[PATCH] max6875: new i2c device driver
This patch adds support for the MAX6875/MAX6874 chips.
Signed-off-by: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
diff --git a/drivers/i2c/chips/max6875.c b/drivers/i2c/chips/max6875.c
new file mode 100644
index 0000000..fe6b150
--- /dev/null
+++ b/drivers/i2c/chips/max6875.c
@@ -0,0 +1,473 @@
+/*
+ max6875.c - driver for MAX6874/MAX6875
+
+ Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
+
+ Based on i2c/chips/eeprom.c
+
+ The MAX6875 has two EEPROM sections: config and user.
+ At reset, the config EEPROM is read into the registers.
+
+ This driver make 3 binary files available in sysfs:
+ reg_config - direct access to the registers
+ eeprom_config - acesses configuration eeprom space
+ eeprom_user - free for application use
+
+ In our application, we put device serial & model numbers in user eeprom.
+
+ Notes:
+ 1) The datasheet says that register 0x44 / EEPROM 0x8044 should NOT
+ be overwritten, so the driver explicitly prevents that.
+ 2) It's a good idea to keep the config (0x45) locked in config EEPROM.
+ You can temporarily enable config writes by changing register 0x45.
+
+ 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/config.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/i2c-sensor.h>
+
+/* Addresses to scan */
+static unsigned short normal_i2c[] = {0x50, 0x52, I2C_CLIENT_END};
+static unsigned int normal_isa[] = {I2C_CLIENT_ISA_END};
+
+/* Insmod parameters */
+SENSORS_INSMOD_1(max6875);
+
+/* this param will prevent 'accidental' writes to the eeprom */
+static int allow_write = 0;
+module_param(allow_write, int, 0);
+MODULE_PARM_DESC(allow_write,
+ "Enable write access:\n"
+ "*0: Read only\n"
+ " 1: Read/Write access");
+
+/* The MAX6875 can only read/write 16 bytes at a time */
+#define SLICE_SIZE 16
+#define SLICE_BITS 4
+
+/* CONFIG EEPROM is at addresses 0x8000 - 0x8045, registers are at 0 - 0x45 */
+#define CONFIG_EEPROM_BASE 0x8000
+#define CONFIG_EEPROM_SIZE 0x0046
+#define CONFIG_EEPROM_SLICES 5
+
+/* 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_BLOCK_WRITE 0x83
+#define MAX6875_CMD_BLOCK_READ 0x84
+#define MAX6875_CMD_REBOOT 0x88
+
+enum max6875_area_type {
+ max6875_register_config=0,
+ max6875_eeprom_config,
+ max6875_eeprom_user,
+ max6857_max
+};
+
+struct eeprom_block {
+ enum max6875_area_type type;
+ u8 slices;
+ u32 size;
+ u32 valid;
+ u32 base;
+ unsigned long *updated;
+ u8 *data;
+};
+
+/* Each client has this additional data */
+struct max6875_data {
+ struct i2c_client client;
+ struct semaphore update_lock;
+ struct eeprom_block blocks[max6857_max];
+ /* the above structs point into the arrays below */
+ u8 data[USER_EEPROM_SIZE + (CONFIG_EEPROM_SIZE*2)];
+ unsigned long last_updated[USER_EEPROM_SLICES + (CONFIG_EEPROM_SLICES*2)];
+};
+
+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 int max6875_update_slice(struct i2c_client *client,
+ struct eeprom_block *blk,
+ int slice)
+{
+ struct max6875_data *data = i2c_get_clientdata(client);
+ int i, j, addr, count;
+ u8 rdbuf[SLICE_SIZE];
+ int retval = 0;
+
+ if (slice >= blk->slices)
+ return -1;
+
+ down(&data->update_lock);
+
+ if (!(blk->valid & (1 << slice)) ||
+ (jiffies - blk->updated[slice] > 300 * HZ) ||
+ (jiffies < blk->updated[slice])) {
+ dev_dbg(&client->dev, "Starting eeprom update, slice %u, base %u\n",
+ slice, blk->base);
+
+ addr = blk->base + (slice << SLICE_BITS);
+ count = blk->size - (slice << SLICE_BITS);
+ if (count > SLICE_SIZE) {
+ count = SLICE_SIZE;
+ }
+
+ /* Preset the read address */
+ if (addr < 0x100) {
+ /* select the register */
+ if (i2c_smbus_write_byte(client, addr & 0xFF)) {
+ dev_dbg(&client->dev, "max6875 register select has failed!\n");
+ retval = -1;
+ goto exit;
+ }
+ } else {
+ /* select the eeprom */
+ if (i2c_smbus_write_byte_data(client, addr >> 8, addr & 0xFF)) {
+ dev_dbg(&client->dev, "max6875 address set has failed!\n");
+ retval = -1;
+ goto exit;
+ }
+ }
+
+ if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+ if (i2c_smbus_read_i2c_block_data(client, MAX6875_CMD_BLOCK_READ,
+ rdbuf) != SLICE_SIZE)
+ {
+ retval = -1;
+ goto exit;
+ }
+
+ memcpy(&blk->data[slice << SLICE_BITS], rdbuf, count);
+ } else {
+ for (i = 0; i < count; i++) {
+ j = i2c_smbus_read_byte(client);
+ if (j < 0)
+ {
+ retval = -1;
+ goto exit;
+ }
+ blk->data[(slice << SLICE_BITS) + i] = (u8) j;
+ }
+ }
+ blk->updated[slice] = jiffies;
+ blk->valid |= (1 << slice);
+ }
+ exit:
+ up(&data->update_lock);
+ return retval;
+}
+
+static ssize_t max6875_read(struct kobject *kobj, char *buf, loff_t off, size_t count,
+ enum max6875_area_type area_type)
+{
+ struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
+ struct max6875_data *data = i2c_get_clientdata(client);
+ struct eeprom_block *blk;
+ int slice;
+
+ blk = &data->blocks[area_type];
+
+ if (off > blk->size)
+ return 0;
+ if (off + count > blk->size)
+ count = blk->size - off;
+
+ /* Only refresh slices which contain requested bytes */
+ for (slice = (off >> SLICE_BITS); slice <= ((off + count - 1) >> SLICE_BITS); slice++)
+ max6875_update_slice(client, blk, slice);
+
+ memcpy(buf, &blk->data[off], count);
+
+ return count;
+}
+
+static ssize_t max6875_user_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
+{
+ return max6875_read(kobj, buf, off, count, max6875_eeprom_user);
+}
+
+static ssize_t max6875_config_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
+{
+ return max6875_read(kobj, buf, off, count, max6875_eeprom_config);
+}
+
+static ssize_t max6875_cfgreg_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
+{
+ return max6875_read(kobj, buf, off, count, max6875_register_config);
+}
+
+
+static ssize_t max6875_write(struct kobject *kobj, char *buf, loff_t off, size_t count,
+ enum max6875_area_type area_type)
+{
+ struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
+ struct max6875_data *data = i2c_get_clientdata(client);
+ struct eeprom_block *blk;
+ int slice, addr, retval;
+ ssize_t sent = 0;
+
+ blk = &data->blocks[area_type];
+
+ if (off > blk->size)
+ return 0;
+ if ((off + count) > blk->size)
+ count = blk->size - off;
+
+ if (down_interruptible(&data->update_lock))
+ return -EAGAIN;
+
+ /* writing to a register is done with i2c_smbus_write_byte_data() */
+ if (blk->type == max6875_register_config) {
+ for (sent = 0; sent < count; sent++) {
+ addr = off + sent;
+ if (addr == 0x44)
+ continue;
+
+ retval = i2c_smbus_write_byte_data(client, addr, buf[sent]);
+ }
+ } else {
+ int cmd, val;
+
+ /* We are writing to EEPROM */
+ for (sent = 0; sent < count; sent++) {
+ addr = blk->base + off + sent;
+ cmd = addr >> 8;
+ val = (addr & 0xff) | (buf[sent] << 8); // reversed
+
+ if (addr == 0x8044)
+ continue;
+
+ retval = i2c_smbus_write_word_data(client, cmd, val);
+
+ if (retval) {
+ goto error_exit;
+ }
+
+ /* A write takes up to 11 ms */
+ msleep(11);
+ }
+ }
+
+ /* Invalidate the scratch buffer */
+ for (slice = (off >> SLICE_BITS); slice <= ((off + count - 1) >> SLICE_BITS); slice++)
+ blk->valid &= ~(1 << slice);
+
+ error_exit:
+ up(&data->update_lock);
+
+ return sent;
+}
+
+static ssize_t max6875_user_write(struct kobject *kobj, char *buf, loff_t off, size_t count)
+{
+ return max6875_write(kobj, buf, off, count, max6875_eeprom_user);
+}
+
+static ssize_t max6875_config_write(struct kobject *kobj, char *buf, loff_t off, size_t count)
+{
+ return max6875_write(kobj, buf, off, count, max6875_eeprom_config);
+}
+
+static ssize_t max6875_cfgreg_write(struct kobject *kobj, char *buf, loff_t off, size_t count)
+{
+ return max6875_write(kobj, buf, off, count, max6875_register_config);
+}
+
+static struct bin_attribute user_eeprom_attr = {
+ .attr = {
+ .name = "eeprom_user",
+ .mode = S_IRUGO | S_IWUSR | S_IWGRP,
+ .owner = THIS_MODULE,
+ },
+ .size = USER_EEPROM_SIZE,
+ .read = max6875_user_read,
+ .write = max6875_user_write,
+};
+
+static struct bin_attribute config_eeprom_attr = {
+ .attr = {
+ .name = "eeprom_config",
+ .mode = S_IRUGO | S_IWUSR,
+ .owner = THIS_MODULE,
+ },
+ .size = CONFIG_EEPROM_SIZE,
+ .read = max6875_config_read,
+ .write = max6875_config_write,
+};
+
+static struct bin_attribute config_register_attr = {
+ .attr = {
+ .name = "reg_config",
+ .mode = S_IRUGO | S_IWUSR,
+ .owner = THIS_MODULE,
+ },
+ .size = CONFIG_EEPROM_SIZE,
+ .read = max6875_cfgreg_read,
+ .write = max6875_cfgreg_write,
+};
+
+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 *new_client;
+ struct max6875_data *data;
+ int err = 0;
+
+ /* There are three ways we can read the EEPROM data:
+ (1) I2C block reads (faster, but unsupported by most adapters)
+ (2) Consecutive byte reads (100% overhead)
+ (3) Regular byte data reads (200% overhead)
+ The third method is not implemented by this driver because all
+ known adapters support at least the second. */
+ if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA |
+ I2C_FUNC_SMBUS_BYTE |
+ I2C_FUNC_SMBUS_WRITE_BYTE_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 eeprom_{read,write}_value. */
+ if (!(data = kmalloc(sizeof(struct max6875_data), GFP_KERNEL))) {
+ err = -ENOMEM;
+ goto exit;
+ }
+ memset(data, 0, sizeof(struct max6875_data));
+
+ new_client = &data->client;
+ i2c_set_clientdata(new_client, data);
+ new_client->addr = address;
+ new_client->adapter = adapter;
+ new_client->driver = &max6875_driver;
+ new_client->flags = 0;
+
+ /* Setup the user section */
+ data->blocks[max6875_eeprom_user].type = max6875_eeprom_user;
+ data->blocks[max6875_eeprom_user].slices = USER_EEPROM_SLICES;
+ data->blocks[max6875_eeprom_user].size = USER_EEPROM_SIZE;
+ data->blocks[max6875_eeprom_user].base = USER_EEPROM_BASE;
+ data->blocks[max6875_eeprom_user].data = data->data;
+ data->blocks[max6875_eeprom_user].updated = data->last_updated;
+
+ /* Setup the config section */
+ data->blocks[max6875_eeprom_config].type = max6875_eeprom_config;
+ data->blocks[max6875_eeprom_config].slices = CONFIG_EEPROM_SLICES;
+ data->blocks[max6875_eeprom_config].size = CONFIG_EEPROM_SIZE;
+ data->blocks[max6875_eeprom_config].base = CONFIG_EEPROM_BASE;
+ data->blocks[max6875_eeprom_config].data = &data->data[USER_EEPROM_SIZE];
+ data->blocks[max6875_eeprom_config].updated = &data->last_updated[USER_EEPROM_SLICES];
+
+ /* Setup the register section */
+ data->blocks[max6875_register_config].type = max6875_register_config;
+ data->blocks[max6875_register_config].slices = CONFIG_EEPROM_SLICES;
+ data->blocks[max6875_register_config].size = CONFIG_EEPROM_SIZE;
+ data->blocks[max6875_register_config].base = 0;
+ data->blocks[max6875_register_config].data = &data->data[USER_EEPROM_SIZE+CONFIG_EEPROM_SIZE];
+ data->blocks[max6875_register_config].updated = &data->last_updated[USER_EEPROM_SLICES+CONFIG_EEPROM_SLICES];
+
+ /* Init the data */
+ memset(data->data, 0xff, sizeof(data->data));
+
+ /* Fill in the remaining client fields */
+ strlcpy(new_client->name, "max6875", I2C_NAME_SIZE);
+ init_MUTEX(&data->update_lock);
+
+ /* Verify that the chip is really what we think it is */
+ if ((max6875_update_slice(new_client, &data->blocks[max6875_eeprom_config], 4) < 0) ||
+ (max6875_update_slice(new_client, &data->blocks[max6875_register_config], 4) < 0))
+ goto exit_kfree;
+
+ /* 0x41,0x42 must be zero and 0x40 must match in eeprom and registers */
+ if ((data->blocks[max6875_eeprom_config].data[0x41] != 0) ||
+ (data->blocks[max6875_eeprom_config].data[0x42] != 0) ||
+ (data->blocks[max6875_register_config].data[0x41] != 0) ||
+ (data->blocks[max6875_register_config].data[0x42] != 0) ||
+ (data->blocks[max6875_eeprom_config].data[0x40] !=
+ data->blocks[max6875_register_config].data[0x40]))
+ goto exit_kfree;
+
+ /* Tell the I2C layer a new client has arrived */
+ if ((err = i2c_attach_client(new_client)))
+ goto exit_kfree;
+
+ /* create the sysfs eeprom files with the correct permissions */
+ if (allow_write == 0) {
+ user_eeprom_attr.attr.mode &= ~S_IWUGO;
+ user_eeprom_attr.write = NULL;
+ config_eeprom_attr.attr.mode &= ~S_IWUGO;
+ config_eeprom_attr.write = NULL;
+ config_register_attr.attr.mode &= ~S_IWUGO;
+ config_register_attr.write = NULL;
+ }
+ sysfs_create_bin_file(&new_client->dev.kobj, &user_eeprom_attr);
+ sysfs_create_bin_file(&new_client->dev.kobj, &config_eeprom_attr);
+ sysfs_create_bin_file(&new_client->dev.kobj, &config_register_attr);
+
+ return 0;
+
+exit_kfree:
+ kfree(data);
+exit:
+ return err;
+}
+
+static int max6875_detach_client(struct i2c_client *client)
+{
+ int err;
+
+ err = i2c_detach_client(client);
+ if (err) {
+ dev_err(&client->dev, "Client deregistration failed, client not detached.\n");
+ 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);