xref: /openbmc/linux/arch/x86/kernel/early_printk.c (revision e8e0929d)
1 #include <linux/console.h>
2 #include <linux/kernel.h>
3 #include <linux/init.h>
4 #include <linux/string.h>
5 #include <linux/screen_info.h>
6 #include <linux/usb/ch9.h>
7 #include <linux/pci_regs.h>
8 #include <linux/pci_ids.h>
9 #include <linux/errno.h>
10 #include <asm/io.h>
11 #include <asm/processor.h>
12 #include <asm/fcntl.h>
13 #include <asm/setup.h>
14 #include <xen/hvc-console.h>
15 #include <asm/pci-direct.h>
16 #include <asm/fixmap.h>
17 #include <asm/pgtable.h>
18 #include <linux/usb/ehci_def.h>
19 
20 /* Simple VGA output */
21 #define VGABASE		(__ISA_IO_base + 0xb8000)
22 
23 static int max_ypos = 25, max_xpos = 80;
24 static int current_ypos = 25, current_xpos;
25 
26 static void early_vga_write(struct console *con, const char *str, unsigned n)
27 {
28 	char c;
29 	int  i, k, j;
30 
31 	while ((c = *str++) != '\0' && n-- > 0) {
32 		if (current_ypos >= max_ypos) {
33 			/* scroll 1 line up */
34 			for (k = 1, j = 0; k < max_ypos; k++, j++) {
35 				for (i = 0; i < max_xpos; i++) {
36 					writew(readw(VGABASE+2*(max_xpos*k+i)),
37 					       VGABASE + 2*(max_xpos*j + i));
38 				}
39 			}
40 			for (i = 0; i < max_xpos; i++)
41 				writew(0x720, VGABASE + 2*(max_xpos*j + i));
42 			current_ypos = max_ypos-1;
43 		}
44 		if (c == '\n') {
45 			current_xpos = 0;
46 			current_ypos++;
47 		} else if (c != '\r')  {
48 			writew(((0x7 << 8) | (unsigned short) c),
49 			       VGABASE + 2*(max_xpos*current_ypos +
50 						current_xpos++));
51 			if (current_xpos >= max_xpos) {
52 				current_xpos = 0;
53 				current_ypos++;
54 			}
55 		}
56 	}
57 }
58 
59 static struct console early_vga_console = {
60 	.name =		"earlyvga",
61 	.write =	early_vga_write,
62 	.flags =	CON_PRINTBUFFER,
63 	.index =	-1,
64 };
65 
66 /* Serial functions loosely based on a similar package from Klaus P. Gerlicher */
67 
68 static int early_serial_base = 0x3f8;  /* ttyS0 */
69 
70 #define XMTRDY          0x20
71 
72 #define DLAB		0x80
73 
74 #define TXR             0       /*  Transmit register (WRITE) */
75 #define RXR             0       /*  Receive register  (READ)  */
76 #define IER             1       /*  Interrupt Enable          */
77 #define IIR             2       /*  Interrupt ID              */
78 #define FCR             2       /*  FIFO control              */
79 #define LCR             3       /*  Line control              */
80 #define MCR             4       /*  Modem control             */
81 #define LSR             5       /*  Line Status               */
82 #define MSR             6       /*  Modem Status              */
83 #define DLL             0       /*  Divisor Latch Low         */
84 #define DLH             1       /*  Divisor latch High        */
85 
86 static int early_serial_putc(unsigned char ch)
87 {
88 	unsigned timeout = 0xffff;
89 
90 	while ((inb(early_serial_base + LSR) & XMTRDY) == 0 && --timeout)
91 		cpu_relax();
92 	outb(ch, early_serial_base + TXR);
93 	return timeout ? 0 : -1;
94 }
95 
96 static void early_serial_write(struct console *con, const char *s, unsigned n)
97 {
98 	while (*s && n-- > 0) {
99 		if (*s == '\n')
100 			early_serial_putc('\r');
101 		early_serial_putc(*s);
102 		s++;
103 	}
104 }
105 
106 #define DEFAULT_BAUD 9600
107 
108 static __init void early_serial_init(char *s)
109 {
110 	unsigned char c;
111 	unsigned divisor;
112 	unsigned baud = DEFAULT_BAUD;
113 	char *e;
114 
115 	if (*s == ',')
116 		++s;
117 
118 	if (*s) {
119 		unsigned port;
120 		if (!strncmp(s, "0x", 2)) {
121 			early_serial_base = simple_strtoul(s, &e, 16);
122 		} else {
123 			static const int __initconst bases[] = { 0x3f8, 0x2f8 };
124 
125 			if (!strncmp(s, "ttyS", 4))
126 				s += 4;
127 			port = simple_strtoul(s, &e, 10);
128 			if (port > 1 || s == e)
129 				port = 0;
130 			early_serial_base = bases[port];
131 		}
132 		s += strcspn(s, ",");
133 		if (*s == ',')
134 			s++;
135 	}
136 
137 	outb(0x3, early_serial_base + LCR);	/* 8n1 */
138 	outb(0, early_serial_base + IER);	/* no interrupt */
139 	outb(0, early_serial_base + FCR);	/* no fifo */
140 	outb(0x3, early_serial_base + MCR);	/* DTR + RTS */
141 
142 	if (*s) {
143 		baud = simple_strtoul(s, &e, 0);
144 		if (baud == 0 || s == e)
145 			baud = DEFAULT_BAUD;
146 	}
147 
148 	divisor = 115200 / baud;
149 	c = inb(early_serial_base + LCR);
150 	outb(c | DLAB, early_serial_base + LCR);
151 	outb(divisor & 0xff, early_serial_base + DLL);
152 	outb((divisor >> 8) & 0xff, early_serial_base + DLH);
153 	outb(c & ~DLAB, early_serial_base + LCR);
154 }
155 
156 static struct console early_serial_console = {
157 	.name =		"earlyser",
158 	.write =	early_serial_write,
159 	.flags =	CON_PRINTBUFFER,
160 	.index =	-1,
161 };
162 
163 /* Direct interface for emergencies */
164 static struct console *early_console = &early_vga_console;
165 static int __initdata early_console_initialized;
166 
167 asmlinkage void early_printk(const char *fmt, ...)
168 {
169 	char buf[512];
170 	int n;
171 	va_list ap;
172 
173 	va_start(ap, fmt);
174 	n = vscnprintf(buf, sizeof(buf), fmt, ap);
175 	early_console->write(early_console, buf, n);
176 	va_end(ap);
177 }
178 
179 static inline void early_console_register(struct console *con, int keep_early)
180 {
181 	if (early_console->index != -1) {
182 		printk(KERN_CRIT "ERROR: earlyprintk= %s already used\n",
183 		       con->name);
184 		return;
185 	}
186 	early_console = con;
187 	if (keep_early)
188 		early_console->flags &= ~CON_BOOT;
189 	else
190 		early_console->flags |= CON_BOOT;
191 	register_console(early_console);
192 }
193 
194 static int __init setup_early_printk(char *buf)
195 {
196 	int keep;
197 
198 	if (!buf)
199 		return 0;
200 
201 	if (early_console_initialized)
202 		return 0;
203 	early_console_initialized = 1;
204 
205 	keep = (strstr(buf, "keep") != NULL);
206 
207 	while (*buf != '\0') {
208 		if (!strncmp(buf, "serial", 6)) {
209 			early_serial_init(buf + 6);
210 			early_console_register(&early_serial_console, keep);
211 		}
212 		if (!strncmp(buf, "ttyS", 4)) {
213 			early_serial_init(buf + 4);
214 			early_console_register(&early_serial_console, keep);
215 		}
216 		if (!strncmp(buf, "vga", 3) &&
217 		    boot_params.screen_info.orig_video_isVGA == 1) {
218 			max_xpos = boot_params.screen_info.orig_video_cols;
219 			max_ypos = boot_params.screen_info.orig_video_lines;
220 			current_ypos = boot_params.screen_info.orig_y;
221 			early_console_register(&early_vga_console, keep);
222 		}
223 #ifdef CONFIG_EARLY_PRINTK_DBGP
224 		if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4))
225 			early_console_register(&early_dbgp_console, keep);
226 #endif
227 #ifdef CONFIG_HVC_XEN
228 		if (!strncmp(buf, "xen", 3))
229 			early_console_register(&xenboot_console, keep);
230 #endif
231 		buf++;
232 	}
233 	return 0;
234 }
235 
236 early_param("earlyprintk", setup_early_printk);
237