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1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * From Coreboot file device/oprom/realmode/x86.c
4  *
5  * Copyright (C) 2007 Advanced Micro Devices, Inc.
6  * Copyright (C) 2009-2010 coresystems GmbH
7  */
8 #include <common.h>
9 #include <bios_emul.h>
10 #include <vbe.h>
11 #include <linux/linkage.h>
12 #include <asm/cache.h>
13 #include <asm/processor.h>
14 #include <asm/i8259.h>
15 #include <asm/io.h>
16 #include <asm/post.h>
17 #include "bios.h"
18 
19 /* Interrupt handlers for each interrupt the ROM can call */
20 static int (*int_handler[256])(void);
21 
22 /* to have a common register file for interrupt handlers */
23 X86EMU_sysEnv _X86EMU_env;
24 
25 asmlinkage void (*realmode_call)(u32 addr, u32 eax, u32 ebx, u32 ecx, u32 edx,
26 				 u32 esi, u32 edi);
27 
28 asmlinkage void (*realmode_interrupt)(u32 intno, u32 eax, u32 ebx, u32 ecx,
29 				      u32 edx, u32 esi, u32 edi);
30 
setup_realmode_code(void)31 static void setup_realmode_code(void)
32 {
33 	memcpy((void *)REALMODE_BASE, &asm_realmode_code,
34 	       asm_realmode_code_size);
35 
36 	/* Ensure the global pointers are relocated properly. */
37 	realmode_call = PTR_TO_REAL_MODE(asm_realmode_call);
38 	realmode_interrupt = PTR_TO_REAL_MODE(__realmode_interrupt);
39 
40 	debug("Real mode stub @%x: %d bytes\n", REALMODE_BASE,
41 	      asm_realmode_code_size);
42 }
43 
setup_rombios(void)44 static void setup_rombios(void)
45 {
46 	const char date[] = "06/11/99";
47 	memcpy((void *)0xffff5, &date, 8);
48 
49 	const char ident[] = "PCI_ISA";
50 	memcpy((void *)0xfffd9, &ident, 7);
51 
52 	/* system model: IBM-AT */
53 	writeb(0xfc, 0xffffe);
54 }
55 
int_exception_handler(void)56 static int int_exception_handler(void)
57 {
58 	/* compatibility shim */
59 	struct eregs reg_info = {
60 		.eax = M.x86.R_EAX,
61 		.ecx = M.x86.R_ECX,
62 		.edx = M.x86.R_EDX,
63 		.ebx = M.x86.R_EBX,
64 		.esp = M.x86.R_ESP,
65 		.ebp = M.x86.R_EBP,
66 		.esi = M.x86.R_ESI,
67 		.edi = M.x86.R_EDI,
68 		.vector = M.x86.intno,
69 		.error_code = 0,
70 		.eip = M.x86.R_EIP,
71 		.cs = M.x86.R_CS,
72 		.eflags = M.x86.R_EFLG
73 	};
74 	struct eregs *regs = &reg_info;
75 
76 	debug("Oops, exception %d while executing option rom\n", regs->vector);
77 	cpu_hlt();
78 
79 	return 0;
80 }
81 
int_unknown_handler(void)82 static int int_unknown_handler(void)
83 {
84 	debug("Unsupported software interrupt #0x%x eax 0x%x\n",
85 	      M.x86.intno, M.x86.R_EAX);
86 
87 	return -1;
88 }
89 
90 /* setup interrupt handlers for mainboard */
bios_set_interrupt_handler(int intnum,int (* int_func)(void))91 void bios_set_interrupt_handler(int intnum, int (*int_func)(void))
92 {
93 	int_handler[intnum] = int_func;
94 }
95 
setup_interrupt_handlers(void)96 static void setup_interrupt_handlers(void)
97 {
98 	int i;
99 
100 	/*
101 	 * The first 16 int_handler functions are not BIOS services,
102 	 * but the CPU-generated exceptions ("hardware interrupts")
103 	 */
104 	for (i = 0; i < 0x10; i++)
105 		int_handler[i] = &int_exception_handler;
106 
107 	/* Mark all other int_handler calls as unknown first */
108 	for (i = 0x10; i < 0x100; i++) {
109 		/* Skip if bios_set_interrupt_handler() isn't called first */
110 		if (int_handler[i])
111 			continue;
112 
113 		 /*
114 		  * Now set the default functions that are actually needed
115 		  * to initialize the option roms. The board may override
116 		  * these with bios_set_interrupt_handler()
117 		 */
118 		switch (i) {
119 		case 0x10:
120 			int_handler[0x10] = &int10_handler;
121 			break;
122 		case 0x12:
123 			int_handler[0x12] = &int12_handler;
124 			break;
125 		case 0x16:
126 			int_handler[0x16] = &int16_handler;
127 			break;
128 		case 0x1a:
129 			int_handler[0x1a] = &int1a_handler;
130 			break;
131 		default:
132 			int_handler[i] = &int_unknown_handler;
133 			break;
134 		}
135 	}
136 }
137 
write_idt_stub(void * target,u8 intnum)138 static void write_idt_stub(void *target, u8 intnum)
139 {
140 	unsigned char *codeptr;
141 
142 	codeptr = (unsigned char *)target;
143 	memcpy(codeptr, &__idt_handler, __idt_handler_size);
144 	codeptr[3] = intnum; /* modify int# in the code stub. */
145 }
146 
setup_realmode_idt(void)147 static void setup_realmode_idt(void)
148 {
149 	struct realmode_idt *idts = NULL;
150 	int i;
151 
152 	/*
153 	 * Copy IDT stub code for each interrupt. This might seem wasteful
154 	 * but it is really simple
155 	 */
156 	 for (i = 0; i < 256; i++) {
157 		idts[i].cs = 0;
158 		idts[i].offset = 0x1000 + (i * __idt_handler_size);
159 		write_idt_stub((void *)((ulong)idts[i].offset), i);
160 	}
161 
162 	/*
163 	 * Many option ROMs use the hard coded interrupt entry points in the
164 	 * system bios. So install them at the known locations.
165 	 */
166 
167 	/* int42 is the relocated int10 */
168 	write_idt_stub((void *)0xff065, 0x42);
169 	/* BIOS Int 11 Handler F000:F84D */
170 	write_idt_stub((void *)0xff84d, 0x11);
171 	/* BIOS Int 12 Handler F000:F841 */
172 	write_idt_stub((void *)0xff841, 0x12);
173 	/* BIOS Int 13 Handler F000:EC59 */
174 	write_idt_stub((void *)0xfec59, 0x13);
175 	/* BIOS Int 14 Handler F000:E739 */
176 	write_idt_stub((void *)0xfe739, 0x14);
177 	/* BIOS Int 15 Handler F000:F859 */
178 	write_idt_stub((void *)0xff859, 0x15);
179 	/* BIOS Int 16 Handler F000:E82E */
180 	write_idt_stub((void *)0xfe82e, 0x16);
181 	/* BIOS Int 17 Handler F000:EFD2 */
182 	write_idt_stub((void *)0xfefd2, 0x17);
183 	/* ROM BIOS Int 1A Handler F000:FE6E */
184 	write_idt_stub((void *)0xffe6e, 0x1a);
185 }
186 
187 #ifdef CONFIG_FRAMEBUFFER_SET_VESA_MODE
vbe_get_mode_info(struct vbe_mode_info * mi)188 static u8 vbe_get_mode_info(struct vbe_mode_info *mi)
189 {
190 	u16 buffer_seg;
191 	u16 buffer_adr;
192 	char *buffer;
193 
194 	debug("VBE: Getting information about VESA mode %04x\n",
195 	      mi->video_mode);
196 	buffer = PTR_TO_REAL_MODE(asm_realmode_buffer);
197 	buffer_seg = (((unsigned long)buffer) >> 4) & 0xff00;
198 	buffer_adr = ((unsigned long)buffer) & 0xffff;
199 
200 	realmode_interrupt(0x10, VESA_GET_MODE_INFO, 0x0000, mi->video_mode,
201 			   0x0000, buffer_seg, buffer_adr);
202 	memcpy(mi->mode_info_block, buffer, sizeof(struct vbe_mode_info));
203 	mi->valid = true;
204 
205 	return 0;
206 }
207 
vbe_set_mode(struct vbe_mode_info * mi)208 static u8 vbe_set_mode(struct vbe_mode_info *mi)
209 {
210 	int video_mode = mi->video_mode;
211 
212 	debug("VBE: Setting VESA mode %#04x\n", video_mode);
213 	/* request linear framebuffer mode */
214 	video_mode |= (1 << 14);
215 	/* don't clear the framebuffer, we do that later */
216 	video_mode |= (1 << 15);
217 	realmode_interrupt(0x10, VESA_SET_MODE, video_mode,
218 			   0x0000, 0x0000, 0x0000, 0x0000);
219 
220 	return 0;
221 }
222 
vbe_set_graphics(int vesa_mode,struct vbe_mode_info * mode_info)223 static void vbe_set_graphics(int vesa_mode, struct vbe_mode_info *mode_info)
224 {
225 	unsigned char *framebuffer;
226 
227 	mode_info->video_mode = (1 << 14) | vesa_mode;
228 	vbe_get_mode_info(mode_info);
229 
230 	framebuffer = (unsigned char *)(ulong)mode_info->vesa.phys_base_ptr;
231 	debug("VBE: resolution:  %dx%d@%d\n",
232 	      le16_to_cpu(mode_info->vesa.x_resolution),
233 	      le16_to_cpu(mode_info->vesa.y_resolution),
234 	      mode_info->vesa.bits_per_pixel);
235 	debug("VBE: framebuffer: %p\n", framebuffer);
236 	if (!framebuffer) {
237 		debug("VBE: Mode does not support linear framebuffer\n");
238 		return;
239 	}
240 
241 	mode_info->video_mode &= 0x3ff;
242 	vbe_set_mode(mode_info);
243 }
244 #endif /* CONFIG_FRAMEBUFFER_SET_VESA_MODE */
245 
bios_run_on_x86(struct udevice * dev,unsigned long addr,int vesa_mode,struct vbe_mode_info * mode_info)246 void bios_run_on_x86(struct udevice *dev, unsigned long addr, int vesa_mode,
247 		     struct vbe_mode_info *mode_info)
248 {
249 	pci_dev_t pcidev = dm_pci_get_bdf(dev);
250 	u32 num_dev;
251 
252 	num_dev = PCI_BUS(pcidev) << 8 | PCI_DEV(pcidev) << 3 |
253 			PCI_FUNC(pcidev);
254 
255 	/* Needed to avoid exceptions in some ROMs */
256 	interrupt_init();
257 
258 	/* Set up some legacy information in the F segment */
259 	setup_rombios();
260 
261 	/* Set up C interrupt handlers */
262 	setup_interrupt_handlers();
263 
264 	/* Set up real-mode IDT */
265 	setup_realmode_idt();
266 
267 	/* Make sure the code is placed. */
268 	setup_realmode_code();
269 
270 	debug("Calling Option ROM at %lx, pci device %#x...", addr, num_dev);
271 
272 	/* Option ROM entry point is at OPROM start + 3 */
273 	realmode_call(addr + 0x0003, num_dev, 0xffff, 0x0000, 0xffff, 0x0,
274 		      0x0);
275 	debug("done\n");
276 
277 #ifdef CONFIG_FRAMEBUFFER_SET_VESA_MODE
278 	if (vesa_mode != -1)
279 		vbe_set_graphics(vesa_mode, mode_info);
280 #endif
281 }
282 
interrupt_handler(u32 intnumber,u32 gsfs,u32 dses,u32 edi,u32 esi,u32 ebp,u32 esp,u32 ebx,u32 edx,u32 ecx,u32 eax,u32 cs_ip,u16 stackflags)283 asmlinkage int interrupt_handler(u32 intnumber, u32 gsfs, u32 dses,
284 				 u32 edi, u32 esi, u32 ebp, u32 esp,
285 				 u32 ebx, u32 edx, u32 ecx, u32 eax,
286 				 u32 cs_ip, u16 stackflags)
287 {
288 	u32 ip;
289 	u32 cs;
290 	u32 flags;
291 	int ret = 0;
292 
293 	ip = cs_ip & 0xffff;
294 	cs = cs_ip >> 16;
295 	flags = stackflags;
296 
297 #ifdef CONFIG_REALMODE_DEBUG
298 	debug("oprom: INT# 0x%x\n", intnumber);
299 	debug("oprom: eax: %08x ebx: %08x ecx: %08x edx: %08x\n",
300 	      eax, ebx, ecx, edx);
301 	debug("oprom: ebp: %08x esp: %08x edi: %08x esi: %08x\n",
302 	      ebp, esp, edi, esi);
303 	debug("oprom:  ip: %04x      cs: %04x   flags: %08x\n",
304 	      ip, cs, flags);
305 	debug("oprom: stackflags = %04x\n", stackflags);
306 #endif
307 
308 	/*
309 	 * Fetch arguments from the stack and put them to a place
310 	 * suitable for the interrupt handlers
311 	 */
312 	M.x86.R_EAX = eax;
313 	M.x86.R_ECX = ecx;
314 	M.x86.R_EDX = edx;
315 	M.x86.R_EBX = ebx;
316 	M.x86.R_ESP = esp;
317 	M.x86.R_EBP = ebp;
318 	M.x86.R_ESI = esi;
319 	M.x86.R_EDI = edi;
320 	M.x86.intno = intnumber;
321 	M.x86.R_EIP = ip;
322 	M.x86.R_CS = cs;
323 	M.x86.R_EFLG = flags;
324 
325 	/* Call the interrupt handler for this interrupt number */
326 	ret = int_handler[intnumber]();
327 
328 	/*
329 	 * This code is quite strange...
330 	 *
331 	 * Put registers back on the stack. The assembler code will pop them
332 	 * later. We force (volatile!) changing the values of the parameters
333 	 * of this function. We know that they stay alive on the stack after
334 	 * we leave this function.
335 	 */
336 	*(volatile u32 *)&eax = M.x86.R_EAX;
337 	*(volatile u32 *)&ecx = M.x86.R_ECX;
338 	*(volatile u32 *)&edx = M.x86.R_EDX;
339 	*(volatile u32 *)&ebx = M.x86.R_EBX;
340 	*(volatile u32 *)&esi = M.x86.R_ESI;
341 	*(volatile u32 *)&edi = M.x86.R_EDI;
342 	flags = M.x86.R_EFLG;
343 
344 	/* Pass success or error back to our caller via the CARRY flag */
345 	if (ret) {
346 		flags &= ~1; /* no error: clear carry */
347 	} else {
348 		debug("int%02x call returned error\n", intnumber);
349 		flags |= 1;  /* error: set carry */
350 	}
351 	*(volatile u16 *)&stackflags = flags;
352 
353 	return ret;
354 }
355