drivers/i2c/chips/max6875.c - linux - Git at Google

 /*
     max6875.c - driver for MAX6874/MAX6875

     Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>

     Based on i2c/chips/eeprom.c

     The MAX6875 has a bank of registers and two banks of EEPROM.
     Address ranges are defined as follows:
      * 0x0000 - 0x0046 = configuration registers
      * 0x8000 - 0x8046 = configuration EEPROM
      * 0x8100 - 0x82FF = user EEPROM

     This driver makes the user EEPROM available for read.

     The registers & config EEPROM should be accessed via i2c-dev.

     The MAX6875 ignores the lowest address bit, so each chip responds to
     two addresses - 0x50/0x51 and 0x52/0x53.

     Note that the MAX6875 uses i2c_smbus_write_byte_data() to set the read
     address, so this driver is destructive if loaded for the wrong EEPROM chip.

     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; version 2 of the License.
 */

 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/module.h>
 #include <linux/slab.h>
 #include <linux/i2c.h>
 #include <linux/i2c-sensor.h>
 #include <asm/semaphore.h>

 /* Do not scan - the MAX6875 access method will write to some EEPROM chips */
 static unsigned short normal_i2c[] = {I2C_CLIENT_END};

 /* Insmod parameters */
 SENSORS_INSMOD_1(max6875);

 /* The MAX6875 can only read/write 16 bytes at a time */
 #define SLICE_SIZE			16
 #define SLICE_BITS			4

 /* USER EEPROM is at addresses 0x8100 - 0x82FF */
 #define USER_EEPROM_BASE		0x8100
 #define USER_EEPROM_SIZE		0x0200
 #define USER_EEPROM_SLICES		32

 /* MAX6875 commands */
 #define MAX6875_CMD_BLK_READ		0x84

 /* Each client has this additional data */
 struct max6875_data {
 	struct i2c_client	client;
 	struct semaphore	update_lock;

 	u32			valid;
 	u8			data[USER_EEPROM_SIZE];
 	unsigned long		last_updated[USER_EEPROM_SLICES];
 };

 static int max6875_attach_adapter(struct i2c_adapter *adapter);
 static int max6875_detect(struct i2c_adapter *adapter, int address, int kind);
 static int max6875_detach_client(struct i2c_client *client);

 /* This is the driver that will be inserted */
 static struct i2c_driver max6875_driver = {
 	.owner		= THIS_MODULE,
 	.name		= "max6875",
 	.flags		= I2C_DF_NOTIFY,
 	.attach_adapter	= max6875_attach_adapter,
 	.detach_client	= max6875_detach_client,
 };

 static void max6875_update_slice(struct i2c_client *client, int slice)
 {
 	struct max6875_data *data = i2c_get_clientdata(client);
 	int i, j, addr;
 	u8 *buf;

 	if (slice >= USER_EEPROM_SLICES)
 		return;

 	down(&data->update_lock);

 	buf = &data->data[slice << SLICE_BITS];

 	if (!(data->valid & (1 << slice)) ||
 	    time_after(jiffies, data->last_updated[slice])) {

 		dev_dbg(&client->dev, "Starting update of slice %u\n", slice);

 		data->valid &= ~(1 << slice);

 		addr = USER_EEPROM_BASE + (slice << SLICE_BITS);

 		/* select the eeprom address */
 		if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) {
 			dev_err(&client->dev, "address set failed\n");
 			goto exit_up;
 		}

 		if (i2c_check_functionality(client->adapter,
 					    I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
 			if (i2c_smbus_read_i2c_block_data(client,
 							  MAX6875_CMD_BLK_READ,
 							  buf) != SLICE_SIZE) {
 				goto exit_up;
 			}
 		} else {
 			for (i = 0; i < SLICE_SIZE; i++) {
 				j = i2c_smbus_read_byte(client);
 				if (j < 0) {
 					goto exit_up;
 				}
 				buf[i] = j;
 			}
 		}
 		data->last_updated[slice] = jiffies;
 		data->valid |= (1 << slice);
 	}
 exit_up:
 	up(&data->update_lock);
 }

 static ssize_t max6875_read(struct kobject *kobj, char *buf, loff_t off,
 			    size_t count)
 {
 	struct i2c_client *client = kobj_to_i2c_client(kobj);
 	struct max6875_data *data = i2c_get_clientdata(client);
 	int slice, max_slice;

 	if (off > USER_EEPROM_SIZE)
 		return 0;

 	if (off + count > USER_EEPROM_SIZE)
 		count = USER_EEPROM_SIZE - off;

 	/* refresh slices which contain requested bytes */
 	max_slice = (off + count - 1) >> SLICE_BITS;
 	for (slice = (off >> SLICE_BITS); slice <= max_slice; slice++)
 		max6875_update_slice(client, slice);

 	memcpy(buf, &data->data[off], count);

 	return count;
 }

 static struct bin_attribute user_eeprom_attr = {
 	.attr = {
 		.name = "eeprom",
 		.mode = S_IRUGO,
 		.owner = THIS_MODULE,
 	},
 	.size = USER_EEPROM_SIZE,
 	.read = max6875_read,
 };

 static int max6875_attach_adapter(struct i2c_adapter *adapter)
 {
 	return i2c_detect(adapter, &addr_data, max6875_detect);
 }

 /* This function is called by i2c_detect */
 static int max6875_detect(struct i2c_adapter *adapter, int address, int kind)
 {
 	struct i2c_client *real_client;
 	struct i2c_client *fake_client;
 	struct max6875_data *data;
 	int err = 0;

 	/* Prevent 24rf08 corruption (in case of user error) */
 	if (kind < 0)
 		i2c_smbus_xfer(adapter, address, 0, 0, 0,
 			       I2C_SMBUS_QUICK, NULL);

 	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA
 				     | I2C_FUNC_SMBUS_READ_BYTE))
 		return 0;

 	/* Only check even addresses */
 	if (address & 1)
 		return 0;

 	if (!(data = kmalloc(sizeof(struct max6875_data), GFP_KERNEL)))
 		return -ENOMEM;
 	memset(data, 0, sizeof(struct max6875_data));

 	/* A fake client is created on the odd address */
 	if (!(fake_client = kmalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
 		err = -ENOMEM;
 		goto exit_kfree1;
 	}
 	memset(fake_client, 0, sizeof(struct i2c_client));

 	/* Init real i2c_client */
 	real_client = &data->client;
 	i2c_set_clientdata(real_client, data);
 	real_client->addr = address;
 	real_client->adapter = adapter;
 	real_client->driver = &max6875_driver;
 	real_client->flags = 0;
 	strlcpy(real_client->name, "max6875", I2C_NAME_SIZE);
 	init_MUTEX(&data->update_lock);

 	/* Init fake client data */
 	/* set the client data to the i2c_client so that it will get freed */
 	i2c_set_clientdata(fake_client, fake_client);
 	fake_client->addr = address | 1;
 	fake_client->adapter = adapter;
 	fake_client->driver = &max6875_driver;
 	fake_client->flags = 0;
 	strlcpy(fake_client->name, "max6875 subclient", I2C_NAME_SIZE);

 	/* Prevent 24RF08 corruption (in case of user error) */
 	i2c_smbus_write_quick(real_client, 0);

 	if ((err = i2c_attach_client(real_client)) != 0)
 		goto exit_kfree2;

 	if ((err = i2c_attach_client(fake_client)) != 0)
 		goto exit_detach;

 	sysfs_create_bin_file(&real_client->dev.kobj, &user_eeprom_attr);

 	return 0;

 exit_detach:
 	i2c_detach_client(real_client);
 exit_kfree2:
 	kfree(fake_client);
 exit_kfree1:
 	kfree(data);
 	return err;
 }

 static int max6875_detach_client(struct i2c_client *client)
 {
 	int err;

 	err = i2c_detach_client(client);
 	if (err)
 		return err;
 	kfree(i2c_get_clientdata(client));
 	return 0;
 }

 static int __init max6875_init(void)
 {
 	return i2c_add_driver(&max6875_driver);
 }

 static void __exit max6875_exit(void)
 {
 	i2c_del_driver(&max6875_driver);
 }


 MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
 MODULE_DESCRIPTION("MAX6875 driver");
 MODULE_LICENSE("GPL");

 module_init(max6875_init);
 module_exit(max6875_exit);
	/*
	max6875.c - driver for MAX6874/MAX6875

	Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>

	Based on i2c/chips/eeprom.c

	The MAX6875 has a bank of registers and two banks of EEPROM.
	Address ranges are defined as follows:
	* 0x0000 - 0x0046 = configuration registers
	* 0x8000 - 0x8046 = configuration EEPROM
	* 0x8100 - 0x82FF = user EEPROM

	This driver makes the user EEPROM available for read.

	The registers & config EEPROM should be accessed via i2c-dev.

	The MAX6875 ignores the lowest address bit, so each chip responds to
	two addresses - 0x50/0x51 and 0x52/0x53.

	Note that the MAX6875 uses i2c_smbus_write_byte_data() to set the read
	address, so this driver is destructive if loaded for the wrong EEPROM chip.

	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; version 2 of the License.
	*/

	#include <linux/kernel.h>
	#include <linux/init.h>
	#include <linux/module.h>
	#include <linux/slab.h>
	#include <linux/i2c.h>
	#include <linux/i2c-sensor.h>
	#include <asm/semaphore.h>

	/* Do not scan - the MAX6875 access method will write to some EEPROM chips */
	static unsigned short normal_i2c[] = {I2C_CLIENT_END};

	/* Insmod parameters */
	SENSORS_INSMOD_1(max6875);

	/* The MAX6875 can only read/write 16 bytes at a time */
	#define SLICE_SIZE 16
	#define SLICE_BITS 4

	/* USER EEPROM is at addresses 0x8100 - 0x82FF */
	#define USER_EEPROM_BASE 0x8100
	#define USER_EEPROM_SIZE 0x0200
	#define USER_EEPROM_SLICES 32

	/* MAX6875 commands */
	#define MAX6875_CMD_BLK_READ 0x84

	/* Each client has this additional data */
	struct max6875_data {
	struct i2c_client client;
	struct semaphore update_lock;

	u32 valid;
	u8 data[USER_EEPROM_SIZE];
	unsigned long last_updated[USER_EEPROM_SLICES];
	};

	static int max6875_attach_adapter(struct i2c_adapter *adapter);
	static int max6875_detect(struct i2c_adapter *adapter, int address, int kind);
	static int max6875_detach_client(struct i2c_client *client);

	/* This is the driver that will be inserted */
	static struct i2c_driver max6875_driver = {
	.owner = THIS_MODULE,
	.name = "max6875",
	.flags = I2C_DF_NOTIFY,
	.attach_adapter = max6875_attach_adapter,
	.detach_client = max6875_detach_client,
	};

	static void max6875_update_slice(struct i2c_client *client, int slice)
	{
	struct max6875_data *data = i2c_get_clientdata(client);
	int i, j, addr;
	u8 *buf;

	if (slice >= USER_EEPROM_SLICES)
	return;

	down(&data->update_lock);

	buf = &data->data[slice << SLICE_BITS];

	if (!(data->valid & (1 << slice)) \|\|
	time_after(jiffies, data->last_updated[slice])) {

	dev_dbg(&client->dev, "Starting update of slice %u\n", slice);

	data->valid &= ~(1 << slice);

	addr = USER_EEPROM_BASE + (slice << SLICE_BITS);

	/* select the eeprom address */
	if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) {
	dev_err(&client->dev, "address set failed\n");
	goto exit_up;
	}

	if (i2c_check_functionality(client->adapter,
	I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
	if (i2c_smbus_read_i2c_block_data(client,
	MAX6875_CMD_BLK_READ,
	buf) != SLICE_SIZE) {
	goto exit_up;
	}
	} else {
	for (i = 0; i < SLICE_SIZE; i++) {
	j = i2c_smbus_read_byte(client);
	if (j < 0) {
	goto exit_up;
	}
	buf[i] = j;
	}
	}
	data->last_updated[slice] = jiffies;
	data->valid \|= (1 << slice);
	}
	exit_up:
	up(&data->update_lock);
	}

	static ssize_t max6875_read(struct kobject kobj, char buf, loff_t off,
	size_t count)
	{
	struct i2c_client *client = kobj_to_i2c_client(kobj);
	struct max6875_data *data = i2c_get_clientdata(client);
	int slice, max_slice;

	if (off > USER_EEPROM_SIZE)
	return 0;

	if (off + count > USER_EEPROM_SIZE)
	count = USER_EEPROM_SIZE - off;

	/* refresh slices which contain requested bytes */
	max_slice = (off + count - 1) >> SLICE_BITS;
	for (slice = (off >> SLICE_BITS); slice <= max_slice; slice++)
	max6875_update_slice(client, slice);

	memcpy(buf, &data->data[off], count);

	return count;
	}

	static struct bin_attribute user_eeprom_attr = {
	.attr = {
	.name = "eeprom",
	.mode = S_IRUGO,
	.owner = THIS_MODULE,
	},
	.size = USER_EEPROM_SIZE,
	.read = max6875_read,
	};

	static int max6875_attach_adapter(struct i2c_adapter *adapter)
	{
	return i2c_detect(adapter, &addr_data, max6875_detect);
	}

	/* This function is called by i2c_detect */
	static int max6875_detect(struct i2c_adapter *adapter, int address, int kind)
	{
	struct i2c_client *real_client;
	struct i2c_client *fake_client;
	struct max6875_data *data;
	int err = 0;

	/* Prevent 24rf08 corruption (in case of user error) */
	if (kind < 0)
	i2c_smbus_xfer(adapter, address, 0, 0, 0,
	I2C_SMBUS_QUICK, NULL);

	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA
	\| I2C_FUNC_SMBUS_READ_BYTE))
	return 0;

	/* Only check even addresses */
	if (address & 1)
	return 0;

	if (!(data = kmalloc(sizeof(struct max6875_data), GFP_KERNEL)))
	return -ENOMEM;
	memset(data, 0, sizeof(struct max6875_data));

	/* A fake client is created on the odd address */
	if (!(fake_client = kmalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
	err = -ENOMEM;
	goto exit_kfree1;
	}
	memset(fake_client, 0, sizeof(struct i2c_client));

	/* Init real i2c_client */
	real_client = &data->client;
	i2c_set_clientdata(real_client, data);
	real_client->addr = address;
	real_client->adapter = adapter;
	real_client->driver = &max6875_driver;
	real_client->flags = 0;
	strlcpy(real_client->name, "max6875", I2C_NAME_SIZE);
	init_MUTEX(&data->update_lock);

	/* Init fake client data */
	/* set the client data to the i2c_client so that it will get freed */
	i2c_set_clientdata(fake_client, fake_client);
	fake_client->addr = address \| 1;
	fake_client->adapter = adapter;
	fake_client->driver = &max6875_driver;
	fake_client->flags = 0;
	strlcpy(fake_client->name, "max6875 subclient", I2C_NAME_SIZE);

	/* Prevent 24RF08 corruption (in case of user error) */
	i2c_smbus_write_quick(real_client, 0);

	if ((err = i2c_attach_client(real_client)) != 0)
	goto exit_kfree2;

	if ((err = i2c_attach_client(fake_client)) != 0)
	goto exit_detach;

	sysfs_create_bin_file(&real_client->dev.kobj, &user_eeprom_attr);

	return 0;

	exit_detach:
	i2c_detach_client(real_client);
	exit_kfree2:
	kfree(fake_client);
	exit_kfree1:
	kfree(data);
	return err;
	}

	static int max6875_detach_client(struct i2c_client *client)
	{
	int err;

	err = i2c_detach_client(client);
	if (err)
	return err;
	kfree(i2c_get_clientdata(client));
	return 0;
	}

	static int __init max6875_init(void)
	{
	return i2c_add_driver(&max6875_driver);
	}

	static void __exit max6875_exit(void)
	{
	i2c_del_driver(&max6875_driver);
	}


	MODULE_AUTHOR("Ben Gardner <bgardner@wabtec.com>");
	MODULE_DESCRIPTION("MAX6875 driver");
	MODULE_LICENSE("GPL");

	module_init(max6875_init);
	module_exit(max6875_exit);