Re: [Xen-devel] [PATCH -v3] watchdog, SP5100: Check if firmware has set correct value in tcobase.

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Wed, Mar 16, 2011 at 08:01:07PM -0700, Yinghai Lu wrote:
> 
> Stefano found SP5100 TCO watchdog driver using wrong address.
> 
> [    9.148536] SP5100 TCO timer: SP5100 TCO WatchDog Timer Driver v0.01
> [    9.148628] DEBUG __ioremap_caller WARNING address=b8fe00 size=8 valid=1 reserved=1
> 
> and e820 said that range is RAM.
> 
> We should check if we can use that reading out. BIOS could just program wrong address there.
> 
> -v2: Mike pointed out one path need one release.
> -v3: corrected logic checking with request_mem_region_exclusive()
>      Found by Konrad.

Yinghai:
Not sure what you are using as a base, but I had to modify this patch
to go on top of 2.6.38. Here is the patch that applies cleanly:

diff --git a/drivers/watchdog/sp5100_tco.c b/drivers/watchdog/sp5100_tco.c
index 8083728..9cbca8b 100644
--- a/drivers/watchdog/sp5100_tco.c
+++ b/drivers/watchdog/sp5100_tco.c
@@ -42,6 +42,7 @@
 #define PFX TCO_MODULE_NAME ": "
 
 /* internal variables */
+static u32 tcobase_phys;
 static void __iomem *tcobase;
 static unsigned int pm_iobase;
 static DEFINE_SPINLOCK(tco_lock);	/* Guards the hardware */
@@ -305,10 +306,16 @@ static unsigned char __devinit sp5100_tco_setupdevice(void)
 	/* Low three bits of BASE0 are reserved. */
 	val = val << 8 | (inb(SP5100_IO_PM_DATA_REG) & 0xf8);
 
+	if (!request_mem_region_exclusive(val, SP5100_WDT_MEM_MAP_SIZE, "SP5100 TCO")) {
+                printk(KERN_ERR PFX "mmio address 0x%04x already in use\n", val);
+                goto unreg_region;
+        }
+        tcobase_phys = val;
+
 	tcobase = ioremap(val, SP5100_WDT_MEM_MAP_SIZE);
 	if (tcobase == 0) {
 		printk(KERN_ERR PFX "failed to get tcobase address\n");
-		goto unreg_region;
+		goto unreg_mem_region;
 	}
 
 	/* Enable watchdog decode bit */
@@ -346,7 +353,8 @@ static unsigned char __devinit sp5100_tco_setupdevice(void)
 	/* Done */
 	return 1;
 
-	iounmap(tcobase);
+unreg_mem_region:
+	release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
 unreg_region:
 	release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
 exit:
@@ -401,6 +409,7 @@ static int __devinit sp5100_tco_init(struct platform_device *dev)
 
 exit:
 	iounmap(tcobase);
+	release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
 	release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
 	return ret;
 }
@@ -414,6 +423,7 @@ static void __devexit sp5100_tco_cleanup(void)
 	/* Deregister */
 	misc_deregister(&sp5100_tco_miscdev);
 	iounmap(tcobase);
+	release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
 	release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
 }
 
> 
> 
> Reported-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> Signed-off-by:Yinghai Lu <yinghai@kernel.org>
> Acked-by: Mike Waychison <mikew@google.com>
> Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> 
> ---
>  drivers/watchdog/sp5100_tco.c |   14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> Index: linux-2.6/drivers/watchdog/sp5100_tco.c
> ===================================================================
> --- linux-2.6.orig/drivers/watchdog/sp5100_tco.c
> +++ linux-2.6/drivers/watchdog/sp5100_tco.c
> @@ -42,6 +42,7 @@
>  #define PFX TCO_MODULE_NAME ": "
>  /* internal variables */
> +static u32 tcobase_phys;
>  static void __iomem *tcobase;
>  static unsigned int pm_iobase;
>  static DEFINE_SPINLOCK(tco_lock);	/* Guards the hardware */
> @@ -305,10 +306,16 @@ static unsigned char __devinit sp5100_tc
>  	/* Low three bits of BASE0 are reserved. */
>  	val = val << 8 | (inb(SP5100_IO_PM_DATA_REG) & 0xf8);
> +	if (!request_mem_region_exclusive(val, SP5100_WDT_MEM_MAP_SIZE, "SP5100 TCO")) {
> +		printk(KERN_ERR PFX "mmio address 0x%04x already in use\n", val);
> +		goto unreg_region;
> +	}
> +	tcobase_phys = val;
> +
>  	tcobase = ioremap(val, SP5100_WDT_MEM_MAP_SIZE);
>  	if (tcobase == 0) {
>  		printk(KERN_ERR PFX "failed to get tcobase address\n");
> -		goto unreg_region;
> +		goto unreg_mem_region;
>  	}
>  	/* Enable watchdog decode bit */
> @@ -346,7 +353,8 @@ static unsigned char __devinit sp5100_tc
>  	/* Done */
>  	return 1;
> -	iounmap(tcobase);
> +unreg_mem_region:
> +	release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
>  unreg_region:
>  	release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
>  exit:
> @@ -401,6 +409,7 @@ static int __devinit sp5100_tco_init(str
>  exit:
>  	iounmap(tcobase);
> +	release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
>  	release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
>  	return ret;
>  }
> @@ -414,6 +423,7 @@ static void __devexit sp5100_tco_cleanup
>  	/* Deregister */
>  	misc_deregister(&sp5100_tco_miscdev);
>  	iounmap(tcobase);
> +	release_mem_region(tcobase_phys, SP5100_WDT_MEM_MAP_SIZE);
>  	release_region(pm_iobase, SP5100_PM_IOPORTS_SIZE);
>  }
> 
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