Bootloader firmware expects the following traffic for
RESET_PROCESSOR:

S Addr Wr [A] 0x0b [A] 0x01 [A] P

using ziirave_firm_write_byte() will result in

S Addr Wr [A] 0x0b [A] 0x01 [A] 0x01 [A] P

which happens to work because firmware will ignore any extra bytes and
expected magic value matches byte count sent by
i2c_smbus_write_block_data(). Fix this by converting the code to use
i2c_smbus_write_byte_data() instead.

Signed-off-by: Andrey Smirnov <andrew.smir...@gmail.com>
Cc: Chris Healy <cphe...@gmail.com>
Cc: Guenter Roeck <li...@roeck-us.net>
Cc: Rick Ramstetter <r...@anteaterllc.com>
Cc: linux-watch...@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
---
 drivers/watchdog/ziirave_wdt.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/watchdog/ziirave_wdt.c b/drivers/watchdog/ziirave_wdt.c
index a598780d73d3..92df27350e41 100644
--- a/drivers/watchdog/ziirave_wdt.c
+++ b/drivers/watchdog/ziirave_wdt.c
@@ -73,6 +73,7 @@ static char *ziirave_reasons[] = {"power cycle", "hw 
watchdog", NULL, NULL,
 #define ZIIRAVE_CMD_DOWNLOAD_PACKET            0x0e
 
 #define ZIIRAVE_CMD_JUMP_TO_BOOTLOADER_MAGIC   1
+#define ZIIRAVE_CMD_RESET_PROCESSOR_MAGIC      1
 
 #define ZIIRAVE_FW_VERSION_FMT "02.%02u.%02u"
 #define ZIIRAVE_BL_VERSION_FMT "01.%02u.%02u"
@@ -433,8 +434,9 @@ static int ziirave_firm_upload(struct watchdog_device *wdd,
        }
 
        /* Reset the processor */
-       ret = ziirave_firm_write_byte(wdd, ZIIRAVE_CMD_RESET_PROCESSOR, 1,
-                                     false);
+       ret = i2c_smbus_write_byte_data(client,
+                                       ZIIRAVE_CMD_RESET_PROCESSOR,
+                                       ZIIRAVE_CMD_RESET_PROCESSOR_MAGIC);
        if (ret) {
                dev_err(&client->dev,
                        "Failed to reset the watchdog: %d\n", ret);
-- 
2.21.0

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