xref: /openbmc/u-boot/arch/x86/lib/bios.c (revision 85fc970d)
1 /*
2  * From Coreboot file device/oprom/realmode/x86.c
3  *
4  * Copyright (C) 2007 Advanced Micro Devices, Inc.
5  * Copyright (C) 2009-2010 coresystems GmbH
6  *
7  * SPDX-License-Identifier:	GPL-2.0
8  */
9 #include <common.h>
10 #include <bios_emul.h>
11 #include <vbe.h>
12 #include <linux/linkage.h>
13 #include <asm/cache.h>
14 #include <asm/processor.h>
15 #include <asm/i8259.h>
16 #include <asm/io.h>
17 #include <asm/post.h>
18 #include "bios.h"
19 
20 /* Interrupt handlers for each interrupt the ROM can call */
21 static int (*int_handler[256])(void);
22 
23 /* to have a common register file for interrupt handlers */
24 X86EMU_sysEnv _X86EMU_env;
25 
26 asmlinkage void (*realmode_call)(u32 addr, u32 eax, u32 ebx, u32 ecx, u32 edx,
27 				 u32 esi, u32 edi);
28 
29 asmlinkage void (*realmode_interrupt)(u32 intno, u32 eax, u32 ebx, u32 ecx,
30 				      u32 edx, u32 esi, u32 edi);
31 
32 static void setup_realmode_code(void)
33 {
34 	memcpy((void *)REALMODE_BASE, &asm_realmode_code,
35 	       asm_realmode_code_size);
36 
37 	/* Ensure the global pointers are relocated properly. */
38 	realmode_call = PTR_TO_REAL_MODE(asm_realmode_call);
39 	realmode_interrupt = PTR_TO_REAL_MODE(__realmode_interrupt);
40 
41 	debug("Real mode stub @%x: %d bytes\n", REALMODE_BASE,
42 	      asm_realmode_code_size);
43 }
44 
45 static void setup_rombios(void)
46 {
47 	const char date[] = "06/11/99";
48 	memcpy((void *)0xffff5, &date, 8);
49 
50 	const char ident[] = "PCI_ISA";
51 	memcpy((void *)0xfffd9, &ident, 7);
52 
53 	/* system model: IBM-AT */
54 	writeb(0xfc, 0xffffe);
55 }
56 
57 static int int_exception_handler(void)
58 {
59 	/* compatibility shim */
60 	struct eregs reg_info = {
61 		.eax = M.x86.R_EAX,
62 		.ecx = M.x86.R_ECX,
63 		.edx = M.x86.R_EDX,
64 		.ebx = M.x86.R_EBX,
65 		.esp = M.x86.R_ESP,
66 		.ebp = M.x86.R_EBP,
67 		.esi = M.x86.R_ESI,
68 		.edi = M.x86.R_EDI,
69 		.vector = M.x86.intno,
70 		.error_code = 0,
71 		.eip = M.x86.R_EIP,
72 		.cs = M.x86.R_CS,
73 		.eflags = M.x86.R_EFLG
74 	};
75 	struct eregs *regs = &reg_info;
76 
77 	debug("Oops, exception %d while executing option rom\n", regs->vector);
78 	cpu_hlt();
79 
80 	return 0;
81 }
82 
83 static int int_unknown_handler(void)
84 {
85 	debug("Unsupported software interrupt #0x%x eax 0x%x\n",
86 	      M.x86.intno, M.x86.R_EAX);
87 
88 	return -1;
89 }
90 
91 /* setup interrupt handlers for mainboard */
92 void bios_set_interrupt_handler(int intnum, int (*int_func)(void))
93 {
94 	int_handler[intnum] = int_func;
95 }
96 
97 static void setup_interrupt_handlers(void)
98 {
99 	int i;
100 
101 	/*
102 	 * The first 16 int_handler functions are not BIOS services,
103 	 * but the CPU-generated exceptions ("hardware interrupts")
104 	 */
105 	for (i = 0; i < 0x10; i++)
106 		int_handler[i] = &int_exception_handler;
107 
108 	/* Mark all other int_handler calls as unknown first */
109 	for (i = 0x10; i < 0x100; i++) {
110 		/* Skip if bios_set_interrupt_handler() isn't called first */
111 		if (int_handler[i])
112 			continue;
113 
114 		 /*
115 		  * Now set the default functions that are actually needed
116 		  * to initialize the option roms. The board may override
117 		  * these with bios_set_interrupt_handler()
118 		 */
119 		switch (i) {
120 		case 0x10:
121 			int_handler[0x10] = &int10_handler;
122 			break;
123 		case 0x12:
124 			int_handler[0x12] = &int12_handler;
125 			break;
126 		case 0x16:
127 			int_handler[0x16] = &int16_handler;
128 			break;
129 		case 0x1a:
130 			int_handler[0x1a] = &int1a_handler;
131 			break;
132 		default:
133 			int_handler[i] = &int_unknown_handler;
134 			break;
135 		}
136 	}
137 }
138 
139 static void write_idt_stub(void *target, u8 intnum)
140 {
141 	unsigned char *codeptr;
142 
143 	codeptr = (unsigned char *)target;
144 	memcpy(codeptr, &__idt_handler, __idt_handler_size);
145 	codeptr[3] = intnum; /* modify int# in the code stub. */
146 }
147 
148 static void setup_realmode_idt(void)
149 {
150 	struct realmode_idt *idts = NULL;
151 	int i;
152 
153 	/*
154 	 * Copy IDT stub code for each interrupt. This might seem wasteful
155 	 * but it is really simple
156 	 */
157 	 for (i = 0; i < 256; i++) {
158 		idts[i].cs = 0;
159 		idts[i].offset = 0x1000 + (i * __idt_handler_size);
160 		write_idt_stub((void *)((ulong)idts[i].offset), i);
161 	}
162 
163 	/*
164 	 * Many option ROMs use the hard coded interrupt entry points in the
165 	 * system bios. So install them at the known locations.
166 	 */
167 
168 	/* int42 is the relocated int10 */
169 	write_idt_stub((void *)0xff065, 0x42);
170 	/* BIOS Int 11 Handler F000:F84D */
171 	write_idt_stub((void *)0xff84d, 0x11);
172 	/* BIOS Int 12 Handler F000:F841 */
173 	write_idt_stub((void *)0xff841, 0x12);
174 	/* BIOS Int 13 Handler F000:EC59 */
175 	write_idt_stub((void *)0xfec59, 0x13);
176 	/* BIOS Int 14 Handler F000:E739 */
177 	write_idt_stub((void *)0xfe739, 0x14);
178 	/* BIOS Int 15 Handler F000:F859 */
179 	write_idt_stub((void *)0xff859, 0x15);
180 	/* BIOS Int 16 Handler F000:E82E */
181 	write_idt_stub((void *)0xfe82e, 0x16);
182 	/* BIOS Int 17 Handler F000:EFD2 */
183 	write_idt_stub((void *)0xfefd2, 0x17);
184 	/* ROM BIOS Int 1A Handler F000:FE6E */
185 	write_idt_stub((void *)0xffe6e, 0x1a);
186 }
187 
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 
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 
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 
245 void bios_run_on_x86(struct udevice *dev, unsigned long addr, int vesa_mode,
246 		     struct vbe_mode_info *mode_info)
247 {
248 	pci_dev_t pcidev = dm_pci_get_bdf(dev);
249 	u32 num_dev;
250 
251 	num_dev = PCI_BUS(pcidev) << 8 | PCI_DEV(pcidev) << 3 |
252 			PCI_FUNC(pcidev);
253 
254 	/* Needed to avoid exceptions in some ROMs */
255 	interrupt_init();
256 
257 	/* Set up some legacy information in the F segment */
258 	setup_rombios();
259 
260 	/* Set up C interrupt handlers */
261 	setup_interrupt_handlers();
262 
263 	/* Set up real-mode IDT */
264 	setup_realmode_idt();
265 
266 	/* Make sure the code is placed. */
267 	setup_realmode_code();
268 
269 	debug("Calling Option ROM at %lx, pci device %#x...", addr, num_dev);
270 
271 	/* Option ROM entry point is at OPROM start + 3 */
272 	realmode_call(addr + 0x0003, num_dev, 0xffff, 0x0000, 0xffff, 0x0,
273 		      0x0);
274 	debug("done\n");
275 
276 	if (vesa_mode != -1)
277 		vbe_set_graphics(vesa_mode, mode_info);
278 }
279 
280 asmlinkage int interrupt_handler(u32 intnumber, u32 gsfs, u32 dses,
281 				 u32 edi, u32 esi, u32 ebp, u32 esp,
282 				 u32 ebx, u32 edx, u32 ecx, u32 eax,
283 				 u32 cs_ip, u16 stackflags)
284 {
285 	u32 ip;
286 	u32 cs;
287 	u32 flags;
288 	int ret = 0;
289 
290 	ip = cs_ip & 0xffff;
291 	cs = cs_ip >> 16;
292 	flags = stackflags;
293 
294 #ifdef CONFIG_REALMODE_DEBUG
295 	debug("oprom: INT# 0x%x\n", intnumber);
296 	debug("oprom: eax: %08x ebx: %08x ecx: %08x edx: %08x\n",
297 	      eax, ebx, ecx, edx);
298 	debug("oprom: ebp: %08x esp: %08x edi: %08x esi: %08x\n",
299 	      ebp, esp, edi, esi);
300 	debug("oprom:  ip: %04x      cs: %04x   flags: %08x\n",
301 	      ip, cs, flags);
302 	debug("oprom: stackflags = %04x\n", stackflags);
303 #endif
304 
305 	/*
306 	 * Fetch arguments from the stack and put them to a place
307 	 * suitable for the interrupt handlers
308 	 */
309 	M.x86.R_EAX = eax;
310 	M.x86.R_ECX = ecx;
311 	M.x86.R_EDX = edx;
312 	M.x86.R_EBX = ebx;
313 	M.x86.R_ESP = esp;
314 	M.x86.R_EBP = ebp;
315 	M.x86.R_ESI = esi;
316 	M.x86.R_EDI = edi;
317 	M.x86.intno = intnumber;
318 	M.x86.R_EIP = ip;
319 	M.x86.R_CS = cs;
320 	M.x86.R_EFLG = flags;
321 
322 	/* Call the interrupt handler for this interrupt number */
323 	ret = int_handler[intnumber]();
324 
325 	/*
326 	 * This code is quite strange...
327 	 *
328 	 * Put registers back on the stack. The assembler code will pop them
329 	 * later. We force (volatile!) changing the values of the parameters
330 	 * of this function. We know that they stay alive on the stack after
331 	 * we leave this function.
332 	 */
333 	*(volatile u32 *)&eax = M.x86.R_EAX;
334 	*(volatile u32 *)&ecx = M.x86.R_ECX;
335 	*(volatile u32 *)&edx = M.x86.R_EDX;
336 	*(volatile u32 *)&ebx = M.x86.R_EBX;
337 	*(volatile u32 *)&esi = M.x86.R_ESI;
338 	*(volatile u32 *)&edi = M.x86.R_EDI;
339 	flags = M.x86.R_EFLG;
340 
341 	/* Pass success or error back to our caller via the CARRY flag */
342 	if (ret) {
343 		flags &= ~1; /* no error: clear carry */
344 	} else {
345 		debug("int%02x call returned error\n", intnumber);
346 		flags |= 1;  /* error: set carry */
347 	}
348 	*(volatile u16 *)&stackflags = flags;
349 
350 	return ret;
351 }
352