[PATCH v3 0/2] firmware: arm_scmi: Augment SMC/HVC to allow optional interrupt

[PATCH v3 0/2] firmware: arm_scmi: Augment SMC/HVC to allow optional interrupt

[Jim Quinlan]

v3 -- Changed interrupt name from "message-serviced" to "a2p" (RobH)

v2 -- Correct commit message, s/msg/message/, and remove extra WS on
      "dt-bindings" commit (Sudeep)
   -- Change interrupt name to "message-serviced", move irq assignent to end
      of function. (Sudeep)

v1 -- original.


Jim Quinlan (2):
  dt-bindings: arm: Add optional interrupt to smc/hvc SCMI transport
  firmware: arm_scmi: Augment SMC/HVC to allow optional interrupt

 .../devicetree/bindings/arm/arm,scmi.txt      |  8 ++++
 drivers/firmware/arm_scmi/smc.c               | 38 ++++++++++++++++++-
 2 files changed, 45 insertions(+), 1 deletion(-)

-- 
2.17.1

[PATCH v3 1/2] dt-bindings: arm: Add optional interrupt to smc/hvc SCMI transport

[Jim Quinlan]

In normal use of smc/hvc transport in SCMI the message completion is
indicated by the return of the SMC call.  This commit provides for an
optional interrupt named "message-serviced" which is used instead to
indicate the completion of a message.

Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
---
 Documentation/devicetree/bindings/arm/arm,scmi.txt | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/Documentation/devicetree/bindings/arm/arm,scmi.txt b/Documentation/devicetree/bindings/arm/arm,scmi.txt
index b5ce5b39bb9c..667d58e0a659 100644
--- a/Documentation/devicetree/bindings/arm/arm,scmi.txt
+++ b/Documentation/devicetree/bindings/arm/arm,scmi.txt
@@ -31,6 +31,14 @@ Optional properties:
 
 - mbox-names: shall be "tx" or "rx" depending on mboxes entries.
 
+- interrupts : when using smc or hvc transports, this optional
+	 property indicates that msg completion by the platform is indicated
+	 by an interrupt rather than by the return of the smc call. This
+	 should not be used except when the platform requires such behavior.
+
+- interrupt-names : if "interrupts" is present, interrupt-names must also
+	 be present and have the value "a2p".
+
 See Documentation/devicetree/bindings/mailbox/mailbox.txt for more details
 about the generic mailbox controller and client driver bindings.
 
-- 
2.17.1

[PATCH v3 2/2] firmware: arm_scmi: Augment SMC/HVC to allow optional interrupt

[Jim Quinlan]

The SMC/HVC SCMI transport is modified to allow the completion of an SCMI
message to be indicated by an interrupt rather than the return of the smc
call.  This accommodates the existing behavior of the BrcmSTB SCMI
"platform" whose SW is already out in the field and cannot be changed.

Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>
---
 drivers/firmware/arm_scmi/smc.c | 38 ++++++++++++++++++++++++++++++++-
 1 file changed, 37 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/arm_scmi/smc.c b/drivers/firmware/arm_scmi/smc.c
index 82a82a5dc86a..fd41d436e34b 100644
--- a/drivers/firmware/arm_scmi/smc.c
+++ b/drivers/firmware/arm_scmi/smc.c
@@ -9,9 +9,11 @@
 #include <linux/arm-smccc.h>
 #include <linux/device.h>
 #include <linux/err.h>
+#include <linux/interrupt.h>
 #include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/of_address.h>
+#include <linux/of_irq.h>
 #include <linux/slab.h>
 
 #include "common.h"
@@ -23,6 +25,8 @@
  * @shmem: Transmit/Receive shared memory area
  * @shmem_lock: Lock to protect access to Tx/Rx shared memory area
  * @func_id: smc/hvc call function id
+ * @irq: Optional; employed when platforms indicates msg completion by intr.
+ * @tx_complete: Optional, employed only when irq is valid.
  */
 
 struct scmi_smc {
@@ -30,8 +34,19 @@ struct scmi_smc {
 	struct scmi_shared_mem __iomem *shmem;
 	struct mutex shmem_lock;
 	u32 func_id;
+	int irq;
+	struct completion tx_complete;
 };
 
+static irqreturn_t smc_msg_done_isr(int irq, void *data)
+{
+	struct scmi_smc *scmi_info = data;
+
+	complete(&scmi_info->tx_complete);
+
+	return IRQ_HANDLED;
+}
+
 static bool smc_chan_available(struct device *dev, int idx)
 {
 	struct device_node *np = of_parse_phandle(dev->of_node, "shmem", 0);
@@ -51,7 +66,7 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
 	struct resource res;
 	struct device_node *np;
 	u32 func_id;
-	int ret;
+	int ret, irq = 0;
 
 	if (!tx)
 		return -ENODEV;
@@ -79,10 +94,29 @@ static int smc_chan_setup(struct scmi_chan_info *cinfo, struct device *dev,
 	if (ret < 0)
 		return ret;
 
+	/*
+	 * If there is an interrupt named "a2p", then the
+	 * service and completion of a message is signaled by an interrupt
+	 * rather than by the return of the SMC call.
+	 */
+	ret = of_irq_get_byname(cdev->of_node, "a2p");
+	if (ret > 0) {
+		irq = ret;
+		ret = devm_request_irq(dev, irq, smc_msg_done_isr,
+				       IRQF_NO_SUSPEND,
+				       dev_name(dev),
+				       scmi_info);
+		if (ret) {
+			dev_err(dev, "failed to setup SCMI smc irq\n");
+			return ret;
+		}
+		init_completion(&scmi_info->tx_complete);
+	}
 	scmi_info->func_id = func_id;
 	scmi_info->cinfo = cinfo;
 	mutex_init(&scmi_info->shmem_lock);
 	cinfo->transport_info = scmi_info;
+	scmi_info->irq = irq;
 
 	return 0;
 }
@@ -111,6 +145,8 @@ static int smc_send_message(struct scmi_chan_info *cinfo,
 	shmem_tx_prepare(scmi_info->shmem, xfer);
 
 	arm_smccc_1_1_invoke(scmi_info->func_id, 0, 0, 0, 0, 0, 0, 0, &res);
+	if (scmi_info->irq)
+		wait_for_completion(&scmi_info->tx_complete);
 	scmi_rx_callback(scmi_info->cinfo, shmem_read_header(scmi_info->shmem));
 
 	mutex_unlock(&scmi_info->shmem_lock);
-- 
2.17.1

Re: [PATCH v3 1/2] dt-bindings: arm: Add optional interrupt to smc/hvc SCMI transport

[Rob Herring]

On Wed, Dec 16, 2020 at 03:58:01PM -0500, Jim Quinlan wrote:
> In normal use of smc/hvc transport in SCMI the message completion is
> indicated by the return of the SMC call.  This commit provides for an
> optional interrupt named "message-serviced" which is used instead to

s/message-serviced/a2p/

> indicate the completion of a message.
> 
> Signed-off-by: Jim Quinlan <james.quinlan@broadcom.com>

checkpatch.pl reports your author and Sob emails don't match.

> ---
>  Documentation/devicetree/bindings/arm/arm,scmi.txt | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/arm/arm,scmi.txt b/Documentation/devicetree/bindings/arm/arm,scmi.txt
> index b5ce5b39bb9c..667d58e0a659 100644
> --- a/Documentation/devicetree/bindings/arm/arm,scmi.txt
> +++ b/Documentation/devicetree/bindings/arm/arm,scmi.txt
> @@ -31,6 +31,14 @@ Optional properties:
>  
>  - mbox-names: shall be "tx" or "rx" depending on mboxes entries.
>  
> +- interrupts : when using smc or hvc transports, this optional
> +	 property indicates that msg completion by the platform is indicated
> +	 by an interrupt rather than by the return of the smc call. This
> +	 should not be used except when the platform requires such behavior.
> +
> +- interrupt-names : if "interrupts" is present, interrupt-names must also
> +	 be present and have the value "a2p".
> +
>  See Documentation/devicetree/bindings/mailbox/mailbox.txt for more details
>  about the generic mailbox controller and client driver bindings.
>  
> -- 
> 2.17.1
>