Commit 0231d000 authored by Prarit Bhargava's avatar Prarit Bhargava Committed by Rafael J. Wysocki
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ACPI: SPCR: Make SPCR available to x86 



SPCR is currently only enabled or ARM64 and x86 can use SPCR to setup
an early console.

General fixes include updating Documentation & Kconfig (for x86),
updating comments, and changing parse_spcr() to acpi_parse_spcr(),
and earlycon_init_is_deferred to earlycon_acpi_spcr_enable to be
more descriptive.

On x86, many systems have a valid SPCR table but the table version is
not 2 so the table version check must be a warning.

On ARM64 when the kernel parameter earlycon is used both the early console
and console are enabled.  On x86, only the earlycon should be enabled by
by default.  Modify acpi_parse_spcr() to allow options for initializing
the early console and console separately.

Signed-off-by: default avatarPrarit Bhargava <prarit@redhat.com>
Acked-by: default avatarIngo Molnar <mingo@kernel.org>
Reviewed-by: default avatarMark Salter <msalter@redhat.com>
Tested-by: default avatarMark Salter <msalter@redhat.com>
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
parent 89067434

Documentation/admin-guide/kernel-parameters.txt

+6 −3
Original line number Diff line number Diff line
@@ -917,9 +917,12 @@ 


	earlycon=	[KNL] Output early console device and options.



			When used with no options, the early console is

			determined by the stdout-path property in device

			tree's chosen node.

			[ARM64] The early console is determined by the

			stdout-path property in device tree's chosen node,

			or determined by the ACPI SPCR table.



			[X86] When used with no options the early console is

			determined by the ACPI SPCR table.



		cdns,<addr>[,options]

			Start an early, polled-mode console on a Cadence

arch/arm64/kernel/acpi.c

+2 −2
Original line number Diff line number Diff line
@@ -230,10 +230,10 @@ void __init acpi_boot_table_init(void) 


done:

	if (acpi_disabled) {

		if (earlycon_init_is_deferred)

		if (earlycon_acpi_spcr_enable)

			early_init_dt_scan_chosen_stdout();

	} else {

		parse_spcr(earlycon_init_is_deferred);

		acpi_parse_spcr(earlycon_acpi_spcr_enable, true);

		if (IS_ENABLED(CONFIG_ACPI_BGRT))

			acpi_table_parse(ACPI_SIG_BGRT, acpi_parse_bgrt);

	}

arch/x86/kernel/acpi/boot.c

+3 −0
Original line number Diff line number Diff line
@@ -36,6 +36,7 @@ 
#include <linux/ioport.h>

#include <linux/pci.h>

#include <linux/efi-bgrt.h>

#include <linux/serial_core.h>



#include <asm/e820/api.h>

#include <asm/irqdomain.h>
@@ -1625,6 +1626,8 @@ int __init acpi_boot_init(void) 
	if (!acpi_noirq)

		x86_init.pci.init = pci_acpi_init;



	/* Do not enable ACPI SPCR console by default */

	acpi_parse_spcr(earlycon_acpi_spcr_enable, false);

	return 0;

}

drivers/acpi/Kconfig

+6 −1
Original line number Diff line number Diff line
@@ -79,7 +79,12 @@ config ACPI_DEBUGGER_USER 
endif



config ACPI_SPCR_TABLE

	bool

	bool "ACPI Serial Port Console Redirection Support"

	default y if X86

	help

	  Enable support for Serial Port Console Redirection (SPCR) Table.

	  This table provides information about the configuration of the

	  earlycon console.



config ACPI_LPIT

	bool

drivers/acpi/spcr.c

+15 −14
Original line number Diff line number Diff line
@@ -21,7 +21,7 @@ 
 * occasionally getting stuck as 1. To avoid the potential for a hang, check

 * TXFE == 0 instead of BUSY == 1. This may not be suitable for all UART

 * implementations, so only do so if an affected platform is detected in

 * parse_spcr().

 * acpi_parse_spcr().

 */

bool qdf2400_e44_present;

EXPORT_SYMBOL(qdf2400_e44_present);
@@ -74,19 +74,21 @@ static bool xgene_8250_erratum_present(struct acpi_table_spcr *tb) 
}



/**

 * parse_spcr() - parse ACPI SPCR table and add preferred console

 * acpi_parse_spcr() - parse ACPI SPCR table and add preferred console

 *

 * @earlycon: set up earlycon for the console specified by the table

 * @enable_earlycon: set up earlycon for the console specified by the table

 * @enable_console: setup 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.

 * console is registered and if @enable_earlycon is true, earlycon is set up.

 * If @enable_console is true the system console is also configured.

 *

 * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called

 * from arch initialization code as soon as the DT/ACPI decision is made.

 *

 */

int __init parse_spcr(bool earlycon)

int __init acpi_parse_spcr(bool enable_earlycon, bool enable_console)

{

	static char opts[64];

	struct acpi_table_spcr *table;
@@ -105,11 +107,8 @@ int __init parse_spcr(bool earlycon) 
	if (ACPI_FAILURE(status))

		return -ENOENT;



	if (table->header.revision < 2) {

		err = -ENOENT;

		pr_err("wrong table version\n");

		goto done;

	}

	if (table->header.revision < 2)

		pr_info("SPCR table version %d\n", table->header.revision);



	if (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {

		switch (ACPI_ACCESS_BIT_WIDTH((
@@ -185,7 +184,7 @@ int __init parse_spcr(bool earlycon) 
	 */

	if (qdf2400_erratum_44_present(&table->header)) {

		qdf2400_e44_present = true;

		if (earlycon)

		if (enable_earlycon)

			uart = "qdf2400_e44";

	}
@@ -205,11 +204,13 @@ int __init parse_spcr(bool earlycon) 


	pr_info("console: %s\n", opts);



	if (earlycon)

	if (enable_earlycon)

		setup_earlycon(opts);



	if (enable_console)

		err = add_preferred_console(uart, 0, opts + strlen(uart) + 1);



	else

		err = 0;

done:

	acpi_put_table((struct acpi_table_header *)table);

	return err;

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