mpc5200: a4m2k: Implement custom "dynamic" watchdog support

This patch adds a custom U-Boot command "wdogtoggle" which enables the
external hardware watchdog toggling via an GPIO pin on the a4m2k
board. After issuing this commands, the watchdog will be serviced
by U-Boot so that the user can use all U-Boot commands from the
prompt.

Signed-off-by: Stefan Roese <sr@denx.de>

board/a3m071/a3m071.c

@@ -255,7 +255,7 @@ void spl_board_init(void)
 	 * MPC5XXX_WU_GPIO_DIR direction is already 0 (INPUT)
 	 * set bit 0(msb) to 1
 	 */
-	setbits_be32((void *)MPC5XXX_WU_GPIO_ENABLE, 1 << (31 - 0));
+	setbits_be32((void *)MPC5XXX_WU_GPIO_ENABLE, CONFIG_WDOG_GPIO_PIN);
 
 #if defined(CONFIG_A4M2K)
 	/* Setup USB[x] as MPCDiag[0..3] GPIO outputs */
@@ -410,3 +410,57 @@ int spl_start_uboot(void)
 	return 1;
 }
 #endif
+
+#if defined(CONFIG_HW_WATCHDOG)
+static int watchdog_toggle;
+
+void hw_watchdog_reset(void)
+{
+	int val;
+
+	/*
+	 * Check if watchdog is enabled via user command
+	 */
+	if ((gd->flags & GD_FLG_RELOC) && watchdog_toggle) {
+		/* Set direction to output */
+		setbits_be32((void *)MPC5XXX_WU_GPIO_DIR, CONFIG_WDOG_GPIO_PIN);
+
+		/*
+		 * Toggle watchdog output
+		 */
+		val = (in_be32((void *)MPC5XXX_WU_GPIO_DATA_O) &
+		       CONFIG_WDOG_GPIO_PIN);
+		if (val) {
+			clrbits_be32((void *)MPC5XXX_WU_GPIO_DATA_O,
+				     CONFIG_WDOG_GPIO_PIN);
+		} else {
+			setbits_be32((void *)MPC5XXX_WU_GPIO_DATA_O,
+				     CONFIG_WDOG_GPIO_PIN);
+		}
+	}
+}
+
+int do_wdog_toggle(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
+{
+	if (argc != 2)
+		goto usage;
+
+	if (strncmp(argv[1], "on", 2) == 0)
+		watchdog_toggle = 1;
+	else if (strncmp(argv[1], "off", 3) == 0)
+		watchdog_toggle = 0;
+	else
+		goto usage;
+
+	return 0;
+usage:
+	printf("Usage: wdogtoggle %s\n", cmdtp->usage);
+	return 1;
+}
+
+U_BOOT_CMD(
+	wdogtoggle, CONFIG_SYS_MAXARGS, 2, do_wdog_toggle,
+	"toggle GPIO pin to service watchdog",
+	"[on/off] - Switch watchdog toggling via GPIO pin on/off"
+);
+#endif

include/configs/a3m071.h

@@ -166,6 +166,11 @@
 #define CONFIG_SYS_GPS_PORT_CONFIG_2	0x1005C005
 #endif
 
+#define CONFIG_WDOG_GPIO_PIN		GPIO_WKUP_7
+#if defined(CONFIG_A4M2K) && !defined(CONFIG_SPL_BUILD)
+#define CONFIG_HW_WATCHDOG		/* Use external HW-Watchdog	*/
+#endif
+
 /*
  * Configuration matrix
  *                        MSB                          LSB