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: Paul Mundt <lethal@linux-sh.org>
This commit is contained in:
Paul Mundt 2006-09-27 17:53:59 +09:00
parent 781125ca58
commit f118420be8
2 changed files with 59 additions and 1 deletions

View file

@ -510,6 +510,14 @@ config SH_WDT
To compile this driver as a module, choose M here: the
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
config WATCHDOG_CP1XXX

View file

@ -27,7 +27,7 @@
#include <linux/notifier.h>
#include <linux/ioport.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <asm/io.h>
#include <asm/uaccess.h>
#include <asm/watchdog.h>
@ -257,6 +257,55 @@ static ssize_t sh_wdt_write(struct file *file, const char *buf,
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
* @inode: inode of device
@ -342,6 +391,7 @@ static const struct file_operations sh_wdt_fops = {
.ioctl = sh_wdt_ioctl,
.open = sh_wdt_open,
.release = sh_wdt_close,
.mmap = sh_wdt_mmap,
};
static struct watchdog_info sh_wdt_info = {