[PATCH v3 1/3] drivers: mailbox: zynqmp: handle multiple child nodes

[Tanmay Shah <tanmay.shah@amd.com>]

As of now only one child node is handled by zynqmp-ipi
mailbox driver. Upon introducing remoteproc r5 core mailbox
nodes, found few enhancements in Xilinx zynqmp mailbox driver
as following:

- fix mailbox child node counts
  If child mailbox node status is disabled it causes
  crash in interrupt handler. Fix this by assigning
  only available child node during driver probe.

- fix typo in IPI documentation %s/12/32/
  Xilinx IPI message buffers allows 32-byte data transfer.
  Fix documentation that says 12 bytes

- fix bug in zynqmp-ipi isr handling
  Multiple IPI channels are mapped to same interrupt handler.
  Current isr implementation handles only one channel per isr.
  Fix this behavior by checking isr status bit of all child
  mailbox nodes.

Fixes: 4981b82ba2ff ("mailbox: ZynqMP IPI mailbox controller")
Signed-off-by: Tanmay Shah <tanmay.shah@amd.com>
---

Changelog:
  - This is first version of this change, however posting as part of the series
    that has version v3.

v2: https://lore.kernel.org/all/20230126213154.1707300-1-tanmay.shah@amd.com/

 drivers/mailbox/zynqmp-ipi-mailbox.c       | 8 ++++----
 include/linux/mailbox/zynqmp-ipi-message.h | 2 +-
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/mailbox/zynqmp-ipi-mailbox.c b/drivers/mailbox/zynqmp-ipi-mailbox.c
index 12e004ff1a14..b1498f6f06e1 100644
--- a/drivers/mailbox/zynqmp-ipi-mailbox.c
+++ b/drivers/mailbox/zynqmp-ipi-mailbox.c
@@ -152,7 +152,7 @@ static irqreturn_t zynqmp_ipi_interrupt(int irq, void *data)
 	struct zynqmp_ipi_message *msg;
 	u64 arg0, arg3;
 	struct arm_smccc_res res;
-	int ret, i;
+	int ret, i, status = IRQ_NONE;
 
 	(void)irq;
 	arg0 = SMC_IPI_MAILBOX_STATUS_ENQUIRY;
@@ -170,11 +170,11 @@ static irqreturn_t zynqmp_ipi_interrupt(int irq, void *data)
 				memcpy_fromio(msg->data, mchan->req_buf,
 					      msg->len);
 				mbox_chan_received_data(chan, (void *)msg);
-				return IRQ_HANDLED;
+				status = IRQ_HANDLED;
 			}
 		}
 	}
-	return IRQ_NONE;
+	return status;
 }
 
 /**
@@ -634,7 +634,7 @@ static int zynqmp_ipi_probe(struct platform_device *pdev)
 	struct zynqmp_ipi_mbox *mbox;
 	int num_mboxes, ret = -EINVAL;
 
-	num_mboxes = of_get_child_count(np);
+	num_mboxes = of_get_available_child_count(np);
 	pdata = devm_kzalloc(dev, sizeof(*pdata) + (num_mboxes * sizeof(*mbox)),
 			     GFP_KERNEL);
 	if (!pdata)
diff --git a/include/linux/mailbox/zynqmp-ipi-message.h b/include/linux/mailbox/zynqmp-ipi-message.h
index 35ce84c8ca02..31d8046d945e 100644
--- a/include/linux/mailbox/zynqmp-ipi-message.h
+++ b/include/linux/mailbox/zynqmp-ipi-message.h
@@ -9,7 +9,7 @@
  * @data: message payload
  *
  * This is the structure for data used in mbox_send_message
- * the maximum length of data buffer is fixed to 12 bytes.
+ * the maximum length of data buffer is fixed to 32 bytes.
  * Client is supposed to be aware of this.
  */
 struct zynqmp_ipi_message {
-- 
2.25.1