1 files changed, 261 insertions, 0 deletions
diff --git a/drivers/i2c/chips/max6875.c b/drivers/i2c/chips/max6875.c
new file mode 100644
index 000000000000..9e1aeb69abf9
--- /dev/null
+++ b/drivers/i2c/chips/max6875.c
@@ -0,0 +1,261 @@
+/*
+    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 <asm/semaphore.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 semaphore	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 = {
+	.owner		= THIS_MODULE,
+	.name		= "max6875",
+	.flags		= I2C_DF_NOTIFY,
+	.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;
+
+	down(&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:
+	up(&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 = kmalloc(sizeof(struct max6875_data), GFP_KERNEL)))
+		return -ENOMEM;
+	memset(data, 0, sizeof(struct max6875_data));
+
+	/* 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);
+
+	/* 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);