xilinx: zynqmp: pm_service: Fix APU only restart

Existing code blocks each IPI send request in ipi_mb_notify()
function till pmu clears respective bit in ipi observation
register.

After sending PM_SYSTEM_SHUTDOWN request to PMU, PMU will
restart APU. While PMU is restarting APU, ATF is running out
of OCM, which can cause read/write hang from/to OCM.
There is no need to wait for notification from PMU in case
of SystemShutdown request in ATF, as APU is going to restart.

This patch fixes APU only restart issue.
Signed-off-by: Tejas Patel <tejasp@xilinx.com>
Acked-by: Wendy Liang <wendy.liang@xilinx.com>

plat/xilinx/zynqmp/pm_service/pm_api_sys.c

@@ -244,7 +244,7 @@ enum pm_ret_status pm_system_shutdown(unsigned int type, unsigned int subtype)
 	}
 
 	PM_PACK_PAYLOAD3(payload, PM_SYSTEM_SHUTDOWN, type, subtype);
-	return pm_ipi_send(primary_proc, payload);
+	return pm_ipi_send_non_blocking(primary_proc, payload);
 }
 
 /* APIs for managing PM slaves: */

plat/xilinx/zynqmp/pm_service/pm_ipi.c

@@ -26,6 +26,9 @@
 #define IPI_BUFFER_REQ_OFFSET	0x0U
 #define IPI_BUFFER_RESP_OFFSET	0x20U
 
+#define IPI_BLOCKING		1
+#define IPI_NON_BLOCKING	0
+
 DEFINE_BAKERY_LOCK(pm_secure_lock);
 
 const struct pm_ipi apu_ipi = {
@@ -63,7 +66,8 @@ int pm_ipi_init(const struct pm_proc *proc)
  * @return	Returns status, either success or error+reason
  */
 static enum pm_ret_status pm_ipi_send_common(const struct pm_proc *proc,
-					     uint32_t payload[PAYLOAD_ARG_CNT])
+					     uint32_t payload[PAYLOAD_ARG_CNT],
+					     uint32_t is_blocking)
 {
 	unsigned int offset = 0;
 	uintptr_t buffer_base = proc->ipi->buffer_base +
@@ -75,12 +79,38 @@ static enum pm_ret_status pm_ipi_send_common(const struct pm_proc *proc,
 		mmio_write_32(buffer_base + offset, payload[i]);
 		offset += PAYLOAD_ARG_SIZE;
 	}
+
 	/* Generate IPI to PMU */
-	ipi_mb_notify(proc->ipi->apu_ipi_id, proc->ipi->pmu_ipi_id, 1);
+	ipi_mb_notify(proc->ipi->apu_ipi_id, proc->ipi->pmu_ipi_id,
+		      is_blocking);
 
 	return PM_RET_SUCCESS;
 }
 
+/**
+ * pm_ipi_send_non_blocking() - Sends IPI request to the PMU without blocking
+ *			        notification
+ * @proc	Pointer to the processor who is initiating request
+ * @payload	API id and call arguments to be written in IPI buffer
+ *
+ * Send an IPI request to the power controller.
+ *
+ * @return	Returns status, either success or error+reason
+ */
+enum pm_ret_status pm_ipi_send_non_blocking(const struct pm_proc *proc,
+					    uint32_t payload[PAYLOAD_ARG_CNT])
+{
+	enum pm_ret_status ret;
+
+	bakery_lock_get(&pm_secure_lock);
+
+	ret = pm_ipi_send_common(proc, payload, IPI_NON_BLOCKING);
+
+	bakery_lock_release(&pm_secure_lock);
+
+	return ret;
+}
+
 /**
  * pm_ipi_send() - Sends IPI request to the PMU
  * @proc	Pointer to the processor who is initiating request
@@ -97,7 +127,7 @@ enum pm_ret_status pm_ipi_send(const struct pm_proc *proc,
 
 	bakery_lock_get(&pm_secure_lock);
 
-	ret = pm_ipi_send_common(proc, payload);
+	ret = pm_ipi_send_common(proc, payload, IPI_BLOCKING);
 
 	bakery_lock_release(&pm_secure_lock);
 
@@ -179,7 +209,7 @@ enum pm_ret_status pm_ipi_send_sync(const struct pm_proc *proc,
 
 	bakery_lock_get(&pm_secure_lock);
 
-	ret = pm_ipi_send_common(proc, payload);
+	ret = pm_ipi_send_common(proc, payload, IPI_BLOCKING);
 	if (ret != PM_RET_SUCCESS)
 		goto unlock;
 

plat/xilinx/zynqmp/pm_service/pm_ipi.h

@@ -13,6 +13,8 @@ int pm_ipi_init(const struct pm_proc *proc);
 
 enum pm_ret_status pm_ipi_send(const struct pm_proc *proc,
 			       uint32_t payload[PAYLOAD_ARG_CNT]);
+enum pm_ret_status pm_ipi_send_non_blocking(const struct pm_proc *proc,
+					    uint32_t payload[PAYLOAD_ARG_CNT]);
 enum pm_ret_status pm_ipi_send_sync(const struct pm_proc *proc,
 				    uint32_t payload[PAYLOAD_ARG_CNT],
 				    unsigned int *value, size_t count);