[PATCH][Bionic][SRU Artful] watchdog: sbsa: use 32-bit read for WCV

[dann frazier]

From: Jayachandran C <jnair at caviumnetworks.com>

BugLink: https://bugs.launchpad.net/bugs/1755595

According to SBSA spec v3.1 section 5.3:
  All registers are 32 bits in size and should be accessed using
  32-bit reads and writes. If an access size other than 32 bits
  is used then the results are IMPLEMENTATION DEFINED.
  [...]
  The Generic Watchdog is little-endian

The current code uses readq to read the watchdog compare register
which does a 64-bit access. This fails on ThunderX2 which does not
implement 64-bit access to this register.

Fix this by using lo_hi_readq() that does two 32-bit reads.

Signed-off-by: Jayachandran C <jnair at caviumnetworks.com>
Reviewed-by: Guenter Roeck <linux at roeck-us.net>
Signed-off-by: Guenter Roeck <linux at roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim at iguana.be>
(cherry picked from commit 93ac3deb7c220cbcec032a967220a1f109d58431)
Signed-off-by: dann frazier <dann.frazier at canonical.com>
---
 drivers/watchdog/sbsa_gwdt.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/watchdog/sbsa_gwdt.c b/drivers/watchdog/sbsa_gwdt.c
index 316c2eb122d2..e8bd9887c566 100644
--- a/drivers/watchdog/sbsa_gwdt.c
+++ b/drivers/watchdog/sbsa_gwdt.c
@@ -50,6 +50,7 @@
  */
 
 #include <linux/io.h>
+#include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/moduleparam.h>
@@ -159,7 +160,7 @@ static unsigned int sbsa_gwdt_get_timeleft(struct watchdog_device *wdd)
 	    !(readl(gwdt->control_base + SBSA_GWDT_WCS) & SBSA_GWDT_WCS_WS0))
 		timeleft += readl(gwdt->control_base + SBSA_GWDT_WOR);
 
-	timeleft += readq(gwdt->control_base + SBSA_GWDT_WCV) -
+	timeleft += lo_hi_readq(gwdt->control_base + SBSA_GWDT_WCV) -
 		    arch_counter_get_cntvct();
 
 	do_div(timeleft, gwdt->clk);
-- 
2.16.2