soc: mediatek: cmdq: add cmdq_dev_get_client_reg function

GCE cannot know the register base address, this function
can help cmdq client to get the cmdq_client_reg structure.
Signed-off-by: Bibby Hsieh <bibby.hsieh@mediatek.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Reviewed-by: Houlong Wei <houlong.wei@mediatek.com>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

drivers/soc/mediatek/mtk-cmdq-helper.c

@@ -28,6 +28,35 @@ struct cmdq_instruction {
 	u8 op;
 };
 
+int cmdq_dev_get_client_reg(struct device *dev,
+			    struct cmdq_client_reg *client_reg, int idx)
+{
+	struct of_phandle_args spec;
+	int err;
+
+	if (!client_reg)
+		return -ENOENT;
+
+	err = of_parse_phandle_with_fixed_args(dev->of_node,
+					       "mediatek,gce-client-reg",
+					       3, idx, &spec);
+	if (err < 0) {
+		dev_err(dev,
+			"error %d can't parse gce-client-reg property (%d)",
+			err, idx);
+
+		return err;
+	}
+
+	client_reg->subsys = (u8)spec.args[0];
+	client_reg->offset = (u16)spec.args[1];
+	client_reg->size = (u16)spec.args[2];
+	of_node_put(spec.np);
+
+	return 0;
+}
+EXPORT_SYMBOL(cmdq_dev_get_client_reg);
+
 static void cmdq_client_timeout(struct timer_list *t)
 {
 	struct cmdq_client *client = from_timer(client, t, timer);

include/linux/soc/mediatek/mtk-cmdq.h

@@ -15,6 +15,12 @@
 
 struct cmdq_pkt;
 
+struct cmdq_client_reg {
+	u8 subsys;
+	u16 offset;
+	u16 size;
+};
+
 struct cmdq_client {
 	spinlock_t lock;
 	u32 pkt_cnt;
@@ -24,6 +30,21 @@ struct cmdq_client {
 	u32 timeout_ms; /* in unit of microsecond */
 };
 
+/**
+ * cmdq_dev_get_client_reg() - parse cmdq client reg from the device
+ *			       node of CMDQ client
+ * @dev:	device of CMDQ mailbox client
+ * @client_reg: CMDQ client reg pointer
+ * @idx:	the index of desired reg
+ *
+ * Return: 0 for success; else the error code is returned
+ *
+ * Help CMDQ client parsing the cmdq client reg
+ * from the device node of CMDQ client.
+ */
+int cmdq_dev_get_client_reg(struct device *dev,
+			    struct cmdq_client_reg *client_reg, int idx);
+
 /**
  * cmdq_mbox_create() - create CMDQ mailbox client and channel
  * @dev:	device of CMDQ mailbox client