[PATCH v2 1/4] dmaengine: ti: k3-udma-glue: Add function to parse channel by ID

[Siddharth Vadapalli <s-vadapalli@ti.com>]

The existing helper function of_k3_udma_glue_parse() fetches the DMA
Channel thread ID from the device-tree node. This makes it necessary to
have a device-tree node with the Channel thread IDs populated. However,
in the case where the thread ID is known by alternate methods (an
example being that of Firmware running on remote core sharing details of
the thread IDs), there is no equivalent function to implement the
functionality of the existing of_k3_udma_glue_parse() function. In such
cases, the driver utilizing the DMA APIs might not even have a
device-tree node to begin with, since it could be probed with other
methods (RPMsg-Bus for example).

Add the of_k3_udma_glue_parse_chn_by_id() helper function which accepts
the thread ID as an argument, thereby making it unnecessary to have a
device-tree node for obtaining the thread ID.

Since of_k3_udma_glue_parse() and of_k3_udma_glue_parse_chn_by_id()
share a lot of code in common, create a new function to handle the
common code which is named as of_k3_udma_glue_parse_chn_common().

Signed-off-by: Siddharth Vadapalli <s-vadapalli@ti.com>
---
Changes since v1:
- Updated commit message indicating that this patch is helpful for cases
  where the driver utilizing the DMA APIs might not be probed by a
  device-tree node.
- Removed unnecessary return value check within
  "of_k3_udma_glue_parse_chn()" function since it will fall through to
  "out_put_spec" anyway.
- Removed unnecessary return value check within
  "of_k3_udma_glue_parse_chn_by_id()" function since it will fall through
  to "out_put_spec" anyway.

 drivers/dma/ti/k3-udma-glue.c | 79 ++++++++++++++++++++++-------------
 1 file changed, 51 insertions(+), 28 deletions(-)

diff --git a/drivers/dma/ti/k3-udma-glue.c b/drivers/dma/ti/k3-udma-glue.c
index c278d5facf7d..d8781625034b 100644
--- a/drivers/dma/ti/k3-udma-glue.c
+++ b/drivers/dma/ti/k3-udma-glue.c
@@ -111,6 +111,35 @@ static int of_k3_udma_glue_parse(struct device_node *udmax_np,
 	return 0;
 }
 
+static int of_k3_udma_glue_parse_chn_common(struct k3_udma_glue_common *common, u32 thread_id,
+					    bool tx_chn)
+{
+	if (tx_chn && !(thread_id & K3_PSIL_DST_THREAD_ID_OFFSET))
+		return -EINVAL;
+
+	if (!tx_chn && (thread_id & K3_PSIL_DST_THREAD_ID_OFFSET))
+		return -EINVAL;
+
+	/* get psil endpoint config */
+	common->ep_config = psil_get_ep_config(thread_id);
+	if (IS_ERR(common->ep_config)) {
+		dev_err(common->dev,
+			"No configuration for psi-l thread 0x%04x\n",
+			thread_id);
+		return PTR_ERR(common->ep_config);
+	}
+
+	common->epib = common->ep_config->needs_epib;
+	common->psdata_size = common->ep_config->psd_size;
+
+	if (tx_chn)
+		common->dst_thread = thread_id;
+	else
+		common->src_thread = thread_id;
+
+	return 0;
+}
+
 static int of_k3_udma_glue_parse_chn(struct device_node *chn_np,
 		const char *name, struct k3_udma_glue_common *common,
 		bool tx_chn)
@@ -153,38 +182,32 @@ static int of_k3_udma_glue_parse_chn(struct device_node *chn_np,
 		common->atype_asel = dma_spec.args[1];
 	}
 
-	if (tx_chn && !(thread_id & K3_PSIL_DST_THREAD_ID_OFFSET)) {
-		ret = -EINVAL;
-		goto out_put_spec;
-	}
-
-	if (!tx_chn && (thread_id & K3_PSIL_DST_THREAD_ID_OFFSET)) {
-		ret = -EINVAL;
-		goto out_put_spec;
-	}
-
-	/* get psil endpoint config */
-	common->ep_config = psil_get_ep_config(thread_id);
-	if (IS_ERR(common->ep_config)) {
-		dev_err(common->dev,
-			"No configuration for psi-l thread 0x%04x\n",
-			thread_id);
-		ret = PTR_ERR(common->ep_config);
-		goto out_put_spec;
-	}
-
-	common->epib = common->ep_config->needs_epib;
-	common->psdata_size = common->ep_config->psd_size;
-
-	if (tx_chn)
-		common->dst_thread = thread_id;
-	else
-		common->src_thread = thread_id;
+	ret = of_k3_udma_glue_parse_chn_common(common, thread_id, tx_chn);
 
 out_put_spec:
 	of_node_put(dma_spec.np);
 	return ret;
-};
+}
+
+static int
+of_k3_udma_glue_parse_chn_by_id(struct device_node *udmax_np, struct k3_udma_glue_common *common,
+				bool tx_chn, u32 thread_id)
+{
+	int ret = 0;
+
+	if (unlikely(!udmax_np))
+		return -EINVAL;
+
+	ret = of_k3_udma_glue_parse(udmax_np, common);
+	if (ret)
+		goto out_put_spec;
+
+	ret = of_k3_udma_glue_parse_chn_common(common, thread_id, tx_chn);
+
+out_put_spec:
+	of_node_put(udmax_np);
+	return ret;
+}
 
 static void k3_udma_glue_dump_tx_chn(struct k3_udma_glue_tx_channel *tx_chn)
 {
-- 
2.34.1