diff --git a/drivers/mailbox/pcc.c b/drivers/mailbox/pcc.c
index 80310b48bfb6..94885e411085 100644
--- a/drivers/mailbox/pcc.c
+++ b/drivers/mailbox/pcc.c
@@ -92,6 +92,13 @@ struct pcc_chan_reg {
  * @error: PCC register bundle for the error status register
  * @plat_irq: platform interrupt
  * @type: PCC subspace type
+ * @plat_irq_flags: platform interrupt flags
+ * @chan_in_use: this flag is used just to check if the interrupt needs
+ *		handling when it is shared. Since only one transfer can occur
+ *		at a time and mailbox takes care of locking, this flag can be
+ *		accessed without a lock. Note: the type only support the
+ *		communication from OSPM to Platform, like type3, use it, and
+ *		other types completely ignore it.
  */
 struct pcc_chan_info {
 	struct pcc_mbox_chan chan;
@@ -102,6 +109,8 @@ struct pcc_chan_info {
 	struct pcc_chan_reg error;
 	int plat_irq;
 	u8 type;
+	unsigned int plat_irq_flags;
+	bool chan_in_use;
 };
 
 #define to_pcc_chan_info(c) container_of(c, struct pcc_chan_info, chan)
@@ -225,6 +234,12 @@ static int pcc_map_interrupt(u32 interrupt, u32 flags)
 	return acpi_register_gsi(NULL, interrupt, trigger, polarity);
 }
 
+static bool pcc_chan_plat_irq_can_be_shared(struct pcc_chan_info *pchan)
+{
+	return (pchan->plat_irq_flags & ACPI_PCCT_INTERRUPT_MODE) ==
+		ACPI_LEVEL_SENSITIVE;
+}
+
 static bool pcc_mbox_cmd_complete_check(struct pcc_chan_info *pchan)
 {
 	u64 val;
@@ -242,6 +257,7 @@ static bool pcc_mbox_cmd_complete_check(struct pcc_chan_info *pchan)
 	 * command complete.
 	 */
 	val &= pchan->cmd_complete.status_mask;
+
 	/*
 	 * If this is PCC slave subspace channel, and the command complete
 	 * bit 0 indicates that Platform is sending a notification and OSPM
@@ -268,6 +284,10 @@ static irqreturn_t pcc_mbox_irq(int irq, void *p)
 	int ret;
 
 	pchan = chan->con_priv;
+	if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_MASTER_SUBSPACE &&
+	    !pchan->chan_in_use)
+		return IRQ_NONE;
+
 	if (!pcc_mbox_cmd_complete_check(pchan))
 		return IRQ_NONE;
 
@@ -289,9 +309,12 @@ static irqreturn_t pcc_mbox_irq(int irq, void *p)
 	/*
 	 * The PCC slave subspace channel needs to set the command complete bit
 	 * and ring doorbell after processing message.
+	 *
+	 * The PCC master subspace channel clears chan_in_use to free channel.
 	 */
 	if (pchan->type == ACPI_PCCT_TYPE_EXT_PCC_SLAVE_SUBSPACE)
 		pcc_send_data(chan, NULL);
+	pchan->chan_in_use = false;
 
 	return IRQ_HANDLED;
 }
@@ -371,7 +394,11 @@ static int pcc_send_data(struct mbox_chan *chan, void *data)
 	if (ret)
 		return ret;
 
-	return pcc_chan_reg_read_modify_write(&pchan->db);
+	ret = pcc_chan_reg_read_modify_write(&pchan->db);
+	if (!ret && pchan->plat_irq > 0)
+		pchan->chan_in_use = true;
+
+	return ret;
 }
 
 /**
@@ -384,11 +411,14 @@ static int pcc_send_data(struct mbox_chan *chan, void *data)
 static int pcc_startup(struct mbox_chan *chan)
 {
 	struct pcc_chan_info *pchan = chan->con_priv;
+	unsigned long irqflags;
 	int rc;
 
 	if (pchan->plat_irq > 0) {
-		rc = devm_request_irq(chan->mbox->dev, pchan->plat_irq, pcc_mbox_irq, 0,
-				      MBOX_IRQ_NAME, chan);
+		irqflags = pcc_chan_plat_irq_can_be_shared(pchan) ?
+						IRQF_SHARED | IRQF_ONESHOT : 0;
+		rc = devm_request_irq(chan->mbox->dev, pchan->plat_irq, pcc_mbox_irq,
+				      irqflags, MBOX_IRQ_NAME, chan);
 		if (unlikely(rc)) {
 			dev_err(chan->mbox->dev, "failed to register PCC interrupt %d\n",
 				pchan->plat_irq);
@@ -494,6 +524,7 @@ static int pcc_parse_subspace_irq(struct pcc_chan_info *pchan,
 		       pcct_ss->platform_interrupt);
 		return -EINVAL;
 	}
+	pchan->plat_irq_flags = pcct_ss->flags;
 
 	if (pcct_ss->header.type == ACPI_PCCT_TYPE_HW_REDUCED_SUBSPACE_TYPE2) {
 		struct acpi_pcct_hw_reduced_type2 *pcct2_ss = (void *)pcct_ss;
@@ -515,6 +546,12 @@ static int pcc_parse_subspace_irq(struct pcc_chan_info *pchan,
 					"PLAT IRQ ACK");
 	}
 
+	if (pcc_chan_plat_irq_can_be_shared(pchan) &&
+	    !pchan->plat_irq_ack.gas) {
+		pr_err("PCC subspace has level IRQ with no ACK register\n");
+		return -EINVAL;
+	}
+
 	return ret;
 }