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

Thomas Zimmermann
2021-04-16T09:00:59Z

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@suse.de>
Tested-by: nerdopolis <bluescreen_avenger@verizon.net>
---
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