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Subject[PATCH 4.9 176/329] watchdog: sbsa: use 32-bit read for WCV
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Jayachandran C <jnair@caviumnetworks.com>

[ Upstream commit 93ac3deb7c220cbcec032a967220a1f109d58431 ]

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@caviumnetworks.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/watchdog/sbsa_gwdt.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

--- 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_timele
!(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);

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