Re: [PATCH 2/3] hwmon: f71882fg: use a muxed resource lock for theSuper I/O port

From: Giel van Schijndel
Date: Sun Apr 25 2010 - 06:36:08 EST


On Thu, Mar 25, 2010 at 02:17:42PM +0100, Giel van Schijndel wrote:
> Sleep while acquiring a resource lock on the Super I/O port. This should
> prevent collisions from causing the hardware probe to fail with -EBUSY.

Fix a bug which caused f71882fg_find() to pretend to be succesfull on
Super I/O ports which didn't have a Fintek chip attached. This was
caused by returning 0 instead of -ENODEV, adding several 'err = -ENODEV'
statements preceding the 'goto exit' statements fixed this.

Patch follows this line:
========================================================================
Sleep while acquiring a resource lock on the Super I/O port. This should
prevent collisions from causing the hardware probe to fail with -EBUSY.

Signed-off-by: Giel van Schijndel <me@xxxxxxxxx>
---
drivers/hwmon/f71882fg.c | 32 +++++++++++++++++++-------------
1 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/drivers/hwmon/f71882fg.c b/drivers/hwmon/f71882fg.c
index 7857ed3..85512a7 100644
--- a/drivers/hwmon/f71882fg.c
+++ b/drivers/hwmon/f71882fg.c
@@ -113,7 +113,7 @@ static struct platform_device *f71882fg_pdev;
/* Super-I/O Function prototypes */
static inline int superio_inb(int base, int reg);
static inline int superio_inw(int base, int reg);
-static inline void superio_enter(int base);
+static inline int superio_enter(int base);
static inline void superio_select(int base, int ld);
static inline void superio_exit(int base);

@@ -883,11 +883,20 @@ static int superio_inw(int base, int reg)
return val;
}

-static inline void superio_enter(int base)
+static inline int superio_enter(int base)
{
+ /* Don't step on other drivers' I/O space by accident */
+ if (!request_muxed_region(base, 2, DRVNAME)) {
+ printk(KERN_ERR DRVNAME ": I/O address 0x%04x already in use\n",
+ (int)base);
+ return -EBUSY;
+ }
+
/* according to the datasheet the key must be send twice! */
outb(SIO_UNLOCK_KEY, base);
outb(SIO_UNLOCK_KEY, base);
+
+ return 0;
}

static inline void superio_select(int base, int ld)
@@ -899,6 +908,7 @@ static inline void superio_select(int base, int ld)
static inline void superio_exit(int base)
{
outb(SIO_LOCK_KEY, base);
+ release_region(base, 2);
}

static inline int fan_from_reg(u16 reg)
@@ -2239,21 +2249,15 @@ static int f71882fg_remove(struct platform_device *pdev)
static int __init f71882fg_find(int sioaddr, unsigned short *address,
struct f71882fg_sio_data *sio_data)
{
- int err = -ENODEV;
u16 devid;
-
- /* Don't step on other drivers' I/O space by accident */
- if (!request_region(sioaddr, 2, DRVNAME)) {
- printk(KERN_ERR DRVNAME ": I/O address 0x%04x already in use\n",
- (int)sioaddr);
- return -EBUSY;
- }
-
- superio_enter(sioaddr);
+ int err = superio_enter(sioaddr);
+ if (err)
+ return err;

devid = superio_inw(sioaddr, SIO_REG_MANID);
if (devid != SIO_FINTEK_ID) {
pr_debug(DRVNAME ": Not a Fintek device\n");
+ err = -ENODEV;
goto exit;
}

@@ -2280,6 +2284,7 @@ static int __init f71882fg_find(int sioaddr, unsigned short *address,
default:
printk(KERN_INFO DRVNAME ": Unsupported Fintek device: %04x\n",
(unsigned int)devid);
+ err = -ENODEV;
goto exit;
}

@@ -2290,12 +2295,14 @@ static int __init f71882fg_find(int sioaddr, unsigned short *address,

if (!(superio_inb(sioaddr, SIO_REG_ENABLE) & 0x01)) {
printk(KERN_WARNING DRVNAME ": Device not activated\n");
+ err = -ENODEV;
goto exit;
}

*address = superio_inw(sioaddr, SIO_REG_ADDR);
if (*address == 0) {
printk(KERN_WARNING DRVNAME ": Base address not set\n");
+ err = -ENODEV;
goto exit;
}
*address &= ~(REGION_LENGTH - 1); /* Ignore 3 LSB */
@@ -2306,7 +2313,6 @@ static int __init f71882fg_find(int sioaddr, unsigned short *address,
(int)superio_inb(sioaddr, SIO_REG_DEVREV));
exit:
superio_exit(sioaddr);
- release_region(sioaddr, 2);
return err;
}

--
1.6.4.4


--
Met vriendelijke groet,
With kind regards,
Giel van Schijndel

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