remoteproc: imx_dsp_rproc: Add support for DSP-specific features

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@nxp.com>
Link: https://lore.kernel.org/r/20250416075613.2116792-1-iuliana.prodan@oss.nxp.com
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>

drivers/remoteproc/imx_dsp_rproc.c

@@ -36,9 +36,18 @@ 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 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 NOT to wait for a FW_READY response.
+ */
+#define FEATURE_DONT_WAIT_FW_READY		BIT(0)
+
 /* att flags */
 /* DSP own area */
 #define ATT_OWN					BIT(31)
@@ -73,6 +82,10 @@ MODULE_PARM_DESC(no_mailboxes,
 
 #define IMX8ULP_SIP_HIFI_XRDC			0xc200000e
 
+#define FW_RSC_NXP_S_MAGIC			((uint32_t)'n' << 24 |	\
+						 (uint32_t)'x' << 16 |	\
+						 (uint32_t)'p' << 8 |	\
+						 (uint32_t)'s')
 /*
  * enum - Predefined Mailbox Messages
  *
@@ -139,6 +152,24 @@ 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
+ * @magic_num: 32-bit magic number
+ * @version: version of data structure
+ * @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 magic_num;
+	uint32_t version;
+	uint32_t features;
+} __packed;
+
 static const struct imx_rproc_att imx_dsp_rproc_att_imx8qm[] = {
 	/* dev addr , sys addr  , size	    , flags */
 	{ 0x596e8000, 0x556e8000, 0x00008000, ATT_OWN },
@@ -297,6 +328,66 @@ 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;
+	struct device *dev = rproc->dev.parent;
+
+	if (!imx_dsp_rsc) {
+		dev_dbg(dev, "Invalid fw_rsc_imx_dsp.\n");
+		return RSC_IGNORED;
+	}
+
+	/* Make sure resource isn't truncated */
+	if (sizeof(struct fw_rsc_imx_dsp) > avail ||
+	    sizeof(struct fw_rsc_imx_dsp) != imx_dsp_rsc->len) {
+		dev_dbg(dev, "Resource fw_rsc_imx_dsp is truncated.\n");
+		return RSC_IGNORED;
+	}
+
+	/*
+	 * If FW_RSC_NXP_S_MAGIC number is not found then
+	 * wait for fw_ready reply (default work flow)
+	 */
+	if (imx_dsp_rsc->magic_num != FW_RSC_NXP_S_MAGIC) {
+		dev_dbg(dev, "Invalid resource table magic number.\n");
+		return RSC_IGNORED;
+	}
+
+	/*
+	 * For now, in struct fw_rsc_imx_dsp, version 0,
+	 * only FEATURE_DONT_WAIT_FW_READY is valid.
+	 *
+	 * When adding new features, please upgrade version.
+	 */
+	if (imx_dsp_rsc->version > 0) {
+		dev_warn(dev, "Unexpected fw_rsc_imx_dsp version %d.\n",
+			 imx_dsp_rsc->version);
+		return RSC_IGNORED;
+	}
+
+	if (imx_dsp_rsc->features & FEATURE_DONT_WAIT_FW_READY)
+		priv->flags &= ~WAIT_FW_READY;
+
+	return RSC_HANDLED;
+}
+
 /*
  * Start function for rproc_ops
  *
@@ -335,8 +426,8 @@ static int imx_dsp_rproc_start(struct rproc *rproc)
 
 	if (ret)
 		dev_err(dev, "Failed to enable remote core!\n");
-	else
+	else if (priv->flags & WAIT_FW_READY)
-		ret = imx_dsp_rproc_ready(rproc);
+		return imx_dsp_rproc_ready(rproc);
 
 	return ret;
 }
@@ -939,6 +1030,7 @@ 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,
@@ -1058,6 +1150,8 @@ static int imx_dsp_rproc_probe(struct platform_device *pdev)
 	priv = rproc->priv;
 	priv->rproc = rproc;
 	priv->dsp_dcfg = dsp_dcfg;
+	/* By default, host waits for fw_ready reply */
+	priv->flags |= WAIT_FW_READY;
 
 	if (no_mailboxes)
 		imx_dsp_rproc_mbox_init = imx_dsp_rproc_mbox_no_alloc;