diff options
Diffstat (limited to 'drivers/hwmon/ads7828.c')
| -rw-r--r-- | drivers/hwmon/ads7828.c | 297 |
1 files changed, 297 insertions, 0 deletions
diff --git a/drivers/hwmon/ads7828.c b/drivers/hwmon/ads7828.c new file mode 100644 index 000000000000..6b8a73ef404c --- /dev/null +++ b/drivers/hwmon/ads7828.c @@ -0,0 +1,297 @@ +/* + 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 <steve@linuxrealtime.co.uk> + + Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads7828.pdf + + 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/module.h> +#include <linux/init.h> +#include <linux/slab.h> +#include <linux/jiffies.h> +#include <linux/i2c.h> +#include <linux/hwmon.h> +#include <linux/hwmon-sysfs.h> +#include <linux/err.h> +#include <linux/mutex.h> + +/* The ADS7828 registers */ +#define ADS7828_NCH 8 /* 8 channels of 12-bit A-D supported */ +#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */ +#define ADS7828_CMD_SD_DIFF 0x00 /* Differential inputs */ +#define ADS7828_CMD_PD0 0x0 /* Power Down between A-D conversions */ +#define ADS7828_CMD_PD1 0x04 /* Internal ref OFF && A-D ON */ +#define ADS7828_CMD_PD2 0x08 /* Internal ref ON && A-D OFF */ +#define ADS7828_CMD_PD3 0x0C /* Internal ref ON && A-D ON */ +#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */ + +/* Addresses to scan */ +static unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b, + I2C_CLIENT_END }; + +/* Insmod parameters */ +I2C_CLIENT_INSMOD_1(ads7828); + +/* Other module parameters */ +static int se_input = 1; /* Default is SE, 0 == diff */ +static int int_vref = 1; /* Default is internal ref ON */ +static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */ +module_param(se_input, bool, S_IRUGO); +module_param(int_vref, bool, S_IRUGO); +module_param(vref_mv, int, S_IRUGO); + +/* Global Variables */ +static u8 ads7828_cmd_byte; /* cmd byte without channel bits */ +static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */ + +/* Each client has this additional data */ +struct ads7828_data { + struct i2c_client client; + struct device *hwmon_dev; + struct mutex update_lock; /* mutex protect updates */ + char valid; /* !=0 if following fields are valid */ + unsigned long last_updated; /* In jiffies */ + u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */ +}; + +/* Function declaration - necessary due to function dependencies */ +static int ads7828_detect(struct i2c_adapter *adapter, int address, int kind); + +/* The ADS7828 returns the 12-bit sample in two bytes, + these are read as a word then byte-swapped */ +static u16 ads7828_read_value(struct i2c_client *client, u8 reg) +{ + return swab16(i2c_smbus_read_word_data(client, reg)); +} + +static inline u8 channel_cmd_byte(int ch) +{ + /* cmd byte C2,C1,C0 - see datasheet */ + u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4); + cmd |= ads7828_cmd_byte; + return cmd; +} + +/* 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 = channel_cmd_byte(ch); + data->adc_input[ch] = ads7828_read_value(client, cmd); + } + data->last_updated = jiffies; + data->valid = 1; + } + + mutex_unlock(&data->update_lock); + + return data; +} + +/* sysfs callback function */ +static ssize_t 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); + /* Print value (in mV as specified in sysfs-interface documentation) */ + return sprintf(buf, "%d\n", (data->adc_input[attr->index] * + ads7828_lsb_resol)/1000); +} + +#define in_reg(offset)\ +static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\ + NULL, offset) + +in_reg(0); +in_reg(1); +in_reg(2); +in_reg(3); +in_reg(4); +in_reg(5); +in_reg(6); +in_reg(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_attach_adapter(struct i2c_adapter *adapter) +{ + if (!(adapter->class & I2C_CLASS_HWMON)) + return 0; + return i2c_probe(adapter, &addr_data, ads7828_detect); +} + +static int ads7828_detach_client(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); + i2c_detach_client(client); + kfree(i2c_get_clientdata(client)); + return 0; +} + +/* This is the driver that will be inserted */ +static struct i2c_driver ads7828_driver = { + .driver = { + .name = "ads7828", + }, + .attach_adapter = ads7828_attach_adapter, + .detach_client = ads7828_detach_client, +}; + +/* This function is called by i2c_probe */ +static int ads7828_detect(struct i2c_adapter *adapter, int address, int kind) +{ + struct i2c_client *client; + struct ads7828_data *data; + int err = 0; + const char *name = ""; + + /* Check we have a valid client */ + if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) + goto exit; + + /* OK. For now, we presume we have a valid client. We now create the + client structure, even though we cannot fill it completely yet. + But it allows us to access ads7828_read_value. */ + data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL); + if (!data) { + err = -ENOMEM; + goto exit; + } + + client = &data->client; + i2c_set_clientdata(client, data); + client->addr = address; + client->adapter = adapter; + client->driver = &ads7828_driver; + + /* Now, we do the remaining detection. There is no identification + dedicated register so attempt to sanity check using knowledge of + the chip + - Read from the 8 channel addresses + - Check the top 4 bits of each result are not set (12 data bits) + */ + if (kind < 0) { + int ch; + for (ch = 0; ch < ADS7828_NCH; ch++) { + u16 in_data; + u8 cmd = channel_cmd_byte(ch); + in_data = ads7828_read_value(client, cmd); + if (in_data & 0xF000) { + printk(KERN_DEBUG + "%s : Doesn't look like an ads7828 device\n", + __FUNCTION__); + goto exit_free; + } + } + } + + /* Determine the chip type - only one kind supported! */ + if (kind <= 0) + kind = ads7828; + + if (kind == ads7828) + name = "ads7828"; + + /* Fill in the remaining client fields, put it into the global list */ + strlcpy(client->name, name, I2C_NAME_SIZE); + + mutex_init(&data->update_lock); + + /* Tell the I2C layer a new client has arrived */ + err = i2c_attach_client(client); + if (err) + goto exit_free; + + /* Register sysfs hooks */ + err = sysfs_create_group(&client->dev.kobj, &ads7828_group); + if (err) + goto exit_detach; + + data->hwmon_dev = hwmon_device_register(&client->dev); + if (IS_ERR(data->hwmon_dev)) { + err = PTR_ERR(data->hwmon_dev); + goto exit_remove; + } + + return 0; + +exit_remove: + sysfs_remove_group(&client->dev.kobj, &ads7828_group); +exit_detach: + i2c_detach_client(client); +exit_free: + kfree(data); +exit: + return err; +} + +static int __init sensors_ads7828_init(void) +{ + /* Initialize the command byte according to module parameters */ + ads7828_cmd_byte = se_input ? + ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF; + ads7828_cmd_byte |= int_vref ? + ADS7828_CMD_PD3 : ADS7828_CMD_PD1; + + /* Calculate the LSB resolution */ + ads7828_lsb_resol = (vref_mv*1000)/4096; + + return i2c_add_driver(&ads7828_driver); +} + +static void __exit sensors_ads7828_exit(void) +{ + i2c_del_driver(&ads7828_driver); +} + +MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>"); +MODULE_DESCRIPTION("ADS7828 driver"); +MODULE_LICENSE("GPL"); + +module_init(sensors_ads7828_init); +module_exit(sensors_ads7828_exit); |