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 #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/mod_devicetable.h>
  20
  21 #ifdef CONFIG_FIX_EARLYCON_MEM
  22 #include <asm/fixmap.h>
  23 #endif
  24
  25 #include <asm/serial.h>
  26
  27 static struct console early_con = {
  28         .name =         "uart", /* 8250 console switch requires this name */
  29         .flags =        CON_PRINTBUFFER | CON_BOOT,
  30         .index =        -1,
  31 };
  32
  33 static struct earlycon_device early_console_dev = {
  34         .con = &early_con,
  35 };
  36
  37 static const struct of_device_id __earlycon_of_table_sentinel
  38         __used __section(__earlycon_of_table_end);
  39
  40 static void __iomem * __init earlycon_map(unsigned long paddr, size_t size)
  41 {
  42         void __iomem *base;
  43 #ifdef CONFIG_FIX_EARLYCON_MEM
  44         set_fixmap_io(FIX_EARLYCON_MEM_BASE, paddr & PAGE_MASK);
  45         base = (void __iomem *)__fix_to_virt(FIX_EARLYCON_MEM_BASE);
  46         base += paddr & ~PAGE_MASK;
  47 #else
  48         base = ioremap(paddr, size);
  49 #endif
  50         if (!base)
  51                 pr_err("%s: Couldn't map 0x%llx\n", __func__,
  52                        (unsigned long long)paddr);
  53
  54         return base;
  55 }
  56
  57 static int __init parse_options(struct earlycon_device *device,
  58                                 char *options)
  59 {
  60         struct uart_port *port = &device->port;
  61         int mmio, mmio32, length;
  62         unsigned long addr;
  63
  64         if (!options)
  65                 return -ENODEV;
  66
  67         mmio = !strncmp(options, "mmio,", 5);
  68         mmio32 = !strncmp(options, "mmio32,", 7);
  69         if (mmio || mmio32) {
  70                 port->iotype = (mmio ? UPIO_MEM : UPIO_MEM32);
  71                 options += mmio ? 5 : 7;
  72                 addr = simple_strtoul(options, NULL, 0);
  73                 port->mapbase = addr;
  74                 if (mmio32)
  75                         port->regshift = 2;
  76         } else if (!strncmp(options, "io,", 3)) {
  77                 port->iotype = UPIO_PORT;
  78                 options += 3;
  79                 addr = simple_strtoul(options, NULL, 0);
  80                 port->iobase = addr;
  81                 mmio = 0;
  82         } else if (!strncmp(options, "0x", 2)) {
  83                 port->iotype = UPIO_MEM;
  84                 addr = simple_strtoul(options, NULL, 0);
  85                 port->mapbase = addr;
  86         } else {
  87                 return -EINVAL;
  88         }
  89
  90         port->uartclk = BASE_BAUD * 16;
  91
  92         options = strchr(options, ',');
  93         if (options) {
  94                 options++;
  95                 device->baud = simple_strtoul(options, NULL, 0);
  96                 length = min(strcspn(options, " ") + 1,
  97                              (size_t)(sizeof(device->options)));
  98                 strlcpy(device->options, options, length);
  99         }
 100
 101         if (mmio || mmio32)
 102                 pr_info("Early serial console at MMIO%s 0x%llx (options '%s')\n",
 103                         mmio32 ? "32" : "",
 104                         (unsigned long long)port->mapbase,
 105                         device->options);
 106         else
 107                 pr_info("Early serial console at I/O port 0x%lx (options '%s')\n",
 108                         port->iobase,
 109                         device->options);
 110
 111         return 0;
 112 }
 113
 114 int __init setup_earlycon(char *buf, const char *match,
 115                           int (*setup)(struct earlycon_device *, const char *))
 116 {
 117         int err;
 118         size_t len;
 119         struct uart_port *port = &early_console_dev.port;
 120
 121         if (!buf || !match || !setup)
 122                 return 0;
 123
 124         len = strlen(match);
 125         if (strncmp(buf, match, len))
 126                 return 0;
 127         if (buf[len] && (buf[len] != ','))
 128                 return 0;
 129
 130         buf += len + 1;
 131
 132         err = parse_options(&early_console_dev, buf);
 133         /* On parsing error, pass the options buf to the setup function */
 134         if (!err)
 135                 buf = NULL;
 136
 137         if (port->mapbase)
 138                 port->membase = earlycon_map(port->mapbase, 64);
 139
 140         early_console_dev.con->data = &early_console_dev;
 141         err = setup(&early_console_dev, buf);
 142         if (err < 0)
 143                 return err;
 144         if (!early_console_dev.con->write)
 145                 return -ENODEV;
 146
 147         register_console(early_console_dev.con);
 148         return 0;
 149 }
 150
 151 int __init of_setup_earlycon(unsigned long addr,
 152                              int (*setup)(struct earlycon_device *, const char *))
 153 {
 154         int err;
 155         struct uart_port *port = &early_console_dev.port;
 156
 157         port->iotype = UPIO_MEM;
 158         port->mapbase = addr;
 159         port->uartclk = BASE_BAUD * 16;
 160         port->membase = earlycon_map(addr, SZ_4K);
 161
 162         early_console_dev.con->data = &early_console_dev;
 163         err = setup(&early_console_dev, NULL);
 164         if (err < 0)
 165                 return err;
 166         if (!early_console_dev.con->write)
 167                 return -ENODEV;
 168
 169
 170         register_console(early_console_dev.con);
 171         return 0;
 172 }