Snow: Retry accesses to PMU before hard reset

Previously, after the first error when trying to reset the pmu over i2c,
the ec would immediately give up and force a hard reset.  Since i2c can
be a little flaky from time to time, to prevent unneeded resets this
allows the EC 3 attempts to configure it nicely it before it forces the
whole system to reset.

BUG=chrome-os-partner:14156
TEST=Boot machine successfully multiple times.  Add a line in to force a
failure whenever the pmu is accessed to simulate a total failure and
check the EC logs, it should try 3 times on startup and on shutdown
before finally resorting to a hard reset.  If you add a fake failure that
only triggers once, the machine should still turn out without incident.
Without any fake failures, everything should work as normal.
BRANCH=snow

Original-Change-Id: I1f453e9a6acc59d63e4cc80cffb58684f104ca6d
Signed-off-by: Charlie Mooney <charliemooney@chromium.org>

Change-Id: If67283ab29d5e1193a0466309050b20a165498a6
Signed-off-by: Charlie Mooney <charliemooney@chromium.org>
Reviewed-on: https://gerrit.chromium.org/gerrit/33549
Reviewed-by: Che-Liang Chiou <clchiou@chromium.org>

2 files changed, 43 insertions, 29 deletions

diff --git a/common/gaia_power.c b/common/gaia_power.c
index 1b3cc61a2a..441f46f634 100644
--- a/common/gaia_power.c
+++ b/common/gaia_power.c
@@ -437,6 +437,8 @@ static int react_to_xpshold(unsigned int timeout_us)
  */
 static void power_off(void)
 {
+	int pmu_shutdown_retries = 3;
+
 	/* Call hooks before we drop power rails */
 	hook_notify(HOOK_CHIPSET_SHUTDOWN, 0);
 	/* switch off all rails */
@@ -449,7 +451,12 @@ static void power_off(void)
 	lid_changed = 0;
 	enable_sleep(SLEEP_MASK_AP_RUN);
 	powerled_set_state(POWERLED_STATE_OFF);
-	if (pmu_shutdown())
+
+	while (--pmu_shutdown_retries >= 0) {
+		if (!pmu_shutdown())
+			break;
+	}
+	if (pmu_shutdown_retries < 0)
 		board_hard_reset();
 	CPUTS("Shutdown complete.\n");
 }
diff --git a/common/pmu_tps65090.c b/common/pmu_tps65090.c
index 64babf46ff..59f913715b 100644
--- a/common/pmu_tps65090.c
+++ b/common/pmu_tps65090.c
@@ -404,44 +404,51 @@ DECLARE_HOOK(HOOK_CHIPSET_PRE_INIT, pmu_init_registers, HOOK_PRIO_DEFAULT);
 
 void pmu_init(void)
 {
-	int failure = 0;
+	int failure = 0, retries_remaining = 3;
 
+	while (--retries_remaining >= 0) {
+		failure = 0;
 #ifdef CONFIG_PMU_BOARD_INIT
-	if (!failure)
-		failure = board_pmu_init();
+		if (!failure)
+			failure = board_pmu_init();
 #else
-	/* Init configuration
-	 *   Fast charge timer    : 2 hours
-	 *   Charger              : disable
-	 *   External pin control : enable
-	 *
-	 * TODO: move settings to battery pack specific init
-	 */
-	if (!failure)
-		failure = pmu_write(CG_CTRL0, 2);
-	/* Limit full charge current to 50%
-	 * TODO: remove this temporary hack.
-	 */
-	if (!failure)
-		failure = pmu_write(CG_CTRL3, 0xbb);
+		/* Init configuration
+		 *   Fast charge timer    : 2 hours
+		 *   Charger              : disable
+		 *   External pin control : enable
+		 *
+		 * TODO: move settings to battery pack specific init
+		 */
+		if (!failure)
+			failure = pmu_write(CG_CTRL0, 2);
+		/* Limit full charge current to 50%
+		 * TODO: remove this temporary hack.
+		 */
+		if (!failure)
+			failure = pmu_write(CG_CTRL3, 0xbb);
 #endif
-	/* Enable interrupts */
-	if (!failure) {
-		failure = pmu_write(IRQ1MASK,
+		/* Enable interrupts */
+		if (!failure) {
+			failure = pmu_write(IRQ1MASK,
 					EVENT_VACG  | /* AC voltage good */
 					EVENT_VSYSG | /* System voltage good */
 					EVENT_VBATG | /* Battery voltage good */
 					EVENT_CGACT | /* Charging status */
 					EVENT_CGCPL); /* Charging complete */
-	}
-	if (!failure)
-		failure = pmu_write(IRQ2MASK, 0);
-	if (!failure)
-		failure = pmu_clear_irq();
+		}
+		if (!failure)
+			failure = pmu_write(IRQ2MASK, 0);
+		if (!failure)
+			failure = pmu_clear_irq();
 
-	/* Enable charger interrupt. */
-	if (!failure)
-		failure = gpio_enable_interrupt(GPIO_CHARGER_INT);
+		/* Enable charger interrupt. */
+		if (!failure)
+			failure = gpio_enable_interrupt(GPIO_CHARGER_INT);
+
+		/* Exit the retry loop if there was no failure */
+		if (!failure)
+			break;
+	}
 
 	if (failure)
 		board_hard_reset();