Support write protect GPIO on pit

Daisy doesn't have a write protect signal, so emulate it as a fake
signal which is always low; this maintains the current behavior on
daisy.

BUG=chrome-os-partner:15613
BRANCH=none
TEST=flashinfo shows gpio not asserted
     then short across the WP screw and flashinfo shows it asserted

Change-Id: I329424efe1c3b065976e17395e2bf9588cdce88c
Signed-off-by: Randall Spangler <rspangler@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/51500
Reviewed-by: Vic Yang <victoryang@chromium.org>

board/daisy/board.c

@@ -94,6 +94,9 @@ const struct gpio_info gpio_list[GPIO_COUNT] = {
 	{"KB_OUT10",    GPIO_C, (1<<5),  GPIO_KB_OUTPUT, NULL},
 	{"KB_OUT11",    GPIO_C, (1<<6),  GPIO_KB_OUTPUT, NULL},
 	{"KB_OUT12",    GPIO_C, (1<<7),  GPIO_KB_OUTPUT, NULL},
+
+	/* Unimplemented signals which we need to emulate for now */
+	GPIO_SIGNAL_NOT_IMPLEMENTED("WP_L"),
 };
 
 /* I2C ports */

board/daisy/board.h

@@ -112,6 +112,8 @@ enum gpio_signal {
 	GPIO_KB_OUT10,
 	GPIO_KB_OUT11,
 	GPIO_KB_OUT12,
+	/* Unimplemented signals we emulate */
+	GPIO_WP_L,
 	/* Number of GPIOs; not an actual GPIO */
 	GPIO_COUNT
 };

chip/stm32/flash-stm32l15x.c

@@ -7,6 +7,7 @@
 
 #include "console.h"
 #include "flash.h"
+#include "gpio.h"
 #include "registers.h"
 #include "task.h"
 #include "timer.h"
@@ -309,14 +310,9 @@ uint32_t flash_get_protect(void)
 	int not_protected[2] = {0};
 	int i;
 
-	/*
-	 * TODO: (crosbug.com/p/15613) write protect scheme
-	 *
-	 * Always enable write protect until we have WP pin.  For developer to
-	 * unlock WP, please use stm32mon -u and immediately re-program the
-	 * pstate sector.
-	 */
-	flags |= EC_FLASH_PROTECT_GPIO_ASSERTED;
+	/* Check write protect GPIO */
+	if (gpio_get_level(GPIO_WP_L) == 0)
+		flags |= EC_FLASH_PROTECT_GPIO_ASSERTED;
 
 	/* Scan flash protection */
 	for (i = 0; i < PHYSICAL_BANKS; i++) {