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.
+ 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 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
+ This driver makes the user EEPROM available for read.
- In our application, we put device serial & model numbers in user eeprom.
+ The registers & config EEPROM should be accessed via i2c-dev.
- 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.
+ 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/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>
+#include <asm/semaphore.h>
-/* Addresses to scan */
-/* No address scanned by default, as this could corrupt standard EEPROMS. */
+/* Do not scan - the MAX6875 access method will write to some EEPROM chips */
static unsigned short normal_i2c[] = {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;
-};
+#define MAX6875_CMD_BLK_READ 0x84
/* 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)];
+
+ u32 valid;
+ u8 data[USER_EEPROM_SIZE];
+ unsigned long last_updated[USER_EEPROM_SLICES];
};
static int max6875_attach_adapter(struct i2c_adapter *adapter);
.detach_client = max6875_detach_client,
};
-static int max6875_update_slice(struct i2c_client *client,
- struct eeprom_block *blk,
- int slice)
+static void max6875_update_slice(struct i2c_client *client, int slice)
{
struct max6875_data *data = i2c_get_clientdata(client);
- int i, j, addr, count;
- u8 rdbuf[SLICE_SIZE];
+ int i, j, addr;
+ u8 *buf;
int retval = 0;
- if (slice >= blk->slices)
- return -1;
+ if (slice >= USER_EEPROM_SLICES)
+ return;
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",
+ 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, blk->base);
- addr = blk->base + (slice << SLICE_BITS);
- count = blk->size - (slice << SLICE_BITS);
- if (count > SLICE_SIZE) {
- count = SLICE_SIZE;
- }
+ data->valid &= ~(1 << slice);
- /* 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;
- }
+ 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");
+ retval = -1;
+ 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_BLOCK_READ,
- rdbuf) != SLICE_SIZE)
- {
+ 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) {
retval = -1;
- goto exit;
+ goto exit_up;
}
-
- memcpy(&blk->data[slice << SLICE_BITS], rdbuf, count);
} else {
- for (i = 0; i < count; i++) {
+ for (i = 0; i < SLICE_SIZE; i++) {
j = i2c_smbus_read_byte(client);
- if (j < 0)
- {
+ if (j < 0) {
retval = -1;
- goto exit;
+ goto exit_up;
}
- blk->data[(slice << SLICE_BITS) + i] = (u8) j;
+ buf[i] = j;
}
}
- blk->updated[slice] = jiffies;
- blk->valid |= (1 << slice);
+ data->last_updated[slice] = jiffies;
+ data->valid |= (1 << slice);
}
- exit:
+exit_up:
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)
+static inline struct i2c_client *kobj_to_i2c_client(struct kobject *kobj)
{
- return max6875_read(kobj, buf, off, count, max6875_eeprom_config);
+ return to_i2c_client(container_of(kobj, struct device, kobj));
}
-static ssize_t max6875_cfgreg_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
+static ssize_t max6875_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 i2c_client *client = kobj_to_i2c_client(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];
+ int slice, max_slice;
- if (off > blk->size)
+ if (off > USER_EEPROM_SIZE)
return 0;
- if ((off + count) > blk->size)
- count = blk->size - off;
- if (down_interruptible(&data->update_lock))
- return -EAGAIN;
+ if (off + count > USER_EEPROM_SIZE)
+ count = USER_EEPROM_SIZE - off;
- /* 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;
+ /* 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);
- 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;
- }
+ memcpy(buf, &data->data[off], count);
- /* 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);
+ return count;
}
static struct bin_attribute user_eeprom_attr = {
.attr = {
- .name = "eeprom_user",
- .mode = S_IRUGO | S_IWUSR | S_IWGRP,
+ .name = "eeprom",
+ .mode = S_IRUGO,
.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,
+ .size = USER_EEPROM_SIZE,
+ .read = max6875_read,
};
static int max6875_attach_adapter(struct i2c_adapter *adapter)
/* 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 i2c_client *real_client;
+ struct i2c_client *fake_client;
struct max6875_data *data;
int err = 0;
- /* Prevent 24RF08 corruption (in case of user error) */
+ /* Prevent 24rf08 corruption (in case of user error) */
if (kind < 0)
i2c_smbus_xfer(adapter, address, 0, 0, 0,
I2C_SMBUS_QUICK, NULL);
- /* 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;
- }
+ if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_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));
- 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);
+ /* 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);
- /* 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);
+ /* 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-dummy", 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_kfree:
+exit_detach:
+ i2c_detach_client(real_client);
+exit_kfree2:
+ kfree(fake_client);
+exit_kfree1:
kfree(data);
-exit:
return err;
}
err = i2c_detach_client(client);
if (err) {
- dev_err(&client->dev, "Client deregistration failed, client not detached.\n");
+ dev_err(&client->dev, "i2c_detach_client() failed\n");
return err;
}
-
kfree(i2c_get_clientdata(client));
-
return 0;
}
projects / linux-2.6-omap-h63xx.git / commitdiff