root/arch/x86/kernel/early_printk.c

DEFINITIONS

1. early_vga_write
2. io_serial_in
3. io_serial_out
4. early_serial_putc
5. early_serial_write
6. early_serial_hw_init
7. early_serial_init
8. mem32_serial_out
9. mem32_serial_in
10. early_pci_serial_init
11. early_console_register
12. setup_early_printk

   1 // SPDX-License-Identifier: GPL-2.0
   2 #include <linux/console.h>
   3 #include <linux/kernel.h>
   4 #include <linux/init.h>
   5 #include <linux/string.h>
   6 #include <linux/screen_info.h>
   7 #include <linux/usb/ch9.h>
   8 #include <linux/pci_regs.h>
   9 #include <linux/pci_ids.h>
  10 #include <linux/errno.h>
  11 #include <asm/io.h>
  12 #include <asm/processor.h>
  13 #include <asm/fcntl.h>
  14 #include <asm/setup.h>
  15 #include <xen/hvc-console.h>
  16 #include <asm/pci-direct.h>
  17 #include <asm/fixmap.h>
  18 #include <asm/intel-mid.h>
  19 #include <asm/pgtable.h>
  20 #include <linux/usb/ehci_def.h>
  21 #include <linux/usb/xhci-dbgp.h>
  22 #include <linux/efi.h>
  23 #include <asm/efi.h>
  24 #include <asm/pci_x86.h>
  25 
  26 /* Simple VGA output */
  27 #define VGABASE         (__ISA_IO_base + 0xb8000)
  28 
  29 static int max_ypos = 25, max_xpos = 80;
  30 static int current_ypos = 25, current_xpos;
  31 
  32 static void early_vga_write(struct console *con, const char *str, unsigned n)
  33 {
  34         char c;
  35         int  i, k, j;
  36 
  37         while ((c = *str++) != '\0' && n-- > 0) {
  38                 if (current_ypos >= max_ypos) {
  39                         /* scroll 1 line up */
  40                         for (k = 1, j = 0; k < max_ypos; k++, j++) {
  41                                 for (i = 0; i < max_xpos; i++) {
  42                                         writew(readw(VGABASE+2*(max_xpos*k+i)),
  43                                                VGABASE + 2*(max_xpos*j + i));
  44                                 }
  45                         }
  46                         for (i = 0; i < max_xpos; i++)
  47                                 writew(0x720, VGABASE + 2*(max_xpos*j + i));
  48                         current_ypos = max_ypos-1;
  49                 }
  50 #ifdef CONFIG_KGDB_KDB
  51                 if (c == '\b') {
  52                         if (current_xpos > 0)
  53                                 current_xpos--;
  54                 } else if (c == '\r') {
  55                         current_xpos = 0;
  56                 } else
  57 #endif
  58                 if (c == '\n') {
  59                         current_xpos = 0;
  60                         current_ypos++;
  61                 } else if (c != '\r')  {
  62                         writew(((0x7 << 8) | (unsigned short) c),
  63                                VGABASE + 2*(max_xpos*current_ypos +
  64                                                 current_xpos++));
  65                         if (current_xpos >= max_xpos) {
  66                                 current_xpos = 0;
  67                                 current_ypos++;
  68                         }
  69                 }
  70         }
  71 }
  72 
  73 static struct console early_vga_console = {
  74         .name =         "earlyvga",
  75         .write =        early_vga_write,
  76         .flags =        CON_PRINTBUFFER,
  77         .index =        -1,
  78 };
  79 
  80 /* Serial functions loosely based on a similar package from Klaus P. Gerlicher */
  81 
  82 static unsigned long early_serial_base = 0x3f8;  /* ttyS0 */
  83 
  84 #define XMTRDY          0x20
  85 
  86 #define DLAB            0x80
  87 
  88 #define TXR             0       /*  Transmit register (WRITE) */
  89 #define RXR             0       /*  Receive register  (READ)  */
  90 #define IER             1       /*  Interrupt Enable          */
  91 #define IIR             2       /*  Interrupt ID              */
  92 #define FCR             2       /*  FIFO control              */
  93 #define LCR             3       /*  Line control              */
  94 #define MCR             4       /*  Modem control             */
  95 #define LSR             5       /*  Line Status               */
  96 #define MSR             6       /*  Modem Status              */
  97 #define DLL             0       /*  Divisor Latch Low         */
  98 #define DLH             1       /*  Divisor latch High        */
  99 
 100 static unsigned int io_serial_in(unsigned long addr, int offset)
 101 {
 102         return inb(addr + offset);
 103 }
 104 
 105 static void io_serial_out(unsigned long addr, int offset, int value)
 106 {
 107         outb(value, addr + offset);
 108 }
 109 
 110 static unsigned int (*serial_in)(unsigned long addr, int offset) = io_serial_in;
 111 static void (*serial_out)(unsigned long addr, int offset, int value) = io_serial_out;
 112 
 113 static int early_serial_putc(unsigned char ch)
 114 {
 115         unsigned timeout = 0xffff;
 116 
 117         while ((serial_in(early_serial_base, LSR) & XMTRDY) == 0 && --timeout)
 118                 cpu_relax();
 119         serial_out(early_serial_base, TXR, ch);
 120         return timeout ? 0 : -1;
 121 }
 122 
 123 static void early_serial_write(struct console *con, const char *s, unsigned n)
 124 {
 125         while (*s && n-- > 0) {
 126                 if (*s == '\n')
 127                         early_serial_putc('\r');
 128                 early_serial_putc(*s);
 129                 s++;
 130         }
 131 }
 132 
 133 static __init void early_serial_hw_init(unsigned divisor)
 134 {
 135         unsigned char c;
 136 
 137         serial_out(early_serial_base, LCR, 0x3);        /* 8n1 */
 138         serial_out(early_serial_base, IER, 0);  /* no interrupt */
 139         serial_out(early_serial_base, FCR, 0);  /* no fifo */
 140         serial_out(early_serial_base, MCR, 0x3);        /* DTR + RTS */
 141 
 142         c = serial_in(early_serial_base, LCR);
 143         serial_out(early_serial_base, LCR, c | DLAB);
 144         serial_out(early_serial_base, DLL, divisor & 0xff);
 145         serial_out(early_serial_base, DLH, (divisor >> 8) & 0xff);
 146         serial_out(early_serial_base, LCR, c & ~DLAB);
 147 }
 148 
 149 #define DEFAULT_BAUD 9600
 150 
 151 static __init void early_serial_init(char *s)
 152 {
 153         unsigned divisor;
 154         unsigned long baud = DEFAULT_BAUD;
 155         char *e;
 156 
 157         if (*s == ',')
 158                 ++s;
 159 
 160         if (*s) {
 161                 unsigned port;
 162                 if (!strncmp(s, "0x", 2)) {
 163                         early_serial_base = simple_strtoul(s, &e, 16);
 164                 } else {
 165                         static const int __initconst bases[] = { 0x3f8, 0x2f8 };
 166 
 167                         if (!strncmp(s, "ttyS", 4))
 168                                 s += 4;
 169                         port = simple_strtoul(s, &e, 10);
 170                         if (port > 1 || s == e)
 171                                 port = 0;
 172                         early_serial_base = bases[port];
 173                 }
 174                 s += strcspn(s, ",");
 175                 if (*s == ',')
 176                         s++;
 177         }
 178 
 179         if (*s) {
 180                 baud = simple_strtoull(s, &e, 0);
 181 
 182                 if (baud == 0 || s == e)
 183                         baud = DEFAULT_BAUD;
 184         }
 185 
 186         /* Convert from baud to divisor value */
 187         divisor = 115200 / baud;
 188 
 189         /* These will always be IO based ports */
 190         serial_in = io_serial_in;
 191         serial_out = io_serial_out;
 192 
 193         /* Set up the HW */
 194         early_serial_hw_init(divisor);
 195 }
 196 
 197 #ifdef CONFIG_PCI
 198 static void mem32_serial_out(unsigned long addr, int offset, int value)
 199 {
 200         u32 __iomem *vaddr = (u32 __iomem *)addr;
 201         /* shift implied by pointer type */
 202         writel(value, vaddr + offset);
 203 }
 204 
 205 static unsigned int mem32_serial_in(unsigned long addr, int offset)
 206 {
 207         u32 __iomem *vaddr = (u32 __iomem *)addr;
 208         /* shift implied by pointer type */
 209         return readl(vaddr + offset);
 210 }
 211 
 212 /*
 213  * early_pci_serial_init()
 214  *
 215  * This function is invoked when the early_printk param starts with "pciserial"
 216  * The rest of the param should be "[force],B:D.F,baud", where B, D & F describe
 217  * the location of a PCI device that must be a UART device. "force" is optional
 218  * and overrides the use of an UART device with a wrong PCI class code.
 219  */
 220 static __init void early_pci_serial_init(char *s)
 221 {
 222         unsigned divisor;
 223         unsigned long baud = DEFAULT_BAUD;
 224         u8 bus, slot, func;
 225         u32 classcode, bar0;
 226         u16 cmdreg;
 227         char *e;
 228         int force = 0;
 229 
 230         if (*s == ',')
 231                 ++s;
 232 
 233         if (*s == 0)
 234                 return;
 235 
 236         /* Force the use of an UART device with wrong class code */
 237         if (!strncmp(s, "force,", 6)) {
 238                 force = 1;
 239                 s += 6;
 240         }
 241 
 242         /*
 243          * Part the param to get the BDF values
 244          */
 245         bus = (u8)simple_strtoul(s, &e, 16);
 246         s = e;
 247         if (*s != ':')
 248                 return;
 249         ++s;
 250         slot = (u8)simple_strtoul(s, &e, 16);
 251         s = e;
 252         if (*s != '.')
 253                 return;
 254         ++s;
 255         func = (u8)simple_strtoul(s, &e, 16);
 256         s = e;
 257 
 258         /* A baud might be following */
 259         if (*s == ',')
 260                 s++;
 261 
 262         /*
 263          * Find the device from the BDF
 264          */
 265         cmdreg = read_pci_config(bus, slot, func, PCI_COMMAND);
 266         classcode = read_pci_config(bus, slot, func, PCI_CLASS_REVISION);
 267         bar0 = read_pci_config(bus, slot, func, PCI_BASE_ADDRESS_0);
 268 
 269         /*
 270          * Verify it is a UART type device
 271          */
 272         if (((classcode >> 16 != PCI_CLASS_COMMUNICATION_MODEM) &&
 273              (classcode >> 16 != PCI_CLASS_COMMUNICATION_SERIAL)) ||
 274            (((classcode >> 8) & 0xff) != 0x02)) /* 16550 I/F at BAR0 */ {
 275                 if (!force)
 276                         return;
 277         }
 278 
 279         /*
 280          * Determine if it is IO or memory mapped
 281          */
 282         if (bar0 & 0x01) {
 283                 /* it is IO mapped */
 284                 serial_in = io_serial_in;
 285                 serial_out = io_serial_out;
 286                 early_serial_base = bar0&0xfffffffc;
 287                 write_pci_config(bus, slot, func, PCI_COMMAND,
 288                                                 cmdreg|PCI_COMMAND_IO);
 289         } else {
 290                 /* It is memory mapped - assume 32-bit alignment */
 291                 serial_in = mem32_serial_in;
 292                 serial_out = mem32_serial_out;
 293                 /* WARNING! assuming the address is always in the first 4G */
 294                 early_serial_base =
 295                         (unsigned long)early_ioremap(bar0 & 0xfffffff0, 0x10);
 296                 write_pci_config(bus, slot, func, PCI_COMMAND,
 297                                                 cmdreg|PCI_COMMAND_MEMORY);
 298         }
 299 
 300         /*
 301          * Initialize the hardware
 302          */
 303         if (*s) {
 304                 if (strcmp(s, "nocfg") == 0)
 305                         /* Sometimes, we want to leave the UART alone
 306                          * and assume the BIOS has set it up correctly.
 307                          * "nocfg" tells us this is the case, and we
 308                          * should do no more setup.
 309                          */
 310                         return;
 311                 if (kstrtoul(s, 0, &baud) < 0 || baud == 0)
 312                         baud = DEFAULT_BAUD;
 313         }
 314 
 315         /* Convert from baud to divisor value */
 316         divisor = 115200 / baud;
 317 
 318         /* Set up the HW */
 319         early_serial_hw_init(divisor);
 320 }
 321 #endif
 322 
 323 static struct console early_serial_console = {
 324         .name =         "earlyser",
 325         .write =        early_serial_write,
 326         .flags =        CON_PRINTBUFFER,
 327         .index =        -1,
 328 };
 329 
 330 static void early_console_register(struct console *con, int keep_early)
 331 {
 332         if (con->index != -1) {
 333                 printk(KERN_CRIT "ERROR: earlyprintk= %s already used\n",
 334                        con->name);
 335                 return;
 336         }
 337         early_console = con;
 338         if (keep_early)
 339                 early_console->flags &= ~CON_BOOT;
 340         else
 341                 early_console->flags |= CON_BOOT;
 342         register_console(early_console);
 343 }
 344 
 345 static int __init setup_early_printk(char *buf)
 346 {
 347         int keep;
 348 
 349         if (!buf)
 350                 return 0;
 351 
 352         if (early_console)
 353                 return 0;
 354 
 355         keep = (strstr(buf, "keep") != NULL);
 356 
 357         while (*buf != '\0') {
 358                 if (!strncmp(buf, "serial", 6)) {
 359                         buf += 6;
 360                         early_serial_init(buf);
 361                         early_console_register(&early_serial_console, keep);
 362                         if (!strncmp(buf, ",ttyS", 5))
 363                                 buf += 5;
 364                 }
 365                 if (!strncmp(buf, "ttyS", 4)) {
 366                         early_serial_init(buf + 4);
 367                         early_console_register(&early_serial_console, keep);
 368                 }
 369 #ifdef CONFIG_PCI
 370                 if (!strncmp(buf, "pciserial", 9)) {
 371                         early_pci_serial_init(buf + 9);
 372                         early_console_register(&early_serial_console, keep);
 373                         buf += 9; /* Keep from match the above "serial" */
 374                 }
 375 #endif
 376                 if (!strncmp(buf, "vga", 3) &&
 377                     boot_params.screen_info.orig_video_isVGA == 1) {
 378                         max_xpos = boot_params.screen_info.orig_video_cols;
 379                         max_ypos = boot_params.screen_info.orig_video_lines;
 380                         current_ypos = boot_params.screen_info.orig_y;
 381                         early_console_register(&early_vga_console, keep);
 382                 }
 383 #ifdef CONFIG_EARLY_PRINTK_DBGP
 384                 if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4))
 385                         early_console_register(&early_dbgp_console, keep);
 386 #endif
 387 #ifdef CONFIG_HVC_XEN
 388                 if (!strncmp(buf, "xen", 3))
 389                         early_console_register(&xenboot_console, keep);
 390 #endif
 391 #ifdef CONFIG_EARLY_PRINTK_USB_XDBC
 392                 if (!strncmp(buf, "xdbc", 4))
 393                         early_xdbc_parse_parameter(buf + 4);
 394 #endif
 395 
 396                 buf++;
 397         }
 398         return 0;
 399 }
 400 
 401 early_param("earlyprintk", setup_early_printk);