drivers/tty/serial/earlycon.c

   1 /*
   2  * Copyright (C) 2014 Linaro Ltd.
   3  * Author: Rob Herring <robh@kernel.org>
   4  *
   5  * Based on 8250 earlycon:
   6  * (c) Copyright 2004 Hewlett-Packard Development Company, L.P.
   7  *      Bjorn Helgaas <bjorn.helgaas@hp.com>
   8  *
   9  * This program is free software: you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License version 2 as
  11  * published by the Free Software Foundation.
  12  */
  13
  14 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  15
  16 #include <linux/console.h>
  17 #include <linux/kernel.h>
  18 #include <linux/init.h>
  19 #include <linux/io.h>
  20 #include <linux/serial_core.h>
  21 #include <linux/sizes.h>
  22 #include <linux/of.h>
  23 #include <linux/of_fdt.h>
  24 #include <linux/acpi.h>
  25
  26 #ifdef CONFIG_FIX_EARLYCON_MEM
  27 #include <asm/fixmap.h>
  28 #endif
  29
  30 #include <asm/serial.h>
  31
  32 static struct console early_con = {
  33         .name =         "uart",         /* fixed up at earlycon registration */
  34         .flags =        CON_PRINTBUFFER | CON_BOOT,
  35         .index =        0,
  36 };
  37
  38 static struct earlycon_device early_console_dev = {
  39         .con = &early_con,
  40 };
  41
  42 static void __iomem * __init earlycon_map(resource_size_t paddr, size_t size)
  43 {
  44         void __iomem *base;
  45 #ifdef CONFIG_FIX_EARLYCON_MEM
  46         set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK);
  47         base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
  48         base += paddr & ~PAGE_MASK;
  49 #else
  50         base = ioremap(paddr, size);
  51 #endif
  52         if (!base)
  53                 pr_err("%s: Couldn't map %pa\n", __func__, &paddr);
  54
  55         return base;
  56 }
  57
  58 static void __init earlycon_init(struct earlycon_device *device,
  59                                  const char *name)
  60 {
  61         struct console *earlycon = device->con;
  62         struct uart_port *port = &device->port;
  63         const char *s;
  64         size_t len;
  65
  66         /* scan backwards from end of string for first non-numeral */
  67         for (s = name + strlen(name);
  68              s > name && s[-1] >= '0' && s[-1] <= '9';
  69              s--)
  70                 ;
  71         if (*s)
  72                 earlycon->index = simple_strtoul(s, NULL, 10);
  73         len = s - name;
  74         strlcpy(earlycon->name, name, min(len + 1, sizeof(earlycon->name)));
  75         earlycon->data = &early_console_dev;
  76
  77         if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
  78             port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
  79                 pr_info("%s%d at MMIO%s %pa (options '%s')\n",
  80                         earlycon->name, earlycon->index,
  81                         (port->iotype == UPIO_MEM) ? "" :
  82                         (port->iotype == UPIO_MEM16) ? "16" :
  83                         (port->iotype == UPIO_MEM32) ? "32" : "32be",
  84                         &port->mapbase, device->options);
  85         else
  86                 pr_info("%s%d at I/O port 0x%lx (options '%s')\n",
  87                         earlycon->name, earlycon->index,
  88                         port->iobase, device->options);
  89 }
  90
  91 static int __init parse_options(struct earlycon_device *device, char *options)
  92 {
  93         struct uart_port *port = &device->port;
  94         int length;
  95         resource_size_t addr;
  96
  97         if (uart_parse_earlycon(options, &port->iotype, &addr, &options))
  98                 return -EINVAL;
  99
 100         switch (port->iotype) {
 101         case UPIO_MEM:
 102                 port->mapbase = addr;
 103                 break;
 104         case UPIO_MEM16:
 105                 port->regshift = 1;
 106                 port->mapbase = addr;
 107                 break;
 108         case UPIO_MEM32:
 109         case UPIO_MEM32BE:
 110                 port->regshift = 2;
 111                 port->mapbase = addr;
 112                 break;
 113         case UPIO_PORT:
 114                 port->iobase = addr;
 115                 break;
 116         default:
 117                 return -EINVAL;
 118         }
 119
 120         if (options) {
 121                 device->baud = simple_strtoul(options, NULL, 0);
 122                 length = min(strcspn(options, " ") + 1,
 123                              (size_t)(sizeof(device->options)));
 124                 strlcpy(device->options, options, length);
 125         }
 126
 127         return 0;
 128 }
 129
 130 static int __init register_earlycon(char *buf, const struct earlycon_id *match)
 131 {
 132         int err;
 133         struct uart_port *port = &early_console_dev.port;
 134
 135         /* On parsing error, pass the options buf to the setup function */
 136         if (buf && !parse_options(&early_console_dev, buf))
 137                 buf = NULL;
 138
 139         spin_lock_init(&port->lock);
 140         port->uartclk = BASE_BAUD * 16;
 141         if (port->mapbase)
 142                 port->membase = earlycon_map(port->mapbase, 64);
 143
 144         earlycon_init(&early_console_dev, match->name);
 145         err = match->setup(&early_console_dev, buf);
 146         if (err < 0)
 147                 return err;
 148         if (!early_console_dev.con->write)
 149                 return -ENODEV;
 150
 151         register_console(early_console_dev.con);
 152         return 0;
 153 }
 154
 155 /**
 156  *      setup_earlycon - match and register earlycon console
 157  *      @buf:   earlycon param string
 158  *
 159  *      Registers the earlycon console matching the earlycon specified
 160  *      in the param string @buf. Acceptable param strings are of the form
 161  *         <name>,io|mmio|mmio32|mmio32be,<addr>,<options>
 162  *         <name>,0x<addr>,<options>
 163  *         <name>,<options>
 164  *         <name>
 165  *
 166  *      Only for the third form does the earlycon setup() method receive the
 167  *      <options> string in the 'options' parameter; all other forms set
 168  *      the parameter to NULL.
 169  *
 170  *      Returns 0 if an attempt to register the earlycon was made,
 171  *      otherwise negative error code
 172  */
 173 int __init setup_earlycon(char *buf)
 174 {
 175         const struct earlycon_id *match;
 176
 177         if (!buf || !buf[0])
 178                 return -EINVAL;
 179
 180         if (early_con.flags & CON_ENABLED)
 181                 return -EALREADY;
 182
 183         for (match = __earlycon_table; match < __earlycon_table_end; match++) {
 184                 size_t len = strlen(match->name);
 185
 186                 if (strncmp(buf, match->name, len))
 187                         continue;
 188
 189                 if (buf[len]) {
 190                         if (buf[len] != ',')
 191                                 continue;
 192                         buf += len + 1;
 193                 } else
 194                         buf = NULL;
 195
 196                 return register_earlycon(buf, match);
 197         }
 198
 199         return -ENOENT;
 200 }
 201
 202 /*
 203  * When CONFIG_ACPI_SPCR_TABLE is defined, "earlycon" without parameters in
 204  * command line does not start DT earlycon immediately, instead it defers
 205  * starting it until DT/ACPI decision is made.  At that time if ACPI is enabled
 206  * call parse_spcr(), else call early_init_dt_scan_chosen_stdout()
 207  */
 208 bool earlycon_init_is_deferred __initdata;
 209
 210 /* early_param wrapper for setup_earlycon() */
 211 static int __init param_setup_earlycon(char *buf)
 212 {
 213         int err;
 214
 215         /*
 216          * Just 'earlycon' is a valid param for devicetree earlycons;
 217          * don't generate a warning from parse_early_params() in that case
 218          */
 219         if (!buf || !buf[0]) {
 220                 if (IS_ENABLED(CONFIG_ACPI_SPCR_TABLE)) {
 221                         earlycon_init_is_deferred = true;
 222                         return 0;
 223                 } else {
 224                         return early_init_dt_scan_chosen_stdout();
 225                 }
 226         }
 227
 228         err = setup_earlycon(buf);
 229         if (err == -ENOENT || err == -EALREADY)
 230                 return 0;
 231         return err;
 232 }
 233 early_param("earlycon", param_setup_earlycon);
 234
 235 #ifdef CONFIG_OF_EARLY_FLATTREE
 236
 237 int __init of_setup_earlycon(const struct earlycon_id *match,
 238                              unsigned long node,
 239                              const char *options)
 240 {
 241         int err;
 242         struct uart_port *port = &early_console_dev.port;
 243         const __be32 *val;
 244         bool big_endian;
 245         u64 addr;
 246
 247         spin_lock_init(&port->lock);
 248         port->iotype = UPIO_MEM;
 249         addr = of_flat_dt_translate_address(node);
 250         if (addr == OF_BAD_ADDR) {
 251                 pr_warn("[%s] bad address\n", match->name);
 252                 return -ENXIO;
 253         }
 254         port->mapbase = addr;
 255         port->uartclk = BASE_BAUD * 16;
 256         port->membase = earlycon_map(port->mapbase, SZ_4K);
 257
 258         val = of_get_flat_dt_prop(node, "reg-offset", NULL);
 259         if (val)
 260                 port->mapbase += be32_to_cpu(*val);
 261         val = of_get_flat_dt_prop(node, "reg-shift", NULL);
 262         if (val)
 263                 port->regshift = be32_to_cpu(*val);
 264         big_endian = of_get_flat_dt_prop(node, "big-endian", NULL) != NULL ||
 265                 (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
 266                  of_get_flat_dt_prop(node, "native-endian", NULL) != NULL);
 267         val = of_get_flat_dt_prop(node, "reg-io-width", NULL);
 268         if (val) {
 269                 switch (be32_to_cpu(*val)) {
 270                 case 1:
 271                         port->iotype = UPIO_MEM;
 272                         break;
 273                 case 2:
 274                         port->iotype = UPIO_MEM16;
 275                         break;
 276                 case 4:
 277                         port->iotype = (big_endian) ? UPIO_MEM32BE : UPIO_MEM32;
 278                         break;
 279                 default:
 280                         pr_warn("[%s] unsupported reg-io-width\n", match->name);
 281                         return -EINVAL;
 282                 }
 283         }
 284
 285         if (options) {
 286                 strlcpy(early_console_dev.options, options,
 287                         sizeof(early_console_dev.options));
 288         }
 289         earlycon_init(&early_console_dev, match->name);
 290         err = match->setup(&early_console_dev, options);
 291         if (err < 0)
 292                 return err;
 293         if (!early_console_dev.con->write)
 294                 return -ENODEV;
 295
 296
 297         register_console(early_console_dev.con);
 298         return 0;
 299 }
 300
 301 #endif /* CONFIG_OF_EARLY_FLATTREE */