watchdog: ziirave_wdt: Drop status polling code

Bootloader firmware doesn't implement DOWNLOAD_START or
DOWNLOAD_PACKET in a non-blocking way. It will stretch the clock of
the first status byte read until the operation is complete. Polling
for the status is not really necessary since it will always succed on
the first try. Replace polling code with a simple single byte read to
simplify things.

Signed-off-by: Andrey Smirnov <andrew.smirnov@gmail.com>
Cc: Chris Healy <cphealy@gmail.com>
Cc: Guenter Roeck <linux@roeck-us.net>
Cc: Rick Ramstetter <rick@anteaterllc.com>
Cc: linux-watchdog@vger.kernel.org
Cc: linux-kernel@vger.kernel.org
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20190812200906.31344-20-andrew.smirnov@gmail.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>

drivers/watchdog/ziirave_wdt.c

@@ -57,11 +57,6 @@ static char *ziirave_reasons[] = {"power cycle", "hw watchdog", NULL, NULL,
 
 /* Received and ready for next Download packet. */
 #define ZIIRAVE_FIRM_DOWNLOAD_ACK	1
-/* Currently writing to flash. Retry Download status in a moment! */
-#define ZIIRAVE_FIRM_DOWNLOAD_BUSY	2
-
-/* Wait for ACK timeout in ms */
-#define ZIIRAVE_FIRM_WAIT_FOR_ACK_TIMEOUT	50
 
 /* Firmware commands */
 #define ZIIRAVE_CMD_DOWNLOAD_START		0x10
@@ -175,25 +170,16 @@ static unsigned int ziirave_wdt_get_timeleft(struct watchdog_device *wdd)
 	return ret;
 }
 
-static int ziirave_firm_wait_for_ack(struct watchdog_device *wdd)
+static int ziirave_firm_read_ack(struct watchdog_device *wdd)
 {
 	struct i2c_client *client = to_i2c_client(wdd->parent);
 	int ret;
-	unsigned long timeout;
-
-	timeout = jiffies + msecs_to_jiffies(ZIIRAVE_FIRM_WAIT_FOR_ACK_TIMEOUT);
-	do {
-		if (time_after(jiffies, timeout))
-			return -ETIMEDOUT;
 
-		usleep_range(5000, 10000);
-
-		ret = i2c_smbus_read_byte(client);
-		if (ret < 0) {
-			dev_err(&client->dev, "Failed to read byte\n");
-			return ret;
-		}
-	} while (ret == ZIIRAVE_FIRM_DOWNLOAD_BUSY);
+	ret = i2c_smbus_read_byte(client);
+	if (ret < 0) {
+		dev_err(&client->dev, "Failed to read status byte\n");
+		return ret;
+	}
 
 	return ret == ZIIRAVE_FIRM_DOWNLOAD_ACK ? 0 : -EIO;
 }
@@ -226,7 +212,7 @@ static int ziirave_firm_write_block_data(struct watchdog_device *wdd,
 	}
 
 	if (wait_for_ack)
-		ret = ziirave_firm_wait_for_ack(wdd);
+		ret = ziirave_firm_read_ack(wdd);
 
 	return ret;
 }