298 строки
8.3 KiB
C
298 строки
8.3 KiB
C
/*
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ads7828.c - lm_sensors driver for ads7828 12-bit 8-channel ADC
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(C) 2007 EADS Astrium
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This driver is based on the lm75 and other lm_sensors/hwmon drivers
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Written by Steve Hardy <steve@linuxrealtime.co.uk>
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Datasheet available at: http://focus.ti.com/lit/ds/symlink/ads7828.pdf
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/slab.h>
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#include <linux/jiffies.h>
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#include <linux/i2c.h>
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#include <linux/hwmon.h>
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#include <linux/hwmon-sysfs.h>
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#include <linux/err.h>
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#include <linux/mutex.h>
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/* The ADS7828 registers */
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#define ADS7828_NCH 8 /* 8 channels of 12-bit A-D supported */
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#define ADS7828_CMD_SD_SE 0x80 /* Single ended inputs */
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#define ADS7828_CMD_SD_DIFF 0x00 /* Differential inputs */
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#define ADS7828_CMD_PD0 0x0 /* Power Down between A-D conversions */
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#define ADS7828_CMD_PD1 0x04 /* Internal ref OFF && A-D ON */
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#define ADS7828_CMD_PD2 0x08 /* Internal ref ON && A-D OFF */
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#define ADS7828_CMD_PD3 0x0C /* Internal ref ON && A-D ON */
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#define ADS7828_INT_VREF_MV 2500 /* Internal vref is 2.5V, 2500mV */
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/* Addresses to scan */
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static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4b,
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I2C_CLIENT_END };
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/* Insmod parameters */
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I2C_CLIENT_INSMOD_1(ads7828);
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/* Other module parameters */
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static int se_input = 1; /* Default is SE, 0 == diff */
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static int int_vref = 1; /* Default is internal ref ON */
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static int vref_mv = ADS7828_INT_VREF_MV; /* set if vref != 2.5V */
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module_param(se_input, bool, S_IRUGO);
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module_param(int_vref, bool, S_IRUGO);
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module_param(vref_mv, int, S_IRUGO);
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/* Global Variables */
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static u8 ads7828_cmd_byte; /* cmd byte without channel bits */
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static unsigned int ads7828_lsb_resol; /* resolution of the ADC sample lsb */
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/* Each client has this additional data */
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struct ads7828_data {
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struct i2c_client client;
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struct device *hwmon_dev;
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struct mutex update_lock; /* mutex protect updates */
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char valid; /* !=0 if following fields are valid */
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unsigned long last_updated; /* In jiffies */
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u16 adc_input[ADS7828_NCH]; /* ADS7828_NCH 12-bit samples */
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};
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/* Function declaration - necessary due to function dependencies */
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static int ads7828_detect(struct i2c_adapter *adapter, int address, int kind);
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/* The ADS7828 returns the 12-bit sample in two bytes,
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these are read as a word then byte-swapped */
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static u16 ads7828_read_value(struct i2c_client *client, u8 reg)
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{
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return swab16(i2c_smbus_read_word_data(client, reg));
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}
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static inline u8 channel_cmd_byte(int ch)
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{
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/* cmd byte C2,C1,C0 - see datasheet */
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u8 cmd = (((ch>>1) | (ch&0x01)<<2)<<4);
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cmd |= ads7828_cmd_byte;
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return cmd;
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}
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/* Update data for the device (all 8 channels) */
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static struct ads7828_data *ads7828_update_device(struct device *dev)
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{
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struct i2c_client *client = to_i2c_client(dev);
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struct ads7828_data *data = i2c_get_clientdata(client);
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mutex_lock(&data->update_lock);
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if (time_after(jiffies, data->last_updated + HZ + HZ / 2)
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|| !data->valid) {
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unsigned int ch;
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dev_dbg(&client->dev, "Starting ads7828 update\n");
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for (ch = 0; ch < ADS7828_NCH; ch++) {
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u8 cmd = channel_cmd_byte(ch);
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data->adc_input[ch] = ads7828_read_value(client, cmd);
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}
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data->last_updated = jiffies;
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data->valid = 1;
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}
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mutex_unlock(&data->update_lock);
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return data;
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}
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/* sysfs callback function */
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static ssize_t show_in(struct device *dev, struct device_attribute *da,
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char *buf)
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{
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struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
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struct ads7828_data *data = ads7828_update_device(dev);
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/* Print value (in mV as specified in sysfs-interface documentation) */
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return sprintf(buf, "%d\n", (data->adc_input[attr->index] *
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ads7828_lsb_resol)/1000);
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}
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#define in_reg(offset)\
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static SENSOR_DEVICE_ATTR(in##offset##_input, S_IRUGO, show_in,\
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NULL, offset)
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in_reg(0);
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in_reg(1);
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in_reg(2);
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in_reg(3);
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in_reg(4);
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in_reg(5);
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in_reg(6);
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in_reg(7);
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static struct attribute *ads7828_attributes[] = {
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&sensor_dev_attr_in0_input.dev_attr.attr,
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&sensor_dev_attr_in1_input.dev_attr.attr,
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&sensor_dev_attr_in2_input.dev_attr.attr,
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&sensor_dev_attr_in3_input.dev_attr.attr,
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&sensor_dev_attr_in4_input.dev_attr.attr,
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&sensor_dev_attr_in5_input.dev_attr.attr,
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&sensor_dev_attr_in6_input.dev_attr.attr,
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&sensor_dev_attr_in7_input.dev_attr.attr,
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NULL
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};
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static const struct attribute_group ads7828_group = {
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.attrs = ads7828_attributes,
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};
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static int ads7828_attach_adapter(struct i2c_adapter *adapter)
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{
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if (!(adapter->class & I2C_CLASS_HWMON))
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return 0;
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return i2c_probe(adapter, &addr_data, ads7828_detect);
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}
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static int ads7828_detach_client(struct i2c_client *client)
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{
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struct ads7828_data *data = i2c_get_clientdata(client);
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hwmon_device_unregister(data->hwmon_dev);
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sysfs_remove_group(&client->dev.kobj, &ads7828_group);
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i2c_detach_client(client);
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kfree(i2c_get_clientdata(client));
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return 0;
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}
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/* This is the driver that will be inserted */
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static struct i2c_driver ads7828_driver = {
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.driver = {
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.name = "ads7828",
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},
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.attach_adapter = ads7828_attach_adapter,
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.detach_client = ads7828_detach_client,
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};
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/* This function is called by i2c_probe */
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static int ads7828_detect(struct i2c_adapter *adapter, int address, int kind)
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{
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struct i2c_client *client;
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struct ads7828_data *data;
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int err = 0;
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const char *name = "";
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/* Check we have a valid client */
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if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA))
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goto exit;
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/* OK. For now, we presume we have a valid client. We now create the
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client structure, even though we cannot fill it completely yet.
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But it allows us to access ads7828_read_value. */
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data = kzalloc(sizeof(struct ads7828_data), GFP_KERNEL);
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if (!data) {
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err = -ENOMEM;
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goto exit;
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}
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client = &data->client;
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i2c_set_clientdata(client, data);
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client->addr = address;
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client->adapter = adapter;
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client->driver = &ads7828_driver;
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/* Now, we do the remaining detection. There is no identification
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dedicated register so attempt to sanity check using knowledge of
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the chip
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- Read from the 8 channel addresses
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- Check the top 4 bits of each result are not set (12 data bits)
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*/
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if (kind < 0) {
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int ch;
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for (ch = 0; ch < ADS7828_NCH; ch++) {
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u16 in_data;
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u8 cmd = channel_cmd_byte(ch);
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in_data = ads7828_read_value(client, cmd);
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if (in_data & 0xF000) {
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printk(KERN_DEBUG
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"%s : Doesn't look like an ads7828 device\n",
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__FUNCTION__);
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goto exit_free;
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}
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}
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}
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/* Determine the chip type - only one kind supported! */
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if (kind <= 0)
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kind = ads7828;
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if (kind == ads7828)
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name = "ads7828";
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/* Fill in the remaining client fields, put it into the global list */
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strlcpy(client->name, name, I2C_NAME_SIZE);
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mutex_init(&data->update_lock);
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/* Tell the I2C layer a new client has arrived */
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err = i2c_attach_client(client);
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if (err)
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goto exit_free;
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/* Register sysfs hooks */
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err = sysfs_create_group(&client->dev.kobj, &ads7828_group);
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if (err)
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goto exit_detach;
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data->hwmon_dev = hwmon_device_register(&client->dev);
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if (IS_ERR(data->hwmon_dev)) {
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err = PTR_ERR(data->hwmon_dev);
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goto exit_remove;
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}
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return 0;
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exit_remove:
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sysfs_remove_group(&client->dev.kobj, &ads7828_group);
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exit_detach:
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i2c_detach_client(client);
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exit_free:
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kfree(data);
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exit:
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return err;
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}
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static int __init sensors_ads7828_init(void)
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{
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/* Initialize the command byte according to module parameters */
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ads7828_cmd_byte = se_input ?
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ADS7828_CMD_SD_SE : ADS7828_CMD_SD_DIFF;
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ads7828_cmd_byte |= int_vref ?
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ADS7828_CMD_PD3 : ADS7828_CMD_PD1;
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/* Calculate the LSB resolution */
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ads7828_lsb_resol = (vref_mv*1000)/4096;
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return i2c_add_driver(&ads7828_driver);
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}
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static void __exit sensors_ads7828_exit(void)
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{
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i2c_del_driver(&ads7828_driver);
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}
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MODULE_AUTHOR("Steve Hardy <steve@linuxrealtime.co.uk>");
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MODULE_DESCRIPTION("ADS7828 driver");
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MODULE_LICENSE("GPL");
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module_init(sensors_ads7828_init);
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module_exit(sensors_ads7828_exit);
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