[PATCH V2 1/2] ACPI: PCC: add check for platform interrupt

[Huisong Li <lihuisong@xxxxxxxxxx>]

Currently, PCC Operation Region driver senses the completion of command by
interrupt way. If platform can not generate an interrupt when a command
complete, the caller never gets the desired result. So let's reject the
setup of the PCC address space on platform that do not support interrupt
mode.

Signed-off-by: Huisong Li <lihuisong@xxxxxxxxxx>
---
 drivers/acpi/acpi_pcc.c | 47 +++++++++++++++++++++++++----------------
 1 file changed, 29 insertions(+), 18 deletions(-)

diff --git a/drivers/acpi/acpi_pcc.c b/drivers/acpi/acpi_pcc.c
index 3e252be047b8..8efd08e469aa 100644
--- a/drivers/acpi/acpi_pcc.c
+++ b/drivers/acpi/acpi_pcc.c
@@ -53,6 +53,7 @@ acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
 	struct pcc_data *data;
 	struct acpi_pcc_info *ctx = handler_context;
 	struct pcc_mbox_chan *pcc_chan;
+	static acpi_status ret;
 
 	data = kzalloc(sizeof(*data), GFP_KERNEL);
 	if (!data)
@@ -69,23 +70,35 @@ acpi_pcc_address_space_setup(acpi_handle region_handle, u32 function,
 	if (IS_ERR(data->pcc_chan)) {
 		pr_err("Failed to find PCC channel for subspace %d\n",
 		       ctx->subspace_id);
-		kfree(data);
-		return AE_NOT_FOUND;
+		ret = AE_NOT_FOUND;
+		goto request_channel_fail;
 	}
 
 	pcc_chan = data->pcc_chan;
+	if (!pcc_chan->mchan->mbox->txdone_irq) {
+		pr_err("This channel-%d does not support interrupt.\n",
+		       ctx->subspace_id);
+		ret = AE_SUPPORT;
+		goto request_channel_fail;
+	}
 	data->pcc_comm_addr = acpi_os_ioremap(pcc_chan->shmem_base_addr,
 					      pcc_chan->shmem_size);
 	if (!data->pcc_comm_addr) {
 		pr_err("Failed to ioremap PCC comm region mem for %d\n",
 		       ctx->subspace_id);
-		pcc_mbox_free_channel(data->pcc_chan);
-		kfree(data);
-		return AE_NO_MEMORY;
+		ret = AE_NO_MEMORY;
+		goto ioremap_fail;
 	}
 
 	*region_context = data;
 	return AE_OK;
+
+ioremap_fail:
+	pcc_mbox_free_channel(data->pcc_chan);
+request_channel_fail:
+	kfree(data);
+
+	return ret;
 }
 
 static acpi_status
@@ -106,19 +119,17 @@ acpi_pcc_address_space_handler(u32 function, acpi_physical_address addr,
 	if (ret < 0)
 		return AE_ERROR;
 
-	if (data->pcc_chan->mchan->mbox->txdone_irq) {
-		/*
-		 * pcc_chan->latency is just a Nominal value. In reality the remote
-		 * processor could be much slower to reply. So add an arbitrary
-		 * amount of wait on top of Nominal.
-		 */
-		usecs_lat = PCC_CMD_WAIT_RETRIES_NUM * data->pcc_chan->latency;
-		ret = wait_for_completion_timeout(&data->done,
-						  usecs_to_jiffies(usecs_lat));
-		if (ret == 0) {
-			pr_err("PCC command executed timeout!\n");
-			return AE_TIME;
-		}
+	/*
+	 * pcc_chan->latency is just a Nominal value. In reality the remote
+	 * processor could be much slower to reply. So add an arbitrary
+	 * amount of wait on top of Nominal.
+	 */
+	usecs_lat = PCC_CMD_WAIT_RETRIES_NUM * data->pcc_chan->latency;
+	ret = wait_for_completion_timeout(&data->done,
+						usecs_to_jiffies(usecs_lat));
+	if (ret == 0) {
+		pr_err("PCC command executed timeout!\n");
+		return AE_TIME;
 	}
 
 	mbox_chan_txdone(data->pcc_chan->mchan, ret);
-- 
2.22.0