hwmon: Add support for Texas Instruments/Burr-Brown ADS7828 (5812f928) · Commits · e / devices / android_kernel_oneplus_sm8150

Documentation/hwmon/ads7828

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		Kernel driver ads7828
		=====================

		Supported chips:
		* Texas Instruments/Burr-Brown ADS7828
		Prefix: 'ads7828'
		Addresses scanned: I2C 0x48, 0x49, 0x4a, 0x4b
		Datasheet: Publicly available at the Texas Instruments website :
		http://focus.ti.com/lit/ds/symlink/ads7828.pdf

		Authors:
		Steve Hardy <steve@linuxrealtime.co.uk>

		Module Parameters
		-----------------

		* se_input: bool (default Y)
		Single ended operation - set to N for differential mode
		* int_vref: bool (default Y)
		Operate with the internal 2.5V reference - set to N for external reference
		* vref_mv: int (default 2500)
		If using an external reference, set this to the reference voltage in mV

		Description
		-----------

		This driver implements support for the Texas Instruments ADS7828.

		This device is a 12-bit 8-channel A-D converter.

		It can operate in single ended mode (8 +ve inputs) or in differential mode,
		where 4 differential pairs can be measured.

		The chip also has the facility to use an external voltage reference. This
		may be required if your hardware supplies the ADS7828 from a 5V supply, see
		the datasheet for more details.

drivers/hwmon/Kconfig

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		@@ -588,6 +588,16 @@ config SENSORS_SMSC47B397
		This driver can also be built as a module. If so, the module
		will be called smsc47b397.

		config SENSORS_ADS7828
		tristate "Texas Instruments ADS7828"
		depends on I2C
		help
		If you say yes here you get support for Texas Instruments ADS7828
		12-bit 8-channel ADC device.

		This driver can also be built as a module. If so, the module
		will be called ads7828.

		config SENSORS_THMC50
		tristate "Texas Instruments THMC50 / Analog Devices ADM1022"
		depends on I2C && EXPERIMENTAL

drivers/hwmon/Makefile

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		@@ -22,6 +22,7 @@ obj-$(CONFIG_SENSORS_ADM1026) += adm1026.o
		obj-$(CONFIG_SENSORS_ADM1029) += adm1029.o
		obj-$(CONFIG_SENSORS_ADM1031) += adm1031.o
		obj-$(CONFIG_SENSORS_ADM9240) += adm9240.o
		obj-$(CONFIG_SENSORS_ADS7828) += ads7828.o
		obj-$(CONFIG_SENSORS_ADT7470) += adt7470.o
		obj-$(CONFIG_SENSORS_APPLESMC) += applesmc.o
		obj-$(CONFIG_SENSORS_AMS) += ams/

drivers/hwmon/ads7828.c

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		/*
		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);