[PATCH v3 2/9] video/aperture: Add a helper for determining if an unmoved aperture contain FB

[Sui Jingfeng <sui.jingfeng@linux.dev>]

From: Sui Jingfeng <suijingfeng@loongson.cn>

This patch is intended to form a uniform approach to determining if an
unmoved aperture contains the firmware FB. I believe that the global
screen_info is more about video-specific things.

Putting it in video/aperture.c helps form a uniform approach.

Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Javier Martinez Canillas <javierm@redhat.com>
Cc: Helge Deller <deller@gmx.de>
Signed-off-by: Sui Jingfeng <suijingfeng@loongson.cn>
---
 drivers/video/aperture.c | 36 ++++++++++++++++++++++++++++++++++++
 include/linux/aperture.h |  7 +++++++
 2 files changed, 43 insertions(+)

diff --git a/drivers/video/aperture.c b/drivers/video/aperture.c
index 34eb962cfae8..f03dfcabc303 100644
--- a/drivers/video/aperture.c
+++ b/drivers/video/aperture.c
@@ -6,6 +6,7 @@
 #include <linux/mutex.h>
 #include <linux/pci.h>
 #include <linux/platform_device.h>
+#include <linux/screen_info.h>
 #include <linux/slab.h>
 #include <linux/sysfb.h>
 #include <linux/types.h>
@@ -406,3 +407,38 @@ bool aperture_contain_firmware_fb(resource_size_t ap_start, resource_size_t ap_e
 	return false;
 }
 EXPORT_SYMBOL(aperture_contain_firmware_fb);
+
+/**
+ * aperture_contain_firmware_fb_nonreloc - Detect if the firmware framebuffer
+ * belong to a non-relocatable aperture, such as the aperture of platform
+ * device. Note that this function relay on the global screen info.
+ * @ap_start: the aperture's start address in physical memory
+ * @ap_end: the aperture's end address in physical memory
+ *
+ * Returns:
+ * true if there is a firmware framebuffer belong to the aperture passed in,
+ * or false otherwise.
+ */
+bool aperture_contain_firmware_fb_nonreloc(resource_size_t ap_start, resource_size_t ap_end)
+{
+	u64 fb_start;
+	u64 fb_end;
+
+	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE) {
+		fb_start = (u64)screen_info.ext_lfb_base << 32 | screen_info.lfb_base;
+		fb_end = fb_start + screen_info.lfb_size;
+	} else {
+		fb_start = screen_info.lfb_base;
+		fb_end = fb_start + screen_info.lfb_size;
+	}
+
+	/* No firmware framebuffer support */
+	if (!fb_start || !fb_end)
+		return false;
+
+	if (fb_start >= ap_start && fb_end <= ap_end)
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL(aperture_contain_firmware_fb_nonreloc);
diff --git a/include/linux/aperture.h b/include/linux/aperture.h
index d4dc5917c49b..906d23532b56 100644
--- a/include/linux/aperture.h
+++ b/include/linux/aperture.h
@@ -21,6 +21,8 @@ int __aperture_remove_legacy_vga_devices(struct pci_dev *pdev);
 int aperture_remove_conflicting_pci_devices(struct pci_dev *pdev, const char *name);
 
 bool aperture_contain_firmware_fb(resource_size_t ap_start, resource_size_t ap_end);
+
+bool aperture_contain_firmware_fb_nonreloc(resource_size_t ap_start, resource_size_t ap_end);
 #else
 static inline int devm_aperture_acquire_for_platform_device(struct platform_device *pdev,
 							    resource_size_t base,
@@ -49,6 +51,11 @@ static inline bool aperture_contain_firmware_fb(resource_size_t ap_start, resour
 {
 	return false;
 }
+
+static bool aperture_contain_firmware_fb_nonreloc(resource_size_t ap_start, resource_size_t ap_end)
+{
+	return false;
+}
 #endif
 
 /**
-- 
2.25.1