[PATCH] rpmsg: qcom_smd: Access APCS through mailbox framework

[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>
---
 drivers/rpmsg/qcom_smd.c | 62 +++++++++++++++++++++++++++++++++---------------
 1 file changed, 43 insertions(+), 19 deletions(-)

diff --git a/drivers/rpmsg/qcom_smd.c b/drivers/rpmsg/qcom_smd.c
index b01774e9fac0..ef2a526ebc8f 100644
--- a/drivers/rpmsg/qcom_smd.c
+++ b/drivers/rpmsg/qcom_smd.c
@@ -14,6 +14,7 @@
 
 #include <linux/interrupt.h>
 #include <linux/io.h>
+#include <linux/mailbox_client.h>
 #include <linux/mfd/syscon.h>
 #include <linux/module.h>
 #include <linux/of_irq.h>
@@ -107,6 +108,8 @@ static const struct {
  * @ipc_regmap:		regmap handle holding the outgoing ipc register
  * @ipc_offset:		offset within @ipc_regmap of the register for ipc
  * @ipc_bit:		bit in the register at @ipc_offset of @ipc_regmap
+ * @mbox_client:	mailbox client handle
+ * @mbox_chan:		apcs ipc mailbox channel handle
  * @channels:		list of all channels detected on this edge
  * @channels_lock:	guard for modifications of @channels
  * @allocated:		array of bitmaps representing already allocated channels
@@ -129,6 +132,9 @@ struct qcom_smd_edge {
 	int ipc_offset;
 	int ipc_bit;
 
+	struct mbox_client mbox_client;
+	struct mbox_chan *mbox_chan;
+
 	struct list_head channels;
 	spinlock_t channels_lock;
 
@@ -365,7 +371,12 @@ static void qcom_smd_signal_channel(struct qcom_smd_channel *channel)
 {
 	struct qcom_smd_edge *edge = channel->edge;
 
-	regmap_write(edge->ipc_regmap, edge->ipc_offset, BIT(edge->ipc_bit));
+	if (edge->mbox_chan) {
+		mbox_send_message(edge->mbox_chan, NULL);
+		mbox_client_txdone(edge->mbox_chan, 0);
+	} else {
+		regmap_write(edge->ipc_regmap, edge->ipc_offset, BIT(edge->ipc_bit));
+	}
 }
 
 /*
@@ -1268,27 +1279,37 @@ static int qcom_smd_parse_edge(struct device *dev,
 	key = "qcom,remote-pid";
 	of_property_read_u32(node, key, &edge->remote_pid);
 
-	syscon_np = of_parse_phandle(node, "qcom,ipc", 0);
-	if (!syscon_np) {
-		dev_err(dev, "no qcom,ipc node\n");
-		return -ENODEV;
-	}
+	edge->mbox_client.dev = dev;
+	edge->mbox_client.knows_txdone = true;
+	edge->mbox_chan = mbox_request_channel(&edge->mbox_client, 0);
+	if (IS_ERR(edge->mbox_chan)) {
+		if (PTR_ERR(edge->mbox_chan) != -ENODEV)
+			return PTR_ERR(edge->mbox_chan);
 
-	edge->ipc_regmap = syscon_node_to_regmap(syscon_np);
-	if (IS_ERR(edge->ipc_regmap))
-		return PTR_ERR(edge->ipc_regmap);
+		edge->mbox_chan = NULL;
 
-	key = "qcom,ipc";
-	ret = of_property_read_u32_index(node, key, 1, &edge->ipc_offset);
-	if (ret < 0) {
-		dev_err(dev, "no offset in %s\n", key);
-		return -EINVAL;
-	}
+		syscon_np = of_parse_phandle(node, "qcom,ipc", 0);
+		if (!syscon_np) {
+			dev_err(dev, "no qcom,ipc node\n");
+			return -ENODEV;
+		}
 
-	ret = of_property_read_u32_index(node, key, 2, &edge->ipc_bit);
-	if (ret < 0) {
-		dev_err(dev, "no bit in %s\n", key);
-		return -EINVAL;
+		edge->ipc_regmap = syscon_node_to_regmap(syscon_np);
+		if (IS_ERR(edge->ipc_regmap))
+			return PTR_ERR(edge->ipc_regmap);
+
+		key = "qcom,ipc";
+		ret = of_property_read_u32_index(node, key, 1, &edge->ipc_offset);
+		if (ret < 0) {
+			dev_err(dev, "no offset in %s\n", key);
+			return -EINVAL;
+		}
+
+		ret = of_property_read_u32_index(node, key, 2, &edge->ipc_bit);
+		if (ret < 0) {
+			dev_err(dev, "no bit in %s\n", key);
+			return -EINVAL;
+		}
 	}
 
 	ret = of_property_read_string(node, "label", &edge->name);
@@ -1394,6 +1415,8 @@ struct qcom_smd_edge *qcom_smd_register_edge(struct device *parent,
 	return edge;
 
 unregister_dev:
+	if (!IS_ERR_OR_NULL(edge->mbox_chan))
+		mbox_free_channel(edge->mbox_chan);
 	put_device(&edge->dev);
 	return ERR_PTR(ret);
 }
@@ -1422,6 +1445,7 @@ int qcom_smd_unregister_edge(struct qcom_smd_edge *edge)
 	if (ret)
 		dev_warn(&edge->dev, "can't remove smd device: %d\n", ret);
 
+	mbox_free_channel(edge->mbox_chan);
 	device_unregister(&edge->dev);
 
 	return 0;
-- 
2.15.0