(no subject)

[Nat Gurumoorthy]

There are 3 different drivers that touch the it87 hardware registers.
The 3 drivers have been written independently and access the it87 hardware
registers assuming they are the only driver accessing it. This change
attempts to serialize access to the hardware by using
"request_muxed_region" macro defined by Alan Cox. Call to this macro
will hold off the requestor if the resource is currently busy.
The use of the above macro makes it possible to get rid of
spinlocks in it8712f_wdt.c and it87_wdt.c watchdog drivers.
This also greatly simplifies the implementation of it87_wdt.c driver.

01 - Changes to it87 watchdog driver to use "request_muxed_region"
 drivers/watchdog/it8712f_wdt.c
 drivers/watchdog/it87_wdt.c

02 - Chages to hwmon it87 driver to use "request_muxed_region"
 drivers/hwmon/it87.c

 drivers/hwmon/it87.c           |   14 +++-
 drivers/watchdog/it8712f_wdt.c |   60 ++++++++++----
 drivers/watchdog/it87_wdt.c    |  165 +++++++++++++++++++++++----------------
 3 files changed, 152 insertions(+), 87 deletions(-)
diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c

Signed-off-by: Nat Gurumoorthy <natg@google.com>

Patch History:
v8:
- Return the error actually returned by superio_enter and not -EBUSY.
  Notifier routines return NOTIFY_DONE even if underlying calls from
  notifier to routines that invoke superio_enter return with error.
  Make sure release routines returns do proper clean up even if calls to
  superio_enter fail.

v7:
- superio_enter return error if call to "request_muxed_region" fails. Rest
  of the changes deal with error returns from superio_enter. Changes to
  it87_wdt.c are untested.

v6:
- Pay attention to value returned by request_muxed_region. The first call to
  request_muxed_region will attempt 10 times to reserve the region before it
  gives up. This will typically get called from the driver init routines. If this
  succeeds then subsequent calls wait forever for the resource to be available.

v5:
- Remove unnecessary while from superio_enter.

v4:
- Remove extra braces in superio_enter routines.

v3:
- Totally abandon the spinlock based approach and use "request_muxed_region" to
  hold off requestors if the resource is busy.

v2:
- More verbose patch headers. Add In-Reply-To: field.

[PATCH v8 1/2] Use "request_muxed_region" in it87 watchdog drivers

[Nat Gurumoorthy]

01 - Changes to it87 watchdog driver to use "request_muxed_region"
Serialize access to the hardware by using "request_muxed_region" macro defined
by Alan Cox. Call to this macro will hold off the requestor if the resource is
currently busy. 

The use of the above macro makes it possible to get rid of
spinlocks in it8712f_wdt.c and it87_wdt.c watchdog drivers.
This also greatly simplifies the implementation of it87_wdt.c driver.

 "superio_enter" will return an error if call to "request_muxed_region" fails. 
Rest of the code change is to ripple an error return from superio_enter to
the top level.

Signed-off-by: Nat Gurumoorthy <natg@google.com>
---

diff --git a/drivers/watchdog/it8712f_wdt.c b/drivers/watchdog/it8712f_wdt.c
index 6143f52..84447d9 100644
--- a/drivers/watchdog/it8712f_wdt.c
+++ b/drivers/watchdog/it8712f_wdt.c
@@ -51,7 +51,6 @@ MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
 
 static unsigned long wdt_open;
 static unsigned expect_close;
-static spinlock_t io_lock;
 static unsigned char revision;
 
 /* Dog Food address - We use the game port address */
@@ -121,20 +120,27 @@ static inline void superio_select(int ldn)
 	outb(ldn, VAL);
 }
 
-static inline void superio_enter(void)
+static inline int
+superio_enter(void)
 {
-	spin_lock(&io_lock);
+	/*
+	 * Try to reserve REG and REG + 1 for exclusive access.
+	 */
+	if (!request_muxed_region(REG, 2, NAME))
+		return -EBUSY;
+
 	outb(0x87, REG);
 	outb(0x01, REG);
 	outb(0x55, REG);
 	outb(0x55, REG);
+	return 0;
 }
 
 static inline void superio_exit(void)
 {
 	outb(0x02, REG);
 	outb(0x02, VAL);
-	spin_unlock(&io_lock);
+	release_region(REG, 2);
 }
 
 static inline void it8712f_wdt_ping(void)
@@ -173,10 +179,13 @@ static int it8712f_wdt_get_status(void)
 		return 0;
 }
 
-static void it8712f_wdt_enable(void)
+static int it8712f_wdt_enable(void)
 {
+	int ret = superio_enter();
+	if (ret)
+		return ret;
+
 	printk(KERN_DEBUG NAME ": enabling watchdog timer\n");
-	superio_enter();
 	superio_select(LDN_GPIO);
 
 	superio_outb(wdt_control_reg, WDT_CONTROL);
@@ -186,13 +195,18 @@ static void it8712f_wdt_enable(void)
 	superio_exit();
 
 	it8712f_wdt_ping();
+
+	return 0;
 }
 
-static void it8712f_wdt_disable(void)
+static int it8712f_wdt_disable(void)
 {
-	printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
+	int ret = superio_enter();
+
+	if (ret)
+		return ret;
 
-	superio_enter();
+	printk(KERN_DEBUG NAME ": disabling watchdog timer\n");
 	superio_select(LDN_GPIO);
 
 	superio_outb(0, WDT_CONFIG);
@@ -202,6 +216,7 @@ static void it8712f_wdt_disable(void)
 	superio_outb(0, WDT_TIMEOUT);
 
 	superio_exit();
+	return 0;
 }
 
 static int it8712f_wdt_notify(struct notifier_block *this,
@@ -252,6 +267,7 @@ static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
 						WDIOF_MAGICCLOSE,
 	};
 	int value;
+	int ret;
 
 	switch (cmd) {
 	case WDIOC_GETSUPPORT:
@@ -259,7 +275,9 @@ static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
 			return -EFAULT;
 		return 0;
 	case WDIOC_GETSTATUS:
-		superio_enter();
+		ret = superio_enter();
+		if (ret)
+			return ret;
 		superio_select(LDN_GPIO);
 
 		value = it8712f_wdt_get_status();
@@ -280,7 +298,9 @@ static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
 		if (value > (max_units * 60))
 			return -EINVAL;
 		margin = value;
-		superio_enter();
+		ret = superio_enter();
+		if (ret)
+			return -EBUSY;
 		superio_select(LDN_GPIO);
 
 		it8712f_wdt_update_margin();
@@ -299,10 +319,14 @@ static long it8712f_wdt_ioctl(struct file *file, unsigned int cmd,
 
 static int it8712f_wdt_open(struct inode *inode, struct file *file)
 {
+	int ret;
 	/* only allow one at a time */
 	if (test_and_set_bit(0, &wdt_open))
 		return -EBUSY;
-	it8712f_wdt_enable();
+
+	ret = it8712f_wdt_enable();
+	if (ret)
+		return ret;
 	return nonseekable_open(inode, file);
 }
 
@@ -313,7 +337,8 @@ static int it8712f_wdt_release(struct inode *inode, struct file *file)
 			": watchdog device closed unexpectedly, will not"
 			" disable the watchdog timer\n");
 	} else if (!nowayout) {
-		it8712f_wdt_disable();
+		if (it8712f_wdt_disable())
+			printk(KERN_WARNING NAME "Watchdog disable failed\n");
 	}
 	expect_close = 0;
 	clear_bit(0, &wdt_open);
@@ -340,8 +365,10 @@ static int __init it8712f_wdt_find(unsigned short *address)
 {
 	int err = -ENODEV;
 	int chip_type;
+	int ret = superio_enter();
+	if (ret)
+		return ret;
 
-	superio_enter();
 	chip_type = superio_inw(DEVID);
 	if (chip_type != IT8712F_DEVID)
 		goto exit;
@@ -382,8 +409,6 @@ static int __init it8712f_wdt_init(void)
 {
 	int err = 0;
 
-	spin_lock_init(&io_lock);
-
 	if (it8712f_wdt_find(&address))
 		return -ENODEV;
 
@@ -392,7 +417,8 @@ static int __init it8712f_wdt_init(void)
 		return -EBUSY;
 	}
 
-	it8712f_wdt_disable();
+	if (it8712f_wdt_disable())
+		return -EBUSY;
 
 	err = register_reboot_notifier(&it8712f_wdt_notifier);
 	if (err) {
diff --git a/drivers/watchdog/it87_wdt.c b/drivers/watchdog/it87_wdt.c
index b1bc72f..4def56d 100644
--- a/drivers/watchdog/it87_wdt.c
+++ b/drivers/watchdog/it87_wdt.c
@@ -137,7 +137,6 @@
 
 static	unsigned int base, gpact, ciract, max_units, chip_type;
 static	unsigned long wdt_status;
-static	DEFINE_SPINLOCK(spinlock);
 
 static	int nogameport = DEFAULT_NOGAMEPORT;
 static	int exclusive  = DEFAULT_EXCLUSIVE;
@@ -163,18 +162,27 @@ MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started, default="
 
 /* Superio Chip */
 
-static inline void superio_enter(void)
+static inline int
+superio_enter(void)
 {
+	/*
+	 * Try to reserve REG and REG + 1 for exclusive access.
+	 */
+	if (!request_muxed_region(REG, 2, WATCHDOG_NAME))
+		return -EBUSY;
+
 	outb(0x87, REG);
 	outb(0x01, REG);
 	outb(0x55, REG);
 	outb(0x55, REG);
+	return 0;
 }
 
 static inline void superio_exit(void)
 {
 	outb(0x02, REG);
 	outb(0x02, VAL);
+	release_region(REG, 2);
 }
 
 static inline void superio_select(int ldn)
@@ -255,12 +263,11 @@ static void wdt_keepalive(void)
 	set_bit(WDTS_KEEPALIVE, &wdt_status);
 }
 
-static void wdt_start(void)
+static int wdt_start(void)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&spinlock, flags);
-	superio_enter();
+	int ret = superio_enter();
+	if (ret)
+		return ret;
 
 	superio_select(GPIO);
 	if (test_bit(WDTS_USE_GP, &wdt_status))
@@ -270,15 +277,15 @@ static void wdt_start(void)
 	wdt_update_timeout();
 
 	superio_exit();
-	spin_unlock_irqrestore(&spinlock, flags);
+
+	return 0;
 }
 
-static void wdt_stop(void)
+static int wdt_stop(void)
 {
-	unsigned long flags;
-
-	spin_lock_irqsave(&spinlock, flags);
-	superio_enter();
+	int ret = superio_enter();
+	if (ret)
+		return ret;
 
 	superio_select(GPIO);
 	superio_outb(0x00, WDTCTRL);
@@ -288,7 +295,7 @@ static void wdt_stop(void)
 		superio_outb(0x00, WDTVALMSB);
 
 	superio_exit();
-	spin_unlock_irqrestore(&spinlock, flags);
+	return 0;
 }
 
 /**
@@ -303,8 +310,6 @@ static void wdt_stop(void)
 
 static int wdt_set_timeout(int t)
 {
-	unsigned long flags;
-
 	if (t < 1 || t > max_units * 60)
 		return -EINVAL;
 
@@ -313,14 +318,15 @@ static int wdt_set_timeout(int t)
 	else
 		timeout = t;
 
-	spin_lock_irqsave(&spinlock, flags);
 	if (test_bit(WDTS_TIMER_RUN, &wdt_status)) {
-		superio_enter();
+		int ret = superio_enter();
+		if (ret)
+			return ret;
+
 		superio_select(GPIO);
 		wdt_update_timeout();
 		superio_exit();
 	}
-	spin_unlock_irqrestore(&spinlock, flags);
 	return 0;
 }
 
@@ -339,12 +345,12 @@ static int wdt_set_timeout(int t)
 
 static int wdt_get_status(int *status)
 {
-	unsigned long flags;
-
 	*status = 0;
 	if (testmode) {
-		spin_lock_irqsave(&spinlock, flags);
-		superio_enter();
+		int ret = superio_enter();
+		if (ret)
+			return ret;
+
 		superio_select(GPIO);
 		if (superio_inb(WDTCTRL) & WDT_ZERO) {
 			superio_outb(0x00, WDTCTRL);
@@ -353,7 +359,6 @@ static int wdt_get_status(int *status)
 		}
 
 		superio_exit();
-		spin_unlock_irqrestore(&spinlock, flags);
 	}
 	if (test_and_clear_bit(WDTS_KEEPALIVE, &wdt_status))
 		*status |= WDIOF_KEEPALIVEPING;
@@ -379,9 +384,17 @@ static int wdt_open(struct inode *inode, struct file *file)
 	if (exclusive && test_and_set_bit(WDTS_DEV_OPEN, &wdt_status))
 		return -EBUSY;
 	if (!test_and_set_bit(WDTS_TIMER_RUN, &wdt_status)) {
+		int ret;
 		if (nowayout && !test_and_set_bit(WDTS_LOCKED, &wdt_status))
 			__module_get(THIS_MODULE);
-		wdt_start();
+
+		ret = wdt_start();
+		if (ret) {
+			clear_bit(WDTS_LOCKED, &wdt_status);
+			clear_bit(WDTS_TIMER_RUN, &wdt_status);
+			clear_bit(WDTS_DEV_OPEN, &wdt_status);
+			return ret;
+		}
 	}
 	return nonseekable_open(inode, file);
 }
@@ -403,7 +416,16 @@ static int wdt_release(struct inode *inode, struct file *file)
 {
 	if (test_bit(WDTS_TIMER_RUN, &wdt_status)) {
 		if (test_and_clear_bit(WDTS_EXPECTED, &wdt_status)) {
-			wdt_stop();
+			int ret = wdt_stop();
+			if (ret) {
+				/*
+				 * Stop failed. Just keep the watchdog alive
+				 * and hope nothing bad happens.
+				 */
+				set_bit(WDTS_EXPECTED, &wdt_status);
+				wdt_keepalive();
+				return ret;
+			}
 			clear_bit(WDTS_TIMER_RUN, &wdt_status);
 		} else {
 			wdt_keepalive();
@@ -484,7 +506,8 @@ static long wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 				    &ident, sizeof(ident)) ? -EFAULT : 0;
 
 	case WDIOC_GETSTATUS:
-		wdt_get_status(&status);
+		if (wdt_get_status(&status))
+			return -EBUSY;
 		return put_user(status, uarg.i);
 
 	case WDIOC_GETBOOTSTATUS:
@@ -500,14 +523,22 @@ static long wdt_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 
 		switch (new_options) {
 		case WDIOS_DISABLECARD:
-			if (test_bit(WDTS_TIMER_RUN, &wdt_status))
-				wdt_stop();
+			if (test_bit(WDTS_TIMER_RUN, &wdt_status)) {
+				int ret = wdt_stop();
+				if (ret)
+					return ret;
+			}
 			clear_bit(WDTS_TIMER_RUN, &wdt_status);
 			return 0;
 
 		case WDIOS_ENABLECARD:
-			if (!test_and_set_bit(WDTS_TIMER_RUN, &wdt_status))
-				wdt_start();
+			if (!test_and_set_bit(WDTS_TIMER_RUN, &wdt_status)) {
+				int ret = wdt_start();
+				if (ret) {
+					clear_bit(WDTS_TIMER_RUN, &wdt_status);
+					return ret;
+				}
+			}
 			return 0;
 
 		default:
@@ -560,16 +591,17 @@ static int __init it87_wdt_init(void)
 	int rc = 0;
 	int try_gameport = !nogameport;
 	u8  chip_rev;
-	unsigned long flags;
+	int ret;
 
 	wdt_status = 0;
 
-	spin_lock_irqsave(&spinlock, flags);
-	superio_enter();
+	ret = superio_enter();
+	if (ret)
+		return ret;
+
 	chip_type = superio_inw(CHIPID);
 	chip_rev  = superio_inb(CHIPREV) & 0x0f;
 	superio_exit();
-	spin_unlock_irqrestore(&spinlock, flags);
 
 	switch (chip_type) {
 	case IT8702_ID:
@@ -603,8 +635,9 @@ static int __init it87_wdt_init(void)
 		return -ENODEV;
 	}
 
-	spin_lock_irqsave(&spinlock, flags);
-	superio_enter();
+	ret = superio_enter();
+	if (ret)
+		return ret;
 
 	superio_select(GPIO);
 	superio_outb(WDT_TOV1, WDTCFG);
@@ -621,18 +654,17 @@ static int __init it87_wdt_init(void)
 		gpact = superio_inb(ACTREG);
 		superio_outb(0x01, ACTREG);
 		superio_exit();
-		spin_unlock_irqrestore(&spinlock, flags);
 		if (request_region(base, 1, WATCHDOG_NAME))
 			set_bit(WDTS_USE_GP, &wdt_status);
 		else
 			rc = -EIO;
 	} else {
 		superio_exit();
-		spin_unlock_irqrestore(&spinlock, flags);
 	}
 
 	/* If we haven't Gameport support, try to get CIR support */
 	if (!test_bit(WDTS_USE_GP, &wdt_status)) {
+		int ret;
 		if (!request_region(CIR_BASE, 8, WATCHDOG_NAME)) {
 			if (rc == -EIO)
 				printk(KERN_ERR PFX
@@ -646,8 +678,9 @@ static int __init it87_wdt_init(void)
 			goto err_out;
 		}
 		base = CIR_BASE;
-		spin_lock_irqsave(&spinlock, flags);
-		superio_enter();
+		ret = superio_enter();
+		if (ret)
+			return ret;
 
 		superio_select(CIR);
 		superio_outw(base, BASEREG);
@@ -660,7 +693,6 @@ static int __init it87_wdt_init(void)
 		}
 
 		superio_exit();
-		spin_unlock_irqrestore(&spinlock, flags);
 	}
 
 	if (timeout < 1 || timeout > max_units * 60) {
@@ -711,21 +743,23 @@ err_out_reboot:
 err_out_region:
 	release_region(base, test_bit(WDTS_USE_GP, &wdt_status) ? 1 : 8);
 	if (!test_bit(WDTS_USE_GP, &wdt_status)) {
-		spin_lock_irqsave(&spinlock, flags);
-		superio_enter();
+		ret = superio_enter();
+		if (ret)
+			return ret;
+
 		superio_select(CIR);
 		superio_outb(ciract, ACTREG);
 		superio_exit();
-		spin_unlock_irqrestore(&spinlock, flags);
 	}
 err_out:
 	if (try_gameport) {
-		spin_lock_irqsave(&spinlock, flags);
-		superio_enter();
+		ret = superio_enter();
+		if (ret)
+			return ret;
+
 		superio_select(GAMEPORT);
 		superio_outb(gpact, ACTREG);
 		superio_exit();
-		spin_unlock_irqrestore(&spinlock, flags);
 	}
 
 	return rc;
@@ -733,27 +767,22 @@ err_out:
 
 static void __exit it87_wdt_exit(void)
 {
-	unsigned long flags;
-	int nolock;
-
-	nolock = !spin_trylock_irqsave(&spinlock, flags);
-	superio_enter();
-	superio_select(GPIO);
-	superio_outb(0x00, WDTCTRL);
-	superio_outb(0x00, WDTCFG);
-	superio_outb(0x00, WDTVALLSB);
-	if (max_units > 255)
-		superio_outb(0x00, WDTVALMSB);
-	if (test_bit(WDTS_USE_GP, &wdt_status)) {
-		superio_select(GAMEPORT);
-		superio_outb(gpact, ACTREG);
-	} else {
-		superio_select(CIR);
-		superio_outb(ciract, ACTREG);
+	if (superio_enter() == 0) {
+		superio_select(GPIO);
+		superio_outb(0x00, WDTCTRL);
+		superio_outb(0x00, WDTCFG);
+		superio_outb(0x00, WDTVALLSB);
+		if (max_units > 255)
+			superio_outb(0x00, WDTVALMSB);
+		if (test_bit(WDTS_USE_GP, &wdt_status)) {
+			superio_select(GAMEPORT);
+			superio_outb(gpact, ACTREG);
+		} else {
+			superio_select(CIR);
+			superio_outb(ciract, ACTREG);
+		}
+		superio_exit();
 	}
-	superio_exit();
-	if (!nolock)
-		spin_unlock_irqrestore(&spinlock, flags);
 
 	misc_deregister(&wdt_miscdev);
 	unregister_reboot_notifier(&wdt_notifier);

[PATCH v8 2/2] Use "request_muxed_region" in it87 hwmon drivers

[Nat Gurumoorthy]

02 - Chages to hwmon it87 driver to use "request_muxed_region"
Serialize access to the hardware by using "request_muxed_region" macro defined
by Alan Cox. Call to this macro will hold off the requestor if the resource is
currently busy. "superio_enter" will return an error if call to 
"request_muxed_region" fails. Rest of the code change is to ripple an error
return from superio_enter to the top level.

Signed-off-by: Nat Gurumoorthy <natg@google.com>
---

diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index 316b648..fa3ff02 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -108,13 +108,20 @@ superio_select(int ldn)
 	outb(ldn, VAL);
 }
 
-static inline void
+static inline int
 superio_enter(void)
 {
+	/*
+	 * Try to reserve REG and REG + 1 for exclusive access.
+	 */
+	if (!request_muxed_region(REG, 2, DRVNAME))
+		return -EBUSY;
+
 	outb(0x87, REG);
 	outb(0x01, REG);
 	outb(0x55, REG);
 	outb(0x55, REG);
+	return 0;
 }
 
 static inline void
@@ -122,6 +129,7 @@ superio_exit(void)
 {
 	outb(0x02, REG);
 	outb(0x02, VAL);
+	release_region(REG, 2);
 }
 
 /* Logical device 4 registers */
@@ -1546,7 +1554,9 @@ static int __init it87_find(unsigned short *address,
 	u16 chip_type;
 	const char *board_vendor, *board_name;
 
-	superio_enter();
+	if (superio_enter())
+		return -EBUSY;
+
 	chip_type = force_id ? force_id : superio_inw(DEVID);
 
 	switch (chip_type) {
-- 
1.7.3.1

Re:

[Guenter Roeck]

On Fri, 2011-05-06 at 14:52 -0400, Nat Gurumoorthy wrote:
> There are 3 different drivers that touch the it87 hardware registers.
> The 3 drivers have been written independently and access the it87 hardware
> registers assuming they are the only driver accessing it. This change
> attempts to serialize access to the hardware by using
> "request_muxed_region" macro defined by Alan Cox. Call to this macro
> will hold off the requestor if the resource is currently busy.
> The use of the above macro makes it possible to get rid of
> spinlocks in it8712f_wdt.c and it87_wdt.c watchdog drivers.
> This also greatly simplifies the implementation of it87_wdt.c driver.
> 
> 01 - Changes to it87 watchdog driver to use "request_muxed_region"
>  drivers/watchdog/it8712f_wdt.c
>  drivers/watchdog/it87_wdt.c
> 
> 02 - Chages to hwmon it87 driver to use "request_muxed_region"
>  drivers/hwmon/it87.c
> 
>  drivers/hwmon/it87.c           |   14 +++-
>  drivers/watchdog/it8712f_wdt.c |   60 ++++++++++----
>  drivers/watchdog/it87_wdt.c    |  165 +++++++++++++++++++++++----------------
>  3 files changed, 152 insertions(+), 87 deletions(-)
> diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
> 
> Signed-off-by: Nat Gurumoorthy <natg@google.com>
> 
> Patch History:
> v8:
> - Return the error actually returned by superio_enter and not -EBUSY.

Hi Nat,

Your use of -EBUSY vs. the returned error code is still inconsistent,
for superio_enter() as well as for other functions returning an error
code.

Also, the following line split is really unnecessary.

-static inline void superio_enter(void)
+static inline int
+superio_enter(void)

Guenter

Re:

[Natarajan Gurumoorthy]

Guenter,
    Good catch. Forgot to checkin drivers/hwmon/it87.c. Also found a
couple of places I missed in driver/watch/it8712_wdt.c. Patch #9 will
be shipped later tonight. Got pulled off to do something else. Expect
patch late tonight.

Regards
Nat


On Fri, May 6, 2011 at 12:13 PM, Guenter Roeck
<guenter.roeck@ericsson.com> wrote:
> On Fri, 2011-05-06 at 14:52 -0400, Nat Gurumoorthy wrote:
>> There are 3 different drivers that touch the it87 hardware registers.
>> The 3 drivers have been written independently and access the it87 hardware
>> registers assuming they are the only driver accessing it. This change
>> attempts to serialize access to the hardware by using
>> "request_muxed_region" macro defined by Alan Cox. Call to this macro
>> will hold off the requestor if the resource is currently busy.
>> The use of the above macro makes it possible to get rid of
>> spinlocks in it8712f_wdt.c and it87_wdt.c watchdog drivers.
>> This also greatly simplifies the implementation of it87_wdt.c driver.
>>
>> 01 - Changes to it87 watchdog driver to use "request_muxed_region"
>>  drivers/watchdog/it8712f_wdt.c
>>  drivers/watchdog/it87_wdt.c
>>
>> 02 - Chages to hwmon it87 driver to use "request_muxed_region"
>>  drivers/hwmon/it87.c
>>
>>  drivers/hwmon/it87.c           |   14 +++-
>>  drivers/watchdog/it8712f_wdt.c |   60 ++++++++++----
>>  drivers/watchdog/it87_wdt.c    |  165 +++++++++++++++++++++++----------------
>>  3 files changed, 152 insertions(+), 87 deletions(-)
>> diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
>>
>> Signed-off-by: Nat Gurumoorthy <natg@google.com>
>>
>> Patch History:
>> v8:
>> - Return the error actually returned by superio_enter and not -EBUSY.
>
> Hi Nat,
>
> Your use of -EBUSY vs. the returned error code is still inconsistent,
> for superio_enter() as well as for other functions returning an error
> code.
>
> Also, the following line split is really unnecessary.
>
> -static inline void superio_enter(void)
> +static inline int
> +superio_enter(void)
>
> Guenter
>
>
>



-- 
Regards
Nat Gurumoorthy AB6SJ