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Commit f118420b authored by Paul Mundt's avatar Paul Mundt
Browse files

watchdog: Add a simple mmap() stub for shwdt. 



In some applications people have expressed a need for an mmap() method,
so we implement a simple stub for this that maps back a page with the
counter in it.

Signed-off-by: default avatarPaul Mundt <lethal@linux-sh.org>
parent 781125ca

drivers/char/watchdog/Kconfig

+8 −0
Original line number Original line Diff line number Diff line
@@ -510,6 +510,14 @@ config SH_WDT 
	  To compile this driver as a module, choose M here: the

	  To compile this driver as a module, choose M here: the

	  module will be called shwdt.

	  module will be called shwdt.





config SH_WDT_MMAP

	bool "Allow mmap of SH WDT"

	default n

	depends on SH_WDT

	help

	  If you say Y here, user applications will be able to mmap the

	  WDT/CPG registers.

#

# SPARC64 Architecture

# SPARC64 Architecture





config WATCHDOG_CP1XXX

config WATCHDOG_CP1XXX

drivers/char/watchdog/shwdt.c

+51 −1
Original line number Original line Diff line number Diff line
@@ -27,7 +27,7 @@ 
#include <linux/notifier.h>

#include <linux/notifier.h>

#include <linux/ioport.h>

#include <linux/ioport.h>

#include <linux/fs.h>

#include <linux/fs.h>



#include <linux/mm.h>

#include <asm/io.h>

#include <asm/io.h>

#include <asm/uaccess.h>

#include <asm/uaccess.h>

#include <asm/watchdog.h>

#include <asm/watchdog.h>
@@ -257,6 +257,55 @@ static ssize_t sh_wdt_write(struct file *file, const char *buf, 
	return count;

	return count;

}

}





/**

 * 	sh_wdt_mmap - map WDT/CPG registers into userspace

 * 	@file: file structure for the device

 * 	@vma: VMA to map the registers into

 *

 * 	A simple mmap() implementation for the corner cases where the counter

 * 	needs to be mapped in userspace directly. Due to the relatively small

 * 	size of the area, neighbouring registers not necessarily tied to the

 * 	CPG will also be accessible through the register page, so this remains

 * 	configurable for users that really know what they're doing.

 *

 *	Additionaly, the register page maps in the CPG register base relative

 *	to the nearest page-aligned boundary, which requires that userspace do

 *	the appropriate CPU subtype math for calculating the page offset for

 *	the counter value.

 */

static int sh_wdt_mmap(struct file *file, struct vm_area_struct *vma)

{

	int ret = -ENOSYS;



#ifdef CONFIG_SH_WDT_MMAP

	unsigned long addr;



	/* Only support the simple cases where we map in a register page. */

	if (((vma->vm_end - vma->vm_start) != PAGE_SIZE) || vma->vm_pgoff)

		return -EINVAL;



	/*

	 * Pick WTCNT as the start, it's usually the first register after the

	 * FRQCR, and neither one are generally page-aligned out of the box.

	 */

	addr = WTCNT & ~(PAGE_SIZE - 1);



	vma->vm_flags |= VM_IO;

	vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);



	if (io_remap_pfn_range(vma, vma->vm_start, addr >> PAGE_SHIFT,

			       PAGE_SIZE, vma->vm_page_prot)) {

		printk(KERN_ERR PFX "%s: io_remap_pfn_range failed\n",

		       __FUNCTION__);

		return -EAGAIN;

	}



	ret = 0;

#endif



	return ret;

}



/**

/**

 * 	sh_wdt_ioctl - Query Device

 * 	sh_wdt_ioctl - Query Device

 * 	@inode: inode of device

 * 	@inode: inode of device
@@ -342,6 +391,7 @@ static const struct file_operations sh_wdt_fops = { 
	.ioctl		= sh_wdt_ioctl,

	.ioctl		= sh_wdt_ioctl,

	.open		= sh_wdt_open,

	.open		= sh_wdt_open,

	.release	= sh_wdt_close,

	.release	= sh_wdt_close,

	.mmap		= sh_wdt_mmap,

};

};





static struct watchdog_info sh_wdt_info = {

static struct watchdog_info sh_wdt_info = {