Cr50: Add clean functions to hold EC/AP in reset

This moves the various GPIO/PINMUX reconfigurations needed to
occasionally drive a common-pulldown signal into a set of clean
functions. There's no new functionality, it's just abstracting
the control of SYS_RST_L and EC_RST_L into specific functions.

BUG=none
CQ-DEPEND=CL:380484
BRANCH=none
TEST=make buildall; test on relevant hardware

I tested this on Gru, Kevin, and Reef, and it works correctly in
all cases. I used flashrom over CCD to update both AP and EC
firmware on each of those systems.

If you just want a quick check, you can run this instead:

  sudo flashrom -p raiden_debug_spi:target=AP --flash-name
  sudo flashrom -p raiden_debug_spi:target=EC --flash-name

Change-Id: I15fa3b2089d10649bfd17f442e3b261f3b62b92e
Signed-off-by: Bill Richardson <wfrichar@chromium.org>
Reviewed-on: https://chromium-review.googlesource.com/382665
Reviewed-by: Vadim Bendebury <vbendeb@chromium.org>

3 files changed, 82 insertions, 28 deletions

diff --git a/board/cr50/board.c b/board/cr50/board.c
index ce7dae31a4..575d3511dd 100644
--- a/board/cr50/board.c
+++ b/board/cr50/board.c
@@ -14,17 +14,18 @@
 #include "hooks.h"
 #include "i2cs.h"
 #include "init_chip.h"
-#include "registers.h"
 #include "nvmem.h"
+#include "registers.h"
+#include "spi.h"
 #include "system.h"
 #include "task.h"
+#include "tpm_registers.h"
 #include "trng.h"
 #include "uartn.h"
 #include "usb_descriptor.h"
 #include "usb_hid.h"
-#include "util.h"
-#include "spi.h"
 #include "usb_spi.h"
+#include "util.h"
 
 /* Define interrupt and gpio structs */
 #include "gpio_list.h"
@@ -288,20 +289,73 @@ int flash_regions_to_enable(struct g_flash_region *regions,
 
 #define CPRINTS(format, args...) cprints(CC_SYSTEM, format, ## args)
 
+/* This is the interrupt handler to react to SYS_RST_L_IN */
 void sys_rst_asserted(enum gpio_signal signal)
 {
 	/*
 	 * Cr50 drives SYS_RST_L in certain scenarios, in those cases
-	 * asserting this signal should not cause a system reset.
+	 * this signal's assertion should be ignored here.
 	 */
-	CPRINTS("%s resceived signal %d)", __func__, signal);
-	if (usb_spi_update_in_progress())
+	CPRINTS("%s", __func__);
+	if (usb_spi_update_in_progress() || is_sys_rst_asserted())
 		return;
 
 	cflush();
 	system_reset(0);
 }
 
+void assert_sys_rst(void)
+{
+	/*
+	 * We don't have a good (any?) way to easily look up the pinmux/gpio
+	 * assignments in gpio.inc, so they're hard-coded in this routine. This
+	 * assertion is just to ensure it hasn't changed.
+	 */
+	ASSERT(GREAD(PINMUX, GPIO0_GPIO4_SEL) == GC_PINMUX_DIOM0_SEL);
+
+	/* Set SYS_RST_L_OUT as an output, connected to the pad */
+	GWRITE(PINMUX, DIOM0_SEL, GC_PINMUX_GPIO0_GPIO4_SEL);
+	gpio_set_flags(GPIO_SYS_RST_L_OUT, GPIO_OUT_HIGH);
+
+	/* Assert it */
+	gpio_set_level(GPIO_SYS_RST_L_OUT, 0);
+}
+
+void deassert_sys_rst(void)
+{
+	ASSERT(GREAD(PINMUX, GPIO0_GPIO4_SEL) == GC_PINMUX_DIOM0_SEL);
+
+	/* Deassert SYS_RST_L */
+	gpio_set_level(GPIO_SYS_RST_L_OUT, 1);
+
+	/* Set SYS_RST_L_OUT as an input, disconnected from the pad */
+	gpio_set_flags(GPIO_SYS_RST_L_OUT, GPIO_INPUT);
+	GWRITE(PINMUX, DIOM0_SEL, 0);
+}
+
+int is_sys_rst_asserted(void)
+{
+	return (GREAD(PINMUX, DIOM0_SEL) == GC_PINMUX_GPIO0_GPIO4_SEL)
+#ifdef CONFIG_CMD_GPIO_EXTENDED
+		&& (gpio_get_flags(GPIO_SYS_RST_L_OUT) & GPIO_OUTPUT)
+#endif
+		&& (gpio_get_level(GPIO_SYS_RST_L_OUT) == 0);
+}
+
+void assert_ec_rst(void)
+{
+	GWRITE(RBOX, ASSERT_EC_RST, 1);
+}
+void deassert_ec_rst(void)
+{
+	GWRITE(RBOX, ASSERT_EC_RST, 0);
+}
+
+int is_ec_rst_asserted(void)
+{
+	return GREAD(RBOX, ASSERT_EC_RST);
+}
+
 void nvmem_compute_sha(uint8_t *p_buf, int num_bytes,
 		       uint8_t *p_sha, int sha_len)
 {
diff --git a/board/cr50/board.h b/board/cr50/board.h
index ca3ea5d1e7..de0ced7d36 100644
--- a/board/cr50/board.h
+++ b/board/cr50/board.h
@@ -128,6 +128,14 @@ void sys_rst_asserted(enum gpio_signal signal);
 void device_state_on(enum gpio_signal signal);
 void device_state_off(enum gpio_signal signal);
 
+/* Special controls over EC and AP */
+void assert_sys_rst(void);
+void deassert_sys_rst(void);
+int is_sys_rst_asserted(void);
+void assert_ec_rst(void);
+void deassert_ec_rst(void);
+int is_ec_rst_asserted(void);
+
 #endif /* !__ASSEMBLER__ */
 
 /* USB interface indexes (use define rather than enum to expand them) */
diff --git a/board/cr50/usb_spi.c b/board/cr50/usb_spi.c
index 02d6525cdd..9ec9c0e7ad 100644
--- a/board/cr50/usb_spi.c
+++ b/board/cr50/usb_spi.c
@@ -16,46 +16,38 @@
 
 static uint8_t update_in_progress;
 
-void disable_spi(void)
+static void disable_ec_ap_spi(void)
 {
 	/* Configure SPI GPIOs */
 	gpio_set_level(GPIO_AP_FLASH_SELECT, 0);
 	gpio_set_level(GPIO_EC_FLASH_SELECT, 0);
 
 	/* Release AP and EC */
-	GWRITE(RBOX, ASSERT_EC_RST, 0);
-	gpio_set_level(GPIO_SYS_RST_L_OUT, 1);
-
-	/* Set SYS_RST_L as an input otherwise cr50 will hold the AP in reset */
-	gpio_set_flags(GPIO_SYS_RST_L_OUT, GPIO_INPUT);
+	deassert_ec_rst();
+	deassert_sys_rst();
 }
 
-void enable_ec_spi(void)
+static void enable_ec_spi(void)
 {
 	/* Select EC flash */
 	gpio_set_level(GPIO_AP_FLASH_SELECT, 0);
 	gpio_set_level(GPIO_EC_FLASH_SELECT, 1);
 
-	/* hold EC in reset */
-	GWRITE(RBOX, ASSERT_EC_RST, 1);
+	/* Hold EC in reset. This will also hold the AP in reset. */
+	assert_ec_rst();
 }
 
-void enable_ap_spi(void)
+static void enable_ap_spi(void)
 {
 	/* Select AP flash */
 	gpio_set_level(GPIO_AP_FLASH_SELECT, 1);
 	gpio_set_level(GPIO_EC_FLASH_SELECT, 0);
 
-	/* hold the EC in reset */
-	GWRITE(RBOX, ASSERT_EC_RST, 1);
-
-	/* Set SYS_RST_L as an output */
-	ASSERT(GREAD(PINMUX, GPIO0_GPIO4_SEL) == GC_PINMUX_DIOM0_SEL);
-	GWRITE(PINMUX, DIOM0_SEL, GC_PINMUX_GPIO0_GPIO4_SEL);
-	gpio_set_flags(GPIO_SYS_RST_L_OUT, GPIO_OUT_HIGH);
-
-	/* hold AP in reset */
-	gpio_set_level(GPIO_SYS_RST_L_OUT, 0);
+	/*
+	 * On some systems SYS_RST_L is not level sensitive, so the only way to
+	 * be sure we're holding the AP in reset is to hold the EC in reset.
+	 */
+	assert_ec_rst();
 }
 
 int usb_spi_update_in_progress(void)
@@ -80,7 +72,7 @@ void usb_spi_board_enable(struct usb_spi_config const *config)
 	hook_call_deferred(&update_finished_data, -1);
 	update_in_progress = 1;
 
-	disable_spi();
+	disable_ec_ap_spi();
 
 	if (config->state->enabled_host == USB_SPI_EC)
 		enable_ec_spi();
@@ -108,7 +100,7 @@ void usb_spi_board_disable(struct usb_spi_config const *config)
 {
 	CPRINTS("usb_spi disable");
 	spi_enable(CONFIG_SPI_FLASH_PORT, 0);
-	disable_spi();
+	disable_ec_ap_spi();
 
 	/* Disconnect SPI peripheral to tri-state pads */
 	/* Disable internal pull up */