ASoC: SOF: amd: Use semaphore register to synchronize ipc's irq

Add lock and unlock around ipc irq handling code using hw semaphore
register that exhibit special property for register read calls. As
host and DSP firmware uses few shared registers, there is a possible
race condition around those shared registers values. This lock ensure
synchronization between Firmware and host ipc interrupts.

Reviewed-by: Ranjani Sridharan <ranjani.sridharan@linux.intel.com>
Signed-off-by: Ajit Kumar Pandey <AjitKumar.Pandey@amd.com>
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20220304205733.62233-6-pierre-louis.bossart@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>

4 files changed, 30 insertions, 1 deletions

diff --git a/sound/soc/sof/amd/acp-dsp-offset.h b/sound/soc/sof/amd/acp-dsp-offset.h
index 63f13c111b24..40fbf11facba 100644
--- a/sound/soc/sof/amd/acp-dsp-offset.h
+++ b/sound/soc/sof/amd/acp-dsp-offset.h
@@ -61,6 +61,7 @@
 #define ACP_DSP_SW_INTR_STAT                    0x1818
 #define ACP_SW_INTR_TRIG                        0x181C
 #define ACP_ERROR_STATUS			0x18C4
+#define ACP_AXI2DAGB_SEM_0			0x1880
 
 /* Registers from ACP_SHA block */
 #define ACP_SHA_DSP_FW_QUALIFIER		0x1C70
diff --git a/sound/soc/sof/amd/acp-ipc.c b/sound/soc/sof/amd/acp-ipc.c
index cd5af3d85002..9fcd2535fd3b 100644
--- a/sound/soc/sof/amd/acp-ipc.c
+++ b/sound/soc/sof/amd/acp-ipc.c
@@ -62,12 +62,26 @@ int acp_sof_ipc_send_msg(struct snd_sof_dev *sdev, struct snd_sof_ipc_msg *msg)
 {
 	struct acp_dev_data *adata = sdev->pdata->hw_pdata;
 	unsigned int offset = offsetof(struct scratch_ipc_conf, sof_in_box);
+	unsigned int count = ACP_HW_SEM_RETRY_COUNT;
+
+	while (snd_sof_dsp_read(sdev, ACP_DSP_BAR, ACP_AXI2DAGB_SEM_0)) {
+		/* Wait until acquired HW Semaphore Lock or timeout*/
+		count--;
+		if (!count) {
+			dev_err(sdev->dev, "%s: Failed to acquire HW lock\n", __func__);
+			return -EINVAL;
+		}
+	};
 
 	acp_mailbox_write(sdev, offset, msg->msg_data, msg->msg_size);
 	acp_ipc_host_msg_set(sdev);
 
 	/* Trigger host to dsp interrupt for the msg */
 	acpbus_trigger_host_to_dsp_swintr(adata);
+
+	/* Unlock or Release HW Semaphore */
+	snd_sof_dsp_write(sdev, ACP_DSP_BAR, ACP_AXI2DAGB_SEM_0, 0x0);
+
 	return 0;
 }
 EXPORT_SYMBOL_NS(acp_sof_ipc_send_msg, SND_SOC_SOF_AMD_COMMON);
diff --git a/sound/soc/sof/amd/acp.c b/sound/soc/sof/amd/acp.c
index fe9b7dc5bc86..ba8b6427b59f 100644
--- a/sound/soc/sof/amd/acp.c
+++ b/sound/soc/sof/amd/acp.c
@@ -273,7 +273,7 @@ static int acp_memory_init(struct snd_sof_dev *sdev)
 static irqreturn_t acp_irq_thread(int irq, void *context)
 {
 	struct snd_sof_dev *sdev = context;
-	unsigned int val;
+	unsigned int val, count = ACP_HW_SEM_RETRY_COUNT;
 
 	val = snd_sof_dsp_read(sdev, ACP_DSP_BAR, ACP_EXTERNAL_INTR_STAT);
 	if (val & ACP_SHA_STAT) {
@@ -284,9 +284,22 @@ static irqreturn_t acp_irq_thread(int irq, void *context)
 
 	val = snd_sof_dsp_read(sdev, ACP_DSP_BAR, ACP_DSP_SW_INTR_STAT);
 	if (val & ACP_DSP_TO_HOST_IRQ) {
+		while (snd_sof_dsp_read(sdev, ACP_DSP_BAR, ACP_AXI2DAGB_SEM_0)) {
+			/* Wait until acquired HW Semaphore lock or timeout */
+			count--;
+			if (!count) {
+				dev_err(sdev->dev, "%s: Failed to acquire HW lock\n", __func__);
+				return IRQ_NONE;
+			}
+		};
+
 		sof_ops(sdev)->irq_thread(irq, sdev);
 		val |= ACP_DSP_TO_HOST_IRQ;
 		snd_sof_dsp_write(sdev, ACP_DSP_BAR, ACP_DSP_SW_INTR_STAT, val);
+
+		/* Unlock or Release HW Semaphore */
+		snd_sof_dsp_write(sdev, ACP_DSP_BAR, ACP_AXI2DAGB_SEM_0, 0x0);
+
 		return IRQ_HANDLED;
 	}
 
diff --git a/sound/soc/sof/amd/acp.h b/sound/soc/sof/amd/acp.h
index 8ed4e338467f..db1030d36811 100644
--- a/sound/soc/sof/amd/acp.h
+++ b/sound/soc/sof/amd/acp.h
@@ -17,6 +17,7 @@
 
 #define ACP_DSP_BAR	0
 
+#define ACP_HW_SEM_RETRY_COUNT			10
 #define ACP_REG_POLL_INTERVAL                   500
 #define ACP_REG_POLL_TIMEOUT_US                 2000
 #define ACP_DMA_COMPLETE_TIMEOUT_US		5000