remoteproc: k3-dsp: Refactor mbox request code in start

Refactor out the mailbox request and associated ping logic code
from k3_dsp_rproc_start() function into its own separate function
so that it can be re-used in the soon to be added .attach() ops
callback.

Signed-off-by: Suman Anna <s-anna@ti.com>
Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Bjorn Andersson <bjorn.andersson@linaro.org>
Link: https://lore.kernel.org/r/20220213201246.25952-5-s-anna@ti.com

Author: sumananna

drivers/remoteproc/ti_k3_dsp_remoteproc.c

@@ -2,7 +2,7 @@
 /*
  * TI K3 DSP Remote Processor(s) driver
  *
- * Copyright (C) 2018-2020 Texas Instruments Incorporated - https://www.ti.com/
+ * Copyright (C) 2018-2022 Texas Instruments Incorporated - https://www.ti.com/
  *	Suman Anna <s-anna@ti.com>
  */
 
@@ -216,6 +216,43 @@ static int k3_dsp_rproc_release(struct k3_dsp_rproc *kproc)
 	return ret;
 }
 
+static int k3_dsp_rproc_request_mbox(struct rproc *rproc)
+{
+	struct k3_dsp_rproc *kproc = rproc->priv;
+	struct mbox_client *client = &kproc->client;
+	struct device *dev = kproc->dev;
+	int ret;
+
+	client->dev = dev;
+	client->tx_done = NULL;
+	client->rx_callback = k3_dsp_rproc_mbox_callback;
+	client->tx_block = false;
+	client->knows_txdone = false;
+
+	kproc->mbox = mbox_request_channel(client, 0);
+	if (IS_ERR(kproc->mbox)) {
+		ret = -EBUSY;
+		dev_err(dev, "mbox_request_channel failed: %ld\n",
+			PTR_ERR(kproc->mbox));
+		return ret;
+	}
+
+	/*
+	 * Ping the remote processor, this is only for sanity-sake for now;
+	 * there is no functional effect whatsoever.
+	 *
+	 * Note that the reply will _not_ arrive immediately: this message
+	 * will wait in the mailbox fifo until the remote processor is booted.
+	 */
+	ret = mbox_send_message(kproc->mbox, (void *)RP_MBOX_ECHO_REQUEST);
+	if (ret < 0) {
+		dev_err(dev, "mbox_send_message failed: %d\n", ret);
+		mbox_free_channel(kproc->mbox);
+		return ret;
+	}
+
+	return 0;
+}
 /*
  * The C66x DSP cores have a local reset that affects only the CPU, and a
  * generic module reset that powers on the device and allows the DSP internal
@@ -273,37 +310,13 @@ static int k3_dsp_rproc_unprepare(struct rproc *rproc)
 static int k3_dsp_rproc_start(struct rproc *rproc)
 {
 	struct k3_dsp_rproc *kproc = rproc->priv;
-	struct mbox_client *client = &kproc->client;
 	struct device *dev = kproc->dev;
 	u32 boot_addr;
 	int ret;
 
-	client->dev = dev;
-	client->tx_done = NULL;
-	client->rx_callback = k3_dsp_rproc_mbox_callback;
-	client->tx_block = false;
-	client->knows_txdone = false;
-
-	kproc->mbox = mbox_request_channel(client, 0);
-	if (IS_ERR(kproc->mbox)) {
-		ret = -EBUSY;
-		dev_err(dev, "mbox_request_channel failed: %ld\n",
-			PTR_ERR(kproc->mbox));
+	ret = k3_dsp_rproc_request_mbox(rproc);
+	if (ret)
 		return ret;
-	}
-
-	/*
-	 * Ping the remote processor, this is only for sanity-sake for now;
-	 * there is no functional effect whatsoever.
-	 *
-	 * Note that the reply will _not_ arrive immediately: this message
-	 * will wait in the mailbox fifo until the remote processor is booted.
-	 */
-	ret = mbox_send_message(kproc->mbox, (void *)RP_MBOX_ECHO_REQUEST);
-	if (ret < 0) {
-		dev_err(dev, "mbox_send_message failed: %d\n", ret);
-		goto put_mbox;
-	}
 
 	boot_addr = rproc->bootaddr;
 	if (boot_addr & (kproc->data->boot_align_addr - 1)) {