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 */
 32int __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
106done:
107	acpi_put_table((struct acpi_table_header *)table);
108	return err;
109}