[PATCH] I2C: add eeprom i2c chip driver.

This is based on the i2c cvs driver, but ported to 2.6 and rewritten
to use the sysfs binary file interface.

Documentation/i2c/sysfs-interface

@@ -77,7 +77,10 @@ curr_min[1-n]	Current min or hysteresis value.
 curr_input[1-n]	Current input value
 		Fixed point XXXXX, divide by 1000 to get Amps.
 		Read only.
-		
+
+eeprom		Raw EEPROM data in binary form.
+		Read only.
+
 fan_min[1-3]	Fan minimum value
 		Integer value indicating RPM
 		Read/Write.

drivers/i2c/chips/Kconfig

@@ -21,6 +21,18 @@ config SENSORS_ADM1021
 	  This driver can also be built as a module.  If so, the module
 	  will be called adm1021.
 
+config SENSORS_EEPROM
+	tristate "EEPROM (DIMM) reader"
+	depends on I2C && EXPERIMENTAL
+	select I2C_SENSOR
+	help
+	  If you say yes here you get read-only access to the EEPROM data
+	  available on modern memory DIMMs, and which could theoretically
+	  also be available on other devices.
+
+	  This driver can also be built as a module.  If so, the module
+	  will be called eeprom.
+
 config SENSORS_IT87
 	tristate "National Semiconductors IT87 and compatibles"
 	depends on I2C && EXPERIMENTAL

drivers/i2c/chips/Makefile

@@ -6,6 +6,7 @@
 obj-$(CONFIG_SENSORS_W83781D)	+= w83781d.o
 
 obj-$(CONFIG_SENSORS_ADM1021)	+= adm1021.o
+obj-$(CONFIG_SENSORS_EEPROM)	+= eeprom.o
 obj-$(CONFIG_SENSORS_IT87)	+= it87.o
 obj-$(CONFIG_SENSORS_LM75)	+= lm75.o
 obj-$(CONFIG_SENSORS_LM78)	+= lm78.o

drivers/i2c/chips/eeprom.c

+/*
+    eeprom.c - Part of lm_sensors, Linux kernel modules for hardware
+               monitoring
+    Copyright (C) 1998, 1999  Frodo Looijaard <frodol@dds.nl> and
+			       Philip Edelbrock <phil@netroedge.com>
+    Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
+    Copyright (C) 2003 IBM Corp.
+
+    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; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+*/
+
+/* #define DEBUG */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/i2c.h>
+#include <linux/i2c-sensor.h>
+
+/* Addresses to scan */
+static unsigned short normal_i2c[] = { I2C_CLIENT_END };
+static unsigned short normal_i2c_range[] = { 0x50, 0x57, I2C_CLIENT_END };
+static unsigned int normal_isa[] = { I2C_CLIENT_ISA_END };
+static unsigned int normal_isa_range[] = { I2C_CLIENT_ISA_END };
+
+/* Insmod parameters */
+SENSORS_INSMOD_1(eeprom);
+
+static int checksum = 0;
+MODULE_PARM(checksum, "i");
+MODULE_PARM_DESC(checksum, "Only accept eeproms whose checksum is correct");
+
+
+/* EEPROM registers */
+#define EEPROM_REG_CHECKSUM	0x3f
+
+/* EEPROM memory types: */
+#define ONE_K			1
+#define TWO_K			2
+#define FOUR_K			3
+#define EIGHT_K			4
+#define SIXTEEN_K		5
+
+/* Size of EEPROM in bytes */
+#define EEPROM_SIZE		256
+
+/* possible types of eeprom devices */
+enum eeprom_nature {
+	UNKNOWN,
+	VAIO,
+};
+
+/* Each client has this additional data */
+struct eeprom_data {
+	struct semaphore update_lock;
+	char valid;			/* !=0 if following fields are valid */
+	unsigned long last_updated;	/* In jiffies */
+	u8 data[EEPROM_SIZE];		/* Register values */
+};
+
+
+static int eeprom_attach_adapter(struct i2c_adapter *adapter);
+static int eeprom_detect(struct i2c_adapter *adapter, int address, int kind);
+static int eeprom_detach_client(struct i2c_client *client);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver eeprom_driver = {
+	.owner		= THIS_MODULE,
+	.name		= "eeprom",
+	.id		= I2C_DRIVERID_EEPROM,
+	.flags		= I2C_DF_NOTIFY,
+	.attach_adapter	= eeprom_attach_adapter,
+	.detach_client	= eeprom_detach_client,
+};
+
+static int eeprom_id = 0;
+
+static void eeprom_update_client(struct i2c_client *client)
+{
+	struct eeprom_data *data = i2c_get_clientdata(client);
+	int i, j;
+
+	down(&data->update_lock);
+
+	if ((jiffies - data->last_updated > 300 * HZ) |
+	    (jiffies < data->last_updated) || !data->valid) {
+		dev_dbg(&client->dev, "Starting eeprom update\n");
+
+		if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+			for (i=0; i < EEPROM_SIZE; i += I2C_SMBUS_I2C_BLOCK_MAX)
+				if (i2c_smbus_read_i2c_block_data(client, i, data->data + i) != I2C_SMBUS_I2C_BLOCK_MAX)
+					goto exit;
+		} else {
+			if (i2c_smbus_write_byte(client, 0)) {
+				dev_dbg(&client->dev, "eeprom read start has failed!\n");
+				goto exit;
+			}
+			for (i = 0; i < EEPROM_SIZE; i++) {
+				j = i2c_smbus_read_byte(client);
+				if (j < 0)
+					goto exit;
+				data->data[i] = (u8) j;
+			}
+		}
+		data->last_updated = jiffies;
+		data->valid = 1;
+	}
+exit:
+	up(&data->update_lock);
+}
+
+static ssize_t eeprom_read(struct kobject *kobj, char *buf, loff_t off, size_t count)
+{
+	struct i2c_client *client = to_i2c_client(container_of(kobj, struct device, kobj));
+	struct eeprom_data *data = i2c_get_clientdata(client);
+
+	eeprom_update_client(client);
+
+	if (off > EEPROM_SIZE)
+		return 0;
+	if (off + count > EEPROM_SIZE)
+		count = EEPROM_SIZE - off;
+
+	memcpy(buf, &data->data[off], count);
+	return count;
+}
+
+static struct bin_attribute eeprom_attr = {
+	.attr = {
+		.name = "eeprom",
+		.mode = S_IRUGO,
+	},
+	.size = EEPROM_SIZE,
+	.read = eeprom_read,
+};
+
+static int eeprom_attach_adapter(struct i2c_adapter *adapter)
+{
+	return i2c_detect(adapter, &addr_data, eeprom_detect);
+}
+
+/* This function is called by i2c_detect */
+int eeprom_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+	int i, cs;
+	struct i2c_client *new_client;
+	struct eeprom_data *data;
+	enum eeprom_nature nature = UNKNOWN;
+	int err = 0;
+
+	/* Make sure we aren't probing the ISA bus!! This is just a safety check
+	   at this moment; i2c_detect really won't call us. */
+#ifdef DEBUG
+	if (i2c_is_isa_adapter(adapter)) {
+		dev_dbg(&adapter->dev, " eeprom_detect called for an ISA bus adapter?!?\n");
+		return 0;
+	}
+#endif
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_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 (!(new_client = kmalloc(sizeof(struct i2c_client) +
+				   sizeof(struct eeprom_data),
+				   GFP_KERNEL))) {
+		err = -ENOMEM;
+		goto exit;
+	}
+	memset(new_client, 0x00, sizeof(struct i2c_client) +
+				 sizeof(struct eeprom_data));
+
+	data = (struct eeprom_data *) (new_client + 1);
+	memset(data, 0xff, EEPROM_SIZE);
+	i2c_set_clientdata(new_client, data);
+	new_client->addr = address;
+	new_client->adapter = adapter;
+	new_client->driver = &eeprom_driver;
+	new_client->flags = 0;
+
+	/* Now, we do the remaining detection. It is not there, unless you force
+	   the checksum to work out. */
+	if (checksum) {
+		/* prevent 24RF08 corruption */
+		i2c_smbus_write_quick(new_client, 0);
+		cs = 0;
+		for (i = 0; i <= 0x3e; i++)
+			cs += i2c_smbus_read_byte_data(new_client, i);
+		cs &= 0xff;
+		if (i2c_smbus_read_byte_data (new_client, EEPROM_REG_CHECKSUM) != cs)
+			goto exit_kfree;
+	}
+
+	/* Detect the Vaio nature of EEPROMs.
+	   We use the "PCG-" prefix as the signature. */
+	if (address == 0x57) {
+		if (i2c_smbus_read_byte_data(new_client, 0x80) == 'P' && 
+		    i2c_smbus_read_byte_data(new_client, 0x81) == 'C' && 
+		    i2c_smbus_read_byte_data(new_client, 0x82) == 'G' &&
+		    i2c_smbus_read_byte_data(new_client, 0x83) == '-')
+			nature = VAIO;
+	}
+
+	/* If this is a VIAO, then we only allow root to read from this file,
+	   as BIOS passwords can be present here in plaintext */
+	switch (nature) {
+ 	case VAIO:
+		eeprom_attr.attr.mode = S_IRUSR;
+		break;
+	default:
+		eeprom_attr.attr.mode = S_IRUGO;
+	}
+
+	/* Fill in the remaining client fields */
+	strncpy(new_client->name, "eeprom", I2C_NAME_SIZE);
+	new_client->id = eeprom_id++;
+	data->valid = 0;
+	init_MUTEX(&data->update_lock);
+
+	/* Tell the I2C layer a new client has arrived */
+	if ((err = i2c_attach_client(new_client)))
+		goto exit_kfree;
+
+	/* create the sysfs eeprom file */
+	sysfs_create_bin_file(&new_client->dev.kobj, &eeprom_attr);
+
+	return 0;
+
+exit_kfree:
+	kfree(new_client);
+exit:
+	return err;
+}
+
+static int eeprom_detach_client(struct i2c_client *client)
+{
+	int err;
+
+	err = i2c_detach_client(client);
+	if (err) {
+		dev_err(&client->dev, "Client deregistration failed, client not detached.\n");
+		return err;
+	}
+
+	kfree(client);
+
+	return 0;
+}
+
+static int __init eeprom_init(void)
+{
+	return i2c_add_driver(&eeprom_driver);
+}
+
+static void __exit eeprom_exit(void)
+{
+	i2c_del_driver(&eeprom_driver);
+}
+
+
+MODULE_AUTHOR("Frodo Looijaard <frodol@dds.nl> and "
+		"Philip Edelbrock <phil@netroedge.com> and "
+		"Greg Kroah-Hartman <greg@kroah.com>");
+MODULE_DESCRIPTION("I2C EEPROM driver");
+MODULE_LICENSE("GPL");
+
+module_init(eeprom_init);
+module_exit(eeprom_exit);