[PATCH v4 6/9] drm/simpledrm: Initialize framebuffer data from device-tree node

[Thomas Zimmermann <tzimmermann@xxxxxxx>]

A firmware framebuffer might also be specified via device-tree files. If
no device platform data is given, try the DT device node.

v2:
	* add Device Tree match table
	* clean-up parser wrappers

Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
Tested-by: nerdopolis <bluescreen_avenger@xxxxxxxxxxx>
---
 drivers/gpu/drm/tiny/simpledrm.c | 89 ++++++++++++++++++++++++++++++++
 1 file changed, 89 insertions(+)

diff --git a/drivers/gpu/drm/tiny/simpledrm.c b/drivers/gpu/drm/tiny/simpledrm.c
index 64e8a8581d9a..53d6bec7d0b2 100644
--- a/drivers/gpu/drm/tiny/simpledrm.c
+++ b/drivers/gpu/drm/tiny/simpledrm.c
@@ -114,6 +114,74 @@ simplefb_get_format_pd(struct drm_device *dev,
 	return simplefb_get_validated_format(dev, pd->format);
 }
 
+static int
+simplefb_read_u32_of(struct drm_device *dev, struct device_node *of_node,
+		     const char *name, u32 *value)
+{
+	int ret = of_property_read_u32(of_node, name, value);
+
+	if (ret)
+		drm_err(dev, "simplefb: cannot parse framebuffer %s: error %d\n",
+			name, ret);
+	return ret;
+}
+
+static int
+simplefb_read_string_of(struct drm_device *dev, struct device_node *of_node,
+			const char *name, const char **value)
+{
+	int ret = of_property_read_string(of_node, name, value);
+
+	if (ret)
+		drm_err(dev, "simplefb: cannot parse framebuffer %s: error %d\n",
+			name, ret);
+	return ret;
+}
+
+static int
+simplefb_get_width_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 width;
+	int ret = simplefb_read_u32_of(dev, of_node, "width", &width);
+
+	if (ret)
+		return ret;
+	return simplefb_get_validated_int0(dev, "width", width);
+}
+
+static int
+simplefb_get_height_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 height;
+	int ret = simplefb_read_u32_of(dev, of_node, "height", &height);
+
+	if (ret)
+		return ret;
+	return simplefb_get_validated_int0(dev, "height", height);
+}
+
+static int
+simplefb_get_stride_of(struct drm_device *dev, struct device_node *of_node)
+{
+	u32 stride;
+	int ret = simplefb_read_u32_of(dev, of_node, "stride", &stride);
+
+	if (ret)
+		return ret;
+	return simplefb_get_validated_int(dev, "stride", stride);
+}
+
+static const struct drm_format_info *
+simplefb_get_format_of(struct drm_device *dev, struct device_node *of_node)
+{
+	const char *format;
+	int ret = simplefb_read_string_of(dev, of_node, "format", &format);
+
+	if (ret)
+		return ERR_PTR(ret);
+	return simplefb_get_validated_format(dev, format);
+}
+
 /*
  * Simple Framebuffer device
  */
@@ -166,6 +234,7 @@ static int simpledrm_device_init_fb(struct simpledrm_device *sdev)
 	struct drm_device *dev = &sdev->dev;
 	struct platform_device *pdev = sdev->pdev;
 	const struct simplefb_platform_data *pd = dev_get_platdata(&pdev->dev);
+	struct device_node *of_node = pdev->dev.of_node;
 
 	if (pd) {
 		width = simplefb_get_width_pd(dev, pd);
@@ -180,6 +249,19 @@ static int simpledrm_device_init_fb(struct simpledrm_device *sdev)
 		format = simplefb_get_format_pd(dev, pd);
 		if (IS_ERR(format))
 			return PTR_ERR(format);
+	} else if (of_node) {
+		width = simplefb_get_width_of(dev, of_node);
+		if (width < 0)
+			return width;
+		height = simplefb_get_height_of(dev, of_node);
+		if (height < 0)
+			return height;
+		stride = simplefb_get_stride_of(dev, of_node);
+		if (stride < 0)
+			return stride;
+		format = simplefb_get_format_of(dev, of_node);
+		if (IS_ERR(format))
+			return PTR_ERR(format);
 	} else {
 		drm_err(dev, "no simplefb configuration found\n");
 		return -ENODEV;
@@ -534,9 +616,16 @@ static int simpledrm_remove(struct platform_device *pdev)
 	return 0;
 }
 
+static const struct of_device_id simpledrm_of_match_table[] = {
+	{ .compatible = "simple-framebuffer", },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, simpledrm_of_match_table);
+
 static struct platform_driver simpledrm_platform_driver = {
 	.driver = {
 		.name = "simple-framebuffer", /* connect to sysfb */
+		.of_match_table = simpledrm_of_match_table,
 	},
 	.probe = simpledrm_probe,
 	.remove = simpledrm_remove,
-- 
2.31.1

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