From 909a3f0e9d8b0d8001cf6e99808f88eca8e44328 Mon Sep 17 00:00:00 2001
From: Cheng Lingfei <chenglingfei@foxmail.com>
Date: Mon, 24 Aug 2026 20:45:46 +0800
Subject: docs: cgroup-v2: fix misc.events key format description
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In misc cgroup, misc.events does not output a simple "max" key. Instead,
each registered misc resource outputs a separate key suffixed with ".max"
(i.e., "<res>.max").
Update the documentation to clarify that the entry key is "<res>.max".

Suggested-by: Michal Koutný <mkoutny@suse.com>
Signed-off-by: Cheng Lingfei <chenglingfei@foxmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
---
 drivers/video/fbdev/efifb.c | 608 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 608 insertions(+)
 create mode 100644 drivers/video/fbdev/efifb.c

(limited to 'drivers/video/fbdev/efifb.c')

diff --git a/drivers/video/fbdev/efifb.c b/drivers/video/fbdev/efifb.c
new file mode 100644
index 000000000..ad8dec780
--- /dev/null
+++ b/drivers/video/fbdev/efifb.c
@@ -0,0 +1,608 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Framebuffer driver for EFI/UEFI based system
+ *
+ * (c) 2006 Edgar Hucek <gimli@dark-green.com>
+ * Original efi driver written by Gerd Knorr <kraxel@goldbach.in-berlin.de>
+ *
+ */
+
+#include <linux/aperture.h>
+#include <linux/kernel.h>
+#include <linux/efi.h>
+#include <linux/efi-bgrt.h>
+#include <linux/errno.h>
+#include <linux/fb.h>
+#include <linux/platform_device.h>
+#include <linux/printk.h>
+#include <linux/sysfb.h>
+#include <video/vga.h>
+#include <asm/efi.h>
+#include <drm/drm_utils.h> /* For drm_get_panel_orientation_quirk */
+#include <drm/drm_connector.h>  /* For DRM_MODE_PANEL_ORIENTATION_* */
+
+struct bmp_file_header {
+	u16 id;
+	u32 file_size;
+	u32 reserved;
+	u32 bitmap_offset;
+} __packed;
+
+struct bmp_dib_header {
+	u32 dib_header_size;
+	s32 width;
+	s32 height;
+	u16 planes;
+	u16 bpp;
+	u32 compression;
+	u32 bitmap_size;
+	u32 horz_resolution;
+	u32 vert_resolution;
+	u32 colors_used;
+	u32 colors_important;
+} __packed;
+
+static bool use_bgrt = true;
+static bool request_mem_succeeded = false;
+static u64 mem_flags = EFI_MEMORY_WC | EFI_MEMORY_UC;
+
+struct efifb_par {
+	u32 pseudo_palette[16];
+	resource_size_t base;
+	resource_size_t size;
+};
+
+static struct fb_var_screeninfo efifb_defined = {
+	.activate		= FB_ACTIVATE_NOW,
+	.height			= -1,
+	.width			= -1,
+	.right_margin		= 32,
+	.upper_margin		= 16,
+	.lower_margin		= 4,
+	.vsync_len		= 4,
+	.vmode			= FB_VMODE_NONINTERLACED,
+};
+
+static struct fb_fix_screeninfo efifb_fix = {
+	.id			= "EFI VGA",
+	.type			= FB_TYPE_PACKED_PIXELS,
+	.accel			= FB_ACCEL_NONE,
+	.visual			= FB_VISUAL_TRUECOLOR,
+};
+
+static int efifb_setcolreg(unsigned regno, unsigned red, unsigned green,
+			   unsigned blue, unsigned transp,
+			   struct fb_info *info)
+{
+	/*
+	 *  Set a single color register. The values supplied are
+	 *  already rounded down to the hardware's capabilities
+	 *  (according to the entries in the `var' structure). Return
+	 *  != 0 for invalid regno.
+	 */
+
+	if (regno >= info->cmap.len)
+		return 1;
+
+	if (regno < 16) {
+		red   >>= 16 - info->var.red.length;
+		green >>= 16 - info->var.green.length;
+		blue  >>= 16 - info->var.blue.length;
+		((u32 *)(info->pseudo_palette))[regno] =
+			(red   << info->var.red.offset)   |
+			(green << info->var.green.offset) |
+			(blue  << info->var.blue.offset);
+	}
+	return 0;
+}
+
+/*
+ * If fbcon deffered console takeover is configured, the intent is for the
+ * framebuffer to show the boot graphics (e.g. vendor logo) until there is some
+ * (error) message to display. But the boot graphics may have been destroyed by
+ * e.g. option ROM output, detect this and restore the boot graphics.
+ */
+#if defined CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER && \
+    defined CONFIG_ACPI_BGRT
+static void efifb_copy_bmp(u8 *src, u32 *dst, int width, const struct screen_info *si)
+{
+	u8 r, g, b;
+
+	while (width--) {
+		b = *src++;
+		g = *src++;
+		r = *src++;
+		*dst++ = (r << si->red_pos)   |
+			 (g << si->green_pos) |
+			 (b << si->blue_pos);
+	}
+}
+
+#ifdef CONFIG_X86
+/*
+ * On x86 some firmwares use a low non native resolution for the display when
+ * they have shown some text messages. While keeping the bgrt filled with info
+ * for the native resolution. If the bgrt image intended for the native
+ * resolution still fits, it will be displayed very close to the right edge of
+ * the display looking quite bad. This function checks for this.
+ */
+static bool efifb_bgrt_sanity_check(const struct screen_info *si, u32 bmp_width)
+{
+	/*
+	 * All x86 firmwares horizontally center the image (the yoffset
+	 * calculations differ between boards, but xoffset is predictable).
+	 */
+	u32 expected_xoffset = (si->lfb_width - bmp_width) / 2;
+
+	return bgrt_tab.image_offset_x == expected_xoffset;
+}
+#else
+static bool efifb_bgrt_sanity_check(const struct screen_info *si, u32 bmp_width)
+{
+	return true;
+}
+#endif
+
+static void efifb_show_boot_graphics(struct fb_info *info, const struct screen_info *si)
+{
+	u32 bmp_width, bmp_height, bmp_pitch, dst_x, y, src_y;
+	struct bmp_file_header *file_header;
+	struct bmp_dib_header *dib_header;
+	void *bgrt_image = NULL;
+	u8 *dst = info->screen_base;
+
+	if (!use_bgrt)
+		return;
+
+	if (!bgrt_tab.image_address) {
+		pr_info("efifb: No BGRT, not showing boot graphics\n");
+		return;
+	}
+
+	if (bgrt_tab.status & 0x06) {
+		pr_info("efifb: BGRT rotation bits set, not showing boot graphics\n");
+		return;
+	}
+
+	/* Avoid flashing the logo if we're going to print std probe messages */
+	if (console_loglevel > CONSOLE_LOGLEVEL_QUIET)
+		return;
+
+	/* bgrt_tab.status is unreliable, so we don't check it */
+
+	if (si->lfb_depth != 32) {
+		pr_info("efifb: not 32 bits, not showing boot graphics\n");
+		return;
+	}
+
+	bgrt_image = memremap(bgrt_tab.image_address, bgrt_image_size,
+			      MEMREMAP_WB);
+	if (!bgrt_image) {
+		pr_warn("efifb: Ignoring BGRT: failed to map image memory\n");
+		return;
+	}
+
+	if (bgrt_image_size < (sizeof(*file_header) + sizeof(*dib_header)))
+		goto error;
+
+	file_header = bgrt_image;
+	if (file_header->id != 0x4d42 || file_header->reserved != 0)
+		goto error;
+
+	dib_header = bgrt_image + sizeof(*file_header);
+	if (dib_header->dib_header_size != 40 || dib_header->width < 0 ||
+	    dib_header->planes != 1 || dib_header->bpp != 24 ||
+	    dib_header->compression != 0)
+		goto error;
+
+	bmp_width = dib_header->width;
+	bmp_height = abs(dib_header->height);
+	bmp_pitch = round_up(3 * bmp_width, 4);
+
+	if ((file_header->bitmap_offset + bmp_pitch * bmp_height) >
+				bgrt_image_size)
+		goto error;
+
+	if ((bgrt_tab.image_offset_x + bmp_width) > si->lfb_width ||
+	    (bgrt_tab.image_offset_y + bmp_height) > si->lfb_height)
+		goto error;
+
+	if (!efifb_bgrt_sanity_check(si, bmp_width))
+		goto error;
+
+	pr_info("efifb: showing boot graphics\n");
+
+	for (y = 0; y < si->lfb_height; y++, dst += si->lfb_linelength) {
+		/* Only background? */
+		if (y < bgrt_tab.image_offset_y ||
+		    y >= (bgrt_tab.image_offset_y + bmp_height)) {
+			memset(dst, 0, 4 * si->lfb_width);
+			continue;
+		}
+
+		src_y = y - bgrt_tab.image_offset_y;
+		/* Positive header height means upside down row order */
+		if (dib_header->height > 0)
+			src_y = (bmp_height - 1) - src_y;
+
+		memset(dst, 0, bgrt_tab.image_offset_x * 4);
+		dst_x = bgrt_tab.image_offset_x;
+		efifb_copy_bmp(bgrt_image + file_header->bitmap_offset +
+					    src_y * bmp_pitch,
+			       (u32 *)dst + dst_x, bmp_width, si);
+		dst_x += bmp_width;
+		memset((u32 *)dst + dst_x, 0, (si->lfb_width - dst_x) * 4);
+	}
+
+	memunmap(bgrt_image);
+	return;
+
+error:
+	memunmap(bgrt_image);
+	pr_warn("efifb: Ignoring BGRT: unexpected or invalid BMP data\n");
+}
+#else
+static inline void efifb_show_boot_graphics(struct fb_info *info, const struct screen_info *si)
+{ }
+#endif
+
+/*
+ * fb_ops.fb_destroy is called by the last put_fb_info() call at the end
+ * of unregister_framebuffer() or fb_release(). Do any cleanup here.
+ */
+static void efifb_destroy(struct fb_info *info)
+{
+	struct efifb_par *par = info->par;
+
+	if (info->screen_base) {
+		if (mem_flags & (EFI_MEMORY_UC | EFI_MEMORY_WC))
+			iounmap(info->screen_base);
+		else
+			memunmap(info->screen_base);
+	}
+
+	if (request_mem_succeeded)
+		release_mem_region(par->base, par->size);
+	fb_dealloc_cmap(&info->cmap);
+
+	framebuffer_release(info);
+}
+
+static const struct fb_ops efifb_ops = {
+	.owner		= THIS_MODULE,
+	FB_DEFAULT_IOMEM_OPS,
+	.fb_destroy	= efifb_destroy,
+	.fb_setcolreg	= efifb_setcolreg,
+};
+
+static void efifb_setup(struct screen_info *si, char *options)
+{
+	char *this_opt;
+
+	if (options && *options) {
+		while ((this_opt = strsep(&options, ",")) != NULL) {
+			if (!*this_opt) continue;
+
+			efifb_setup_from_dmi(si, this_opt);
+
+			if (!strncmp(this_opt, "base:", 5))
+				si->lfb_base = simple_strtoul(this_opt+5, NULL, 0);
+			else if (!strncmp(this_opt, "stride:", 7))
+				si->lfb_linelength = simple_strtoul(this_opt+7, NULL, 0) * 4;
+			else if (!strncmp(this_opt, "height:", 7))
+				si->lfb_height = simple_strtoul(this_opt+7, NULL, 0);
+			else if (!strncmp(this_opt, "width:", 6))
+				si->lfb_width = simple_strtoul(this_opt+6, NULL, 0);
+			else if (!strcmp(this_opt, "nowc"))
+				mem_flags &= ~EFI_MEMORY_WC;
+			else if (!strcmp(this_opt, "nobgrt"))
+				use_bgrt = false;
+		}
+	}
+}
+
+static inline bool fb_base_is_valid(struct screen_info *si)
+{
+	if (si->lfb_base)
+		return true;
+
+	if (!(si->capabilities & VIDEO_CAPABILITY_64BIT_BASE))
+		return false;
+
+	if (si->ext_lfb_base)
+		return true;
+
+	return false;
+}
+
+#define efifb_attr_decl(name, fmt)					\
+static ssize_t name##_show(struct device *dev,				\
+			   struct device_attribute *attr,		\
+			   char *buf)					\
+{									\
+	struct screen_info *si = dev_get_drvdata(dev);			\
+	if (!si)							\
+		return -ENODEV;						\
+	return sprintf(buf, fmt "\n", (si->lfb_##name));		\
+}									\
+static DEVICE_ATTR_RO(name)
+
+efifb_attr_decl(base, "0x%x");
+efifb_attr_decl(linelength, "%u");
+efifb_attr_decl(height, "%u");
+efifb_attr_decl(width, "%u");
+efifb_attr_decl(depth, "%u");
+
+static struct attribute *efifb_attrs[] = {
+	&dev_attr_base.attr,
+	&dev_attr_linelength.attr,
+	&dev_attr_width.attr,
+	&dev_attr_height.attr,
+	&dev_attr_depth.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(efifb);
+
+static int efifb_probe(struct platform_device *dev)
+{
+	struct sysfb_display_info *dpy;
+	struct screen_info *si;
+	struct fb_info *info;
+	struct efifb_par *par;
+	int err, orientation;
+	unsigned int size_vmode;
+	unsigned int size_remap;
+	unsigned int size_total;
+	char *option = NULL;
+	efi_memory_desc_t md;
+
+	/*
+	 * If we fail probing the device, the kernel might try a different
+	 * driver. We get a copy of the attached screen_info, so that we can
+	 * modify its values without affecting later drivers.
+	 */
+	dpy = dev_get_platdata(&dev->dev);
+	if (!dpy)
+		return -ENODEV;
+
+	si = devm_kmemdup(&dev->dev, &dpy->screen, sizeof(*si), GFP_KERNEL);
+	if (!si)
+		return -ENOMEM;
+
+	dev_set_drvdata(&dev->dev, si);
+
+	if (si->orig_video_isVGA != VIDEO_TYPE_EFI)
+		return -ENODEV;
+
+	if (fb_get_options("efifb", &option))
+		return -ENODEV;
+	efifb_setup(si, option);
+	kfree(option);
+
+	/* We don't get linelength from UGA Draw Protocol, only from
+	 * EFI Graphics Protocol.  So if it's not in DMI, and it's not
+	 * passed in from the user, we really can't use the framebuffer.
+	 */
+	if (!si->lfb_linelength)
+		return -ENODEV;
+
+	if (!si->lfb_depth)
+		si->lfb_depth = 32;
+	if (!si->pages)
+		si->pages = 1;
+	if (!fb_base_is_valid(si)) {
+		printk(KERN_DEBUG "efifb: invalid framebuffer address\n");
+		return -ENODEV;
+	}
+	printk(KERN_INFO "efifb: probing for efifb\n");
+
+	/* just assume they're all unset if any are */
+	if (!si->blue_size) {
+		si->blue_size = 8;
+		si->blue_pos = 0;
+		si->green_size = 8;
+		si->green_pos = 8;
+		si->red_size = 8;
+		si->red_pos = 16;
+		si->rsvd_size = 8;
+		si->rsvd_pos = 24;
+	}
+
+	efifb_fix.smem_start = __screen_info_lfb_base(si);
+
+	efifb_defined.bits_per_pixel = si->lfb_depth;
+	efifb_defined.xres = si->lfb_width;
+	efifb_defined.yres = si->lfb_height;
+	efifb_fix.line_length = si->lfb_linelength;
+
+	/*   size_vmode -- that is the amount of memory needed for the
+	 *                 used video mode, i.e. the minimum amount of
+	 *                 memory we need. */
+	size_vmode = efifb_defined.yres * efifb_fix.line_length;
+
+	/*   size_total -- all video memory we have. Used for
+	 *                 entries, ressource allocation and bounds
+	 *                 checking. */
+	size_total = si->lfb_size;
+	if (size_total < size_vmode)
+		size_total = size_vmode;
+
+	/*   size_remap -- the amount of video memory we are going to
+	 *                 use for efifb.  With modern cards it is no
+	 *                 option to simply use size_total as that
+	 *                 wastes plenty of kernel address space. */
+	size_remap  = size_vmode * 2;
+	if (size_remap > size_total)
+		size_remap = size_total;
+	if (size_remap % PAGE_SIZE)
+		size_remap += PAGE_SIZE - (size_remap % PAGE_SIZE);
+	efifb_fix.smem_len = size_remap;
+
+	if (request_mem_region(efifb_fix.smem_start, size_remap, "efifb")) {
+		request_mem_succeeded = true;
+	} else {
+		/* We cannot make this fatal. Sometimes this comes from magic
+		   spaces our resource handlers simply don't know about */
+		pr_warn("efifb: cannot reserve video memory at 0x%lx\n",
+			efifb_fix.smem_start);
+	}
+
+	info = framebuffer_alloc(sizeof(*par), &dev->dev);
+	if (!info) {
+		err = -ENOMEM;
+		goto err_release_mem;
+	}
+	par = info->par;
+	info->pseudo_palette = par->pseudo_palette;
+
+	par->base = efifb_fix.smem_start;
+	par->size = size_remap;
+
+	if (efi_enabled(EFI_MEMMAP) &&
+	    !efi_mem_desc_lookup(efifb_fix.smem_start, &md)) {
+		if ((efifb_fix.smem_start + efifb_fix.smem_len) >
+		    (md.phys_addr + (md.num_pages << EFI_PAGE_SHIFT))) {
+			pr_err("efifb: video memory @ 0x%lx spans multiple EFI memory regions\n",
+			       efifb_fix.smem_start);
+			err = -EIO;
+			goto err_release_fb;
+		}
+		/*
+		 * If the UEFI memory map covers the efifb region, we may only
+		 * remap it using the attributes the memory map prescribes.
+		 */
+		md.attribute &= EFI_MEMORY_UC | EFI_MEMORY_WC |
+				EFI_MEMORY_WT | EFI_MEMORY_WB;
+		if (md.attribute) {
+			mem_flags |= EFI_MEMORY_WT | EFI_MEMORY_WB;
+			mem_flags &= md.attribute;
+		}
+	}
+	if (mem_flags & EFI_MEMORY_WC)
+		info->screen_base = ioremap_wc(efifb_fix.smem_start,
+					       efifb_fix.smem_len);
+	else if (mem_flags & EFI_MEMORY_UC)
+		info->screen_base = ioremap(efifb_fix.smem_start,
+					    efifb_fix.smem_len);
+	else if (mem_flags & EFI_MEMORY_WT)
+		info->screen_base = memremap(efifb_fix.smem_start,
+					     efifb_fix.smem_len, MEMREMAP_WT);
+	else if (mem_flags & EFI_MEMORY_WB)
+		info->screen_base = memremap(efifb_fix.smem_start,
+					     efifb_fix.smem_len, MEMREMAP_WB);
+	if (!info->screen_base) {
+		pr_err("efifb: abort, cannot remap video memory 0x%x @ 0x%lx\n",
+			efifb_fix.smem_len, efifb_fix.smem_start);
+		err = -EIO;
+		goto err_release_fb;
+	}
+
+	efifb_show_boot_graphics(info, si);
+
+	pr_info("efifb: framebuffer at 0x%lx, using %dk, total %dk\n",
+	       efifb_fix.smem_start, size_remap/1024, size_total/1024);
+	pr_info("efifb: mode is %dx%dx%d, linelength=%d, pages=%d\n",
+	       efifb_defined.xres, efifb_defined.yres,
+	       efifb_defined.bits_per_pixel, efifb_fix.line_length,
+	       si->pages);
+
+	efifb_defined.xres_virtual = efifb_defined.xres;
+	efifb_defined.yres_virtual = efifb_fix.smem_len /
+					efifb_fix.line_length;
+	pr_info("efifb: scrolling: redraw\n");
+	efifb_defined.yres_virtual = efifb_defined.yres;
+
+	/* some dummy values for timing to make fbset happy */
+	efifb_defined.pixclock     = 10000000 / efifb_defined.xres *
+					1000 / efifb_defined.yres;
+	efifb_defined.left_margin  = (efifb_defined.xres / 8) & 0xf8;
+	efifb_defined.hsync_len    = (efifb_defined.xres / 8) & 0xf8;
+
+	efifb_defined.red.offset    = si->red_pos;
+	efifb_defined.red.length    = si->red_size;
+	efifb_defined.green.offset  = si->green_pos;
+	efifb_defined.green.length  = si->green_size;
+	efifb_defined.blue.offset   = si->blue_pos;
+	efifb_defined.blue.length   = si->blue_size;
+	efifb_defined.transp.offset = si->rsvd_pos;
+	efifb_defined.transp.length = si->rsvd_size;
+
+	pr_info("efifb: %s: "
+	       "size=%d:%d:%d:%d, shift=%d:%d:%d:%d\n",
+	       "Truecolor",
+	       si->rsvd_size,
+	       si->red_size,
+	       si->green_size,
+	       si->blue_size,
+	       si->rsvd_pos,
+	       si->red_pos,
+	       si->green_pos,
+	       si->blue_pos);
+
+	efifb_fix.ypanstep  = 0;
+	efifb_fix.ywrapstep = 0;
+
+	info->fbops = &efifb_ops;
+	info->var = efifb_defined;
+	info->fix = efifb_fix;
+
+	orientation = drm_get_panel_orientation_quirk(efifb_defined.xres,
+						      efifb_defined.yres);
+	switch (orientation) {
+	default:
+		info->fbcon_rotate_hint = FB_ROTATE_UR;
+		break;
+	case DRM_MODE_PANEL_ORIENTATION_BOTTOM_UP:
+		info->fbcon_rotate_hint = FB_ROTATE_UD;
+		break;
+	case DRM_MODE_PANEL_ORIENTATION_LEFT_UP:
+		info->fbcon_rotate_hint = FB_ROTATE_CCW;
+		break;
+	case DRM_MODE_PANEL_ORIENTATION_RIGHT_UP:
+		info->fbcon_rotate_hint = FB_ROTATE_CW;
+		break;
+	}
+
+	err = fb_alloc_cmap(&info->cmap, 256, 0);
+	if (err < 0) {
+		pr_err("efifb: cannot allocate colormap\n");
+		goto err_unmap;
+	}
+
+	err = devm_aperture_acquire_for_platform_device(dev, par->base, par->size);
+	if (err) {
+		pr_err("efifb: cannot acquire aperture\n");
+		goto err_fb_dealloc_cmap;
+	}
+	err = devm_register_framebuffer(&dev->dev, info);
+	if (err < 0) {
+		pr_err("efifb: cannot register framebuffer\n");
+		goto err_fb_dealloc_cmap;
+	}
+	fb_info(info, "%s frame buffer device\n", info->fix.id);
+	return 0;
+
+err_fb_dealloc_cmap:
+	fb_dealloc_cmap(&info->cmap);
+err_unmap:
+	if (mem_flags & (EFI_MEMORY_UC | EFI_MEMORY_WC))
+		iounmap(info->screen_base);
+	else
+		memunmap(info->screen_base);
+err_release_fb:
+	framebuffer_release(info);
+err_release_mem:
+	if (request_mem_succeeded)
+		release_mem_region(efifb_fix.smem_start, size_total);
+	return err;
+}
+
+static struct platform_driver efifb_driver = {
+	.driver = {
+		.name = "efi-framebuffer",
+		.dev_groups = efifb_groups,
+	},
+	.probe = efifb_probe,
+};
+
+builtin_platform_driver(efifb_driver);
-- 
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