drivers/tty/serial/earlycon.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2014 Linaro Ltd.
   4  * Author: Rob Herring <robh@kernel.org>
   5  *
   6  * Based on 8250 earlycon:
   7  * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
   8  *      Bjorn Helgaas <bjorn.helgaas@hp.com>
   9  */
  10
  11 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/console.h>
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/io.h>
  17 #include <linux/serial_core.h>
  18 #include <linux/sizes.h>
  19 #include <linux/of.h>
  20 #include <linux/of_fdt.h>
  21 #include <linux/acpi.h>
  22
  23 #ifdef CONFIG_FIX_EARLYCON_MEM
  24 #include <asm/fixmap.h>
  25 #endif
  26
  27 #include <asm/serial.h>
  28
  29 static struct console early_con = {
  30         .name =         "uart",         /* fixed up at earlycon registration */
  31         .flags =        CON_PRINTBUFFER | CON_BOOT,
  32         .index =        0,
  33 };
  34
  35 static struct earlycon_device early_console_dev = {
  36         .con = &early_con,
  37 };
  38
  39 static void __iomem * __init earlycon_map(resource_size_t paddr, size_t size)
  40 {
  41         void __iomem *base;
  42 #ifdef CONFIG_FIX_EARLYCON_MEM
  43         set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK);
  44         base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
  45         base += paddr & ~PAGE_MASK;
  46 #else
  47         base = ioremap(paddr, size);
  48 #endif
  49         if (!base)
  50                 pr_err("%s: Couldn't map %pa\n", __func__, &paddr);
  51
  52         return base;
  53 }
  54
  55 static void __init earlycon_init(struct earlycon_device *device,
  56                                  const char *name)
  57 {
  58         struct console *earlycon = device->con;
  59         const char *s;
  60         size_t len;
  61
  62         /* scan backwards from end of string for first non-numeral */
  63         for (s = name + strlen(name);
  64              s > name && s[-1] >= '0' && s[-1] <= '9';
  65              s--)
  66                 ;
  67         if (*s)
  68                 earlycon->index = simple_strtoul(s, NULL, 10);
  69         len = s - name;
  70         strscpy(earlycon->name, name, min(len + 1, sizeof(earlycon->name)));
  71         earlycon->data = &early_console_dev;
  72 }
  73
  74 static void __init earlycon_print_info(struct earlycon_device *device)
  75 {
  76         struct console *earlycon = device->con;
  77         struct uart_port *port = &device->port;
  78
  79         if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
  80             port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
  81                 pr_info("%s%d at MMIO%s %pa (options '%s')\n",
  82                         earlycon->name, earlycon->index,
  83                         (port->iotype == UPIO_MEM) ? "" :
  84                         (port->iotype == UPIO_MEM16) ? "16" :
  85                         (port->iotype == UPIO_MEM32) ? "32" : "32be",
  86                         &port->mapbase, device->options);
  87         else
  88                 pr_info("%s%d at I/O port 0x%lx (options '%s')\n",
  89                         earlycon->name, earlycon->index,
  90                         port->iobase, device->options);
  91 }
  92
  93 static int __init parse_options(struct earlycon_device *device, char *options)
  94 {
  95         struct uart_port *port = &device->port;
  96         int length;
  97         resource_size_t addr;
  98
  99         if (uart_parse_earlycon(options, &port->iotype, &addr, &options))
 100                 return -EINVAL;
 101
 102         switch (port->iotype) {
 103         case UPIO_MEM:
 104                 port->mapbase = addr;
 105                 break;
 106         case UPIO_MEM16:
 107                 port->regshift = 1;
 108                 port->mapbase = addr;
 109                 break;
 110         case UPIO_MEM32:
 111         case UPIO_MEM32BE:
 112                 port->regshift = 2;
 113                 port->mapbase = addr;
 114                 break;
 115         case UPIO_PORT:
 116                 port->iobase = addr;
 117                 break;
 118         default:
 119                 return -EINVAL;
 120         }
 121
 122         if (options) {
 123                 char *uartclk;
 124
 125                 device->baud = simple_strtoul(options, NULL, 0);
 126                 uartclk = strchr(options, ',');
 127                 if (uartclk && kstrtouint(uartclk + 1, 0, &port->uartclk) < 0)
 128                         pr_warn("[%s] unsupported earlycon uart clkrate option\n",
 129                                 options);
 130                 length = min(strcspn(options, " ") + 1,
 131                              (size_t)(sizeof(device->options)));
 132                 strscpy(device->options, options, length);
 133         }
 134
 135         return 0;
 136 }
 137
 138 static int __init register_earlycon(char *buf, const struct earlycon_id *match)
 139 {
 140         int err;
 141         struct uart_port *port = &early_console_dev.port;
 142
 143         /* On parsing error, pass the options buf to the setup function */
 144         if (buf && !parse_options(&early_console_dev, buf))
 145                 buf = NULL;
 146
 147         spin_lock_init(&port->lock);
 148         if (!port->uartclk)
 149                 port->uartclk = BASE_BAUD * 16;
 150         if (port->mapbase)
 151                 port->membase = earlycon_map(port->mapbase, 64);
 152
 153         earlycon_init(&early_console_dev, match->name);
 154         err = match->setup(&early_console_dev, buf);
 155         earlycon_print_info(&early_console_dev);
 156         if (err < 0)
 157                 return err;
 158         if (!early_console_dev.con->write)
 159                 return -ENODEV;
 160
 161         register_console(early_console_dev.con);
 162         return 0;
 163 }
 164
 165 /**
 166  *      setup_earlycon - match and register earlycon console
 167  *      @buf:   earlycon param string
 168  *
 169  *      Registers the earlycon console matching the earlycon specified
 170  *      in the param string @buf. Acceptable param strings are of the form
 171  *         <name>,io|mmio|mmio32|mmio32be,<addr>,<options>
 172  *         <name>,0x<addr>,<options>
 173  *         <name>,<options>
 174  *         <name>
 175  *
 176  *      Only for the third form does the earlycon setup() method receive the
 177  *      <options> string in the 'options' parameter; all other forms set
 178  *      the parameter to NULL.
 179  *
 180  *      Returns 0 if an attempt to register the earlycon was made,
 181  *      otherwise negative error code
 182  */
 183 int __init setup_earlycon(char *buf)
 184 {
 185         const struct earlycon_id *match;
 186         bool empty_compatible = true;
 187
 188         if (!buf || !buf[0])
 189                 return -EINVAL;
 190
 191         if (console_is_registered(&early_con))
 192                 return -EALREADY;
 193
 194 again:
 195         for (match = __earlycon_table; match < __earlycon_table_end; match++) {
 196                 size_t len = strlen(match->name);
 197
 198                 if (strncmp(buf, match->name, len))
 199                         continue;
 200
 201                 /* prefer entries with empty compatible */
 202                 if (empty_compatible && *match->compatible)
 203                         continue;
 204
 205                 if (buf[len]) {
 206                         if (buf[len] != ',')
 207                                 continue;
 208                         buf += len + 1;
 209                 } else
 210                         buf = NULL;
 211
 212                 return register_earlycon(buf, match);
 213         }
 214
 215         if (empty_compatible) {
 216                 empty_compatible = false;
 217                 goto again;
 218         }
 219
 220         return -ENOENT;
 221 }
 222
 223 /*
 224  * This defers the initialization of the early console until after ACPI has
 225  * been initialized.
 226  */
 227 bool earlycon_acpi_spcr_enable __initdata;
 228
 229 /* early_param wrapper for setup_earlycon() */
 230 static int __init param_setup_earlycon(char *buf)
 231 {
 232         int err;
 233
 234         /* Just 'earlycon' is a valid param for devicetree and ACPI SPCR. */
 235         if (!buf || !buf[0]) {
 236                 if (IS_ENABLED(CONFIG_ACPI_SPCR_TABLE)) {
 237                         earlycon_acpi_spcr_enable = true;
 238                         return 0;
 239                 } else if (!buf) {
 240                         return early_init_dt_scan_chosen_stdout();
 241                 }
 242         }
 243
 244         err = setup_earlycon(buf);
 245         if (err == -ENOENT || err == -EALREADY)
 246                 return 0;
 247         return err;
 248 }
 249 early_param("earlycon", param_setup_earlycon);
 250
 251 /*
 252  * The `console` parameter is overloaded. It's handled here as an early param
 253  * and in `printk.c` as a late param. It's possible to specify an early
 254  * `bootconsole` using `earlycon=uartXXXX` (handled above), or via
 255  * the `console=uartXXX` alias. See the comment in `8250_early.c`.
 256  */
 257 static int __init param_setup_earlycon_console_alias(char *buf)
 258 {
 259         /*
 260          * A plain `console` parameter must not enable the SPCR `bootconsole`
 261          * like a plain `earlycon` does.
 262          *
 263          * A `console=` parameter that specifies an empty value is used to
 264          * disable the `console`, not the `earlycon` `bootconsole`. The
 265          * disabling of the `console` is handled by `printk.c`.
 266          */
 267         if (!buf || !buf[0])
 268                 return 0;
 269
 270         return param_setup_earlycon(buf);
 271 }
 272 early_param("console", param_setup_earlycon_console_alias);
 273
 274 #ifdef CONFIG_OF_EARLY_FLATTREE
 275
 276 int __init of_setup_earlycon(const struct earlycon_id *match,
 277                              unsigned long node,
 278                              const char *options)
 279 {
 280         int err;
 281         struct uart_port *port = &early_console_dev.port;
 282         const __be32 *val;
 283         bool big_endian;
 284         u64 addr;
 285
 286         if (console_is_registered(&early_con))
 287                 return -EALREADY;
 288
 289         spin_lock_init(&port->lock);
 290         port->iotype = UPIO_MEM;
 291         addr = of_flat_dt_translate_address(node);
 292         if (addr == OF_BAD_ADDR) {
 293                 pr_warn("[%s] bad address\n", match->name);
 294                 return -ENXIO;
 295         }
 296         port->mapbase = addr;
 297
 298         val = of_get_flat_dt_prop(node, "reg-offset", NULL);
 299         if (val)
 300                 port->mapbase += be32_to_cpu(*val);
 301         port->membase = earlycon_map(port->mapbase, SZ_4K);
 302
 303         val = of_get_flat_dt_prop(node, "reg-shift", NULL);
 304         if (val)
 305                 port->regshift = be32_to_cpu(*val);
 306         big_endian = of_get_flat_dt_prop(node, "big-endian", NULL) != NULL ||
 307                 (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
 308                  of_get_flat_dt_prop(node, "native-endian", NULL) != NULL);
 309         val = of_get_flat_dt_prop(node, "reg-io-width", NULL);
 310         if (val) {
 311                 switch (be32_to_cpu(*val)) {
 312                 case 1:
 313                         port->iotype = UPIO_MEM;
 314                         break;
 315                 case 2:
 316                         port->iotype = UPIO_MEM16;
 317                         break;
 318                 case 4:
 319                         port->iotype = (big_endian) ? UPIO_MEM32BE : UPIO_MEM32;
 320                         break;
 321                 default:
 322                         pr_warn("[%s] unsupported reg-io-width\n", match->name);
 323                         return -EINVAL;
 324                 }
 325         }
 326
 327         val = of_get_flat_dt_prop(node, "current-speed", NULL);
 328         if (val)
 329                 early_console_dev.baud = be32_to_cpu(*val);
 330
 331         val = of_get_flat_dt_prop(node, "clock-frequency", NULL);
 332         if (val)
 333                 port->uartclk = be32_to_cpu(*val);
 334
 335         if (options) {
 336                 early_console_dev.baud = simple_strtoul(options, NULL, 0);
 337                 strscpy(early_console_dev.options, options,
 338                         sizeof(early_console_dev.options));
 339         }
 340         earlycon_init(&early_console_dev, match->name);
 341         err = match->setup(&early_console_dev, options);
 342         earlycon_print_info(&early_console_dev);
 343         if (err < 0)
 344                 return err;
 345         if (!early_console_dev.con->write)
 346                 return -ENODEV;
 347
 348
 349         register_console(early_console_dev.con);
 350         return 0;
 351 }
 352
 353 #endif /* CONFIG_OF_EARLY_FLATTREE */