/* 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 const 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", __func__); 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);