[PATCH v9 2/2] Use "request_muxed_region" in it87 hwmon drivers

Nat Gurumoorthy
2011-05-07T05:21:57Z

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..bb6405b 100644
--- a/drivers/hwmon/it87.c
+++ b/drivers/hwmon/it87.c
@@ -77,15 +77,13 @@ static struct platform_device *pdev;
#define DEVID 0x20 /* Register: Device ID */
#define DEVREV 0x22 /* Register: Device Revision */

-static inline int
-superio_inb(int reg)
+static inline int superio_inb(int reg)
{
outb(reg, REG);
return inb(VAL);
}

-static inline void
-superio_outb(int reg, int val)
+static inline void superio_outb(int reg, int val)
{
outb(reg, REG);
outb(val, VAL);
@@ -101,27 +99,32 @@ static int superio_inw(int reg)
return val;
}

-static inline void
-superio_select(int ldn)
+static inline void superio_select(int ldn)
{
outb(DEV, REG);
outb(ldn, VAL);
}

-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, DRVNAME))
+ return -EBUSY;
+
outb(0x87, REG);
outb(0x01, REG);
outb(0x55, REG);
outb(0x55, REG);
+ return 0;
}

-static inline void
-superio_exit(void)
+static inline void superio_exit(void)
{
outb(0x02, REG);
outb(0x02, VAL);
+ release_region(REG, 2);
}

/* Logical device 4 registers */
@@ -1542,11 +1545,15 @@ static const struct attribute_group it87_group_label = {
static int __init it87_find(unsigned short *address,
struct it87_sio_data *sio_data)
{
- int err = -ENODEV;
+ int err;
u16 chip_type;
const char *board_vendor, *board_name;

- superio_enter();
+ err = superio_enter();
+ if (err)
+ return err;
+
+ err = -ENODEV;
chip_type = force_id ? force_id : superio_inw(DEVID);

switch (chip_type) {
--
1.7.3.1