[PATCH v2] soc: qcom: smp2p: Access APCS as mailbox client

[Bjorn Andersson <bjorn.andersson@linaro.org>]

Attempt to acquire the APCS IPC through the mailbox framework and fall
back to the old syscon based approach, to allow us to move away from
using the syscon.

Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
---

Changes since v1:
- Added dt binding update
- Specifies knows_txdone on the mailbox client

 .../devicetree/bindings/soc/qcom/qcom,smp2p.txt    |  8 ++++-
 drivers/soc/qcom/Kconfig                           |  1 +
 drivers/soc/qcom/smp2p.c                           | 39 ++++++++++++++++++----
 3 files changed, 41 insertions(+), 7 deletions(-)

diff --git a/Documentation/devicetree/bindings/soc/qcom/qcom,smp2p.txt b/Documentation/devicetree/bindings/soc/qcom/qcom,smp2p.txt
index af9ca37221ce..a35af2dafdad 100644
--- a/Documentation/devicetree/bindings/soc/qcom/qcom,smp2p.txt
+++ b/Documentation/devicetree/bindings/soc/qcom/qcom,smp2p.txt
@@ -17,9 +17,15 @@ processor ID) and a string identifier.
 	Value type: <prop-encoded-array>
 	Definition: one entry specifying the smp2p notification interrupt
 
-- qcom,ipc:
+- mboxes:
 	Usage: required
 	Value type: <prop-encoded-array>
+	Definition: reference to the associated doorbell in APCS, as described
+		    in mailbox/mailbox.txt
+
+- qcom,ipc:
+	Usage: required, unless mboxes is specified
+	Value type: <prop-encoded-array>
 	Definition: three entries specifying the outgoing ipc bit used for
 		    signaling the remote end of the smp2p edge:
 		    - phandle to a syscon node representing the apcs registers
diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index b81374bb6713..40c711583f0d 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -75,6 +75,7 @@ config QCOM_SMEM_STATE
 
 config QCOM_SMP2P
 	tristate "Qualcomm Shared Memory Point to Point support"
+	depends on MAILBOX
 	depends on QCOM_SMEM
 	select QCOM_SMEM_STATE
 	help
diff --git a/drivers/soc/qcom/smp2p.c b/drivers/soc/qcom/smp2p.c
index f51fb2ea7200..669c8baa971b 100644
--- a/drivers/soc/qcom/smp2p.c
+++ b/drivers/soc/qcom/smp2p.c
@@ -18,6 +18,7 @@
 #include <linux/of.h>
 #include <linux/irq.h>
 #include <linux/irqdomain.h>
+#include <linux/mailbox_client.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/platform_device.h>
@@ -126,6 +127,8 @@ struct smp2p_entry {
  * @ipc_regmap:	regmap for the outbound ipc
  * @ipc_offset:	offset within the regmap
  * @ipc_bit:	bit in regmap@offset to kick to signal remote processor
+ * @mbox_client: mailbox client handle
+ * @mbox_chan:	apcs ipc mailbox channel handle
  * @inbound:	list of inbound entries
  * @outbound:	list of outbound entries
  */
@@ -146,6 +149,9 @@ struct qcom_smp2p {
 	int ipc_offset;
 	int ipc_bit;
 
+	struct mbox_client mbox_client;
+	struct mbox_chan *mbox_chan;
+
 	struct list_head inbound;
 	struct list_head outbound;
 };
@@ -154,7 +160,13 @@ static void qcom_smp2p_kick(struct qcom_smp2p *smp2p)
 {
 	/* Make sure any updated data is written before the kick */
 	wmb();
-	regmap_write(smp2p->ipc_regmap, smp2p->ipc_offset, BIT(smp2p->ipc_bit));
+
+	if (smp2p->mbox_chan) {
+		mbox_send_message(smp2p->mbox_chan, NULL);
+		mbox_client_txdone(smp2p->mbox_chan, 0);
+	} else {
+		regmap_write(smp2p->ipc_regmap, smp2p->ipc_offset, BIT(smp2p->ipc_bit));
+	}
 }
 
 /**
@@ -453,10 +465,6 @@ static int qcom_smp2p_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, smp2p);
 
-	ret = smp2p_parse_ipc(smp2p);
-	if (ret)
-		return ret;
-
 	key = "qcom,smem";
 	ret = of_property_read_u32_array(pdev->dev.of_node, key,
 					 smp2p->smem_items, 2);
@@ -483,9 +491,23 @@ static int qcom_smp2p_probe(struct platform_device *pdev)
 		return irq;
 	}
 
+	smp2p->mbox_client.dev = &pdev->dev;
+	smp2p->mbox_client.knows_txdone = true;
+	smp2p->mbox_chan = mbox_request_channel(&smp2p->mbox_client, 0);
+	if (IS_ERR(smp2p->mbox_chan)) {
+		if (PTR_ERR(smp2p->mbox_chan) != -ENODEV)
+			return PTR_ERR(smp2p->mbox_chan);
+
+		smp2p->mbox_chan = NULL;
+
+		ret = smp2p_parse_ipc(smp2p);
+		if (ret)
+			return ret;
+	}
+
 	ret = qcom_smp2p_alloc_outbound_item(smp2p);
 	if (ret < 0)
-		return ret;
+		goto release_mbox;
 
 	for_each_available_child_of_node(pdev->dev.of_node, node) {
 		entry = devm_kzalloc(&pdev->dev, sizeof(*entry), GFP_KERNEL);
@@ -540,6 +562,9 @@ static int qcom_smp2p_probe(struct platform_device *pdev)
 
 	smp2p->out->valid_entries = 0;
 
+release_mbox:
+	mbox_free_channel(smp2p->mbox_chan);
+
 	return ret;
 }
 
@@ -554,6 +579,8 @@ static int qcom_smp2p_remove(struct platform_device *pdev)
 	list_for_each_entry(entry, &smp2p->outbound, node)
 		qcom_smem_state_unregister(entry->state);
 
+	mbox_free_channel(smp2p->mbox_chan);
+
 	smp2p->out->valid_entries = 0;
 
 	return 0;
-- 
2.15.0