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ACPI: parse SPCR and enable matching console

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'ARM Server Base Boot Requiremets' [1] mentions SPCR (Serial Port
Console Redirection Table) [2] as a mandatory ACPI table that
specifies the configuration of serial console.

Defer initialization of DT earlycon until ACPI/DT decision is made.

Parse the ACPI SPCR table, setup earlycon if required,
enable specified console.

Thanks to Peter Hurley for explaining how this should work.

[1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0044a/index.html
[2] https://msdn.microsoft.com/en-us/library/windows/hardware/dn639132(v=vs.85).aspx

Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Tested-by: Christopher Covington <cov@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Aleksey Makarov
2016-09-27 23:54:13 +03:00
committed by Greg Kroah-Hartman
parent d503187b6c
commit ad1696f6f0
6 changed files with 146 additions and 3 deletions
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111
drivers/acpi/spcr.c Normal file
View File

@@ -0,0 +1,111 @@
/*
* Copyright (c) 2012, Intel Corporation
* Copyright (c) 2015, Red Hat, Inc.
* Copyright (c) 2015, 2016 Linaro Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#define pr_fmt(fmt) "ACPI: SPCR: " fmt
#include <linux/acpi.h>
#include <linux/console.h>
#include <linux/kernel.h>
#include <linux/serial_core.h>
/**
* parse_spcr() - parse ACPI SPCR table and add preferred console
*
* @earlycon: set up earlycon for the console specified by the table
*
* For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be
* defined to parse ACPI SPCR table. As a result of the parsing preferred
* console is registered and if @earlycon is true, earlycon is set up.
*
* When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called
* from arch inintialization code as soon as the DT/ACPI decision is made.
*
*/
int __init parse_spcr(bool earlycon)
{
static char opts[64];
struct acpi_table_spcr *table;
acpi_size table_size;
acpi_status status;
char *uart;
char *iotype;
int baud_rate;
int err;
if (acpi_disabled)
return -ENODEV;
status = acpi_get_table_with_size(ACPI_SIG_SPCR, 0,
(struct acpi_table_header **)&table,
&table_size);
if (ACPI_FAILURE(status))
return -ENOENT;
if (table->header.revision < 2) {
err = -ENOENT;
pr_err("wrong table version\n");
goto done;
}
iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ?
"mmio" : "io";
switch (table->interface_type) {
case ACPI_DBG2_ARM_SBSA_32BIT:
iotype = "mmio32";
/* fall through */
case ACPI_DBG2_ARM_PL011:
case ACPI_DBG2_ARM_SBSA_GENERIC:
case ACPI_DBG2_BCM2835:
uart = "pl011";
break;
case ACPI_DBG2_16550_COMPATIBLE:
case ACPI_DBG2_16550_SUBSET:
uart = "uart";
break;
default:
err = -ENOENT;
goto done;
}
switch (table->baud_rate) {
case 3:
baud_rate = 9600;
break;
case 4:
baud_rate = 19200;
break;
case 6:
baud_rate = 57600;
break;
case 7:
baud_rate = 115200;
break;
default:
err = -ENOENT;
goto done;
}
snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype,
table->serial_port.address, baud_rate);
pr_info("console: %s\n", opts);
if (earlycon)
setup_earlycon(opts);
err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);
done:
early_acpi_os_unmap_memory((void __iomem *)table, table_size);
return err;
}