Fix assertion crash in __wait_evt()

mutex_lock() is called from MEC1322_IRQ_ACPIEC0_IBF
interrupt context, causing deadlock and assertion
in __wait_evt().
In the interrupt context it now checks for mutex lock first.
If the mutex is already locked,, it will disable ACPI
interrupts and defer the memmap mutex lock.
Added LPC interrupt disable/enable functions as needed.
Increased deferred function count where needed.

BRANCH=None
BUG=chrome-os-partner:40820
TEST=Test for suspend-resume, cold, warm reboots and
other general stability.

Change-Id: I3dda0d4635a6b6281faf200c8c7b6fcba8877254
Signed-off-by: Chiranjeevi Rapolu <chiranjeevi.rapolu@intel.com>
Reviewed-on: https://chromium-review.googlesource.com/280418
Reviewed-by: Randall Spangler <rspangler@chromium.org>
Reviewed-by: Shawn N <shawnn@chromium.org>
Commit-Queue: Divya Jyothi <divya.jyothi@intel.com>
Tested-by: Divya Jyothi <divya.jyothi@intel.com>

board/glados/board.h

@@ -75,7 +75,7 @@
 #define I2C_PORT_USB_CHARGER_2 MEC1322_I2C3
 
 #undef DEFERRABLE_MAX_COUNT
-#define DEFERRABLE_MAX_COUNT 10
+#define DEFERRABLE_MAX_COUNT 11
 
 #ifndef __ASSEMBLER__
 

board/rambi/board.h

@@ -48,6 +48,9 @@
 #define CONFIG_WIRELESS_SUSPEND \
 	(EC_WIRELESS_SWITCH_WLAN | EC_WIRELESS_SWITCH_WLAN_POWER)
 
+#undef DEFERRABLE_MAX_COUNT
+#define DEFERRABLE_MAX_COUNT 9
+
 #ifndef __ASSEMBLER__
 
 /* I2C ports */

board/samus/board.h

@@ -81,7 +81,7 @@
 /* Do we want EC_WIRELESS_SWITCH_WWAN as well? */
 
 #undef  DEFERRABLE_MAX_COUNT
-#define DEFERRABLE_MAX_COUNT 9
+#define DEFERRABLE_MAX_COUNT 10
 
 #ifndef __ASSEMBLER__
 

chip/it83xx/lpc.c

@@ -638,6 +638,18 @@ void lpcrst_interrupt(enum gpio_signal signal)
 		lpc_get_pltrst_asserted() ? "" : "de");
 }
 
+/* Enable LPC ACPI-EC interrupts */
+void lpc_enable_acpi_interrupts(void)
+{
+	task_enable_irq(IT83XX_IRQ_PMC_IN);
+}
+
+/* Disable LPC ACPI-EC interrupts */
+void lpc_disable_acpi_interrupts(void)
+{
+	task_disable_irq(IT83XX_IRQ_PMC_IN);
+}
+
 static void lpc_resume(void)
 {
 	/* Mask all host events until the host unmasks them itself.  */

chip/lm4/lpc.c

@@ -677,6 +677,18 @@ static void lpc_post_sysjump(void)
 	memcpy(event_mask, prev_mask, sizeof(event_mask));
 }
 
+/* Enable LPC ACPI-EC interrupts */
+void lpc_enable_acpi_interrupts(void)
+{
+	LM4_LPC_LPCIM |= LM4_LPC_INT_MASK(LPC_CH_ACPI, 6);
+}
+
+/* Disable LPC ACPI-EC interrupts */
+void lpc_disable_acpi_interrupts(void)
+{
+	LM4_LPC_LPCIM &= ~(LM4_LPC_INT_MASK(LPC_CH_ACPI, 6));
+}
+
 static void lpc_init(void)
 {
 	/* Enable LPC clock in run and sleep modes. */

chip/mec1322/lpc.c

@@ -557,6 +557,18 @@ int lpc_get_pltrst_asserted(void)
 	return (MEC1322_LPC_BUS_MONITOR & (1<<1)) ? 1 : 0;
 }
 
+/* Enable LPC ACPI-EC0 interrupts */
+void lpc_enable_acpi_interrupts(void)
+{
+	task_enable_irq(MEC1322_IRQ_ACPIEC0_IBF);
+}
+
+/* Disable LPC ACPI-EC0 interrupts */
+void lpc_disable_acpi_interrupts(void)
+{
+	task_disable_irq(MEC1322_IRQ_ACPIEC0_IBF);
+}
+
 /* On boards without a host, this command is used to set up LPC */
 static int lpc_command_init(int argc, char **argv)
 {

chip/npcx/lpc.c

@@ -646,6 +646,19 @@ static void lpc_init(void)
 	/* initial IO port address via SIB-write modules */
 	system_lpc_host_register_init();
 }
+
+/* Enable LPC ACPI-EC interrupts */
+void lpc_enable_acpi_interrupts(void)
+{
+	SET_BIT(NPCX_HIPMCTL(PM_CHAN_1), 0);
+}
+
+/* Disable LPC ACPI-EC interrupts */
+void lpc_disable_acpi_interrupts(void)
+{
+	CLEAR_BIT(NPCX_HIPMCTL(PM_CHAN_1), 0);
+}
+
 /*
  * Set prio to higher than default; this way LPC memory mapped data is ready
  * before other inits try to initialize their memmap data.

common/acpi.c

@@ -41,6 +41,17 @@ static void acpi_unlock_memmap_deferred(void)
 }
 DECLARE_DEFERRED(acpi_unlock_memmap_deferred);
 
+/*
+ * Deferred function to lock memmap and to enable LPC interrupts.
+ * This is due to LPC interrupt was unable to acquire memmap mutex.
+ */
+static void deferred_host_lock_memmap(void)
+{
+	host_lock_memmap();
+	lpc_enable_acpi_interrupts();
+}
+DECLARE_DEFERRED(deferred_host_lock_memmap);
+
 /*
  * This handles AP writes to the EC via the ACPI I/O port. There are only a few
  * ACPI commands (EC_CMD_ACPI_*), but they are all handled here.
@@ -180,8 +191,29 @@ int acpi_ap_to_ec(int is_cmd, uint8_t value, uint8_t *resultptr)
 		*resultptr = evt_index;
 		retval = 1;
 	} else if (acpi_cmd == EC_CMD_ACPI_BURST_ENABLE && !acpi_data_count) {
+		/*
+		 * TODO: The kernel only enables BURST when doing multi-byte
+		 * value reads over the ACPI port. We don't do such reads
+		 * when our memmap data can be accessed directly over LPC,
+		 * so on LM4, for example, this is dead code. We might want
+		 * to re-add the CONFIG, now that we have overhead of one
+		 * deferred function.
+		 */
+		if (host_memmap_is_locked()) {
+			/*
+			 * If already locked by a task, we can not acquire
+			 * the mutex and will have to wait in the interrupt
+			 * context. But then the task will not get chance to
+			 * release the mutex. This will create deadlock
+			 * situation. To avoid the deadlock, disable ACPI
+			 * interrupts and defer locking.
+			 */
+			lpc_disable_acpi_interrupts();
+			hook_call_deferred(deferred_host_lock_memmap, 0);
+		} else {
+			host_lock_memmap();
+		}
 		/* Enter burst mode */
-		host_lock_memmap();
 		lpc_set_acpi_status_mask(EC_LPC_STATUS_BURST_MODE);
 
 		/*

common/host_command.c

@@ -88,6 +88,12 @@ void host_lock_memmap()
 	mutex_lock(&memmap_write_mutex);
 }
 
+/* Returns host memmap lock status */
+int host_memmap_is_locked(void)
+{
+	return (memmap_write_mutex.lock != 0);
+}
+
 void host_unlock_memmap()
 {
 	mutex_unlock(&memmap_write_mutex);

include/host_command.h

@@ -130,6 +130,11 @@ uint8_t *host_get_memmap(int offset);
  */
 void host_lock_memmap(void);
 
+/*
+ * Returns status of host memmap lock.
+ */
+int host_memmap_is_locked(void);
+
 /**
  * Release the memmap write mutex. This function should be called once
  * a multi-byte variable read from ACPI is done, and when updating multi-byte

include/lpc.h

@@ -113,4 +113,11 @@ void lpc_clear_acpi_status_mask(uint8_t mask);
  */
 int lpc_get_pltrst_asserted(void);
 
+
+/* Disable LPC ACPI interrupts */
+void lpc_disable_acpi_interrupts(void);
+
+/* Enable LPC ACPI interrupts */
+void lpc_enable_acpi_interrupts(void);
+
 #endif  /* __CROS_EC_LPC_H */