rpmsg: qcom_smd: Access APCS through mailbox framework

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.

Reviewed-by: Arun Kumar Neelakantam <aneela@codeaurora.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>

2 files changed, 50 insertions, 19 deletions

diff --git a/drivers/rpmsg/Kconfig b/drivers/rpmsg/Kconfig
index 65a9f6b892f0..9b14090e3603 100644
--- a/drivers/rpmsg/Kconfig
+++ b/drivers/rpmsg/Kconfig
@@ -39,6 +39,7 @@ config RPMSG_QCOM_GLINK_SMEM
 
 config RPMSG_QCOM_SMD
         tristate "Qualcomm Shared Memory Driver (SMD)"
+        depends on MAILBOX
         depends on QCOM_SMEM
         select RPMSG
         help
diff --git a/drivers/rpmsg/qcom_smd.c b/drivers/rpmsg/qcom_smd.c
index 5ce9bf7b897d..b07e9a1a9d22 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;
 
@@ -366,7 +372,17 @@ 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) {
+                /*
+                 * We can ignore a failing mbox_send_message() as the only
+                 * possible cause is that the FIFO in the framework is full of
+                 * other writes to the same bit.
+                 */
+                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));
+        }
 }
 
 /*
@@ -1326,27 +1342,37 @@ 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);
@@ -1453,6 +1479,9 @@ 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);
+
         device_unregister(&edge->dev);
         return ERR_PTR(ret);
 }
@@ -1481,6 +1510,7 @@ 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;