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_size table_size;
  37         acpi_status status;
  38         char *uart;
  39         char *iotype;
  40         int baud_rate;
  41         int err;
  42
  43         if (acpi_disabled)
  44                 return -ENODEV;
  45
  46         status = acpi_get_table_with_size(ACPI_SIG_SPCR, 0,
  47                                           (struct acpi_table_header **)&table,
  48                                           &table_size);
  49
  50         if (ACPI_FAILURE(status))
  51                 return -ENOENT;
  52
  53         if (table->header.revision < 2) {
  54                 err = -ENOENT;
  55                 pr_err("wrong table version\n");
  56                 goto done;
  57         }
  58
  59         iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ?
  60                         "mmio" : "io";
  61
  62         switch (table->interface_type) {
  63         case ACPI_DBG2_ARM_SBSA_32BIT:
  64                 iotype = "mmio32";
  65                 /* fall through */
  66         case ACPI_DBG2_ARM_PL011:
  67         case ACPI_DBG2_ARM_SBSA_GENERIC:
  68         case ACPI_DBG2_BCM2835:
  69                 uart = "pl011";
  70                 break;
  71         case ACPI_DBG2_16550_COMPATIBLE:
  72         case ACPI_DBG2_16550_SUBSET:
  73                 uart = "uart";
  74                 break;
  75         default:
  76                 err = -ENOENT;
  77                 goto done;
  78         }
  79
  80         switch (table->baud_rate) {
  81         case 3:
  82                 baud_rate = 9600;
  83                 break;
  84         case 4:
  85                 baud_rate = 19200;
  86                 break;
  87         case 6:
  88                 baud_rate = 57600;
  89                 break;
  90         case 7:
  91                 baud_rate = 115200;
  92                 break;
  93         default:
  94                 err = -ENOENT;
  95                 goto done;
  96         }
  97
  98         snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
  99                  table->serial_port.address, baud_rate);
 100
 101         pr_info("console: %s\n", opts);
 102
 103         if (earlycon)
 104                 setup_earlycon(opts);
 105
 106         err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
 107
 108 done:
 109         early_acpi_os_unmap_memory((void __iomem *)table, table_size);
 110         return err;
 111 }