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path: root/drivers/hwmon/bcm2835-hwmon.c
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/*****************************************************************************
* Copyright 2011 Broadcom Corporation.  All rights reserved.
*
* Unless you and Broadcom execute a separate written software license
* agreement governing use of this software, this software is licensed to you
* under the terms of the GNU General Public License version 2, available at
* http://www.broadcom.com/licenses/GPLv2.php (the "GPL").
*
* Notwithstanding the above, under no circumstances may you combine this
* software in any way with any other Broadcom software provided under a
* license other than the GPL, without Broadcom's express prior written
* consent.
*****************************************************************************/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/hwmon.h>
#include <linux/hwmon-sysfs.h>
#include <linux/platform_device.h>
#include <linux/sysfs.h>
#include <mach/vcio.h>
#include <linux/slab.h>
#include <linux/err.h>

#define MODULE_NAME "bcm2835_hwmon"

/*#define HWMON_DEBUG_ENABLE*/

#ifdef HWMON_DEBUG_ENABLE
#define print_debug(fmt,...) printk(KERN_INFO "%s:%s:%d: "fmt"\n", MODULE_NAME, __func__, __LINE__, ##__VA_ARGS__)
#else
#define print_debug(fmt,...)
#endif
#define print_err(fmt,...) printk(KERN_ERR "%s:%s:%d: "fmt"\n", MODULE_NAME, __func__,__LINE__, ##__VA_ARGS__)
#define print_info(fmt,...) printk(KERN_INFO "%s: "fmt"\n", MODULE_NAME, ##__VA_ARGS__)

#define VC_TAG_GET_TEMP 0x00030006
#define VC_TAG_GET_MAX_TEMP 0x0003000A

/* --- STRUCTS --- */
struct bcm2835_hwmon_data {
	struct device *hwmon_dev;
};

/* tag part of the message */
struct vc_msg_tag {
	uint32_t tag_id;		/* the tag ID for the temperature */
	uint32_t buffer_size;	/* size of the buffer (should be 8) */
	uint32_t request_code;	/* identifies message as a request (should be 0) */
	uint32_t id;			/* extra ID field (should be 0) */
	uint32_t val;			/* returned value of the temperature */
};

/* message structure to be sent to videocore */
struct vc_msg {
	uint32_t msg_size;		/* simply, sizeof(struct vc_msg) */
	uint32_t request_code;		/* holds various information like the success and number of bytes returned (refer to mailboxes wiki) */
	struct vc_msg_tag tag;		/* the tag structure above to make */
	uint32_t end_tag;		/* an end identifier, should be set to NULL */
};

typedef enum {
	TEMP,
	MAX_TEMP,
} temp_type;

/* --- PROTOTYPES --- */
static ssize_t bcm2835_get_temp(struct device *dev, struct device_attribute *attr, char *buf);
static ssize_t bcm2835_get_name(struct device *dev, struct device_attribute *attr, char *buf);

/* --- GLOBALS --- */

static struct bcm2835_hwmon_data *bcm2835_data;
static struct platform_driver bcm2835_hwmon_driver;

static SENSOR_DEVICE_ATTR(name, S_IRUGO,bcm2835_get_name,NULL,0);
static SENSOR_DEVICE_ATTR(temp1_input,S_IRUGO,bcm2835_get_temp,NULL,TEMP);
static SENSOR_DEVICE_ATTR(temp1_max,S_IRUGO,bcm2835_get_temp,NULL,MAX_TEMP);

static struct attribute* bcm2835_attributes[] = {
	&sensor_dev_attr_name.dev_attr.attr,
	&sensor_dev_attr_temp1_input.dev_attr.attr,
	&sensor_dev_attr_temp1_max.dev_attr.attr,
	NULL,
};

static struct attribute_group bcm2835_attr_group = {
	.attrs = bcm2835_attributes,
};

/* --- FUNCTIONS --- */

static ssize_t bcm2835_get_name(struct device *dev, struct device_attribute *attr, char *buf)
{
	return sprintf(buf,"bcm2835_hwmon\n");
}

static ssize_t bcm2835_get_temp(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct vc_msg msg;
	int result;
	uint temp = 0;
	int index = ((struct sensor_device_attribute*)to_sensor_dev_attr(attr))->index;

	print_debug("IN");

	/* wipe all previous message data */
	memset(&msg, 0, sizeof msg);

	/* determine the message type */
	if(index == TEMP)
		msg.tag.tag_id = VC_TAG_GET_TEMP;
	else if (index == MAX_TEMP)
		msg.tag.tag_id = VC_TAG_GET_MAX_TEMP;
	else
	{
		print_debug("Unknown temperature message!");
		return -EINVAL;
	}

	msg.msg_size = sizeof msg;
	msg.tag.buffer_size = 8;

	/* send the message */
	result = bcm_mailbox_property(&msg, sizeof msg);

	/* check if it was all ok and return the rate in milli degrees C */
	if (result == 0 && (msg.request_code & 0x80000000))
		temp = (uint)msg.tag.val;
	#ifdef HWMON_DEBUG_ENABLE
	else
		print_debug("Failed to get temperature!");
	#endif
	print_debug("Got temperature as %u",temp);
	print_debug("OUT");
	return sprintf(buf, "%u\n", temp);
}


static int bcm2835_hwmon_probe(struct platform_device *pdev)
{
	int err;

	print_debug("IN");
	print_debug("HWMON Driver has been probed!");

	/* check that the device isn't null!*/
	if(pdev == NULL)
	{
		print_debug("Platform device is empty!");
		return -ENODEV;
	}

	/* allocate memory for neccessary data */
	bcm2835_data = kzalloc(sizeof(struct bcm2835_hwmon_data),GFP_KERNEL);
	if(!bcm2835_data)
	{
		print_debug("Unable to allocate memory for hwmon data!");
		err = -ENOMEM;
		goto kzalloc_error;
	}

	/* create the sysfs files */
	if(sysfs_create_group(&pdev->dev.kobj, &bcm2835_attr_group))
	{
		print_debug("Unable to create sysfs files!");
		err = -EFAULT;
		goto sysfs_error;
	}

	/* register the hwmon device */
	bcm2835_data->hwmon_dev = hwmon_device_register(&pdev->dev);
	if (IS_ERR(bcm2835_data->hwmon_dev))
	{
		err = PTR_ERR(bcm2835_data->hwmon_dev);
		goto hwmon_error;
	}
	print_debug("OUT");
	return 0;

	/* error goto's */
	hwmon_error:
	sysfs_remove_group(&pdev->dev.kobj, &bcm2835_attr_group);

	sysfs_error:
	kfree(bcm2835_data);

	kzalloc_error:

	return err;

}

static int bcm2835_hwmon_remove(struct platform_device *pdev)
{
	print_debug("IN");
	hwmon_device_unregister(bcm2835_data->hwmon_dev);

	sysfs_remove_group(&pdev->dev.kobj, &bcm2835_attr_group);
	print_debug("OUT");
	return 0;
}

/* Hwmon Driver */
static struct platform_driver bcm2835_hwmon_driver = {
	.probe = bcm2835_hwmon_probe,
	.remove = bcm2835_hwmon_remove,
	.driver = {
				.name = "bcm2835_hwmon",
				.owner = THIS_MODULE,
			},
};

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Dorian Peake");
MODULE_DESCRIPTION("HW Monitor driver for bcm2835 chip");

module_platform_driver(bcm2835_hwmon_driver);