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

[Yinghai Lu <yinghai@xxxxxxxxxx>]

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.


Reported-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Signed-off-by:Yinghai Lu <yinghai@xxxxxxxxxx>
Acked-by: Mike Waychison <mikew@xxxxxxxxxx>
Tested-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>

---
 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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