diff options
Diffstat (limited to 'drivers/hwmon/ads7828.c')
| -rw-r--r-- | drivers/hwmon/ads7828.c | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/drivers/hwmon/ads7828.c b/drivers/hwmon/ads7828.c new file mode 100644 index 00000000000..7092c78f814 --- /dev/null +++ b/drivers/hwmon/ads7828.c @@ -0,0 +1,226 @@ +/* + * ads7828.c - driver for TI ADS7828 8-channel A/D converter and compatibles + * (C) 2007 EADS Astrium + * + * This driver is based on the lm75 and other lm_sensors/hwmon drivers + * + * Written by Steve Hardy <shardy@redhat.com> + * + * ADS7830 support, by Guillaume Roguez <guillaume.roguez@savoirfairelinux.com> + * + * 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 <linux/err.h> +#include <linux/hwmon.h> +#include <linux/hwmon-sysfs.h> +#include <linux/i2c.h> +#include <linux/init.h> +#include <linux/jiffies.h> +#include <linux/module.h> +#include <linux/mutex.h> +#include <linux/platform_data/ads7828.h> +#include <linux/slab.h> + +/* 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 */ + +/* List of supported devices */ +enum ads7828_chips { ads7828, ads7830 }; + +/* 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 */ + s32 (*read_channel)(const struct i2c_client *client, u8 command); +}; + +/* 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] = data->read_channel(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 = dev_get_platdata(&client->dev); + 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 = clamp_val(data->vref_mv, + ADS7828_EXT_VREF_MV_MIN, + ADS7828_EXT_VREF_MV_MAX); + else + data->vref_mv = ADS7828_INT_VREF_MV; + + /* ADS7828 uses 12-bit samples, while ADS7830 is 8-bit */ + if (id->driver_data == ads7828) { + data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 4096); + data->read_channel = i2c_smbus_read_word_swapped; + } else { + data->lsb_resol = DIV_ROUND_CLOSEST(data->vref_mv * 1000, 256); + data->read_channel = i2c_smbus_read_byte_data; + } + + 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", ads7828 }, + { "ads7830", ads7830 }, + { } +}; +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 <shardy@redhat.com>"); +MODULE_DESCRIPTION("Driver for TI ADS7828 A/D converter and compatibles"); |