Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
From:   Jayachandran C <jnair@caviumnetworks.com>
To:     Wim Van Sebroeck <wim@linux-watchdog.org>,
        Guenter Roeck <linux@roeck-us.net>,
        linux-watchdog@vger.kernel.org
Cc:     Fu Wei <fu.wei@linaro.org>, linux-kernel@vger.kernel.org,
        Jayachandran C <jnair@caviumnetworks.com>
Subject: [PATCH] watchdog: sbsa: use 32-bit read for WCV
Date:   Wed, 28 Feb 2018 02:52:20 -0800
Message-Id: <1519815140-5336-1-git-send-email-jnair@caviumnetworks.com>
MIME-Version: 1.0
Content-Type: text/plain
Received-SPF: None (protection.outlook.com: cavium.com does not designate
 permitted sender hosts)
SpamDiagnosticOutput: 1:99
SpamDiagnosticMetadata: NSPM
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 28 Feb 2018 10:53:02.6208 (UTC)
X-MS-Exchange-CrossTenant-Network-Message-Id: 6483cdd7-6dd6-447c-5ffe-08d57e9970f6
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 711e4ccf-2e9b-4bcf-a551-4094005b6194
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CO2PR07MB667
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

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>
---
 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 316c2eb..e8bd988 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);
-- 
2.7.4