[PATCH v2] remoteproc: imx_dsp_rproc: Add support for DSP-specific features

[Iuliana Prodan (OSS)]

From: Iuliana Prodan <iuliana.prodan@xxxxxxx>

Some DSP firmware requires a FW_READY signal before proceeding, while
others do not.
Therefore, add support to handle i.MX DSP-specific features.

Implement handle_rsc callback to handle resource table parsing and to
process DSP-specific resource, to determine if waiting is needed.

Update imx_dsp_rproc_start() to handle this condition accordingly.

Signed-off-by: Iuliana Prodan <iuliana.prodan@xxxxxxx>
---
Changes in v2:
- Reviews from Mathieu Poirier:
  - Use vendor-specific resource table entry.
  - Implement resource handler specific to the i.MX DSP.
- Revise commit message to include recent updates.
- Link to v1: https://lore.kernel.org/all/20250305123923.514386-1-iuliana.prodan@xxxxxxxxxxx/

 drivers/remoteproc/imx_dsp_rproc.c | 59 +++++++++++++++++++++++++++++-
 1 file changed, 57 insertions(+), 2 deletions(-)

diff --git a/drivers/remoteproc/imx_dsp_rproc.c b/drivers/remoteproc/imx_dsp_rproc.c
index b9bb15970966..1729bfbc602e 100644
--- a/drivers/remoteproc/imx_dsp_rproc.c
+++ b/drivers/remoteproc/imx_dsp_rproc.c
@@ -35,9 +35,17 @@ module_param_named(no_mailboxes, no_mailboxes, int, 0644);
 MODULE_PARM_DESC(no_mailboxes,
 		 "There is no mailbox between cores, so ignore remote proc reply after start, default is 0 (off).");
 
+/* Flag indicating that the remote is up and running */
 #define REMOTE_IS_READY				BIT(0)
+/* Flag indicating that the host should wait for a firmware-ready response */
+#define HOST_WAIT_FW_READY			BIT(1)
 #define REMOTE_READY_WAIT_MAX_RETRIES		500
 
+/* This flag is set in the DSP resource table's features field to indicate
+ * that the firmware requires the host to wait for a FW_READY response.
+ */
+#define WAIT_FW_READY				BIT(0)
+
 /* att flags */
 /* DSP own area */
 #define ATT_OWN					BIT(31)
@@ -136,6 +144,19 @@ struct imx_dsp_rproc_dcfg {
 	int (*reset)(struct imx_dsp_rproc *priv);
 };
 
+/**
+ * struct fw_rsc_imx_dsp - i.MX DSP specific info
+ * @len: length of the resource entry
+ * @features: feature flags supported by the i.MX DSP firmware
+ *
+ * This represents a DSP-specific resource in the firmware's
+ * resource table, providing information on supported features.
+ */
+struct fw_rsc_imx_dsp {
+	uint32_t len;
+	uint32_t features;
+};
+
 static const struct imx_rproc_att imx_dsp_rproc_att_imx8qm[] = {
 	/* dev addr , sys addr  , size	    , flags */
 	{ 0x596e8000, 0x556e8000, 0x00008000, ATT_OWN },
@@ -300,6 +321,39 @@ static int imx_dsp_rproc_ready(struct rproc *rproc)
 	return -ETIMEDOUT;
 }
 
+/**
+ * imx_dsp_rproc_handle_rsc() - Handle DSP-specific resource table entries
+ * @rproc: remote processor instance
+ * @rsc_type: resource type identifier
+ * @rsc: pointer to the resource entry
+ * @offset: offset of the resource entry
+ * @avail: available space in the resource table
+ *
+ * Parse the DSP-specific resource entry and update flags accordingly.
+ * If the WAIT_FW_READY feature is set, the host must wait for the firmware
+ * to signal readiness before proceeding with execution.
+ *
+ * Return: RSC_HANDLED if processed successfully, RSC_IGNORED otherwise.
+ */
+static int imx_dsp_rproc_handle_rsc(struct rproc *rproc, u32 rsc_type,
+				    void *rsc, int offset, int avail)
+{
+	struct imx_dsp_rproc *priv = rproc->priv;
+	struct fw_rsc_imx_dsp *imx_dsp_rsc = rsc;
+
+	if (!imx_dsp_rsc || imx_dsp_rsc->len != sizeof(imx_dsp_rsc->features)) {
+		priv->flags |= HOST_WAIT_FW_READY;
+		return RSC_IGNORED;
+	}
+
+	if (imx_dsp_rsc->features & WAIT_FW_READY)
+		priv->flags |= HOST_WAIT_FW_READY;
+	else
+		priv->flags &= ~HOST_WAIT_FW_READY;
+
+	return RSC_HANDLED;
+}
+
 /*
  * Start function for rproc_ops
  *
@@ -335,8 +389,8 @@ static int imx_dsp_rproc_start(struct rproc *rproc)
 
 	if (ret)
 		dev_err(dev, "Failed to enable remote core!\n");
-	else
-		ret = imx_dsp_rproc_ready(rproc);
+	else if (priv->flags & HOST_WAIT_FW_READY)
+		return imx_dsp_rproc_ready(rproc);
 
 	return ret;
 }
@@ -936,6 +990,7 @@ static const struct rproc_ops imx_dsp_rproc_ops = {
 	.kick		= imx_dsp_rproc_kick,
 	.load		= imx_dsp_rproc_elf_load_segments,
 	.parse_fw	= imx_dsp_rproc_parse_fw,
+	.handle_rsc	= imx_dsp_rproc_handle_rsc,
 	.find_loaded_rsc_table = rproc_elf_find_loaded_rsc_table,
 	.sanity_check	= rproc_elf_sanity_check,
 	.get_boot_addr	= rproc_elf_get_boot_addr,
-- 
2.25.1