[PATCH v2 3/3] Change hwmon it87 driver to use it87_io_lock.

[Nat Gurumoorthy]

03 - Adds changes to hwmon driver to use the new lock.
   This patch adds changes to drivers/hwmon/it87.c to use it87_io_lock
to serialize access to the hardware. Added __acquire and __release
annotations wherever needed.
   Change it87 driver entry in Kconfig to issue "select IT87_LOCK"
directive to compile it87_io_lock into the kernel.

Signed-off-by: Nat Gurumoorthy <natg@xxxxxxxxxx>

diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
index 297bc9a..afe671a 100644
--- a/drivers/hwmon/Kconfig
+++ b/drivers/hwmon/Kconfig
@@ -436,6 +436,7 @@ config SENSORS_IBMPEX
 config SENSORS_IT87
 	tristate "ITE IT87xx and compatibles"
 	select HWMON_VID
+	select IT87_LOCK
 	help
 	  If you say yes here you get support for ITE IT8705F, IT8712F,
 	  IT8716F, IT8718F, IT8720F, IT8721F, IT8726F and IT8758E sensor
diff --git a/drivers/hwmon/it87.c b/drivers/hwmon/it87.c
index 316b648..bc32535 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -55,6 +55,8 @@
 #include <linux/dmi.h>
 #include <linux/acpi.h>
 #include <linux/io.h>
+#include <linux/spinlock.h>
+#include <linux/it87_lock.h>
 
 #define DRVNAME "it87"
 
@@ -110,7 +112,9 @@ superio_select(int ldn)
 
 static inline void
 superio_enter(void)
+__acquires(&it87_io_lock)
 {
+	spin_lock(&it87_io_lock);
 	outb(0x87, REG);
 	outb(0x01, REG);
 	outb(0x55, REG);
@@ -119,9 +123,11 @@ superio_enter(void)
 
 static inline void
 superio_exit(void)
+__releases(&it87_io_lock)
 {
 	outb(0x02, REG);
 	outb(0x02, VAL);
+	spin_unlock(&it87_io_lock);
 }
 
 /* Logical device 4 registers */
@@ -1899,8 +1905,12 @@ static int __devexit it87_remove(struct platform_device *pdev)
    would slow down the IT87 access and should not be necessary. */
 static int it87_read_value(struct it87_data *data, u8 reg)
 {
+	int ret;
+	spin_lock(&it87_io_lock);
 	outb_p(reg, data->addr + IT87_ADDR_REG_OFFSET);
-	return inb_p(data->addr + IT87_DATA_REG_OFFSET);
+	ret = inb_p(data->addr + IT87_DATA_REG_OFFSET);
+	spin_unlock(&it87_io_lock);
+	return ret;
 }
 
 /* Must be called with data->update_lock held, except during initialization.
@@ -1908,8 +1918,10 @@ static int it87_read_value(struct it87_data *data, u8 reg)
    would slow down the IT87 access and should not be necessary. */
 static void it87_write_value(struct it87_data *data, u8 reg, u8 value)
 {
+	spin_lock(&it87_io_lock);
 	outb_p(reg, data->addr + IT87_ADDR_REG_OFFSET);
 	outb_p(value, data->addr + IT87_DATA_REG_OFFSET);
+	spin_unlock(&it87_io_lock);
 }
 
 /* Return 1 if and only if the PWM interface is safe to use */
-- 

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