[RFC v2 1/5] drm/dsi: Refactor device creation

[Archit Taneja <architt@codeaurora.org>]

Simplify the mipi dsi device creation process. device_initialize and
device_add don't need to be called separately when creating
mipi_dsi_device's. Use device_register instead to simplify things.

Create a helper function mipi_dsi_device_new which takes in struct
mipi_dsi_device_info and mipi_dsi_host. It clubs the functions
mipi_dsi_device_alloc and mipi_dsi_device_add into one.

mipi_dsi_device_info acts as a template to populate the dsi device
information. This is populated by of_mipi_dsi_device_add and passed to
mipi_dsi_device_new.

Later on, we'll provide mipi_dsi_device_new as a standalone way to create
a dsi device not available via DT.

The new device creation process tries to closely follow what's been done
in i2c_new_device in i2c-core.

Signed-off-by: Archit Taneja <architt@codeaurora.org>
---
 drivers/gpu/drm/drm_mipi_dsi.c | 61 +++++++++++++++++-------------------------
 include/drm/drm_mipi_dsi.h     | 15 +++++++++++
 2 files changed, 40 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/drm_mipi_dsi.c b/drivers/gpu/drm/drm_mipi_dsi.c
index 2d5ca8ee..245ecfe 100644
--- a/drivers/gpu/drm/drm_mipi_dsi.c
+++ b/drivers/gpu/drm/drm_mipi_dsi.c
@@ -102,9 +102,18 @@ static const struct device_type mipi_dsi_device_type = {
 	.release = mipi_dsi_dev_release,
 };
 
-static struct mipi_dsi_device *mipi_dsi_device_alloc(struct mipi_dsi_host *host)
+struct mipi_dsi_device *mipi_dsi_device_new(struct mipi_dsi_host *host,
+					    struct mipi_dsi_device_info *info)
 {
 	struct mipi_dsi_device *dsi;
+	struct device *dev = host->dev;
+	int r;
+
+	if (info->reg > 3) {
+		dev_err(dev, "device node has invalid reg property: %u\n",
+			info->reg);
+		return ERR_PTR(-EINVAL);
+	}
 
 	dsi = kzalloc(sizeof(*dsi), GFP_KERNEL);
 	if (!dsi)
@@ -114,26 +123,27 @@ static struct mipi_dsi_device *mipi_dsi_device_alloc(struct mipi_dsi_host *host)
 	dsi->dev.bus = &mipi_dsi_bus_type;
 	dsi->dev.parent = host->dev;
 	dsi->dev.type = &mipi_dsi_device_type;
+	dsi->dev.of_node = info->node;
+	dsi->channel = info->reg;
 
-	device_initialize(&dsi->dev);
-
-	return dsi;
-}
-
-static int mipi_dsi_device_add(struct mipi_dsi_device *dsi)
-{
-	struct mipi_dsi_host *host = dsi->host;
+	dev_set_name(&dsi->dev, "%s.%d", dev_name(host->dev), info->reg);
 
-	dev_set_name(&dsi->dev, "%s.%d", dev_name(host->dev),  dsi->channel);
+	r = device_register(&dsi->dev);
+	if (r) {
+		dev_err(dev, "failed to register device: %d\n", r);
+		kfree(dsi);
+		return ERR_PTR(r);
+	}
 
-	return device_add(&dsi->dev);
+	return dsi;
 }
+EXPORT_SYMBOL(mipi_dsi_device_new);
 
 static struct mipi_dsi_device *
 of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node)
 {
-	struct mipi_dsi_device *dsi;
 	struct device *dev = host->dev;
+	struct mipi_dsi_device_info info = { };
 	int ret;
 	u32 reg;
 
@@ -144,31 +154,10 @@ of_mipi_dsi_device_add(struct mipi_dsi_host *host, struct device_node *node)
 		return ERR_PTR(-EINVAL);
 	}
 
-	if (reg > 3) {
-		dev_err(dev, "device node %s has invalid reg property: %u\n",
-			node->full_name, reg);
-		return ERR_PTR(-EINVAL);
-	}
-
-	dsi = mipi_dsi_device_alloc(host);
-	if (IS_ERR(dsi)) {
-		dev_err(dev, "failed to allocate DSI device %s: %ld\n",
-			node->full_name, PTR_ERR(dsi));
-		return dsi;
-	}
-
-	dsi->dev.of_node = of_node_get(node);
-	dsi->channel = reg;
+	info.reg = reg;
+	info.node = of_node_get(node);
 
-	ret = mipi_dsi_device_add(dsi);
-	if (ret) {
-		dev_err(dev, "failed to add DSI device %s: %d\n",
-			node->full_name, ret);
-		kfree(dsi);
-		return ERR_PTR(ret);
-	}
-
-	return dsi;
+	return mipi_dsi_device_new(host, &info);
 }
 
 int mipi_dsi_host_register(struct mipi_dsi_host *host)
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index f1d8d0d..90f4f3c 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -140,6 +140,19 @@ enum mipi_dsi_pixel_format {
 };
 
 /**
+ * struct mipi_dsi_device_info - template for creating a mipi_dsi_device
+ * @reg: DSI virtual channel assigned to peripheral
+ * @node: pointer to OF device node
+ *
+ * This is populated and passed to mipi_dsi_device_new to create a new
+ * DSI device
+ */
+struct mipi_dsi_device_info {
+	u32 reg;
+	struct device_node *node;
+};
+
+/**
  * struct mipi_dsi_device - DSI peripheral device
  * @host: DSI host for this peripheral
  * @dev: driver model device node for this peripheral
@@ -174,6 +187,8 @@ ssize_t mipi_dsi_generic_write(struct mipi_dsi_device *dsi, const void *payload,
 ssize_t mipi_dsi_generic_read(struct mipi_dsi_device *dsi, const void *params,
 			      size_t num_params, void *data, size_t size);
 
+struct mipi_dsi_device *mipi_dsi_device_new(struct mipi_dsi_host *host,
+					    struct mipi_dsi_device_info *info);
 /**
  * enum mipi_dsi_dcs_tear_mode - Tearing Effect Output Line mode
  * @MIPI_DSI_DCS_TEAR_MODE_VBLANK: the TE output line consists of V-Blanking
-- 
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