Tegra: bpmp: suspend/resume handlers

This patch adds suspend and resume handlers for the BPMP
interface. Mark the interface as "suspended" before entering
System Suspend and verify that BPMP is alive on exit.

Change-Id: I74ccbc86125079b46d06360fc4c7e8a5acfbdfb2
Signed-off-by: Varun Wadekar <vwadekar@nvidia.com>

plat/nvidia/tegra/common/drivers/bpmp/bpmp.c

@@ -16,7 +16,7 @@
 #include <string.h>
 #include <tegra_def.h>
 
-#define BPMP_TIMEOUT	2
+#define BPMP_TIMEOUT	500 /* 500ms */
 
 static uint32_t channel_base[NR_CHANNELS];
 static uint32_t bpmp_init_state = BPMP_INIT_PENDING;
@@ -115,18 +115,24 @@ int32_t tegra_bpmp_send_receive_atomic(int mrq, const void *ob_data, int ob_sz,
 
 int tegra_bpmp_init(void)
 {
-	uint32_t val, base;
+	uint32_t val, base, timeout = BPMP_TIMEOUT;
 	unsigned int ch;
 	int ret = 0;
 
-	if (bpmp_init_state != BPMP_INIT_COMPLETE) {
+	if (bpmp_init_state == BPMP_INIT_PENDING) {
 
 		/* check if the bpmp processor is alive. */
+		do {
 			val = mmio_read_32(TEGRA_RES_SEMA_BASE + STA_OFFSET);
 			if (val != SIGN_OF_LIFE) {
-			return -ENOTSUP;
+				mdelay(1);
+				timeout--;
 			}
 
+		} while ((val != SIGN_OF_LIFE) && (timeout > 0U));
+
+		if (val == SIGN_OF_LIFE) {
+
 			/* check if clock for the atomics block is enabled */
 			val = mmio_read_32(TEGRA_CAR_RESET_BASE + TEGRA_CLK_ENB_V);
 			if ((val & CAR_ENABLE_ATOMICS) == 0) {
@@ -160,12 +166,58 @@ int tegra_bpmp_init(void)
 			bpmp_init_state = BPMP_INIT_COMPLETE;
 
 			/* the channel values have to be visible across all cpus */
-		flush_dcache_range((uint64_t)channel_base, sizeof(channel_base));
+			flush_dcache_range((uint64_t)channel_base,
+					   sizeof(channel_base));
 			flush_dcache_range((uint64_t)&bpmp_init_state,
 					   sizeof(bpmp_init_state));
 
 			INFO("%s: done\n", __func__);
+
+		} else {
+			ERROR("BPMP not powered on\n");
+			ret = -ETIMEDOUT;
+		}
 	}
 
 	return ret;
 }
+
+void tegra_bpmp_suspend(void)
+{
+	/* freeze the interface */
+	bpmp_init_state = BPMP_SUSPEND_ENTRY;
+	flush_dcache_range((uint64_t)&bpmp_init_state, sizeof(bpmp_init_state));
+}
+
+void tegra_bpmp_resume(void)
+{
+	uint32_t val, timeout = 0;
+
+	if (bpmp_init_state == BPMP_SUSPEND_ENTRY) {
+
+		/* check if the bpmp processor is alive. */
+		do {
+
+			val = mmio_read_32(TEGRA_RES_SEMA_BASE + STA_OFFSET);
+			if (val != SIGN_OF_LIFE) {
+				mdelay(1);
+				timeout++;
+			}
+
+		} while ((val != SIGN_OF_LIFE) && (timeout < BPMP_TIMEOUT));
+
+		if (val == SIGN_OF_LIFE) {
+
+			INFO("%s: BPMP took %d ms to resume\n", __func__, timeout);
+
+			/* mark state as "initialized" */
+			bpmp_init_state = BPMP_INIT_COMPLETE;
+
+			/* state has to be visible across all cpus */
+			flush_dcache_range((uint64_t)&bpmp_init_state,
+					   sizeof(bpmp_init_state));
+		} else {
+			ERROR("BPMP not powered on\n");
+		}
+	}
+}

plat/nvidia/tegra/include/drivers/bpmp.h

@@ -29,6 +29,7 @@
 /* flags to indicate bpmp driver's state */
 #define BPMP_INIT_COMPLETE	0xBEEFF00DU
 #define BPMP_INIT_PENDING	0xDEADBEEFU
+#define BPMP_SUSPEND_ENTRY	0xF00DCAFEU
 
 /* requests serviced by the bpmp */
 #define MRQ_PING		0
@@ -106,6 +107,16 @@ typedef struct mb_data {
  */
 int tegra_bpmp_init(void);
 
+/**
+ * Function to suspend the interface with the bpmp
+ */
+void tegra_bpmp_suspend(void);
+
+/**
+ * Function to resume the interface with the bpmp
+ */
+void tegra_bpmp_resume(void);
+
 /**
  * Handler to send a MRQ_* command to the bpmp
  */