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
  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(unsigned long 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 0x%llx\n", __func__,
  51                        (unsigned long long)paddr);
  52
  53         return base;
  54 }
  55
  56 static void __init earlycon_init(struct earlycon_device *device,
  57                                  const char *name)
  58 {
  59         struct console *earlycon = device->con;
  60         const char *s;
  61         size_t len;
  62
  63         /* scan backwards from end of string for first non-numeral */
  64         for (s = name + strlen(name);
  65              s > name && s[-1] >= '0' && s[-1] <= '9';
  66              s--)
  67                 ;
  68         if (*s)
  69                 earlycon->index = simple_strtoul(s, NULL, 10);
  70         len = s - name;
  71         strlcpy(earlycon->name, name, min(len + 1, sizeof(earlycon->name)));
  72         earlycon->data = &early_console_dev;
  73 }
  74
  75 static int __init parse_options(struct earlycon_device *device, char *options)
  76 {
  77         struct uart_port *port = &device->port;
  78         int length;
  79         unsigned long addr;
  80
  81         if (uart_parse_earlycon(options, &port->iotype, &addr, &options))
  82                 return -EINVAL;
  83
  84         switch (port->iotype) {
  85         case UPIO_MEM:
  86                 port->mapbase = addr;
  87                 break;
  88         case UPIO_MEM16:
  89                 port->regshift = 1;
  90                 port->mapbase = addr;
  91                 break;
  92         case UPIO_MEM32:
  93         case UPIO_MEM32BE:
  94                 port->regshift = 2;
  95                 port->mapbase = addr;
  96                 break;
  97         case UPIO_PORT:
  98                 port->iobase = addr;
  99                 break;
 100         default:
 101                 return -EINVAL;
 102         }
 103
 104         if (options) {
 105                 device->baud = simple_strtoul(options, NULL, 0);
 106                 length = min(strcspn(options, " ") + 1,
 107                              (size_t)(sizeof(device->options)));
 108                 strlcpy(device->options, options, length);
 109         }
 110
 111         if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
 112             port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
 113                 pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n",
 114                         (port->iotype == UPIO_MEM) ? "" :
 115                         (port->iotype == UPIO_MEM16) ? "16" :
 116                         (port->iotype == UPIO_MEM32) ? "32" : "32be",
 117                         (unsigned long long)port->mapbase,
 118                         device->options);
 119         else
 120                 pr_info("Early serial console at I/O port 0x%lx (options '%s')\n",
 121                         port->iobase,
 122                         device->options);
 123
 124         return 0;
 125 }
 126
 127 static int __init register_earlycon(char *buf, const struct earlycon_id *match)
 128 {
 129         int err;
 130         struct uart_port *port = &early_console_dev.port;
 131
 132         /* On parsing error, pass the options buf to the setup function */
 133         if (buf && !parse_options(&early_console_dev, buf))
 134                 buf = NULL;
 135
 136         spin_lock_init(&port->lock);
 137         port->uartclk = BASE_BAUD * 16;
 138         if (port->mapbase)
 139                 port->membase = earlycon_map(port->mapbase, 64);
 140
 141         earlycon_init(&early_console_dev, match->name);
 142         err = match->setup(&early_console_dev, buf);
 143         if (err < 0)
 144                 return err;
 145         if (!early_console_dev.con->write)
 146                 return -ENODEV;
 147
 148         register_console(early_console_dev.con);
 149         return 0;
 150 }
 151
 152 /**
 153  *      setup_earlycon - match and register earlycon console
 154  *      @buf:   earlycon param string
 155  *
 156  *      Registers the earlycon console matching the earlycon specified
 157  *      in the param string @buf. Acceptable param strings are of the form
 158  *         <name>,io|mmio|mmio32|mmio32be,<addr>,<options>
 159  *         <name>,0x<addr>,<options>
 160  *         <name>,<options>
 161  *         <name>
 162  *
 163  *      Only for the third form does the earlycon setup() method receive the
 164  *      <options> string in the 'options' parameter; all other forms set
 165  *      the parameter to NULL.
 166  *
 167  *      Returns 0 if an attempt to register the earlycon was made,
 168  *      otherwise negative error code
 169  */
 170 int __init setup_earlycon(char *buf)
 171 {
 172         const struct earlycon_id *match;
 173
 174         if (!buf || !buf[0])
 175                 return -EINVAL;
 176
 177         if (early_con.flags & CON_ENABLED)
 178                 return -EALREADY;
 179
 180         for (match = __earlycon_table; match < __earlycon_table_end; match++) {
 181                 size_t len = strlen(match->name);
 182
 183                 if (strncmp(buf, match->name, len))
 184                         continue;
 185
 186                 if (buf[len]) {
 187                         if (buf[len] != ',')
 188                                 continue;
 189                         buf += len + 1;
 190                 } else
 191                         buf = NULL;
 192
 193                 return register_earlycon(buf, match);
 194         }
 195
 196         return -ENOENT;
 197 }
 198
 199 /* early_param wrapper for setup_earlycon() */
 200 static int __init param_setup_earlycon(char *buf)
 201 {
 202         int err;
 203
 204         /*
 205          * Just 'earlycon' is a valid param for devicetree earlycons;
 206          * don't generate a warning from parse_early_params() in that case
 207          */
 208         if (!buf || !buf[0])
 209                 return 0;
 210
 211         err = setup_earlycon(buf);
 212         if (err == -ENOENT || err == -EALREADY)
 213                 return 0;
 214         return err;
 215 }
 216 early_param("earlycon", param_setup_earlycon);
 217
 218 #ifdef CONFIG_OF_EARLY_FLATTREE
 219
 220 int __init of_setup_earlycon(unsigned long addr,
 221                              const struct earlycon_id *match,
 222                              const char *options)
 223 {
 224         int err;
 225         struct uart_port *port = &early_console_dev.port;
 226
 227         spin_lock_init(&port->lock);
 228         port->iotype = UPIO_MEM;
 229         port->mapbase = addr;
 230         port->uartclk = BASE_BAUD * 16;
 231         port->membase = earlycon_map(addr, SZ_4K);
 232
 233         if (options) {
 234                 strlcpy(early_console_dev.options, options,
 235                         sizeof(early_console_dev.options));
 236         }
 237         earlycon_init(&early_console_dev, match->name);
 238         err = match->setup(&early_console_dev, options);
 239         if (err < 0)
 240                 return err;
 241         if (!early_console_dev.con->write)
 242                 return -ENODEV;
 243
 244
 245         register_console(early_console_dev.con);
 246         return 0;
 247 }
 248
 249 #endif /* CONFIG_OF_EARLY_FLATTREE */