3 files changed, 269 insertions, 0 deletions

diff --git a/drivers/misc/eeprom/Kconfig b/drivers/misc/eeprom/Kconfig
index 0b21778b7d13..3d31b6644245 100644
--- a/drivers/misc/eeprom/Kconfig
+++ b/drivers/misc/eeprom/Kconfig
@@ -26,4 +26,15 @@ config AT24
           This driver can also be built as a module.  If so, the module
           will be called at24.
 
+config SENSORS_EEPROM
+        tristate "Old I2C EEPROM reader"
+        depends on I2C && EXPERIMENTAL
+        help
+          If you say yes here you get read-only access to the EEPROM data
+          available on modern memory DIMMs and Sony Vaio laptops via I2C. Such
+          EEPROMs could theoretically be available on other devices as well.
+
+          This driver can also be built as a module.  If so, the module
+          will be called eeprom.
+
 endmenu
diff --git a/drivers/misc/eeprom/Makefile b/drivers/misc/eeprom/Makefile
index 72cd478eb53f..a3dad28f2724 100644
--- a/drivers/misc/eeprom/Makefile
+++ b/drivers/misc/eeprom/Makefile
@@ -1 +1,2 @@
 obj-$(CONFIG_AT24)              += at24.o
+obj-$(CONFIG_SENSORS_EEPROM)    += eeprom.o
diff --git a/drivers/misc/eeprom/eeprom.c b/drivers/misc/eeprom/eeprom.c
new file mode 100644
index 000000000000..2c27193aeaa0
--- /dev/null
+++ b/drivers/misc/eeprom/eeprom.c
@@ -0,0 +1,257 @@
+/*
+    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.
+    Copyright (C) 2004 Jean Delvare <khali@linux-fr.org>
+
+    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.
+*/
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/jiffies.h>
+#include <linux/i2c.h>
+#include <linux/mutex.h>
+
+/* Addresses to scan */
+static const unsigned short normal_i2c[] = { 0x50, 0x51, 0x52, 0x53, 0x54,
+                                        0x55, 0x56, 0x57, I2C_CLIENT_END };
+
+/* Insmod parameters */
+I2C_CLIENT_INSMOD_1(eeprom);
+
+
+/* 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 mutex update_lock;
+        u8 valid;                       /* bitfield, bit!=0 if slice is valid */
+        unsigned long last_updated[8];  /* In jiffies, 8 slices */
+        u8 data[EEPROM_SIZE];           /* Register values */
+        enum eeprom_nature nature;
+};
+
+
+static void eeprom_update_client(struct i2c_client *client, u8 slice)
+{
+        struct eeprom_data *data = i2c_get_clientdata(client);
+        int i;
+
+        mutex_lock(&data->update_lock);
+
+        if (!(data->valid & (1 << slice)) ||
+            time_after(jiffies, data->last_updated[slice] + 300 * HZ)) {
+                dev_dbg(&client->dev, "Starting eeprom update, slice %u\n", slice);
+
+                if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK)) {
+                        for (i = slice << 5; i < (slice + 1) << 5; i += 32)
+                                if (i2c_smbus_read_i2c_block_data(client, i,
+                                                        32, data->data + i)
+                                                        != 32)
+                                        goto exit;
+                } else {
+                        for (i = slice << 5; i < (slice + 1) << 5; i += 2) {
+                                int word = i2c_smbus_read_word_data(client, i);
+                                if (word < 0)
+                                        goto exit;
+                                data->data[i] = word & 0xff;
+                                data->data[i + 1] = word >> 8;
+                        }
+                }
+                data->last_updated[slice] = jiffies;
+                data->valid |= (1 << slice);
+        }
+exit:
+        mutex_unlock(&data->update_lock);
+}
+
+static ssize_t eeprom_read(struct kobject *kobj, struct bin_attribute *bin_attr,
+                           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);
+        u8 slice;
+
+        if (off > EEPROM_SIZE)
+                return 0;
+        if (off + count > EEPROM_SIZE)
+                count = EEPROM_SIZE - off;
+
+        /* Only refresh slices which contain requested bytes */
+        for (slice = off >> 5; slice <= (off + count - 1) >> 5; slice++)
+                eeprom_update_client(client, slice);
+
+        /* Hide Vaio private settings to regular users:
+           - BIOS passwords: bytes 0x00 to 0x0f
+           - UUID: bytes 0x10 to 0x1f
+           - Serial number: 0xc0 to 0xdf */
+        if (data->nature == VAIO && !capable(CAP_SYS_ADMIN)) {
+                int i;
+
+                for (i = 0; i < count; i++) {
+                        if ((off + i <= 0x1f) ||
+                            (off + i >= 0xc0 && off + i <= 0xdf))
+                                buf[i] = 0;
+                        else
+                                buf[i] = data->data[off + i];
+                }
+        } else {
+                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,
+};
+
+/* Return 0 if detection is successful, -ENODEV otherwise */
+static int eeprom_detect(struct i2c_client *client, int kind,
+                         struct i2c_board_info *info)
+{
+        struct i2c_adapter *adapter = client->adapter;
+
+        /* EDID EEPROMs are often 24C00 EEPROMs, which answer to all
+           addresses 0x50-0x57, but we only care about 0x50. So decline
+           attaching to addresses >= 0x51 on DDC buses */
+        if (!(adapter->class & I2C_CLASS_SPD) && client->addr >= 0x51)
+                return -ENODEV;
+
+        /* There are four ways we can read the EEPROM data:
+           (1) I2C block reads (faster, but unsupported by most adapters)
+           (2) Word reads (128% overhead)
+           (3) Consecutive byte reads (88% overhead, unsafe)
+           (4) Regular byte data reads (265% overhead)
+           The third and fourth methods are not implemented by this driver
+           because all known adapters support one of the first two. */
+        if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)
+         && !i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))
+                return -ENODEV;
+
+        strlcpy(info->type, "eeprom", I2C_NAME_SIZE);
+
+        return 0;
+}
+
+static int eeprom_probe(struct i2c_client *client,
+                        const struct i2c_device_id *id)
+{
+        struct i2c_adapter *adapter = client->adapter;
+        struct eeprom_data *data;
+        int err;
+
+        if (!(data = kzalloc(sizeof(struct eeprom_data), GFP_KERNEL))) {
+                err = -ENOMEM;
+                goto exit;
+        }
+
+        memset(data->data, 0xff, EEPROM_SIZE);
+        i2c_set_clientdata(client, data);
+        mutex_init(&data->update_lock);
+        data->nature = UNKNOWN;
+
+        /* Detect the Vaio nature of EEPROMs.
+           We use the "PCG-" or "VGN-" prefix as the signature. */
+        if (client->addr == 0x57
+         && i2c_check_functionality(adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA)) {
+                char name[4];
+
+                name[0] = i2c_smbus_read_byte_data(client, 0x80);
+                name[1] = i2c_smbus_read_byte_data(client, 0x81);
+                name[2] = i2c_smbus_read_byte_data(client, 0x82);
+                name[3] = i2c_smbus_read_byte_data(client, 0x83);
+
+                if (!memcmp(name, "PCG-", 4) || !memcmp(name, "VGN-", 4)) {
+                        dev_info(&client->dev, "Vaio EEPROM detected, "
+                                 "enabling privacy protection\n");
+                        data->nature = VAIO;
+                }
+        }
+
+        /* create the sysfs eeprom file */
+        err = sysfs_create_bin_file(&client->dev.kobj, &eeprom_attr);
+        if (err)
+                goto exit_kfree;
+
+        return 0;
+
+exit_kfree:
+        kfree(data);
+exit:
+        return err;
+}
+
+static int eeprom_remove(struct i2c_client *client)
+{
+        sysfs_remove_bin_file(&client->dev.kobj, &eeprom_attr);
+        kfree(i2c_get_clientdata(client));
+
+        return 0;
+}
+
+static const struct i2c_device_id eeprom_id[] = {
+        { "eeprom", 0 },
+        { }
+};
+
+static struct i2c_driver eeprom_driver = {
+        .driver = {
+                .name   = "eeprom",
+        },
+        .probe          = eeprom_probe,
+        .remove         = eeprom_remove,
+        .id_table       = eeprom_id,
+
+        .class          = I2C_CLASS_DDC | I2C_CLASS_SPD,
+        .detect         = eeprom_detect,
+        .address_data   = &addr_data,
+};
+
+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);