firmware/sysfb: Set firmware-framebuffer parent device

Set the firmware framebuffer's parent device, which usually is the
graphics hardware's physical device. Integrates the framebuffer in
the Linux device hierarchy and lets Linux handle dependencies among
devices. For example, the graphics hardware won't be suspended while
the firmware device is still active.

v4:
	* fix build for CONFIG_SYSFB_SIMPLEFB=n, again
v3:
	* fix build for CONFIG_SYSFB_SIMPLEFB=n (Sui)
	* test result of screen_info_pci_dev() for errors (Sui)
v2:
	* detect parent device in sysfb_parent_dev()
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240212090736.11464-4-tzimmermann@suse.de

drivers/firmware/sysfb.c

@@ -29,6 +29,7 @@
 #include <linux/init.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
+#include <linux/pci.h>
 #include <linux/platform_data/simplefb.h>
 #include <linux/platform_device.h>
 #include <linux/screen_info.h>
@@ -69,9 +70,23 @@ void sysfb_disable(void)
 }
 EXPORT_SYMBOL_GPL(sysfb_disable);
 
+static __init struct device *sysfb_parent_dev(const struct screen_info *si)
+{
+	struct pci_dev *pdev;
+
+	pdev = screen_info_pci_dev(si);
+	if (IS_ERR(pdev))
+		return ERR_CAST(pdev);
+	else if (pdev)
+		return &pdev->dev;
+
+	return NULL;
+}
+
 static __init int sysfb_init(void)
 {
 	struct screen_info *si = &screen_info;
+	struct device *parent;
 	struct simplefb_platform_data mode;
 	const char *name;
 	bool compatible;
@@ -83,10 +98,12 @@ static __init int sysfb_init(void)
 
 	sysfb_apply_efi_quirks();
 
+	parent = sysfb_parent_dev(si);
+
 	/* try to create a simple-framebuffer device */
 	compatible = sysfb_parse_mode(si, &mode);
 	if (compatible) {
-		pd = sysfb_create_simplefb(si, &mode);
+		pd = sysfb_create_simplefb(si, &mode, parent);
 		if (!IS_ERR(pd))
 			goto unlock_mutex;
 	}
@@ -109,6 +126,8 @@ static __init int sysfb_init(void)
 		goto unlock_mutex;
 	}
 
+	pd->dev.parent = parent;
+
 	sysfb_set_efifb_fwnode(pd);
 
 	ret = platform_device_add_data(pd, si, sizeof(*si));

drivers/firmware/sysfb_simplefb.c

@@ -91,7 +91,8 @@ __init bool sysfb_parse_mode(const struct screen_info *si,
 }
 
 __init struct platform_device *sysfb_create_simplefb(const struct screen_info *si,
-						     const struct simplefb_platform_data *mode)
+						     const struct simplefb_platform_data *mode,
+						     struct device *parent)
 {
 	struct platform_device *pd;
 	struct resource res;
@@ -143,6 +144,8 @@ __init struct platform_device *sysfb_create_simplefb(const struct screen_info *s
 	if (!pd)
 		return ERR_PTR(-ENOMEM);
 
+	pd->dev.parent = parent;
+
 	sysfb_set_efifb_fwnode(pd);
 
 	ret = platform_device_add_resources(pd, &res, 1);

include/linux/sysfb.h

@@ -91,7 +91,8 @@ static inline void sysfb_set_efifb_fwnode(struct platform_device *pd)
 bool sysfb_parse_mode(const struct screen_info *si,
 		      struct simplefb_platform_data *mode);
 struct platform_device *sysfb_create_simplefb(const struct screen_info *si,
-					      const struct simplefb_platform_data *mode);
+					      const struct simplefb_platform_data *mode,
+					      struct device *parent);
 
 #else /* CONFIG_SYSFB_SIMPLE */
 
@@ -102,7 +103,8 @@ static inline bool sysfb_parse_mode(const struct screen_info *si,
 }
 
 static inline struct platform_device *sysfb_create_simplefb(const struct screen_info *si,
-							    const struct simplefb_platform_data *mode)
+							    const struct simplefb_platform_data *mode,
+							    struct device *parent)
 {
 	return ERR_PTR(-EINVAL);
 }