1// SPDX-License-Identifier: GPL-2.0
  2/*
  3 * Copyright (C) 2013 Intel Corporation; author Matt Fleming
  4 */
  5
  6#include <linux/console.h>
  7#include <linux/efi.h>
  8#include <linux/font.h>
  9#include <linux/io.h>
 10#include <linux/kernel.h>
 11#include <linux/serial_core.h>
 12#include <linux/screen_info.h>
 13
 14#include <asm/early_ioremap.h>
 15
 16static const struct console *earlycon_console __initdata;
 17static const struct font_desc *font;
 18static u32 efi_x, efi_y;
 19static u64 fb_base;
 20static bool fb_wb;
 21static void *efi_fb;
 22
 23/*
 24 * EFI earlycon needs to use early_memremap() to map the framebuffer.
 25 * But early_memremap() is not usable for 'earlycon=efifb keep_bootcon',
 26 * memremap() should be used instead. memremap() will be available after
 27 * paging_init() which is earlier than initcall callbacks. Thus adding this
 28 * early initcall function early_efi_map_fb() to map the whole EFI framebuffer.
 29 */
 30static int __init efi_earlycon_remap_fb(void)
 31{
 32	/* bail if there is no bootconsole or it has been disabled already */
 33	if (!earlycon_console || !(earlycon_console->flags & CON_ENABLED))
 34		return 0;
 35
 36	efi_fb = memremap(fb_base, screen_info.lfb_size,
 37			  fb_wb ? MEMREMAP_WB : MEMREMAP_WC);
 38
 39	return efi_fb ? 0 : -ENOMEM;
 40}
 41early_initcall(efi_earlycon_remap_fb);
 42
 43static int __init efi_earlycon_unmap_fb(void)
 44{
 45	/* unmap the bootconsole fb unless keep_bootcon has left it enabled */
 46	if (efi_fb && !(earlycon_console->flags & CON_ENABLED))
 47		memunmap(efi_fb);
 48	return 0;
 49}
 50late_initcall(efi_earlycon_unmap_fb);
 51
 52static __ref void *efi_earlycon_map(unsigned long start, unsigned long len)
 53{
 54	pgprot_t fb_prot;
 55
 56	if (efi_fb)
 57		return efi_fb + start;
 58
 59	fb_prot = fb_wb ? PAGE_KERNEL : pgprot_writecombine(PAGE_KERNEL);
 60	return early_memremap_prot(fb_base + start, len, pgprot_val(fb_prot));
 61}
 62
 63static __ref void efi_earlycon_unmap(void *addr, unsigned long len)
 64{
 65	if (efi_fb)
 66		return;
 67
 68	early_memunmap(addr, len);
 69}
 70
 71static void efi_earlycon_clear_scanline(unsigned int y)
 72{
 73	unsigned long *dst;
 74	u16 len;
 75
 76	len = screen_info.lfb_linelength;
 77	dst = efi_earlycon_map(y*len, len);
 78	if (!dst)
 79		return;
 80
 81	memset(dst, 0, len);
 82	efi_earlycon_unmap(dst, len);
 83}
 84
 85static void efi_earlycon_scroll_up(void)
 86{
 87	unsigned long *dst, *src;
 88	u16 len;
 89	u32 i, height;
 90
 91	len = screen_info.lfb_linelength;
 92	height = screen_info.lfb_height;
 93
 94	for (i = 0; i < height - font->height; i++) {
 95		dst = efi_earlycon_map(i*len, len);
 96		if (!dst)
 97			return;
 98
 99		src = efi_earlycon_map((i + font->height) * len, len);
100		if (!src) {
101			efi_earlycon_unmap(dst, len);
102			return;
103		}
104
105		memmove(dst, src, len);
106
107		efi_earlycon_unmap(src, len);
108		efi_earlycon_unmap(dst, len);
109	}
110}
111
112static void efi_earlycon_write_char(u32 *dst, unsigned char c, unsigned int h)
113{
114	const u32 color_black = 0x00000000;
115	const u32 color_white = 0x00ffffff;
116	const u8 *src;
117	int m, n, bytes;
118	u8 x;
119
120	bytes = BITS_TO_BYTES(font->width);
121	src = font->data + c * font->height * bytes + h * bytes;
122
123	for (m = 0; m < font->width; m++) {
124		n = m % 8;
125		x = *(src + m / 8);
126		if ((x >> (7 - n)) & 1)
127			*dst = color_white;
128		else
129			*dst = color_black;
130		dst++;
131	}
132}
133
134static void
135efi_earlycon_write(struct console *con, const char *str, unsigned int num)
136{
137	struct screen_info *si;
138	unsigned int len;
139	const char *s;
140	void *dst;
141
142	si = &screen_info;
143	len = si->lfb_linelength;
144
145	while (num) {
146		unsigned int linemax;
147		unsigned int h, count = 0;
148
149		for (s = str; *s && *s != '\n'; s++) {
150			if (count == num)
151				break;
152			count++;
153		}
154
155		linemax = (si->lfb_width - efi_x) / font->width;
156		if (count > linemax)
157			count = linemax;
158
159		for (h = 0; h < font->height; h++) {
160			unsigned int n, x;
161
162			dst = efi_earlycon_map((efi_y + h) * len, len);
163			if (!dst)
164				return;
165
166			s = str;
167			n = count;
168			x = efi_x;
169
170			while (n-- > 0) {
171				efi_earlycon_write_char(dst + x*4, *s, h);
172				x += font->width;
173				s++;
174			}
175
176			efi_earlycon_unmap(dst, len);
177		}
178
179		num -= count;
180		efi_x += count * font->width;
181		str += count;
182
183		if (num > 0 && *s == '\n') {
184			efi_x = 0;
185			efi_y += font->height;
186			str++;
187			num--;
188		}
189
190		if (efi_x + font->width > si->lfb_width) {
191			efi_x = 0;
192			efi_y += font->height;
193		}
194
195		if (efi_y + font->height > si->lfb_height) {
196			u32 i;
197
198			efi_y -= font->height;
199			efi_earlycon_scroll_up();
200
201			for (i = 0; i < font->height; i++)
202				efi_earlycon_clear_scanline(efi_y + i);
203		}
204	}
205}
206
207static int __init efi_earlycon_setup(struct earlycon_device *device,
208				     const char *opt)
209{
210	struct screen_info *si;
211	u16 xres, yres;
212	u32 i;
213
214	if (screen_info.orig_video_isVGA != VIDEO_TYPE_EFI)
215		return -ENODEV;
216
217	fb_base = screen_info.lfb_base;
218	if (screen_info.capabilities & VIDEO_CAPABILITY_64BIT_BASE)
219		fb_base |= (u64)screen_info.ext_lfb_base << 32;
220
221	fb_wb = opt && !strcmp(opt, "ram");
222
223	si = &screen_info;
224	xres = si->lfb_width;
225	yres = si->lfb_height;
226
227	/*
228	 * efi_earlycon_write_char() implicitly assumes a framebuffer with
229	 * 32 bits per pixel.
230	 */
231	if (si->lfb_depth != 32)
232		return -ENODEV;
233
234	font = get_default_font(xres, yres, -1, -1);
235	if (!font)
236		return -ENODEV;
237
238	efi_y = rounddown(yres, font->height) - font->height;
239	for (i = 0; i < (yres - efi_y) / font->height; i++)
240		efi_earlycon_scroll_up();
241
242	device->con->write = efi_earlycon_write;
243	earlycon_console = device->con;
244	return 0;
245}
246EARLYCON_DECLARE(efifb, efi_earlycon_setup);