root/drivers/tty/serial/earlycon.c

DEFINITIONS

1. earlycon_map
2. earlycon_init
3. parse_options
4. register_earlycon
5. setup_earlycon
6. param_setup_earlycon
7. of_setup_earlycon

   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         struct uart_port *port = &device->port;
  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         if (port->iotype == UPIO_MEM || port->iotype == UPIO_MEM16 ||
  75             port->iotype == UPIO_MEM32 || port->iotype == UPIO_MEM32BE)
  76                 pr_info("%s%d at MMIO%s %pa (options '%s')\n",
  77                         earlycon->name, earlycon->index,
  78                         (port->iotype == UPIO_MEM) ? "" :
  79                         (port->iotype == UPIO_MEM16) ? "16" :
  80                         (port->iotype == UPIO_MEM32) ? "32" : "32be",
  81                         &port->mapbase, device->options);
  82         else
  83                 pr_info("%s%d at I/O port 0x%lx (options '%s')\n",
  84                         earlycon->name, earlycon->index,
  85                         port->iobase, device->options);
  86 }
  87 
  88 static int __init parse_options(struct earlycon_device *device, char *options)
  89 {
  90         struct uart_port *port = &device->port;
  91         int length;
  92         resource_size_t addr;
  93 
  94         if (uart_parse_earlycon(options, &port->iotype, &addr, &options))
  95                 return -EINVAL;
  96 
  97         switch (port->iotype) {
  98         case UPIO_MEM:
  99                 port->mapbase = addr;
 100                 break;
 101         case UPIO_MEM16:
 102                 port->regshift = 1;
 103                 port->mapbase = addr;
 104                 break;
 105         case UPIO_MEM32:
 106         case UPIO_MEM32BE:
 107                 port->regshift = 2;
 108                 port->mapbase = addr;
 109                 break;
 110         case UPIO_PORT:
 111                 port->iobase = addr;
 112                 break;
 113         default:
 114                 return -EINVAL;
 115         }
 116 
 117         if (options) {
 118                 device->baud = simple_strtoul(options, NULL, 0);
 119                 length = min(strcspn(options, " ") + 1,
 120                              (size_t)(sizeof(device->options)));
 121                 strlcpy(device->options, options, length);
 122         }
 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 **p_match;
 173 
 174         if (!buf || !buf[0])
 175                 return -EINVAL;
 176 
 177         if (early_con.flags & CON_ENABLED)
 178                 return -EALREADY;
 179 
 180         for (p_match = __earlycon_table; p_match < __earlycon_table_end;
 181              p_match++) {
 182                 const struct earlycon_id *match = *p_match;
 183                 size_t len = strlen(match->name);
 184 
 185                 if (strncmp(buf, match->name, len))
 186                         continue;
 187 
 188                 if (buf[len]) {
 189                         if (buf[len] != ',')
 190                                 continue;
 191                         buf += len + 1;
 192                 } else
 193                         buf = NULL;
 194 
 195                 return register_earlycon(buf, match);
 196         }
 197 
 198         return -ENOENT;
 199 }
 200 
 201 /*
 202  * This defers the initialization of the early console until after ACPI has
 203  * been initialized.
 204  */
 205 bool earlycon_acpi_spcr_enable __initdata;
 206 
 207 /* early_param wrapper for setup_earlycon() */
 208 static int __init param_setup_earlycon(char *buf)
 209 {
 210         int err;
 211 
 212         /* Just 'earlycon' is a valid param for devicetree and ACPI SPCR. */
 213         if (!buf || !buf[0]) {
 214                 if (IS_ENABLED(CONFIG_ACPI_SPCR_TABLE)) {
 215                         earlycon_acpi_spcr_enable = true;
 216                         return 0;
 217                 } else if (!buf) {
 218                         return early_init_dt_scan_chosen_stdout();
 219                 }
 220         }
 221 
 222         err = setup_earlycon(buf);
 223         if (err == -ENOENT || err == -EALREADY)
 224                 return 0;
 225         return err;
 226 }
 227 early_param("earlycon", param_setup_earlycon);
 228 
 229 #ifdef CONFIG_OF_EARLY_FLATTREE
 230 
 231 int __init of_setup_earlycon(const struct earlycon_id *match,
 232                              unsigned long node,
 233                              const char *options)
 234 {
 235         int err;
 236         struct uart_port *port = &early_console_dev.port;
 237         const __be32 *val;
 238         bool big_endian;
 239         u64 addr;
 240 
 241         spin_lock_init(&port->lock);
 242         port->iotype = UPIO_MEM;
 243         addr = of_flat_dt_translate_address(node);
 244         if (addr == OF_BAD_ADDR) {
 245                 pr_warn("[%s] bad address\n", match->name);
 246                 return -ENXIO;
 247         }
 248         port->mapbase = addr;
 249 
 250         val = of_get_flat_dt_prop(node, "reg-offset", NULL);
 251         if (val)
 252                 port->mapbase += be32_to_cpu(*val);
 253         port->membase = earlycon_map(port->mapbase, SZ_4K);
 254 
 255         val = of_get_flat_dt_prop(node, "reg-shift", NULL);
 256         if (val)
 257                 port->regshift = be32_to_cpu(*val);
 258         big_endian = of_get_flat_dt_prop(node, "big-endian", NULL) != NULL ||
 259                 (IS_ENABLED(CONFIG_CPU_BIG_ENDIAN) &&
 260                  of_get_flat_dt_prop(node, "native-endian", NULL) != NULL);
 261         val = of_get_flat_dt_prop(node, "reg-io-width", NULL);
 262         if (val) {
 263                 switch (be32_to_cpu(*val)) {
 264                 case 1:
 265                         port->iotype = UPIO_MEM;
 266                         break;
 267                 case 2:
 268                         port->iotype = UPIO_MEM16;
 269                         break;
 270                 case 4:
 271                         port->iotype = (big_endian) ? UPIO_MEM32BE : UPIO_MEM32;
 272                         break;
 273                 default:
 274                         pr_warn("[%s] unsupported reg-io-width\n", match->name);
 275                         return -EINVAL;
 276                 }
 277         }
 278 
 279         val = of_get_flat_dt_prop(node, "current-speed", NULL);
 280         if (val)
 281                 early_console_dev.baud = be32_to_cpu(*val);
 282 
 283         val = of_get_flat_dt_prop(node, "clock-frequency", NULL);
 284         if (val)
 285                 port->uartclk = be32_to_cpu(*val);
 286 
 287         if (options) {
 288                 early_console_dev.baud = simple_strtoul(options, NULL, 0);
 289                 strlcpy(early_console_dev.options, options,
 290                         sizeof(early_console_dev.options));
 291         }
 292         earlycon_init(&early_console_dev, match->name);
 293         err = match->setup(&early_console_dev, options);
 294         if (err < 0)
 295                 return err;
 296         if (!early_console_dev.con->write)
 297                 return -ENODEV;
 298 
 299 
 300         register_console(early_console_dev.con);
 301         return 0;
 302 }
 303 
 304 #endif /* CONFIG_OF_EARLY_FLATTREE */