This framework allows SCMI protocols to be installed and bound to the agent
so that the agent can manage and utilize them later.

Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org>
Reviewed-by: Simon Glass <s...@chromium.org>
Reviewed-by: Etienne Carriere <etienne.carri...@foss.st.com>
---
V4
* remove 'agent' variable as it should be added in the following commit
v3
* move "per_device_plat_auto" from a earlier patch
* fix comments in "scmi_agent_priv"
* modify an order of include files in scmi_agent.h
v2
* check for availability of protocols
---
 drivers/firmware/scmi/scmi_agent-uclass.c | 100 +++++++++++++++++++++-
 include/scmi_agent-uclass.h               |  15 +++-
 include/scmi_agent.h                      |  14 +++
 3 files changed, 125 insertions(+), 4 deletions(-)

diff --git a/drivers/firmware/scmi/scmi_agent-uclass.c 
b/drivers/firmware/scmi/scmi_agent-uclass.c
index 1fa1e9eef966..482cdaf0c6db 100644
--- a/drivers/firmware/scmi/scmi_agent-uclass.c
+++ b/drivers/firmware/scmi/scmi_agent-uclass.c
@@ -38,6 +38,86 @@ static const struct error_code scmi_linux_errmap[] = {
        { .scmi = SCMI_PROTOCOL_ERROR, .errno = -EPROTO, },
 };
 
+/*
+ * NOTE: The only one instance should exist according to
+ * the current specification and device tree bindings.
+ */
+struct udevice *scmi_agent;
+
+struct udevice *scmi_get_protocol(struct udevice *dev,
+                                 enum scmi_std_protocol id)
+{
+       struct scmi_agent_priv *priv;
+       struct udevice *proto;
+
+       priv = dev_get_uclass_plat(dev);
+       if (!priv) {
+               dev_err(dev, "No priv data found\n");
+               return NULL;
+       }
+
+       switch (id) {
+       case SCMI_PROTOCOL_ID_CLOCK:
+               proto = priv->clock_dev;
+               break;
+       case SCMI_PROTOCOL_ID_RESET_DOMAIN:
+               proto = priv->resetdom_dev;
+               break;
+       case SCMI_PROTOCOL_ID_VOLTAGE_DOMAIN:
+               proto = priv->voltagedom_dev;
+               break;
+       default:
+               dev_err(dev, "Protocol not supported\n");
+               proto = NULL;
+               break;
+       }
+       if (proto && device_probe(proto))
+               dev_err(dev, "Probe failed\n");
+
+       return proto;
+}
+
+/**
+ * scmi_add_protocol - add protocol to agent
+ * @dev:       SCMI agent device
+ * @proto_id:  SCMI protocol ID
+ * @proto:     SCMI protocol device
+ *
+ * Associate the protocol instance, @proto, to the agent, @dev,
+ * for later use.
+ *
+ * Return:     0 on success, error code on failure
+ */
+static int scmi_add_protocol(struct udevice *dev,
+                            enum scmi_std_protocol proto_id,
+                            struct udevice *proto)
+{
+       struct scmi_agent_priv *priv;
+
+       priv = dev_get_uclass_plat(dev);
+       if (!priv) {
+               dev_err(dev, "No priv data found\n");
+               return -ENODEV;
+       }
+
+       switch (proto_id) {
+       case SCMI_PROTOCOL_ID_CLOCK:
+               priv->clock_dev = proto;
+               break;
+       case SCMI_PROTOCOL_ID_RESET_DOMAIN:
+               priv->resetdom_dev = proto;
+               break;
+       case SCMI_PROTOCOL_ID_VOLTAGE_DOMAIN:
+               priv->voltagedom_dev = proto;
+               break;
+       default:
+               dev_err(dev, "Protocol not supported\n");
+               return -EPROTO;
+       }
+
+       return 0;
+}
+
 int scmi_to_linux_errno(s32 scmi_code)
 {
        int n;
@@ -168,9 +248,10 @@ static int scmi_bind_protocols(struct udevice *dev)
        int ret = 0;
        ofnode node;
        const char *name;
+       struct driver *drv;
+       struct udevice *proto;
 
        dev_for_each_subnode(node, dev) {
-               struct driver *drv = NULL;
                u32 protocol_id;
 
                if (!ofnode_is_enabled(node))
@@ -179,6 +260,7 @@ static int scmi_bind_protocols(struct udevice *dev)
                if (ofnode_read_u32(node, "reg", &protocol_id))
                        continue;
 
+               drv = NULL;
                name = ofnode_get_name(node);
                switch (protocol_id) {
                case SCMI_PROTOCOL_ID_CLOCK:
@@ -209,11 +291,22 @@ static int scmi_bind_protocols(struct udevice *dev)
                        continue;
                }
 
-               ret = device_bind(dev, drv, name, NULL, node, NULL);
-               if (ret)
+               ret = device_bind(dev, drv, name, NULL, node, &proto);
+               if (ret) {
+                       dev_err(dev, "failed to bind %s protocol\n", drv->name);
                        break;
+               }
+               ret = scmi_add_protocol(dev, protocol_id, proto);
+               if (ret) {
+                       dev_err(dev, "failed to add protocol: %s, ret: %d\n",
+                               proto->name, ret);
+                       break;
+               }
        }
 
+       if (!ret)
+               scmi_agent = dev;
+
        return ret;
 }
 
@@ -221,5 +314,6 @@ UCLASS_DRIVER(scmi_agent) = {
        .id             = UCLASS_SCMI_AGENT,
        .name           = "scmi_agent",
        .post_bind      = scmi_bind_protocols,
+       .per_device_plat_auto = sizeof(struct scmi_agent_priv),
        .per_child_auto = sizeof(struct scmi_agent_proto_priv),
 };
diff --git a/include/scmi_agent-uclass.h b/include/scmi_agent-uclass.h
index eee46c880a56..258aa0f37596 100644
--- a/include/scmi_agent-uclass.h
+++ b/include/scmi_agent-uclass.h
@@ -5,10 +5,23 @@
 #ifndef _SCMI_AGENT_UCLASS_H
 #define _SCMI_AGENT_UCLASS_H
 
-struct udevice;
+#include <dm/device.h>
+
 struct scmi_msg;
 struct scmi_channel;
 
+/**
+ * struct scmi_agent_priv - private data maintained by agent instance
+ * @clock_dev:         SCMI clock protocol device
+ * @resetdom_dev:      SCMI reset domain protocol device
+ * @voltagedom_dev:    SCMI voltage domain protocol device
+ */
+struct scmi_agent_priv {
+       struct udevice *clock_dev;
+       struct udevice *resetdom_dev;
+       struct udevice *voltagedom_dev;
+};
+
 /**
  * struct scmi_transport_ops - The functions that a SCMI transport layer must 
implement.
  */
diff --git a/include/scmi_agent.h b/include/scmi_agent.h
index 577892029ff8..755986d6c424 100644
--- a/include/scmi_agent.h
+++ b/include/scmi_agent.h
@@ -10,6 +10,7 @@
 #ifndef SCMI_AGENT_H
 #define SCMI_AGENT_H
 
+#include <scmi_protocols.h>
 #include <asm/types.h>
 
 struct udevice;
@@ -74,6 +75,19 @@ int devm_scmi_of_get_channel(struct udevice *dev);
  */
 int devm_scmi_process_msg(struct udevice *dev, struct scmi_msg *msg);
 
+/**
+ * scmi_get_protocol() - get protocol instance
+ *
+ * @dev:       SCMI agent device
+ * @id:                SCMI protocol ID
+ *
+ * Obtain the device instance for given protocol ID, @id.
+ *
+ * Return:     Pointer to the device if found, null otherwise
+ */
+struct udevice *scmi_get_protocol(struct udevice *dev,
+                                 enum scmi_std_protocol id);
+
 /**
  * scmi_to_linux_errno() - Convert an SCMI error code into a Linux errno code
  *
-- 
2.34.1

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