[PATCH] I2C hwmon: hwmon sysfs class

This patch adds the sysfs class "hwmon" for use by hardware monitoring
(sensors) chip drivers.  It also fixes up the related Kconfig/Makefile
bits.

Signed-off-by: Mark M. Hoffman <mhoffman@lightlink.com>
Signed-off-by: Jean Delvare <khali@linux-fr.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 106 insertions, 1 deletions

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index f9aa3faa6b88..8c3911313700 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -12,7 +12,12 @@ config HWMON
 	  of a system. Most modern motherboards include such a device. It
 	  can include temperature sensors, voltage sensors, fan speed
 	  sensors and various additional features such as the ability to
-	  control the speed of the fans.
+	  control the speed of the fans.  If you want this support you
+	  should say Y here and also to the specific driver(s) for your
+	  sensors chip(s) below.
+
+	  This support can also be built as a module.  If so, the module
+	  will be called hwmon.
 
 config SENSORS_ADM1021
 	tristate "Analog Devices ADM1021 and compatibles"
diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
index 2781403a0236..bd1bd59eb149 100644
--- a/drivers/hwmon/Makefile
+++ b/drivers/hwmon/Makefile
@@ -2,6 +2,8 @@
 # Makefile for sensor chip drivers.
 #
 
+obj-$(CONFIG_HWMON)		+= hwmon.o
+
 # asb100, then w83781d go first, as they can override other drivers' addresses.
 obj-$(CONFIG_SENSORS_ASB100)	+= asb100.o
 obj-$(CONFIG_SENSORS_W83627HF)	+= w83627hf.o
diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
new file mode 100644
index 000000000000..9b41c9bd805f
--- /dev/null
+++ b/drivers/hwmon/hwmon.c
@@ -0,0 +1,98 @@
+/*
+    hwmon.c - part of lm_sensors, Linux kernel modules for hardware monitoring
+
+    This file defines the sysfs class "hwmon", for use by sensors drivers.
+
+    Copyright (C) 2005 Mark M. Hoffman <mhoffman@lightlink.com>
+
+    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/module.h>
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/kdev_t.h>
+#include <linux/idr.h>
+#include <linux/hwmon.h>
+
+#define HWMON_ID_PREFIX "hwmon"
+#define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
+
+static struct class *hwmon_class;
+
+static DEFINE_IDR(hwmon_idr);
+
+/**
+ * hwmon_device_register - register w/ hwmon sysfs class
+ * @dev: the device to register
+ *
+ * hwmon_device_unregister() must be called when the class device is no
+ * longer needed.
+ *
+ * Returns the pointer to the new struct class device.
+ */
+struct class_device *hwmon_device_register(struct device *dev)
+{
+	struct class_device *cdev;
+	int id;
+
+	if (idr_pre_get(&hwmon_idr, GFP_KERNEL) == 0)
+		return ERR_PTR(-ENOMEM);
+
+	if (idr_get_new(&hwmon_idr, NULL, &id) < 0)
+		return ERR_PTR(-ENOMEM);
+
+	id = id & MAX_ID_MASK;
+	cdev = class_device_create(hwmon_class, MKDEV(0,0), dev,
+					HWMON_ID_FORMAT, id);
+
+	if (IS_ERR(cdev))
+		idr_remove(&hwmon_idr, id);
+
+	return cdev;
+}
+
+/**
+ * hwmon_device_unregister - removes the previously registered class device
+ *
+ * @cdev: the class device to destroy
+ */
+void hwmon_device_unregister(struct class_device *cdev)
+{
+	int id;
+
+	if (sscanf(cdev->class_id, HWMON_ID_FORMAT, &id) == 1) {
+		class_device_unregister(cdev);
+		idr_remove(&hwmon_idr, id);
+	} else
+		dev_dbg(cdev->dev,
+			"hwmon_device_unregister() failed: bad class ID!\n");
+}
+
+static int __init hwmon_init(void)
+{
+	hwmon_class = class_create(THIS_MODULE, "hwmon");
+	if (IS_ERR(hwmon_class)) {
+		printk(KERN_ERR "hwmon.c: couldn't create sysfs class\n");
+		return PTR_ERR(hwmon_class);
+	}
+	return 0;
+}
+
+static void __exit hwmon_exit(void)
+{
+	class_destroy(hwmon_class);
+}
+
+module_init(hwmon_init);
+module_exit(hwmon_exit);
+
+EXPORT_SYMBOL_GPL(hwmon_device_register);
+EXPORT_SYMBOL_GPL(hwmon_device_unregister);
+
+MODULE_AUTHOR("Mark M. Hoffman <mhoffman@lightlink.com>");
+MODULE_DESCRIPTION("hardware monitoring sysfs/class support");
+MODULE_LICENSE("GPL");
+