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Date:   Wed, 19 Oct 2022 21:46:18 +0100
From:   Cristian Marussi <cristian.marussi@....com>
To:     linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org
Cc:     sudeep.holla@....com, james.quinlan@...adcom.com,
        Jonathan.Cameron@...wei.com, f.fainelli@...il.com,
        etienne.carriere@...aro.org, vincent.guittot@...aro.org,
        souvik.chakravarty@....com, wleavitt@...vell.com,
        peter.hilber@...nsynergy.com, nicola.mazzucato@....com,
        tarek.el-sherbiny@....com, quic_kshivnan@...cinc.com,
        cristian.marussi@....com
Subject: [PATCH v4 03/11] firmware: arm_scmi: Use dedicated devices to initialize channels

Refactor channels initialization to use dedicated devices instead of using
devices borrowed from the SCMI drivers.

Initialize all channels as described in the DT upfront.

Signed-off-by: Cristian Marussi <cristian.marussi@....com>
---
v3 --> v4
- fix missing devm_kfree on failpath in scmi_chan_setup
---
 drivers/firmware/arm_scmi/driver.c | 96 ++++++++++++++++++++++--------
 1 file changed, 72 insertions(+), 24 deletions(-)

diff --git a/drivers/firmware/arm_scmi/driver.c b/drivers/firmware/arm_scmi/driver.c
index 62e02b6475ff..032d1140d631 100644
--- a/drivers/firmware/arm_scmi/driver.c
+++ b/drivers/firmware/arm_scmi/driver.c
@@ -2019,23 +2019,20 @@ static int scmi_xfer_info_init(struct scmi_info *sinfo)
 	return ret;
 }
 
-static int scmi_chan_setup(struct scmi_info *info, struct device *dev,
+static int scmi_chan_setup(struct scmi_info *info, struct device_node *of_node,
 			   int prot_id, bool tx)
 {
 	int ret, idx;
+	char name[32];
 	struct scmi_chan_info *cinfo;
 	struct idr *idr;
+	struct scmi_device *tdev = NULL;
 
 	/* Transmit channel is first entry i.e. index 0 */
 	idx = tx ? 0 : 1;
 	idr = tx ? &info->tx_idr : &info->rx_idr;
 
-	/* check if already allocated, used for multiple device per protocol */
-	cinfo = idr_find(idr, prot_id);
-	if (cinfo)
-		return 0;
-
-	if (!info->desc->ops->chan_available(dev->of_node, idx)) {
+	if (!info->desc->ops->chan_available(of_node, idx)) {
 		cinfo = idr_find(idr, SCMI_PROTOCOL_BASE);
 		if (unlikely(!cinfo)) /* Possible only if platform has no Rx */
 			return -EINVAL;
@@ -2046,26 +2043,43 @@ static int scmi_chan_setup(struct scmi_info *info, struct device *dev,
 	if (!cinfo)
 		return -ENOMEM;
 
-	cinfo->dev = dev;
+	/* Create a unique name for this transport device */
+	snprintf(name, 32, "__scmi_transport_device_%s_%02X",
+		 idx ? "rx" : "tx", prot_id);
+	/* Create a uniquely named, dedicated transport device for this chan */
+	tdev = scmi_device_create(of_node, info->dev, prot_id, name);
+	if (!tdev) {
+		devm_kfree(info->dev, cinfo);
+		return -EINVAL;
+	}
 
+	cinfo->dev = &tdev->dev;
 	ret = info->desc->ops->chan_setup(cinfo, info->dev, tx);
-	if (ret)
+	if (ret) {
+		scmi_device_destroy(tdev);
+		devm_kfree(info->dev, cinfo);
 		return ret;
+	}
 
 	if (tx && is_polling_required(cinfo, info)) {
 		if (is_transport_polling_capable(info))
-			dev_info(dev,
+			dev_info(&tdev->dev,
 				 "Enabled polling mode TX channel - prot_id:%d\n",
 				 prot_id);
 		else
-			dev_warn(dev,
+			dev_warn(&tdev->dev,
 				 "Polling mode NOT supported by transport.\n");
 	}
 
 idr_alloc:
 	ret = idr_alloc(idr, cinfo, prot_id, prot_id + 1, GFP_KERNEL);
 	if (ret != prot_id) {
-		dev_err(dev, "unable to allocate SCMI idr slot err %d\n", ret);
+		dev_err(info->dev,
+			"unable to allocate SCMI idr slot err %d\n", ret);
+		if (tdev) {
+			scmi_device_destroy(tdev);
+			devm_kfree(info->dev, cinfo);
+		}
 		return ret;
 	}
 
@@ -2074,16 +2088,57 @@ static int scmi_chan_setup(struct scmi_info *info, struct device *dev,
 }
 
 static inline int
-scmi_txrx_setup(struct scmi_info *info, struct device *dev, int prot_id)
+scmi_txrx_setup(struct scmi_info *info, struct device_node *of_node,
+		int prot_id)
 {
-	int ret = scmi_chan_setup(info, dev, prot_id, true);
+	int ret = scmi_chan_setup(info, of_node, prot_id, true);
 
 	if (!ret) /* Rx is optional, hence no error check */
-		scmi_chan_setup(info, dev, prot_id, false);
+		scmi_chan_setup(info, of_node, prot_id, false);
 
 	return ret;
 }
 
+/**
+ * scmi_channels_setup  - Helper to initialize all required channels
+ *
+ * @info: The SCMI instance descriptor.
+ *
+ * Initialize all the channels found described in the DT against the underlying
+ * configured transport using custom defined dedicated devices instead of
+ * borrowing devices from the SCMI drivers; this way channels are initialized
+ * upfront during core SCMI stack probing and are operational even if then no
+ * SCMI driver is loaded. (useful to operate in Raw mode)
+ *
+ * Return: 0 on Success
+ */
+static int scmi_channels_setup(struct scmi_info *info)
+{
+	int ret;
+	struct device_node *child, *top_np = info->dev->of_node;
+
+	ret = scmi_txrx_setup(info, top_np, SCMI_PROTOCOL_BASE);
+	if (ret)
+		return ret;
+
+	for_each_available_child_of_node(top_np, child) {
+		u32 prot_id;
+
+		if (of_property_read_u32(child, "reg", &prot_id))
+			continue;
+
+		if (!FIELD_FIT(MSG_PROTOCOL_ID_MASK, prot_id))
+			dev_err(info->dev,
+				"Out of range protocol %d\n", prot_id);
+
+		ret = scmi_txrx_setup(info, child, prot_id);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
 /**
  * scmi_get_protocol_device  - Helper to get/create an SCMI device.
  *
@@ -2133,14 +2188,6 @@ scmi_get_protocol_device(struct device_node *np, struct scmi_info *info,
 		return NULL;
 	}
 
-	if (scmi_txrx_setup(info, &sdev->dev, prot_id)) {
-		dev_err(&sdev->dev, "failed to setup transport\n");
-		scmi_device_destroy(sdev);
-		mutex_unlock(&scmi_syspower_mtx);
-
-		return NULL;
-	}
-
 	if (prot_id == SCMI_PROTOCOL_SYSTEM)
 		scmi_syspower_registered = true;
 
@@ -2432,7 +2479,8 @@ static int scmi_probe(struct platform_device *pdev)
 			return ret;
 	}
 
-	ret = scmi_txrx_setup(info, dev, SCMI_PROTOCOL_BASE);
+	/* Setup all channels described in the DT at first */
+	ret = scmi_channels_setup(info);
 	if (ret)
 		return ret;
 
-- 
2.34.1

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