1 files changed, 123 insertions, 322 deletions

diff --git a/drivers/i2c/chips/max6875.c b/drivers/i2c/chips/max6875.c
index 0230375f72e5..4d4ace4b805f 100644
--- a/drivers/i2c/chips/max6875.c
+++ b/drivers/i2c/chips/max6875.c
@@ -5,97 +5,62 @@
 
     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);
@@ -111,224 +76,98 @@ static struct i2c_driver max6875_driver = {
         .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)
@@ -339,109 +178,73 @@ 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;
 }
 
@@ -451,12 +254,10 @@ static int max6875_detach_client(struct i2c_client *client)
 
         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;
 }