--- /dev/null
+/*
+ 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/mutex.h>
+
+/* Do not scan - the MAX6875 access method will write to some EEPROM chips */
+static 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 client;
+ struct mutex 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 = {
+ .driver = {
+ .name = "max6875",
+ },
+ .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;
+
+ 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,
+ 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, 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_probe(adapter, &addr_data, max6875_detect);
+}
+
+/* This function is called by i2c_probe */
+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;
+
+ 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 = kzalloc(sizeof(struct max6875_data), GFP_KERNEL)))
+ return -ENOMEM;
+
+ /* A fake client is created on the odd address */
+ if (!(fake_client = kzalloc(sizeof(struct i2c_client), GFP_KERNEL))) {
+ err = -ENOMEM;
+ goto exit_kfree1;
+ }
+
+ /* 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);
+ mutex_init(&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);
git://git.onelab.eu / linux-2.6.git / blobdiff