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linux/drivers/watchdog/omap_wdt.c
Arnd Bergmann 6038f373a3 llseek: automatically add .llseek fop 
All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.

The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.

New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time.  Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.

The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.

Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.

Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.

===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
//   but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}

@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}

@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
   *off = E
|
   *off += E
|
   func(..., off, ...)
|
   E = *off
)
...+>
}

@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}

@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
  *off = E
|
  *off += E
|
  func(..., off, ...)
|
  E = *off
)
...+>
}

@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}

@ fops0 @
identifier fops;
@@
struct file_operations fops = {
 ...
};

@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
 .llseek = llseek_f,
...
};

@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
 .read = read_f,
...
};

@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
 .write = write_f,
...
};

@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
 .open = open_f,
...
};

// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
...  .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};

@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
...  .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};

// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
...  .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};

// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};

// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};

@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+	.llseek = default_llseek, /* write accesses f_pos */
};

// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////

@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
 .write = write_f,
 .read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};

@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};

@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};

@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>
2010-10-15 15:53:27 +02:00

465 lines
11 KiB
C
Raw Blame History

/*
* omap_wdt.c
*
* Watchdog driver for the TI OMAP 16xx & 24xx/34xx 32KHz (non-secure) watchdog
*
* Author: MontaVista Software, Inc.
* <gdavis@mvista.com> or <source@mvista.com>
*
* 2003 (c) MontaVista Software, Inc. This file is licensed under the
* terms of the GNU General Public License version 2. This program is
* licensed "as is" without any warranty of any kind, whether express
* or implied.
*
* History:
*
* 20030527: George G. Davis <gdavis@mvista.com>
* Initially based on linux-2.4.19-rmk7-pxa1/drivers/char/sa1100_wdt.c
* (c) Copyright 2000 Oleg Drokin <green@crimea.edu>
* Based on SoftDog driver by Alan Cox <alan@lxorguk.ukuu.org.uk>
*
* Copyright (c) 2004 Texas Instruments.
* 1. Modified to support OMAP1610 32-KHz watchdog timer
* 2. Ported to 2.6 kernel
*
* Copyright (c) 2005 David Brownell
* Use the driver model and standard identifiers; handle bigger timeouts.
*/
#include <linux/module.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/miscdevice.h>
#include <linux/watchdog.h>
#include <linux/reboot.h>
#include <linux/init.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/moduleparam.h>
#include <linux/clk.h>
#include <linux/bitops.h>
#include <linux/io.h>
#include <linux/uaccess.h>
#include <linux/slab.h>
#include <mach/hardware.h>
#include <plat/prcm.h>
#include "omap_wdt.h"
static struct platform_device *omap_wdt_dev;
static unsigned timer_margin;
module_param(timer_margin, uint, 0);
MODULE_PARM_DESC(timer_margin, "initial watchdog timeout (in seconds)");
static unsigned int wdt_trgr_pattern = 0x1234;
static spinlock_t wdt_lock;
struct omap_wdt_dev {
void __iomem *base; /* physical */
struct device *dev;
int omap_wdt_users;
struct clk *ick;
struct clk *fck;
struct resource *mem;
struct miscdevice omap_wdt_miscdev;
};
static void omap_wdt_ping(struct omap_wdt_dev *wdev)
{
void __iomem *base = wdev->base;
/* wait for posted write to complete */
while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
cpu_relax();
wdt_trgr_pattern = ~wdt_trgr_pattern;
__raw_writel(wdt_trgr_pattern, (base + OMAP_WATCHDOG_TGR));
/* wait for posted write to complete */
while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x08)
cpu_relax();
/* reloaded WCRR from WLDR */
}
static void omap_wdt_enable(struct omap_wdt_dev *wdev)
{
void __iomem *base = wdev->base;
/* Sequence to enable the watchdog */
__raw_writel(0xBBBB, base + OMAP_WATCHDOG_SPR);
while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
cpu_relax();
__raw_writel(0x4444, base + OMAP_WATCHDOG_SPR);
while ((__raw_readl(base + OMAP_WATCHDOG_WPS)) & 0x10)
cpu_relax();
}
static void omap_wdt_disable(struct omap_wdt_dev *wdev)
{
void __iomem *base = wdev->base;
/* sequence required to disable watchdog */
__raw_writel(0xAAAA, base + OMAP_WATCHDOG_SPR); /* TIMER_MODE */
while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
cpu_relax();
__raw_writel(0x5555, base + OMAP_WATCHDOG_SPR); /* TIMER_MODE */
while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x10)
cpu_relax();
}
static void omap_wdt_adjust_timeout(unsigned new_timeout)
{
if (new_timeout < TIMER_MARGIN_MIN)
new_timeout = TIMER_MARGIN_DEFAULT;
if (new_timeout > TIMER_MARGIN_MAX)
new_timeout = TIMER_MARGIN_MAX;
timer_margin = new_timeout;
}
static void omap_wdt_set_timeout(struct omap_wdt_dev *wdev)
{
u32 pre_margin = GET_WLDR_VAL(timer_margin);
void __iomem *base = wdev->base;
/* just count up at 32 KHz */
while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
cpu_relax();
__raw_writel(pre_margin, base + OMAP_WATCHDOG_LDR);
while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x04)
cpu_relax();
}
/*
* Allow only one task to hold it open
*/
static int omap_wdt_open(struct inode *inode, struct file *file)
{
struct omap_wdt_dev *wdev = platform_get_drvdata(omap_wdt_dev);
void __iomem *base = wdev->base;
if (test_and_set_bit(1, (unsigned long *)&(wdev->omap_wdt_users)))
return -EBUSY;
clk_enable(wdev->ick); /* Enable the interface clock */
clk_enable(wdev->fck); /* Enable the functional clock */
/* initialize prescaler */
while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
cpu_relax();
__raw_writel((1 << 5) | (PTV << 2), base + OMAP_WATCHDOG_CNTRL);
while (__raw_readl(base + OMAP_WATCHDOG_WPS) & 0x01)
cpu_relax();
file->private_data = (void *) wdev;
omap_wdt_set_timeout(wdev);
omap_wdt_ping(wdev); /* trigger loading of new timeout value */
omap_wdt_enable(wdev);
return nonseekable_open(inode, file);
}
static int omap_wdt_release(struct inode *inode, struct file *file)
{
struct omap_wdt_dev *wdev = file->private_data;
/*
* Shut off the timer unless NOWAYOUT is defined.
*/
#ifndef CONFIG_WATCHDOG_NOWAYOUT
omap_wdt_disable(wdev);
clk_disable(wdev->ick);
clk_disable(wdev->fck);
#else
printk(KERN_CRIT "omap_wdt: Unexpected close, not stopping!\n");
#endif
wdev->omap_wdt_users = 0;
return 0;
}
static ssize_t omap_wdt_write(struct file *file, const char __user *data,
size_t len, loff_t *ppos)
{
struct omap_wdt_dev *wdev = file->private_data;
/* Refresh LOAD_TIME. */
if (len) {
spin_lock(&wdt_lock);
omap_wdt_ping(wdev);
spin_unlock(&wdt_lock);
}
return len;
}
static long omap_wdt_ioctl(struct file *file, unsigned int cmd,
unsigned long arg)
{
struct omap_wdt_dev *wdev;
int new_margin;
static const struct watchdog_info ident = {
.identity = "OMAP Watchdog",
.options = WDIOF_SETTIMEOUT,
.firmware_version = 0,
};
wdev = file->private_data;
switch (cmd) {
case WDIOC_GETSUPPORT:
return copy_to_user((struct watchdog_info __user *)arg, &ident,
sizeof(ident));
case WDIOC_GETSTATUS:
return put_user(0, (int __user *)arg);
case WDIOC_GETBOOTSTATUS:
if (cpu_is_omap16xx())
return put_user(__raw_readw(ARM_SYSST),
(int __user *)arg);
if (cpu_is_omap24xx())
return put_user(omap_prcm_get_reset_sources(),
(int __user *)arg);
case WDIOC_KEEPALIVE:
spin_lock(&wdt_lock);
omap_wdt_ping(wdev);
spin_unlock(&wdt_lock);
return 0;
case WDIOC_SETTIMEOUT:
if (get_user(new_margin, (int __user *)arg))
return -EFAULT;
omap_wdt_adjust_timeout(new_margin);
spin_lock(&wdt_lock);
omap_wdt_disable(wdev);
omap_wdt_set_timeout(wdev);
omap_wdt_enable(wdev);
omap_wdt_ping(wdev);
spin_unlock(&wdt_lock);
/* Fall */
case WDIOC_GETTIMEOUT:
return put_user(timer_margin, (int __user *)arg);
default:
return -ENOTTY;
}
}
static const struct file_operations omap_wdt_fops = {
.owner = THIS_MODULE,
.write = omap_wdt_write,
.unlocked_ioctl = omap_wdt_ioctl,
.open = omap_wdt_open,
.release = omap_wdt_release,
.llseek = no_llseek,
};
static int __devinit omap_wdt_probe(struct platform_device *pdev)
{
struct resource *res, *mem;
struct omap_wdt_dev *wdev;
int ret;
/* reserve static register mappings */
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res) {
ret = -ENOENT;
goto err_get_resource;
}
if (omap_wdt_dev) {
ret = -EBUSY;
goto err_busy;
}
mem = request_mem_region(res->start, resource_size(res), pdev->name);
if (!mem) {
ret = -EBUSY;
goto err_busy;
}
wdev = kzalloc(sizeof(struct omap_wdt_dev), GFP_KERNEL);
if (!wdev) {
ret = -ENOMEM;
goto err_kzalloc;
}
wdev->omap_wdt_users = 0;
wdev->mem = mem;
wdev->ick = clk_get(&pdev->dev, "ick");
if (IS_ERR(wdev->ick)) {
ret = PTR_ERR(wdev->ick);
wdev->ick = NULL;
goto err_clk;
}
wdev->fck = clk_get(&pdev->dev, "fck");
if (IS_ERR(wdev->fck)) {
ret = PTR_ERR(wdev->fck);
wdev->fck = NULL;
goto err_clk;
}
wdev->base = ioremap(res->start, resource_size(res));
if (!wdev->base) {
ret = -ENOMEM;
goto err_ioremap;
}
platform_set_drvdata(pdev, wdev);
clk_enable(wdev->ick);
clk_enable(wdev->fck);
omap_wdt_disable(wdev);
omap_wdt_adjust_timeout(timer_margin);
wdev->omap_wdt_miscdev.parent = &pdev->dev;
wdev->omap_wdt_miscdev.minor = WATCHDOG_MINOR;
wdev->omap_wdt_miscdev.name = "watchdog";
wdev->omap_wdt_miscdev.fops = &omap_wdt_fops;
ret = misc_register(&(wdev->omap_wdt_miscdev));
if (ret)
goto err_misc;
pr_info("OMAP Watchdog Timer Rev 0x%02x: initial timeout %d sec\n",
__raw_readl(wdev->base + OMAP_WATCHDOG_REV) & 0xFF,
timer_margin);
/* autogate OCP interface clock */
__raw_writel(0x01, wdev->base + OMAP_WATCHDOG_SYS_CONFIG);
clk_disable(wdev->ick);
clk_disable(wdev->fck);
omap_wdt_dev = pdev;
return 0;
err_misc:
platform_set_drvdata(pdev, NULL);
iounmap(wdev->base);
err_ioremap:
wdev->base = NULL;
err_clk:
if (wdev->ick)
clk_put(wdev->ick);
if (wdev->fck)
clk_put(wdev->fck);
kfree(wdev);
err_kzalloc:
release_mem_region(res->start, resource_size(res));
err_busy:
err_get_resource:
return ret;
}
static void omap_wdt_shutdown(struct platform_device *pdev)
{
struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
if (wdev->omap_wdt_users)
omap_wdt_disable(wdev);
}
static int __devexit omap_wdt_remove(struct platform_device *pdev)
{
struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
if (!res)
return -ENOENT;
misc_deregister(&(wdev->omap_wdt_miscdev));
release_mem_region(res->start, resource_size(res));
platform_set_drvdata(pdev, NULL);
clk_put(wdev->ick);
clk_put(wdev->fck);
iounmap(wdev->base);
kfree(wdev);
omap_wdt_dev = NULL;
return 0;
}
#ifdef CONFIG_PM
/* REVISIT ... not clear this is the best way to handle system suspend; and
* it's very inappropriate for selective device suspend (e.g. suspending this
* through sysfs rather than by stopping the watchdog daemon). Also, this
* may not play well enough with NOWAYOUT...
*/
static int omap_wdt_suspend(struct platform_device *pdev, pm_message_t state)
{
struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
if (wdev->omap_wdt_users)
omap_wdt_disable(wdev);
return 0;
}
static int omap_wdt_resume(struct platform_device *pdev)
{
struct omap_wdt_dev *wdev = platform_get_drvdata(pdev);
if (wdev->omap_wdt_users) {
omap_wdt_enable(wdev);
omap_wdt_ping(wdev);
}
return 0;
}
#else
#define omap_wdt_suspend NULL
#define omap_wdt_resume NULL
#endif
static struct platform_driver omap_wdt_driver = {
.probe = omap_wdt_probe,
.remove = __devexit_p(omap_wdt_remove),
.shutdown = omap_wdt_shutdown,
.suspend = omap_wdt_suspend,
.resume = omap_wdt_resume,
.driver = {
.owner = THIS_MODULE,
.name = "omap_wdt",
},
};
static int __init omap_wdt_init(void)
{
spin_lock_init(&wdt_lock);
return platform_driver_register(&omap_wdt_driver);
}
static void __exit omap_wdt_exit(void)
{
platform_driver_unregister(&omap_wdt_driver);
}
module_init(omap_wdt_init);
module_exit(omap_wdt_exit);
MODULE_AUTHOR("George G. Davis");
MODULE_LICENSE("GPL");
MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
MODULE_ALIAS("platform:omap_wdt");
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