/* * ads7828.c - lm_sensors driver for ads7828 12-bit 8-channel ADC * (C) 2007 EADS Astrium * * This driver is based on the lm75 and other lm_sensors/hwmon drivers * * Written by Steve Hardy * * For further information, see the Documentation/hwmon/ads7828 file. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ #include #include #include #include #include #include #include #include #include #include /* The ADS7828 registers */ #define ADS7828_NCH 8 /* 8 channels supported */ #define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */ #define ADS7828_CMD_PD1 0x04 /* Internal vref OFF && A/D ON */ #define ADS7828_CMD_PD3 0x0C /* Internal vref ON && A/D ON */ #define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */ #define ADS7828_EXT_VREF_MV_MIN 50 /* External vref min value 0.05V */ #define ADS7828_EXT_VREF_MV_MAX 5250 /* External vref max value 5.25V */ /* Client specific data */ struct ads7828_data { struct device *hwmon_dev; struct mutex update_lock; /* Mutex protecting updates */ unsigned long last_updated; /* Last updated time (in jiffies) */ u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH samples */ bool valid; /* Validity flag */ bool diff_input; /* Differential input */ bool ext_vref; /* External voltage reference */ unsigned int vref_mv; /* voltage reference value */ u8 cmd_byte; /* Command byte without channel bits */ unsigned int lsb_resol; /* Resolution of the ADC sample LSB */ }; /* Command byte C2,C1,C0 - see datasheet */ static inline u8 ads7828_cmd_byte(u8 cmd, int ch) { return cmd | (((ch >> 1) | (ch & 0x01) << 2) << 4); } /* Update data for the device (all 8 channels) */ static struct ads7828_data *ads7828_update_device(struct device *dev) { struct i2c_client *client = to_i2c_client(dev); struct ads7828_data *data = i2c_get_clientdata(client); mutex_lock(&data->update_lock); if (time_after(jiffies, data->last_updated + HZ + HZ / 2) || !data->valid) { unsigned int ch; dev_dbg(&client->dev, "Starting ads7828 update\n"); for (ch = 0; ch < ADS7828_NCH; ch++) { u8 cmd = ads7828_cmd_byte(data->cmd_byte, ch); data->adc_input[ch] = i2c_smbus_read_word_swapped(client, cmd); } data->last_updated = jiffies; data->valid = true; } mutex_unlock(&data->update_lock); return data; } /* sysfs callback function */ static ssize_t ads7828_show_in(struct device *dev, struct device_attribute *da, char *buf) { struct sensor_device_attribute *attr = to_sensor_dev_attr(da); struct ads7828_data *data = ads7828_update_device(dev); unsigned int value = DIV_ROUND_CLOSEST(data->adc_input[attr->index] * data->lsb_resol, 1000); return sprintf(buf, "%d\n", value); } static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ads7828_show_in, NULL, 0); static SENSOR_DEVICE_ATTR(in1_input, S_IRUGO, ads7828_show_in, NULL, 1); static SENSOR_DEVICE_ATTR(in2_input, S_IRUGO, ads7828_show_in, NULL, 2); static SENSOR_DEVICE_ATTR(in3_input, S_IRUGO, ads7828_show_in, NULL, 3); static SENSOR_DEVICE_ATTR(in4_input, S_IRUGO, ads7828_show_in, NULL, 4); static SENSOR_DEVICE_ATTR(in5_input, S_IRUGO, ads7828_show_in, NULL, 5); static SENSOR_DEVICE_ATTR(in6_input, S_IRUGO, ads7828_show_in, NULL, 6); static SENSOR_DEVICE_ATTR(in7_input, S_IRUGO, ads7828_show_in, NULL, 7); static struct attribute *ads7828_attributes[] = { &sensor_dev_attr_in0_input.dev_attr.attr, &sensor_dev_attr_in1_input.dev_attr.attr, &sensor_dev_attr_in2_input.dev_attr.attr, &sensor_dev_attr_in3_input.dev_attr.attr, &sensor_dev_attr_in4_input.dev_attr.attr, &sensor_dev_attr_in5_input.dev_attr.attr, &sensor_dev_attr_in6_input.dev_attr.attr, &sensor_dev_attr_in7_input.dev_attr.attr, NULL }; static const struct attribute_group ads7828_group = { .attrs = ads7828_attributes, }; static int ads7828_remove(struct i2c_client *client) { struct ads7828_data *data = i2c_get_clientdata(client); hwmon_device_unregister(data->hwmon_dev); sysfs_remove_group(&client->dev.kobj, &ads7828_group); return 0; } static int ads7828_probe(struct i2c_client *client, const struct i2c_device_id *id) { struct ads7828_platform_data *pdata = client->dev.platform_data; struct ads7828_data *data; int err; data = devm_kzalloc(&client->dev, sizeof(struct ads7828_data), GFP_KERNEL); if (!data) return -ENOMEM; if (pdata) { data->diff_input = pdata->diff_input; data->ext_vref = pdata->ext_vref; if (data->ext_vref) data->vref_mv = pdata->vref_mv; } /* Bound Vref with min/max values if it was provided */ if (data->vref_mv) data->vref_mv = SENSORS_LIMIT(data->vref_mv, ADS7828_EXT_VREF_MV_MIN, ADS7828_EXT_VREF_MV_MAX); else data->vref_mv = ADS7828_INT_VREF_MV; data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096); data->cmd_byte = data->ext_vref ? ADS7828_CMD_PD1 : ADS7828_CMD_PD3; if (!data->diff_input) data->cmd_byte |= ADS7828_CMD_SD_SE; i2c_set_clientdata(client, data); mutex_init(&data->update_lock); err = sysfs_create_group(&client->dev.kobj, &ads7828_group); if (err) return err; data->hwmon_dev = hwmon_device_register(&client->dev); if (IS_ERR(data->hwmon_dev)) { err = PTR_ERR(data->hwmon_dev); goto error; } return 0; error: sysfs_remove_group(&client->dev.kobj, &ads7828_group); return err; } static const struct i2c_device_id ads7828_device_ids[] = { { "ads7828", 0 }, { } }; MODULE_DEVICE_TABLE(i2c, ads7828_device_ids); static struct i2c_driver ads7828_driver = { .driver = { .name = "ads7828", }, .id_table = ads7828_device_ids, .probe = ads7828_probe, .remove = ads7828_remove, }; module_i2c_driver(ads7828_driver); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Steve Hardy "); MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter");