video: Provide screen_info_get_pci_dev() to find screen_info's PCI device

Add screen_info_get_pci_dev() to find the PCI device of an instance
of screen_info. Does nothing on systems without PCI bus.

v3:
	* search PCI device with pci_get_base_class() (Sui)
v2:
	* remove ret from screen_info_pci_dev() (Javier)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Javier Martinez Canillas <javierm@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240212090736.11464-3-tzimmermann@suse.de

diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index 117cbdbb58c2cbc65c187b2aab471cc221fe4eaf..ffbac4387c670b7403690dd21dcc9cf633debb42 100644 (file)
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -8,6 +8,7 @@ obj-$(CONFIG_VIDEO)               += cmdline.o nomodeset.o
 obj-$(CONFIG_HDMI)                += hdmi.o
 
 screen_info-y                    := screen_info_generic.o
+screen_info-$(CONFIG_PCI)         += screen_info_pci.o
 
 obj-$(CONFIG_VT)                 += console/
 obj-$(CONFIG_FB_STI)             += console/

diff --git a/drivers/video/screen_info_pci.c b/drivers/video/screen_info_pci.c
new file mode 100644 (file)
index 0000000..d8985a5
--- /dev/null
+++ b/drivers/video/screen_info_pci.c
@@ -0,0 +1,48 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/pci.h>
+#include <linux/screen_info.h>
+
+static struct pci_dev *__screen_info_pci_dev(struct resource *res)
+{
+       struct pci_dev *pdev = NULL;
+       const struct resource *r = NULL;
+
+       if (!(res->flags & IORESOURCE_MEM))
+               return NULL;
+
+       while (!r && (pdev = pci_get_base_class(PCI_BASE_CLASS_DISPLAY, pdev))) {
+               r = pci_find_resource(pdev, res);
+       }
+
+       return pdev;
+}
+
+/**
+ * screen_info_pci_dev() - Return PCI parent device that contains screen_info's framebuffer
+ * @si: the screen_info
+ *
+ * Returns:
+ * The screen_info's parent device or NULL on success, or a pointer-encoded
+ * errno value otherwise. The value NULL is not an error. It signals that no
+ * PCI device has been found.
+ */
+struct pci_dev *screen_info_pci_dev(const struct screen_info *si)
+{
+       struct resource res[SCREEN_INFO_MAX_RESOURCES];
+       ssize_t i, numres;
+
+       numres = screen_info_resources(si, res, ARRAY_SIZE(res));
+       if (numres < 0)
+               return ERR_PTR(numres);
+
+       for (i = 0; i < numres; ++i) {
+               struct pci_dev *pdev = __screen_info_pci_dev(&res[i]);
+
+               if (pdev)
+                       return pdev;
+       }
+
+       return NULL;
+}
+EXPORT_SYMBOL(screen_info_pci_dev);

diff --git a/include/linux/screen_info.h b/include/linux/screen_info.h
index e7a02c5609d1259411c0b1545665e001f7d16053..0eae08e3c6f903d04ab7143f6d432e313011e91a 100644 (file)
--- a/include/linux/screen_info.h
+++ b/include/linux/screen_info.h
@@ -9,6 +9,7 @@
  */
 #define SCREEN_INFO_MAX_RESOURCES      3
 
+struct pci_dev;
 struct resource;
 
 static inline bool __screen_info_has_lfb(unsigned int type)
@@ -104,6 +105,15 @@ static inline unsigned int screen_info_video_type(const struct screen_info *si)
 
 ssize_t screen_info_resources(const struct screen_info *si, struct resource *r, size_t num);
 
+#if defined(CONFIG_PCI)
+struct pci_dev *screen_info_pci_dev(const struct screen_info *si);
+#else
+static inline struct pci_dev *screen_info_pci_dev(const struct screen_info *si)
+{
+       return NULL;
+}
+#endif
+
 extern struct screen_info screen_info;
 
 #endif /* _SCREEN_INFO_H */