[PATCH v2] Add support for Dallas DS28CM00 Unique ID chip

[Mark Jackson]

This patch adds support for the (I2C based) DS28CM00 ID chip.
(v2 after running through checkpatch)

Signed-off-by: M.Jackson <mpfj@xxxxxxxxxx> 
---
drivers/i2c/chips/Kconfig    |    7 ++
drivers/i2c/chips/Makefile   |    1 +
drivers/i2c/chips/ds28cm00.c |  166 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 174 insertions(+), 0 deletions(-)

diff --git a/drivers/i2c/chips/Kconfig b/drivers/i2c/chips/Kconfig
index a95cb94..98c06e7 100644
--- a/drivers/i2c/chips/Kconfig
+++ b/drivers/i2c/chips/Kconfig
@@ -172,4 +172,11 @@ config MENELAUS
	  and other features that are often used in portable devices like
	  cell phones and PDAs.

+config DS28CM00
+	tristate "DS28CM00 Serial Number chip"
+	depends on EXPERIMENTAL
+	help
+	  If you say yes here you get support for the Dallas DS28CM00
+	  Serial Number chip.
+
endmenu
diff --git a/drivers/i2c/chips/Makefile b/drivers/i2c/chips/Makefile
index 39e3e69..f674d94 100644
--- a/drivers/i2c/chips/Makefile
+++ b/drivers/i2c/chips/Makefile
@@ -21,6 +21,7 @@ obj-$(CONFIG_ISP1301_OMAP)	+= isp1301_omap.o
obj-$(CONFIG_TPS65010)		+= tps65010.o
obj-$(CONFIG_MENELAUS)		+= menelaus.o
obj-$(CONFIG_SENSORS_TSL2550)	+= tsl2550.o
+obj-$(CONFIG_DS28CM00)		+= ds28cm00.o

ifeq ($(CONFIG_I2C_DEBUG_CHIP),y)
EXTRA_CFLAGS += -DDEBUG
diff --git a/drivers/i2c/chips/ds28cm00.c b/drivers/i2c/chips/ds28cm00.c
new file mode 100644
index 0000000..6abe065
--- /dev/null
+++ b/drivers/i2c/chips/ds28cm00.c
@@ -0,0 +1,166 @@
+/*
+    ds28cm00.c - driver for DS28CM00 Serial ID chip
+
+    Copyright (C) 2008 Mark Jackson <mpfj@xxxxxxxxxx>
+
+    Based on i2c/chips/max6875.c
+
+    The DS28CM00 contains a 64bit unique number.
+    The memory map is defined as follows:
+     * 0x00		= Device Family Code (0x70)
+     * 0x01 - 0x06	= Serial Number (bits 0 to 47)
+     * 0x07		= CRC of addresses 0x00 to 0x06
+     * 0x08		= Control Register (R/W)
+
+    This driver makes the Serial Number available for read.
+
+    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/i2c.h>
+
+static unsigned short normal_i2c[] = {I2C_CLIENT_END};
+
+/* Insmod parameters */
+I2C_CLIENT_INSMOD_1(ds28cm00);
+
+#define DS28CM00_CMD_WRITE	0x50
+#define DS28CM00_CMD_READ	0x51
+
+#define ID_SIZE		9
+
+/* Each client has this additional data */
+struct ds28cm00_data {
+	struct i2c_client	client;
+	struct mutex		update_lock;
+};
+
+static int ds28cm00_attach_adapter(struct i2c_adapter *adapter);
+static int ds28cm00_detect(struct i2c_adapter *adapter, int address, int kind);
+static int ds28cm00_detach_client(struct i2c_client *client);
+
+/* This is the driver that will be inserted */
+static struct i2c_driver ds28cm00_driver = {
+	.driver = {
+		.name	= "ds28cm00",
+	},
+	.attach_adapter	= ds28cm00_attach_adapter,
+	.detach_client	= ds28cm00_detach_client,
+};
+
+static ssize_t ds28cm00_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);
+
+	if (off > ID_SIZE)
+		return 0;
+
+	if (off + count > ID_SIZE)
+		count = ID_SIZE - off;
+
+	if (i2c_smbus_read_i2c_block_data(client, DS28CM00_CMD_READ, count, buf) != count)
+		return 0;
+
+	return count;
+}
+
+static struct bin_attribute id_attr = {
+	.attr = {
+		.name = "id",
+		.mode = S_IRUGO,
+	},
+	.size = ID_SIZE,
+	.read = ds28cm00_read,
+};
+
+static int ds28cm00_attach_adapter(struct i2c_adapter *adapter)
+{
+	return i2c_probe(adapter, &addr_data, ds28cm00_detect);
+}
+
+/* This function is called by i2c_probe */
+static int ds28cm00_detect(struct i2c_adapter *adapter, int address, int kind)
+{
+	struct i2c_client *new_client;
+	struct ds28cm00_data *data;
+	int err = 0;
+
+	printk(KERN_DEBUG "DS28CM00 I2C Serial Number driver\n");
+
+	if (!i2c_check_functionality(adapter, I2C_FUNC_I2C)) {
+		printk(KERN_ALERT "DS28CM00 : failed i2c_check_func()\n");
+		return 0;
+	}
+
+	data = kzalloc(sizeof(struct ds28cm00_data), GFP_KERNEL);
+	if (!data) {
+		printk(KERN_ALERT "DS28CM00 : failed kzalloc()\n");
+		return -ENOMEM;
+	}
+
+	new_client = &data->client;
+	i2c_set_clientdata(new_client, data);
+	new_client->addr = address;
+	new_client->adapter = adapter;
+	new_client->driver = &ds28cm00_driver;
+	new_client->flags = 0;
+	strlcpy(new_client->name, "ds28cm00", I2C_NAME_SIZE);
+
+	/* Tell the I2C layer a new client has arrived */
+	err = i2c_attach_client(new_client);
+	if (err) {
+		printk(KERN_ALERT "DS28CM00 : failed i2c_attach_client()\n");
+		goto exit_kfree;
+	}
+
+	/* Register sysfs hooks */
+	err = sysfs_create_bin_file(&new_client->dev.kobj, &id_attr);
+	if (err) {
+		printk(KERN_ALERT "DS28CM00 : failed sysfs_create_bin_file()\n");
+		goto exit_detach;
+	}
+
+	return 0;
+
+exit_detach:
+	i2c_detach_client(new_client);
+exit_kfree:
+	kfree(data);
+	return err;
+}
+
+static int ds28cm00_detach_client(struct i2c_client *client)
+{
+	int err;
+
+	sysfs_remove_bin_file(&client->dev.kobj, &id_attr);
+
+	err = i2c_detach_client(client);
+	if (err)
+		return err;
+
+	kfree(client);
+
+	return 0;
+}
+
+static int __init ds28cm00_init(void)
+{
+	return i2c_add_driver(&ds28cm00_driver);
+}
+
+static void __exit ds28cm00_exit(void)
+{
+	i2c_del_driver(&ds28cm00_driver);
+}
+
+MODULE_AUTHOR("Mark Jackson <mpfj@xxxxxxxxxx>");
+MODULE_DESCRIPTION("DS28CM00 driver");
+MODULE_LICENSE("GPL");
+
+module_init(ds28cm00_init);
+module_exit(ds28cm00_exit);
--
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