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 bool se_input = 1; /* Default is SE, 0 == diff */ 52 static bool 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 static inline u8 channel_cmd_byte(int ch) 78 { 79 /* cmd byte C2,C1,C0 - see datasheet */ 80 u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4); 81 cmd |= ads7828_cmd_byte; 82 return cmd; 83 } 84 85 /* Update data for the device (all 8 channels) */ 86 static struct ads7828_data *ads7828_update_device(struct device *dev) 87 { 88 struct i2c_client *client = to_i2c_client(dev); 89 struct ads7828_data *data = i2c_get_clientdata(client); 90 91 mutex_lock(&data->update_lock); 92 93 if (time_after(jiffies, data->last_updated + HZ + HZ / 2) 94 || !data->valid) { 95 unsigned int ch; 96 dev_dbg(&client->dev, "Starting ads7828 update\n"); 97 98 for (ch = 0; ch < ADS7828_NCH; ch++) { 99 u8 cmd = channel_cmd_byte(ch); 100 data->adc_input[ch] = 101 i2c_smbus_read_word_swapped(client, cmd); 102 } 103 data->last_updated = jiffies; 104 data->valid = 1; 105 } 106 107 mutex_unlock(&data->update_lock); 108 109 return data; 110 } 111 112 /* sysfs callback function */ 113 static ssize_t show_in(struct device *dev, struct device_attribute *da, 114 char *buf) 115 { 116 struct sensor_device_attribute *attr = to_sensor_dev_attr(da); 117 struct ads7828_data *data = ads7828_update_device(dev); 118 /* Print value (in mV as specified in sysfs-interface documentation) */ 119 return sprintf(buf, "%d\n", (data->adc_input[attr->index] * 120 ads7828_lsb_resol)/1000); 121 } 122 123 #define in_reg(offset)\ 124 static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\ 125 NULL, offset) 126 127 in_reg(0); 128 in_reg(1); 129 in_reg(2); 130 in_reg(3); 131 in_reg(4); 132 in_reg(5); 133 in_reg(6); 134 in_reg(7); 135 136 static struct attribute *ads7828_attributes[] = { 137 &sensor_dev_attr_in0_input.dev_attr.attr, 138 &sensor_dev_attr_in1_input.dev_attr.attr, 139 &sensor_dev_attr_in2_input.dev_attr.attr, 140 &sensor_dev_attr_in3_input.dev_attr.attr, 141 &sensor_dev_attr_in4_input.dev_attr.attr, 142 &sensor_dev_attr_in5_input.dev_attr.attr, 143 &sensor_dev_attr_in6_input.dev_attr.attr, 144 &sensor_dev_attr_in7_input.dev_attr.attr, 145 NULL 146 }; 147 148 static const struct attribute_group ads7828_group = { 149 .attrs = ads7828_attributes, 150 }; 151 152 static int ads7828_remove(struct i2c_client *client) 153 { 154 struct ads7828_data *data = i2c_get_clientdata(client); 155 hwmon_device_unregister(data->hwmon_dev); 156 sysfs_remove_group(&client->dev.kobj, &ads7828_group); 157 return 0; 158 } 159 160 static const struct i2c_device_id ads7828_id[] = { 161 { "ads7828", 0 }, 162 { } 163 }; 164 MODULE_DEVICE_TABLE(i2c, ads7828_id); 165 166 /* This is the driver that will be inserted */ 167 static struct i2c_driver ads7828_driver = { 168 .class = I2C_CLASS_HWMON, 169 .driver = { 170 .name = "ads7828", 171 }, 172 .probe = ads7828_probe, 173 .remove = ads7828_remove, 174 .id_table = ads7828_id, 175 .detect = ads7828_detect, 176 .address_list = normal_i2c, 177 }; 178 179 /* Return 0 if detection is successful, -ENODEV otherwise */ 180 static int ads7828_detect(struct i2c_client *client, 181 struct i2c_board_info *info) 182 { 183 struct i2c_adapter *adapter = client->adapter; 184 int ch; 185 186 /* Check we have a valid client */ 187 if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) 188 return -ENODEV; 189 190 /* 191 * Now, we do the remaining detection. There is no identification 192 * dedicated register so attempt to sanity check using knowledge of 193 * the chip 194 * - Read from the 8 channel addresses 195 * - Check the top 4 bits of each result are not set (12 data bits) 196 */ 197 for (ch = 0; ch < ADS7828_NCH; ch++) { 198 u16 in_data; 199 u8 cmd = channel_cmd_byte(ch); 200 in_data = i2c_smbus_read_word_swapped(client, cmd); 201 if (in_data & 0xF000) { 202 pr_debug("%s : Doesn't look like an ads7828 device\n", 203 __func__); 204 return -ENODEV; 205 } 206 } 207 208 strlcpy(info->type, "ads7828", I2C_NAME_SIZE); 209 210 return 0; 211 } 212 213 static int ads7828_probe(struct i2c_client *client, 214 const struct i2c_device_id *id) 215 { 216 struct ads7828_data *data; 217 int err; 218 219 data = devm_kzalloc(&client->dev, sizeof(struct ads7828_data), 220 GFP_KERNEL); 221 if (!data) 222 return -ENOMEM; 223 224 i2c_set_clientdata(client, data); 225 mutex_init(&data->update_lock); 226 227 /* Register sysfs hooks */ 228 err = sysfs_create_group(&client->dev.kobj, &ads7828_group); 229 if (err) 230 return err; 231 232 data->hwmon_dev = hwmon_device_register(&client->dev); 233 if (IS_ERR(data->hwmon_dev)) { 234 err = PTR_ERR(data->hwmon_dev); 235 goto exit_remove; 236 } 237 238 return 0; 239 240 exit_remove: 241 sysfs_remove_group(&client->dev.kobj, &ads7828_group); 242 return err; 243 } 244 245 static int __init sensors_ads7828_init(void) 246 { 247 /* Initialize the command byte according to module parameters */ 248 ads7828_cmd_byte = se_input ? 249 ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF; 250 ads7828_cmd_byte |= int_vref ? 251 ADS7828_CMD_PD3 : ADS7828_CMD_PD1; 252 253 /* Calculate the LSB resolution */ 254 ads7828_lsb_resol = (vref_mv*1000)/4096; 255 256 return i2c_add_driver(&ads7828_driver); 257 } 258 259 static void __exit sensors_ads7828_exit(void) 260 { 261 i2c_del_driver(&ads7828_driver); 262 } 263 264 MODULE_AUTHOR("Steve Hardy <shardy@redhat.com>"); 265 MODULE_DESCRIPTION("ADS7828 driver"); 266 MODULE_LICENSE("GPL"); 267 268 module_init(sensors_ads7828_init); 269 module_exit(sensors_ads7828_exit); 270