drivers/acpi/spcr.c

   1 /*
   2  * Copyright (c) 2012, Intel Corporation
   3  * Copyright (c) 2015, Red Hat, Inc.
   4  * Copyright (c) 2015, 2016 Linaro Ltd.
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  *
  10  */
  11
  12 #define pr_fmt(fmt) "ACPI: SPCR: " fmt
  13
  14 #include <linux/acpi.h>
  15 #include <linux/console.h>
  16 #include <linux/kernel.h>
  17 #include <linux/serial_core.h>
  18
  19 /**
  20  * parse_spcr() - parse ACPI SPCR table and add preferred console
  21  *
  22  * @earlycon: set up earlycon for the console specified by the table
  23  *
  24  * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
  25  * defined to parse ACPI SPCR table.  As a result of the parsing preferred
  26  * console is registered and if @earlycon is true, earlycon is set up.
  27  *
  28  * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
  29  * from arch inintialization code as soon as the DT/ACPI decision is made.
  30  *
  31  */
  32 int __init parse_spcr(bool earlycon)
  33 {
  34         static char opts[64];
  35         struct acpi_table_spcr *table;
  36         acpi_status status;
  37         char *uart;
  38         char *iotype;
  39         int baud_rate;
  40         int err;
  41
  42         if (acpi_disabled)
  43                 return -ENODEV;
  44
  45         status = acpi_get_table(ACPI_SIG_SPCR, 0,
  46                                 (struct acpi_table_header **)&table);
  47
  48         if (ACPI_FAILURE(status))
  49                 return -ENOENT;
  50
  51         if (table->header.revision < 2) {
  52                 err = -ENOENT;
  53                 pr_err("wrong table version\n");
  54                 goto done;
  55         }
  56
  57         iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ?
  58                         "mmio" : "io";
  59
  60         switch (table->interface_type) {
  61         case ACPI_DBG2_ARM_SBSA_32BIT:
  62                 iotype = "mmio32";
  63                 /* fall through */
  64         case ACPI_DBG2_ARM_PL011:
  65         case ACPI_DBG2_ARM_SBSA_GENERIC:
  66         case ACPI_DBG2_BCM2835:
  67                 uart = "pl011";
  68                 break;
  69         case ACPI_DBG2_16550_COMPATIBLE:
  70         case ACPI_DBG2_16550_SUBSET:
  71                 uart = "uart";
  72                 break;
  73         default:
  74                 err = -ENOENT;
  75                 goto done;
  76         }
  77
  78         switch (table->baud_rate) {
  79         case 3:
  80                 baud_rate = 9600;
  81                 break;
  82         case 4:
  83                 baud_rate = 19200;
  84                 break;
  85         case 6:
  86                 baud_rate = 57600;
  87                 break;
  88         case 7:
  89                 baud_rate = 115200;
  90                 break;
  91         default:
  92                 err = -ENOENT;
  93                 goto done;
  94         }
  95
  96         snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
  97                  table->serial_port.address, baud_rate);
  98
  99         pr_info("console: %s\n", opts);
 100
 101         if (earlycon)
 102                 setup_earlycon(opts);
 103
 104         err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
 105
 106 done:
 107         acpi_put_table((struct acpi_table_header *)table);
 108         return err;
 109 }