On 02/15/2016 10:05 AM, Aleksey Makarov wrote:
> '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.
>
> Parse this table and check if any registered console match the
> description. If it does, enable that console.
>
> Introduce a new function acpi_console_check(). At the uart port
> registration, this function checks if the ACPI SPCR table specifies
> its argument of type struct uart_port to be a console
> and if so calls add_preferred_console().
>
> [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
>
> Signed-off-by: Aleksey Makarov <aleksey.maka...@linaro.org>
> ---
> drivers/acpi/Kconfig | 3 ++
> drivers/acpi/Makefile | 1 +
> drivers/acpi/spcr.c | 97
> ++++++++++++++++++++++++++++++++++++++++
> drivers/tty/serial/serial_core.c | 14 +++++-
> include/linux/acpi.h | 10 +++++
> 5 files changed, 123 insertions(+), 2 deletions(-)
> create mode 100644 drivers/acpi/spcr.c
>
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index 65fb483..5611eb6 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -77,6 +77,9 @@ config ACPI_DEBUGGER_USER
>
> endif
>
> +config ACPI_SPCR_TABLE
> + bool
> +
> config ACPI_SLEEP
> bool
> depends on SUSPEND || HIBERNATION
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 346101c..708b143 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -81,6 +81,7 @@ obj-$(CONFIG_ACPI_EC_DEBUGFS) += ec_sys.o
> obj-$(CONFIG_ACPI_CUSTOM_METHOD)+= custom_method.o
> obj-$(CONFIG_ACPI_BGRT) += bgrt.o
> obj-$(CONFIG_ACPI_CPPC_LIB) += cppc_acpi.o
> +obj-$(CONFIG_ACPI_SPCR_TABLE) += spcr.o
> obj-$(CONFIG_ACPI_DEBUGGER_USER) += acpi_dbg.o
>
> # processor has its own "processor." module_param namespace
> diff --git a/drivers/acpi/spcr.c b/drivers/acpi/spcr.c
> new file mode 100644
> index 0000000..a1eca91
> --- /dev/null
> +++ b/drivers/acpi/spcr.c
> @@ -0,0 +1,97 @@
> +/*
> + * 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>
> +
> +static int acpi_table_parse_spcr(int (*handler)(struct acpi_table_spcr
> *table,
> + void *data), void *data)
> +{
> + struct acpi_table_spcr *table = NULL;
> + acpi_size table_size;
> + acpi_status status;
> + int err;
> +
> + status = acpi_get_table_with_size(ACPI_SIG_SPCR, 0,
> + (struct acpi_table_header **)&table,
> + &table_size);
> +
> + if (ACPI_FAILURE(status))
> + return -ENODEV;
> +
> + err = handler(table, data);
> +
> + early_acpi_os_unmap_memory(table, table_size);
> +
> + return err;
> +}
> +
> +static int spcr_table_handler_check(struct acpi_table_spcr *table, void
> *data)
> +{
> + struct uart_port *uport = data;
> + char *options;
> +
> + if (table->header.revision < 2)
> + return -EOPNOTSUPP;
> +
> + switch (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;
> + }
> +
> + if ((table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY &&
> + table->serial_port.address == (u64)uport->mapbase) ||
> + (table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_IO &&
> + table->serial_port.address == (u64)uport->iobase)) {
> + pr_info("adding preferred console [%s%d]\n", uport->cons->name,
> + uport->line);
> + add_preferred_console(uport->cons->name, uport->line, options);
> + return 1;
> +
> + }
> +
> + return 0;
> +}
> +
> +/**
> + * acpi_console_check - Check if uart matches the console specified by SPCR.
> + *
> + * @uport: uart port to check
> + *
> + * This function checks if the ACPI SPCR table specifies @uport to be a
> console
> + * and if so calls add_preferred_console()
> + *
> + * Return: a non-error value if the console matches.
> + */
> +bool acpi_console_check(struct uart_port *uport)
> +{
> + if (acpi_disabled || console_set_on_cmdline)
> + return false;
> +
> + return acpi_table_parse_spcr(spcr_table_handler_check, uport) > 0;
> +}
> diff --git a/drivers/tty/serial/serial_core.c
> b/drivers/tty/serial/serial_core.c
> index a126a60..459ab54 100644
> --- a/drivers/tty/serial/serial_core.c
> +++ b/drivers/tty/serial/serial_core.c
> @@ -34,6 +34,7 @@
> #include <linux/serial_core.h>
> #include <linux/delay.h>
> #include <linux/mutex.h>
> +#include <linux/acpi.h>
>
> #include <asm/irq.h>
> #include <asm/uaccess.h>
> @@ -2654,8 +2655,17 @@ int uart_add_one_port(struct uart_driver *drv, struct
> uart_port *uport)
> spin_lock_init(&uport->lock);
> lockdep_set_class(&uport->lock, &port_lock_key);
> }
> - if (uport->cons && uport->dev)
> - of_console_check(uport->dev->of_node, uport->cons->name,
> uport->line);
> +
> + /*
> + * Support both open FW and ACPI access to console definitions.
> + * Both of_console_check() and acpi_console_check() will call
> + * add_preferred_console() if a console definition is found.
> + */
> + if (uport->cons && uport->dev) {
> + if (!acpi_console_check(uport))
> + of_console_check(uport->dev->of_node, uport->cons->name,
> + uport->line);
of_console_check() is not a good model for enabling a console.
It's a hack with several shortcomings (and bugs) that is tolerated here
because of its broad applicability to a wide range of platforms and drivers.
I specifically added console matching to enable exactly this kind of
console-selection-via-firmware. Please use that facility.
Regards,
Peter Hurley
> + }
>
> uart_configure_port(drv, state, uport);
>
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 06ed7e5..ea0c297 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -1004,4 +1004,14 @@ static inline struct fwnode_handle
> *acpi_get_next_subnode(struct device *dev,
> #define acpi_probe_device_table(t) ({ int __r = 0; __r;})
> #endif
>
> +struct uart_port;
> +#ifdef CONFIG_ACPI_SPCR_TABLE
> +bool acpi_console_check(struct uart_port *uport);
> +#else
> +static inline bool acpi_console_check(struct uart_port *uport)
> +{
> + return FALSE;
> +}
> +#endif
> +
> #endif /*_LINUX_ACPI_H*/
>
