nmhw21: board: add user reset option via rs232

allow invoking factory reset and recovery boot via:
- uart break, followed by command ('r', 'f')
- using uart rxd as reset line

Co-authored-by: Rene Straub <rene.straub@netmodule.com>
Reviewed-by: Patrick Zysset <patrick.zysset@netmodule.com>

board/nm/nmhw21/board.c

@@ -104,6 +104,7 @@ DECLARE_GLOBAL_DATA_PTR;
 #define GPIO_SIM_SEL		GPIO_TO_PIN(1, 12)
 #define GPIO_SIM_PRES_N		GPIO_TO_PIN(2, 16)
 
+#define GPIO_UART2_RX 		GPIO_TO_PIN(0, 2)	/* UART Rx Pin as GPIO */
 
 
 /*
@@ -133,6 +134,15 @@ DECLARE_GLOBAL_DATA_PTR;
 #define DDR3_CLOCK_FREQUENCY		(400)
 
 
+#define DURATION_FACTORY_RESET		(2000)		/* Reset button time to initiate factory reset */
+#define DURATION_RECOVERY_BOOT		(12000)		/* Reset button time to initiate recovery boot */
+
+#if (DURATION_RECOVERY_BOOT < (DURATION_FACTORY_RESET+1000))
+#error Recovery boot time must be larger than factory reset + 1 second
+#endif
+
+
+
 #if !defined(CONFIG_SPL_BUILD)
 /* Hardware version information of mainboard, loaded by get_hw_version() */
 static int hw_ver = -1;
@@ -1109,53 +1119,431 @@ static void blink_led(int pulses)
 #endif
 }
 
-static void check_reset_button(void)
-{
-	int counter = 0;
 
-	/* Check how long button is pressed */
+#define RESET_CHECK_PERIOD		(100)		/* 100 ms */
-	do {
+
-		if (!get_button_state())
+typedef enum _action_t
+{ 
+	NONE = 0,
+	WAIT,
+	FACTORY_RESET,
+	RECOVERY_BOOT
+} action_t;
+
+
+static void uart2_rx_gpio_pin_mux(void)
+{
+	/* Configure UART2 rxd pin as GPIO */
+	static struct module_pin_mux uart2_gpio_pin_mux[] = {
+		{OFFSET(spi0_sclk), (MODE(7) | PULLUDEN | PULLUP_EN | RXACTIVE)},	/* (A17) uart2_rxd = gpio0_2 */
+		{-1}
+	};
+
+	configure_module_pin_mux(uart2_gpio_pin_mux);
+}
+
+static void uart2_rx_rx_pin_mux(void)
+{
+	/* Configure UART2 rxd pin as rxd function */
+	static struct module_pin_mux uart2_pin_mux[] = {
+		{OFFSET(spi0_sclk), (MODE(1) | PULLUDEN | PULLUP_EN | RXACTIVE)},	/* (A17) uart2_rxd */
+		{-1}
+	};
+
+	configure_module_pin_mux(uart2_pin_mux);
+}
+
+static bool get_rxd_state(void)
+{
+	uart2_rx_gpio_pin_mux();
+
+	(void)gpio_request(GPIO_UART2_RX, "");
+	int val = gpio_get_value(GPIO_UART2_RX);
+	gpio_free(GPIO_UART2_RX);
+
+	uart2_rx_rx_pin_mux();
+
+	return (val == 0);
+}
+
+static int check_button(int time, bool button)
+{
+	/*
+	 * Hardware button logic
+	 * 
+	 * input: 
+	 *   button: current button press state (true = pressed)
+	 * logic:
+	 * - if button is not pressed initially, return action NONE for all
+	 *   invocations (state NO_ACTION)
+	 * - if button pressed initially, return action WAIT and measure duration
+	 *   of press (state PRESSED).
+	 * - while button is pressed, measure time, indicate actions with LED,
+	 * - when button is released, check time and decide on factory reset
+	 *   or recovery boot.  
+	 */
+	typedef enum _state_t { INIT = 0, PRESSED, DONE } state_t;
+
+	static state_t state = INIT;	/* Current state */
+	static action_t act = NONE;	/* Action to report to user, returned at function end */
+	static int duration = 0;
+
+	if (time == 0) {
+		state = INIT;
+	}
+
+	/* TODO: Remove printf, puts */
+	/* printf("button: state %d button %d -> ", state, button); */
+
+	switch (state) {
+		case INIT:
+			if (button) {
+				/* Pressed, start to measure time until released */
+				duration = 0;
+				act = WAIT;
+				state = PRESSED;
+			}
+			else {
+				/* If not pressed, no further action is possible */
+				act = NONE;
+				state = DONE;
+			}
 			break;
 
-		udelay(100*1000);  /* 100ms */
+		case PRESSED:
-		counter += 100;
+			if (button) {
+				duration += RESET_CHECK_PERIOD;
+				if (duration == DURATION_FACTORY_RESET) {
+					/* Indicate factory reset threshold */
+					blink_led(1);
+				}
+				else if (duration == DURATION_RECOVERY_BOOT) {
+					/* Indicate recovery boot threshold and leave state */
+					blink_led(2);
+					act = RECOVERY_BOOT;
+					state = DONE;
+				}
+			}
+			else {
+				/* Check how long button was pressed */
+				if (duration >= DURATION_RECOVERY_BOOT) {
+					act = RECOVERY_BOOT;
+					state = DONE;
+				}
+				else if (duration >= DURATION_FACTORY_RESET) {
+					act = FACTORY_RESET;
+					state = DONE;
+				}
+				else {
+					/* too short, nothing to do */
+					act = NONE;
+					state = DONE;
+				}
+			}
+			break;
 
-		if (counter == 2000) {
+		case DONE:	
+			/* Final state when an action has been chosen */
+			break;
+
+		default:
+			break;
+	}
+
+	/* printf("act %d\n", act); */
+
+	return act;
+}
+
+static int check_break_length(int time, bool rx_line)
+{
+	/*
+	 * RS232 RxD Reset input logic
+	 * 
+	 * Treats RxD line as reset input. Line is considered active when
+	 * break condition applies (RS232 line > 3.0 V)
+	 * 
+	 * input: 
+	 *   rx_line: true if rxd input is '0' (break condition)
+	 * logic:
+	 *   see explanation in check_button()
+	 *   additional logic is added to debounce input
+	 */
+	#define BREAK_DEB_TIME		500
+
+	typedef enum _state_t { WAIT_BREAK = 0, HAVE_BREAK, DONE } state_t;
+
+	static state_t state = WAIT_BREAK;	/* Current state */
+	static action_t act = NONE;		/* Action to report to user, returned at function end */
+	static int duration = 0;
+	static int wait_time = 0;
+
+	if (time == 0) {
+		state = WAIT_BREAK;
+		wait_time = BREAK_DEB_TIME;
+	}
+
+	/* TODO: Remove */
+	/* printf("break length: state %d have_break_cond %d duration %d -> ", state, have_break_cond, duration); */
+
+	switch (state) {
+		case WAIT_BREAK:
+			if (rx_line) {
+				/* Break detected, start to measure time */
+				duration = 0;
+				wait_time = BREAK_DEB_TIME;
+				act = WAIT;
+				state = HAVE_BREAK;
+			}
+
+			if (wait_time > 0) {
+				wait_time -= RESET_CHECK_PERIOD;
+				act = WAIT;
+			}
+			else {
+				/* If no break seen, stop here */
+				act = NONE;
+				state = DONE;
+			}
+			break;
+
+		case HAVE_BREAK:
+			if (rx_line) {
+				wait_time = BREAK_DEB_TIME;
+				duration += RESET_CHECK_PERIOD;
+
+				if (duration == DURATION_FACTORY_RESET) {
 			/* Indicate factory reset threshold */
 			blink_led(1);
 		}
-		else if (counter == 12000) {
+				else if (duration == DURATION_RECOVERY_BOOT) {
-			/* Indicate recovery boot threshold */
+					/* Indicate recovery boot threshold and leave state */
-			blink_led(2);
+					blink_led(2);
-		}
+					act = RECOVERY_BOOT;	/* TODO: maybe remain in state until break removed */
-	} while (counter < 12000);
+					state = DONE;
+				}
+			}
 
-	if (counter < 2000) {
+			if (wait_time > 0) {
-		/* Don't do anything for duration < 2s */
+				wait_time -= RESET_CHECK_PERIOD;
+			}
+			else {
+				/* puts("break condition released\n"); */
+
+				/* Check how long button was pressed */
+				if (duration >= DURATION_RECOVERY_BOOT) {
+					act = RECOVERY_BOOT;
+					state = DONE;
+				}
+				else if (duration >= DURATION_FACTORY_RESET) {
+					act = FACTORY_RESET;
+					state = DONE;
+				}
+				else {
+					/* too short, nothing to do */
+					act = NONE;
+					state = DONE;
+				}
+			}
+			break;
+
+		case DONE:
+			/* Final state when an action has been chosen */
+			break;
+
+		default:
+			break;
 	}
-	else if (counter < 12000)
+
+	/* printf("act %d\n", act); */
+
+	return act;
+}
+
+static int check_break_command(int time, int has_input, int c)
+{
+	/*
+	 * Break command logic
+	 * 
+	 * Tries to receive the break button (system magic key) and a command to execute.
+	 * 
+	 * input: 
+	 *   has_input: true if a character is available
+	 *   c: character code (can be 0x00 for break condition, system magic key)
+	 * logic:
+	 * - waits up to 500 ms to receive a break character. if character is not seen,
+	 *   stops here, action = NONE. if character is detected goes to next state
+	 * - waits up to 500 ms to receive command character. if character is not seen,
+	 *   stops here, action = NONE. if character is detected define action accordingly
+	 *   'f': factory reset
+	 *   'r': recovery boot
+	 */
+	#define BREAK_WAIT_TIME		1000	/* Initial wait time for break character */
+	#define CHARACTER_WAIT_TIME	1500	/* Subsequent wait time for command */
+
+	typedef enum _state_t { WAIT_BREAK = 1, WAIT_COMMAND, DONE } state_t;
+
+	static state_t state = WAIT_BREAK;	/* Current state */
+	static action_t act = NONE;		/* Action to report to user, returned at function end */
+
+	static int wait_time;
+
+	/* TODO: remove */
+	/* printf("break command: state %d, input %d %02x -> ", state, has_input, c); */
+
+	if (time == 0) {
+		state = WAIT_BREAK;
+		wait_time = BREAK_WAIT_TIME;
+	}
+
+	switch (state) {
+		case WAIT_BREAK:	/* Wait for break indication */
+			act = WAIT;
+			if (has_input) {
+				if (c == 0x00) {
+					/* puts("break detected\n"); */
+					wait_time = CHARACTER_WAIT_TIME;
+					state = WAIT_COMMAND;
+				}
+			}
+			
+			if (wait_time > 0) {
+				wait_time -= RESET_CHECK_PERIOD;
+			}
+			else {
+				/* No break received, nothing to do from our side */
+				act = NONE;
+				state = DONE;
+			}
+			break;
+
+		case WAIT_COMMAND:
+			if (has_input) {
+				wait_time = CHARACTER_WAIT_TIME;
+				if (c == 0x00) {
+					/* puts("break detected\n"); */
+					act = WAIT;
+				}
+				else if (c == 'f') {
+					blink_led(1);
+					act = FACTORY_RESET;
+					state = DONE;
+				}
+				else if (c == 'r') {
+			blink_led(2);
+					act = RECOVERY_BOOT;
+					state = DONE;
+		}
+				else {
+					/* Unknown command */
+					act = NONE;
+					state = DONE;
+				}
+			}
+
+			if (wait_time > 0) {
+				wait_time -= RESET_CHECK_PERIOD;
+	}
+			else {
+				/* puts("character timeout\n"); */
+				act = NONE;
+				state = DONE;
+			}
+			break;
+
+		case DONE:
+			/* Final state when an action has been chosen */
+			break;
+
+		default:
+			break;
+	}
+
+	/* printf("act %d\n", act); */
+
+	return act;
+}
+
+static void check_reset_button(void)
 	{
-		/* Do factory reset for duration between 2s and 12s */
+	/*
+	 * Runs state machines of all reset sources to find out if one detects
+	 * an action.
+	 * 
+	 * SMs return
+	 * - WAIT if they are still trying to get a result.
+	 * - NONE if they know there is no action required.
+	 * - FACTORY_RESET, RECOVERY_BOOT if detected.
+	 */
+	action_t action = NONE;
+	int counter = 0;
+
+	do {
+		action_t a_[3];
+		bool button;
+		bool rx_line;
+		int has_input;
+		int c = -1;
+
+		/* Get state machine inputs */
+		button = get_button_state();
+		rx_line = get_rxd_state();
+		has_input = tstc();
+		if (has_input) {
+			c = getc();
+		}
+
+		/* run processing state machines */
+		a_[0] = NONE;
+		a_[1] = NONE;
+		a_[2] = NONE;
+		a_[0] = check_button(counter, button);
+		a_[1] = check_break_length(counter, rx_line);
+		a_[2] = check_break_command(counter, has_input, c);
+
+		/* if all SMs are sure there is not action, stop here */
+		if ((a_[0] == NONE) && (a_[1] == NONE) && (a_[2] == NONE)) {
+			action = NONE;
+			break;
+		}
+
+		/* if one of the SMs has an action, stop here */
+		for (int i=0; i<3; i++) {
+			if ((a_[i] == FACTORY_RESET) || (a_[i] == RECOVERY_BOOT)) {
+				action = a_[i];
+				break;
+			}
+		}
+
+		mdelay(RESET_CHECK_PERIOD);
+		counter += RESET_CHECK_PERIOD;
+
+	} while ((action != FACTORY_RESET) && (action != RECOVERY_BOOT));
+
+	switch (action) {
+		case FACTORY_RESET: {
 		char new_bootargs[512];
 		char *bootargs = getenv("bootargs");
 
-		if (bootargs == 0) bootargs = "";
-
 		puts("Do factory reset during boot...\n");
 
+			if (bootargs == 0) bootargs = "";
 		strncpy(new_bootargs, bootargs, sizeof(new_bootargs));
 		strncat(new_bootargs, " factory-reset", sizeof(new_bootargs));
 
 		setenv("bootargs", new_bootargs);
+			break;
 	}
-	else
+
-	{
+		case RECOVERY_BOOT:
-		/* Boot into recovery for duration > 12s */
 		puts("Booting recovery image...\n");
 
-		/* Set bootcmd to run recovery */
 		setenv("bootcmd", "run recovery");
+			break;
+		
+		default:
+			set_indicator_led(0, 0);
+			break;
 	}
 }