 32 #include <linux/hwmon-sysfs.h> 33 #include <linux/err.h> 34 #include <linux/mutex.h> 35 36 /* The ADS7828 registers */ 37 #define ADS7828_NCH 8 /* 8 channels of 12-bit A-D supported */ 38 #define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */ 39 #define ADS7828_CMD_SD_DIFF 0x00 /* Differential inputs */ 40 #define ADS7828_CMD_PD0 0x0 /* Power Down between A-D conversions */ 41 #define ADS7828_CMD_PD1 0x04 /* Internal ref OFF && A-D ON */ 42 #define ADS7828_CMD_PD2 0x08 /* Internal ref ON && A-D OFF */ 43 #define ADS7828_CMD_PD3 0x0C /* Internal ref ON && A-D ON */ 44 #define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */ 45 46 /* Addresses to scan */ 47 static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, 48 I2C_CLIENT_END }; 49 50 /* Module parameters */ 51 static int se_input = 1; /* Default is SE, 0 == diff */ 52 static int int_vref = 1; /* Default is internal ref ON */ 53 static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */ 54 module_param(se_input, bool, S_IRUGO); 55 module_param(int_vref, bool, S_IRUGO); 56 module_param(vref_mv, int, S_IRUGO); 57 58 /* Global Variables */ 59 static u8 ads7828_cmd_byte; /* cmd byte without channel bits */ 60 static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */ 61 62 /* Each client has this additional data */ 63 struct ads7828_data { 64 struct device *hwmon_dev; 65 struct mutex update_lock; /* mutex protect updates */ 66 char valid; /* !=0 if following fields are valid */ 67 unsigned long last_updated; /* In jiffies */ 68 u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */ 69 }; 70 71 /* Function declaration - necessary due to function dependencies */ 72 static int ads7828_detect(struct i2c_client *client, 73 struct i2c_board_info *info); 74 static int ads7828_probe(struct i2c_client *client, 75 const struct i2c_device_id *id); 76 77 /* The ADS7828 returns the 12-bit sample in two bytes, 78 these are read as a word then byte-swapped */ 79 static u16 ads7828_read_value(struct i2c_client *client, u8 reg) 80 { 81 return swab16(i2c_smbus_read_word_data(client, reg)); 82 } 83 84 static inline u8 channel_cmd_byte(int ch) 85 { 86 /* cmd byte C2,C1,C0 - see datasheet */ 87 u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4); 88 cmd |= ads7828_cmd_byte; 89 return cmd; 90 } 91 92 /* Update data for the device (all 8 channels) */ 93 static struct ads7828_data *ads7828_update_device(struct device *dev) 94 { 95 struct i2c_client *client = to_i2c_client(dev); 96 struct ads7828_data *data = i2c_get_clientdata(client); 97 98 mutex_lock(&data->update_lock); 99 100 if (time_after(jiffies, data->last_updated + HZ + HZ / 2) 101 || !data->valid) { 102 unsigned int ch; 103 dev_dbg(&client->dev, "Starting ads7828 update\n"); 104 105 for (ch = 0; ch < ADS7828_NCH; ch++) { 106 u8 cmd = channel_cmd_byte(ch); 107 data->adc_input[ch] = ads7828_read_value(client, cmd); 108 } 109 data->last_updated = jiffies; 110 data->valid = 1; 111 } 112 113 mutex_unlock(&data->update_lock); 114 115 return data; 116 } 117 118 /* sysfs callback function */ 119 static ssize_t show_in(struct device *dev, struct device_attribute *da, 120 char *buf) 121 { 122 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 123 struct ads7828_data *data = ads7828_update_device(dev); 124 /* Print value (in mV as specified in sysfs-interface documentation) */ 125 return sprintf(buf, "%d\n", (data->adc_input[attr->index] * 126 ads7828_lsb_resol)/1000); 127 } 128 129 #define in_reg(offset)\ 130 static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\ 131 NULL, offset) 132 133 in_reg(0); 134 in_reg(1); 135 in_reg(2); 136 in_reg(3); 137 in_reg(4); 138 in_reg(5); 139 in_reg(6); 140 in_reg(7); 141 142 static struct attribute *ads7828_attributes[] = { 143 &sensor_dev_attr_in0_input.dev_attr.attr, 144 &sensor_dev_attr_in1_input.dev_attr.attr, 145 &sensor_dev_attr_in2_input.dev_attr.attr, 146 &sensor_dev_attr_in3_input.dev_attr.attr, 147 &sensor_dev_attr_in4_input.dev_attr.attr, 148 &sensor_dev_attr_in5_input.dev_attr.attr, 149 &sensor_dev_attr_in6_input.dev_attr.attr, 150 &sensor_dev_attr_in7_input.dev_attr.attr, 151 NULL 152 }; 153 154 static const struct attribute_group ads7828_group = { 155 .attrs = ads7828_attributes, 156 }; 157 158 static int ads7828_remove(struct i2c_client *client) 159 { 160 struct ads7828_data *data = i2c_get_clientdata(client); 161 hwmon_device_unregister(data->hwmon_dev); 162 sysfs_remove_group(&client->dev.kobj, &ads7828_group); 163 kfree(i2c_get_clientdata(client)); 164 return 0; 165 } 166 167 static const struct i2c_device_id ads7828_id[] = { 168 { "ads7828", 0 }, 169 { } 170 }; 171 MODULE_DEVICE_TABLE(i2c, ads7828_id); 172 173 /* This is the driver that will be inserted */ 174 static struct i2c_driver ads7828_driver = { 175 .class = I2C_CLASS_HWMON, 176 .driver = { 177 .name = "ads7828", 178 }, 179 .probe = ads7828_probe, 180 .remove = ads7828_remove, 181 .id_table = ads7828_id, 182 .detect = ads7828_detect, 183 .address_list = normal_i2c, 184 }; 185 186 /* Return 0 if detection is successful, -ENODEV otherwise */ 187 static int ads7828_detect(struct i2c_client *client, 188 struct i2c_board_info *info) 189 { 190 struct i2c_adapter *adapter = client->adapter; 191 int ch; 192 193 /* Check we have a valid client */ 194 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) 195 return -ENODEV; 196 197 /* Now, we do the remaining detection. There is no identification 198 dedicated register so attempt to sanity check using knowledge of 199 the chip 200 - Read from the 8 channel addresses 201 - Check the top 4 bits of each result are not set (12 data bits) 202 */ 203 for (ch = 0; ch < ADS7828_NCH; ch++) { 204 u16 in_data; 205 u8 cmd = channel_cmd_byte(ch); 206 in_data = ads7828_read_value(client, cmd); 207 if (in_data & 0xF000) { 208 pr_debug("%s : Doesn't look like an ads7828 device\n", 209 __func__); 210 return -ENODEV; 211 } 212 } 213 214 strlcpy(info->type, "ads7828", I2C_NAME_SIZE); 215 216 return 0; 217 } 218 219 static int ads7828_probe(struct i2c_client *client, 220 const struct i2c_device_id *id) 221 { 222 struct ads7828_data *data; 223 int err; 224 225 data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL); 226 if (!data) { 227 err = -ENOMEM; 228 goto exit; 229 } 230 231 i2c_set_clientdata(client, data); 232 mutex_init(&data->update_lock); 233 234 /* Register sysfs hooks */ 235 err = sysfs_create_group(&client->dev.kobj, &ads7828_group); 236 if (err) 237 goto exit_free; 238 239 data->hwmon_dev = hwmon_device_register(&client->dev); 240 if (IS_ERR(data->hwmon_dev)) { 241 err = PTR_ERR(data->hwmon_dev); 242 goto exit_remove; 243 } 244 245 return 0; 246 247 exit_remove: 248 sysfs_remove_group(&client->dev.kobj, &ads7828_group); 249 exit_free: 250 kfree(data); 251 exit: 252 return err; 253 } 254 255 static int __init sensors_ads7828_init(void) 256 { 257 /* Initialize the command byte according to module parameters */ 258 ads7828_cmd_byte = se_input ? 259 ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF; 260 ads7828_cmd_byte |= int_vref ? 261 ADS7828_CMD_PD3 : ADS7828_CMD_PD1; 262 263 /* Calculate the LSB resolution */ 264 ads7828_lsb_resol = (vref_mv*1000)/4096; 265 266 return i2c_add_driver(&ads7828_driver); 267 } 268 269 static void __exit sensors_ads7828_exit(void) 270 { 271 i2c_del_driver(&ads7828_driver); 272 } 273 274 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>"); 275 MODULE_DESCRIPTION("ADS7828 driver"); 276 MODULE_LICENSE("GPL"); 277 278 module_init(sensors_ads7828_init); 279 module_exit(sensors_ads7828_exit); 280