i2c/chips: Move max6875 to drivers/misc/eeprom

This driver only reads the user EEPROM of that chip, so we can move it
to the eeprom-directory in order to further clean up (and later remove)
drivers/i2c/chips.

The Kconfig text was updated to match the current functionality,
dropping the meanwhile obsoleted parts.

Defconfigs have been adapted.

Signed-off-by: Wolfram Sang <w.sang@pengutronix.de>
Acked-by: Ben Gardner <gardner.ben@gmail.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>

3 files changed, 261 insertions, 0 deletions

diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
index 89fec052f3b4..9118613af321 100644
--- a/drivers/misc/eeprom/Kconfig
+++ b/drivers/misc/eeprom/Kconfig
@@ -48,6 +48,20 @@ config EEPROM_LEGACY
           This driver can also be built as a module.  If so, the module
           will be called eeprom.
 
+config EEPROM_MAX6875
+        tristate "Maxim MAX6874/5 power supply supervisor"
+        depends on I2C && EXPERIMENTAL
+        help
+          If you say yes here you get read-only support for the user EEPROM of
+          the Maxim MAX6874/5 EEPROM-programmable, quad power-supply
+          sequencer/supervisor.
+
+          All other features of this chip should be accessed via i2c-dev.
+
+          This driver can also be built as a module.  If so, the module
+          will be called max6875.
+
+
 config EEPROM_93CX6
         tristate "EEPROM 93CX6 support"
         help
diff --git a/drivers/misc/eeprom/Makefile b/drivers/misc/eeprom/Makefile
index 539dd8f88128..df3d68ffa9d1 100644
--- a/drivers/misc/eeprom/Makefile
+++ b/drivers/misc/eeprom/Makefile
@@ -1,4 +1,5 @@
 obj-$(CONFIG_EEPROM_AT24)       += at24.o
 obj-$(CONFIG_EEPROM_AT25)       += at25.o
 obj-$(CONFIG_EEPROM_LEGACY)     += eeprom.o
+obj-$(CONFIG_EEPROM_MAX6875)    += max6875.o
 obj-$(CONFIG_EEPROM_93CX6)      += eeprom_93cx6.o
diff --git a/drivers/misc/eeprom/max6875.c b/drivers/misc/eeprom/max6875.c
new file mode 100644
index 000000000000..3c0c58eed347
--- /dev/null
+++ b/drivers/misc/eeprom/max6875.c
@@ -0,0 +1,246 @@
+/*
+    max6875.c - driver for MAX6874/MAX6875
+
+    Copyright (C) 2005 Ben Gardner <bgardner@wabtec.com>
+
+    Based on 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/mutex.h>
+
+/* Do not scan - the MAX6875 access method will write to some EEPROM chips */
+static const unsigned short normal_i2c[] = { I2C_CLIENT_END };
+
+/* Insmod parameters */
+I2C_CLIENT_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       *fake_client;
+        struct mutex            update_lock;
+
+        u32                     valid;
+        u8                      data[USER_EEPROM_SIZE];
+        unsigned long           last_updated[USER_EEPROM_SLICES];
+};
+
+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;
+
+        mutex_lock(&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,
+                                                          SLICE_SIZE,
+                                                          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:
+        mutex_unlock(&data->update_lock);
+}
+
+static ssize_t max6875_read(struct kobject *kobj,
+                            struct bin_attribute *bin_attr,
+                            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,
+        },
+        .size = USER_EEPROM_SIZE,
+        .read = max6875_read,
+};
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int max6875_detect(struct i2c_client *client, int kind,
+                          struct i2c_board_info *info)
+{
+        struct i2c_adapter *adapter = client->adapter;
+
+        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_WRITE_BYTE_DATA
+                                     | I2C_FUNC_SMBUS_READ_BYTE))
+                return -ENODEV;
+
+        /* Only check even addresses */
+        if (client->addr & 1)
+                return -ENODEV;
+
+        strlcpy(info->type, "max6875", I2C_NAME_SIZE);
+
+        return 0;
+}
+
+static int max6875_probe(struct i2c_client *client,
+                         const struct i2c_device_id *id)
+{
+        struct max6875_data *data;
+        int err;
+
+        if (!(data = kzalloc(sizeof(struct max6875_data), GFP_KERNEL)))
+                return -ENOMEM;
+
+        /* A fake client is created on the odd address */
+        data->fake_client = i2c_new_dummy(client->adapter, client->addr + 1);
+        if (!data->fake_client) {
+                err = -ENOMEM;
+                goto exit_kfree;
+        }
+
+        /* Init real i2c_client */
+        i2c_set_clientdata(client, data);
+        mutex_init(&data->update_lock);
+
+        err = sysfs_create_bin_file(&client->dev.kobj, &user_eeprom_attr);
+        if (err)
+                goto exit_remove_fake;
+
+        return 0;
+
+exit_remove_fake:
+        i2c_unregister_device(data->fake_client);
+exit_kfree:
+        kfree(data);
+        return err;
+}
+
+static int max6875_remove(struct i2c_client *client)
+{
+        struct max6875_data *data = i2c_get_clientdata(client);
+
+        i2c_unregister_device(data->fake_client);
+
+        sysfs_remove_bin_file(&client->dev.kobj, &user_eeprom_attr);
+        kfree(data);
+
+        return 0;
+}
+
+static const struct i2c_device_id max6875_id[] = {
+        { "max6875", 0 },
+        { }
+};
+
+static struct i2c_driver max6875_driver = {
+        .driver = {
+                .name   = "max6875",
+        },
+        .probe          = max6875_probe,
+        .remove         = max6875_remove,
+        .id_table       = max6875_id,
+
+        .detect         = max6875_detect,
+        .address_data   = &addr_data,
+};
+
+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);