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Message-ID: <CAHp75VeosA-54-G1oSo3cBo2KRO+rK=Q4DJxmz93WxUPORqf1Q@mail.gmail.com>
Date: Mon, 25 Jan 2016 16:14:22 +0200
From: Andy Shevchenko <andy.shevchenko@...il.com>
To: Aleksey Makarov <aleksey.makarov@...aro.org>
Cc: "linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
linux-arm Mailing List <linux-arm-kernel@...ts.infradead.org>,
"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
Graeme Gregory <graeme.gregory@...aro.org>,
Russell King <linux@....linux.org.uk>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
"Rafael J . Wysocki" <rjw@...ysocki.net>,
Leif Lindholm <leif.lindholm@...aro.org>,
Catalin Marinas <catalin.marinas@....com>,
Will Deacon <will.deacon@....com>, Len Brown <lenb@...nel.org>
Subject: Re: [PATCH 2/3] ACPI: parse SPCR and enable matching console
On Mon, Jan 25, 2016 at 1:45 PM, Aleksey Makarov
<aleksey.makarov@...aro.org> wrote:
> 'ARM Server Base Boot Requiremets' [1] mention SPCR
> (Serial Port Console Redirection Table) [2] as a mandatory ACPI table
> that specifies the configuration of serial console.
>
> Parse this table and check if any registered console match
> the description. If it does, enable that console.
>
> To implement that, introduce a new member
> int (*acpi_match)(struct console *, struct acpi_table_spcr *)
> of struct console. It allows drivers to check if they provide
> a matching console device.
>
> [1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0044a/index.html
> [2] http://msdn.microsoft.com/en-us/library/windows/hardware/dn639131(v=vs.85).aspx
Can you split this to several patches?
I see preparatory patch in console code, i.e.
delete_from_console_list(), adding SPCR support to ACPI, enabling it.
>
> Signed-off-by: Aleksey Makarov <aleksey.makarov@...aro.org>
> ---
> arch/arm64/Kconfig | 1 +
> drivers/acpi/Kconfig | 3 ++
> drivers/acpi/Makefile | 1 +
> drivers/acpi/spcr.c | 85 +++++++++++++++++++++++++++++++++++++++++++++++++
> include/linux/console.h | 12 +++++++
> kernel/printk/printk.c | 82 +++++++++++++++++++++++++++++++++++++----------
> 6 files changed, 167 insertions(+), 17 deletions(-)
> create mode 100644 drivers/acpi/spcr.c
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 573bebc..bf31e3c 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -4,6 +4,7 @@ config ARM64
> select ACPI_GENERIC_GSI if ACPI
> select ACPI_PCI_HOST_GENERIC if ACPI
> select ACPI_REDUCED_HARDWARE_ONLY if ACPI
> + select ACPI_SPCR_TABLE if ACPI
> select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
> select ARCH_HAS_ELF_RANDOMIZE
> select ARCH_HAS_GCOV_PROFILE_ALL
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index e315061..142a338 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -60,6 +60,9 @@ config ACPI_CCA_REQUIRED
> config IORT_TABLE
> bool
>
> +config ACPI_SPCR_TABLE
> + bool
> +
> config ACPI_DEBUGGER
> bool "AML debugger interface (EXPERIMENTAL)"
> select ACPI_DEBUG
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 265eb90..8316859 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -81,6 +81,7 @@ obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o
> obj-$(CONFIG_ACPI_BGRT) += bgrt.o
> obj-$(CONFIG_ACPI_CPPC_LIB) += cppc_acpi.o
> obj-$(CONFIG_IORT_TABLE) += iort.o
> +obj-$(CONFIG_ACPI_SPCR_TABLE) += spcr.o
>
> # processor has its own "processor." module_param namespace
> processor-y := processor_driver.o
> diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
> new file mode 100644
> index 0000000..ccb19a0
> --- /dev/null
> +++ b/drivers/acpi/spcr.c
> @@ -0,0 +1,85 @@
> +/*
> + * 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>
> +
> +static struct acpi_table_spcr *spcr_table;
> +
> +int console_acpi_match(struct console *c, char **options)
> +{
> + int err;
> +
> + if (!c->acpi_match)
> + return -ENODEV;
> +
> + if (!spcr_table)
> + return -EAGAIN;
> +
> + err = c->acpi_match(c, spcr_table);
> + if (err < 0)
> + return err;
> +
> + if (options) {
> + switch (spcr_table->baud_rate) {
> + case 3:
> + *options = "9600";
> + break;
> + case 4:
> + *options = "19200";
> + break;
> + case 6:
> + *options = "57600";
> + break;
> + case 7:
> + *options = "115200";
> + break;
> + default:
> + *options = "";
> + break;
> + }
> + }
> +
> + return err;
> +}
> +
> +static int __init spcr_table_detect(void)
> +{
> + struct acpi_table_header *table;
> + acpi_status status;
> +
> + if (acpi_disabled)
> + return -ENODEV;
> +
> + status = acpi_get_table(ACPI_SIG_SPCR, 0, &table);
> + if (ACPI_FAILURE(status)) {
> + const char *msg = acpi_format_exception(status);
> +
> + pr_err("Failed to get table, %s\n", msg);
> + return -EINVAL;
> + }
> +
> + if (table->revision < 2)
> + return -EOPNOTSUPP;
> +
> + spcr_table = (struct acpi_table_spcr *)table;
> +
> + pr_info("Console at 0x%016llx\n", spcr_table->serial_port.address);
> +
> + acpi_register_consoles_try_again();
> +
> + return 0;
> +}
> +
> +arch_initcall(spcr_table_detect);
> diff --git a/include/linux/console.h b/include/linux/console.h
> index bd19434..94d0bd8 100644
> --- a/include/linux/console.h
> +++ b/include/linux/console.h
> @@ -117,6 +117,7 @@ static inline int con_debug_leave(void)
> #define CON_BRL (32) /* Used for a braille device */
> #define CON_EXTENDED (64) /* Use the extended output format a la /dev/kmsg */
>
> +struct acpi_table_spcr;
> struct console {
> char name[16];
> void (*write)(struct console *, const char *, unsigned);
> @@ -125,6 +126,7 @@ struct console {
> void (*unblank)(void);
> int (*setup)(struct console *, char *);
> int (*match)(struct console *, char *name, int idx, char *options);
> + int (*acpi_match)(struct console *, struct acpi_table_spcr *);
> short flags;
> short index;
> int cflag;
> @@ -132,6 +134,16 @@ struct console {
> struct console *next;
> };
>
> +#ifdef CONFIG_ACPI
> +int console_acpi_match(struct console *c, char **options);
> +#else
> +static inline int console_acpi_match(struct console *c, char **options)
> +{
> + return -ENODEV;
> +}
> +#endif
> +void acpi_register_consoles_try_again(void);
> +
> /*
> * for_each_console() allows you to iterate on each console
> */
> diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
> index 37e531f..3cf8cba 100644
> --- a/kernel/printk/printk.c
> +++ b/kernel/printk/printk.c
> @@ -2430,6 +2430,25 @@ static int __init keep_bootcon_setup(char *str)
>
> early_param("keep_bootcon", keep_bootcon_setup);
>
> +static DEFINE_MUTEX(acpi_consoles_delayed_mutex);
> +static struct console *acpi_consoles_delayed;
> +
> +void acpi_register_consoles_try_again(void)
> +{
> + mutex_lock(&acpi_consoles_delayed_mutex);
> + while (acpi_consoles_delayed) {
> +
> + struct console *c = acpi_consoles_delayed;
> +
> + acpi_consoles_delayed = acpi_consoles_delayed->next;
> +
> + mutex_unlock(&acpi_consoles_delayed_mutex);
> + register_console(c);
> + mutex_lock(&acpi_consoles_delayed_mutex);
> + }
> + mutex_unlock(&acpi_consoles_delayed_mutex);
> +}
> +
> /*
> * The console driver calls this routine during kernel initialization
> * to register the console printing procedure with printk() and to
> @@ -2538,8 +2557,30 @@ void register_console(struct console *newcon)
> break;
> }
>
> - if (!(newcon->flags & CON_ENABLED))
> - return;
> + if (!(newcon->flags & CON_ENABLED)) {
> + char *opts;
> + int err;
> +
> + if (newcon->index < 0)
> + newcon->index = 0;
> +
> + err = console_acpi_match(newcon, &opts);
> +
> + if (err == -EAGAIN) {
> + mutex_lock(&acpi_consoles_delayed_mutex);
> + newcon->next = acpi_consoles_delayed;
> + acpi_consoles_delayed = newcon;
> + mutex_unlock(&acpi_consoles_delayed_mutex);
> + return;
> + } else if (err < 0) {
> + return;
> + } else {
> + if (newcon->setup && newcon->setup(newcon, opts) != 0)
> + return;
> + newcon->flags |= CON_ENABLED | CON_CONSDEV;
> + preferred_console = true;
> + }
> + }
>
> /*
> * If we have a bootconsole, and are switching to a real console,
> @@ -2612,34 +2653,41 @@ void register_console(struct console *newcon)
> }
> EXPORT_SYMBOL(register_console);
>
> +static int delete_from_console_list(struct console **list, struct console *c)
> +{
> + while (*list) {
> + struct console *cur = *list;
> +
> + if (cur == c) {
> + *list = cur->next;
> + return 0;
> + }
> + list = &cur->next;
> + }
> + return 1;
> +}
> +
> int unregister_console(struct console *console)
> {
> - struct console *a, *b;
> int res;
>
> pr_info("%sconsole [%s%d] disabled\n",
> (console->flags & CON_BOOT) ? "boot" : "" ,
> console->name, console->index);
>
> + mutex_lock(&acpi_consoles_delayed_mutex);
> + res = delete_from_console_list(&acpi_consoles_delayed, console);
> + mutex_unlock(&acpi_consoles_delayed_mutex);
> + if (res == 0)
> + return res;
> +
> res = _braille_unregister_console(console);
> if (res)
> return res;
>
> - res = 1;
> console_lock();
> - if (console_drivers == console) {
> - console_drivers=console->next;
> - res = 0;
> - } else if (console_drivers) {
> - for (a=console_drivers->next, b=console_drivers ;
> - a; b=a, a=b->next) {
> - if (a == console) {
> - b->next = a->next;
> - res = 0;
> - break;
> - }
> - }
> - }
> +
> + res = delete_from_console_list(&console_drivers, console);
>
> if (!res && (console->flags & CON_EXTENDED))
> nr_ext_console_drivers--;
> --
> 2.7.0
>
--
With Best Regards,
Andy Shevchenko
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