Change polarity of PROCHOT signal to match EVT

This would throttle proto1 systems, if it weren't for a HW bug which
means we don't have prochot control over proto1 systems at all.

Signed-off-by: Randall Spangler <rspangler@chromium.org>

BUG=chrome-os-partner:8982
TEST=system still boots

Change-Id: Ie42c034141f24795ec2bfee592e194001d3cd174

5 files changed, 27 insertions, 4 deletions

diff --git a/board/link/board.c b/board/link/board.c
index 7edd10e238..4fcc0fa77c 100644
--- a/board/link/board.c
+++ b/board/link/board.c
@@ -74,7 +74,7 @@ const struct gpio_info gpio_list[GPIO_COUNT] = {
 	{"WRITE_PROTECT",       LM4_GPIO_J, (1<<4), GPIO_INT_BOTH,
 	 power_button_interrupt},
 	/* Outputs; all unasserted by default except for reset signals */
-	{"CPU_PROCHOTn",        LM4_GPIO_F, (1<<2), GPIO_HI_Z, NULL},
+	{"CPU_PROCHOT",         LM4_GPIO_F, (1<<2), GPIO_OUT_LOW, NULL},
 	{"ENABLE_1_5V_DDR",     LM4_GPIO_H, (1<<5), GPIO_OUT_LOW, NULL},
 	{"ENABLE_5VALW",        LM4_GPIO_K, (1<<4), GPIO_OUT_LOW, NULL},
 	{"ENABLE_BACKLIGHT",    LM4_GPIO_H, (1<<4), GPIO_OUT_LOW, NULL},
diff --git a/board/link/board.h b/board/link/board.h
index bc9064af06..9aae936a37 100644
--- a/board/link/board.h
+++ b/board/link/board.h
@@ -142,7 +142,7 @@ enum gpio_signal {
 	GPIO_USB2_STATUSn,        /* USB charger port 2 status output */
 	GPIO_WRITE_PROTECT,       /* Write protect input */
 	/* Outputs */
-	GPIO_CPU_PROCHOTn,        /* Force CPU to think it's overheated */
+	GPIO_CPU_PROCHOT,         /* Force CPU to think it's overheated */
 	GPIO_ENABLE_1_5V_DDR,     /* Enable +1.5V_DDR supply */
 	GPIO_ENABLE_5VALW,        /* Enable +5V always on rail */
 	GPIO_ENABLE_BACKLIGHT,    /* Enable backlight power */
diff --git a/common/thermal.c b/common/thermal.c
index 154ddbbfb0..e9296b6433 100644
--- a/common/thermal.c
+++ b/common/thermal.c
@@ -117,10 +117,10 @@ static void overheated_action(void)
 
 	if (overheated[THRESHOLD_WARNING]) {
 		smi_overheated_warning();
-		gpio_set_level(GPIO_CPU_PROCHOTn, 0);
+		chipset_throttle_cpu(1);
 	}
 	else
-		gpio_set_flags(GPIO_CPU_PROCHOTn, 1);
+		chipset_throttle_cpu(0);
 
 	if (fan_ctrl_on) {
 		int i;
diff --git a/common/x86_power.c b/common/x86_power.c
index 115932a33e..4f998b87b1 100644
--- a/common/x86_power.c
+++ b/common/x86_power.c
@@ -93,6 +93,8 @@ static enum x86_state state;  /* Current state */
 static uint32_t in_signals;   /* Current input signal states (IN_PGOOD_*) */
 static uint32_t in_want;      /* Input signal state we're waiting for */
 static int want_g3_exit;      /* Should we exit the G3 state? */
+static int throttle_cpu;      /* Throttle CPU? */
+
 
 /* Update input signal state */
 static void update_in_signals(void)
@@ -263,6 +265,16 @@ void chipset_exit_hard_off(void)
 	task_wake(TASK_ID_X86POWER);
 }
 
+
+void chipset_throttle_cpu(int throttle)
+{
+	throttle_cpu = throttle;
+
+	/* Immediately set throttling if CPU is on */
+	if (state == X86_S0)
+		gpio_set_level(GPIO_CPU_PROCHOT, throttle);
+}
+
 /*****************************************************************************/
 /* Interrupts */
 
@@ -463,6 +475,10 @@ void x86_power_task(void)
 			/* Wait 99ms after all voltages good */
 			usleep(99000);
 
+			/* Throttle CPU if necessary.  This should only be
+			 * asserted when +VCCP is powered (it is by now). */
+			gpio_set_flags(GPIO_CPU_PROCHOT, throttle_cpu);
+
 			/* Set PCH_PWROK */
 			gpio_set_level(GPIO_PCH_PWROK, 1);
 
@@ -487,6 +503,10 @@ void x86_power_task(void)
 			gpio_set_level(GPIO_RADIO_ENABLE_WLAN, 0);
 			gpio_set_level(GPIO_RADIO_ENABLE_BT, 0);
 
+			/* Deassert prochot since CPU is off and we're about
+			 * to drop +VCCP. */
+			gpio_set_flags(GPIO_CPU_PROCHOT, 0);
+
 			/* Turn off power rails */
 			gpio_set_level(GPIO_ENABLE_VS, 0);
 
diff --git a/include/chipset.h b/include/chipset.h
index ac192f29c9..b2f8897ea9 100644
--- a/include/chipset.h
+++ b/include/chipset.h
@@ -38,4 +38,7 @@ int chipset_in_state(int state_mask);
  * already left the state, or was not in the state to begin with. */
 void chipset_exit_hard_off(void);
 
+/* Enable/disable CPU throttling. */
+void chipset_throttle_cpu(int throttle);
+
 #endif  /* __CROS_EC_CHIPSET_H */