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

[Yinghai Lu <yinghai@kernel.org>]

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@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);
  }