[PATCH v3 2/5] ACPI: parse SPCR and enable matching console
Aleksey Makarov
aleksey.makarov at linaro.org
Mon Feb 22 07:03:19 PST 2016
Hi Yury,
Thank you for review/suggestions. I will address it all in the next version except for...
On 02/21/2016 12:42 PM, Yury Norov wrote:
> On Mon, Feb 15, 2016 at 09:05:26PM +0300, 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.makarov at 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;
> Hi Alexey,
>
> Few minor comments...
>
> Are you sure you need thin initialization?
>
>> + 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)
>
> The name of function is not clear for me.
> You're not only checking here, but also
> adding console.
>
>> +{
>> + struct uart_port *uport = data;
>> + char *options;
>> +
>> + if (table->header.revision < 2)
>> + return -EOPNOTSUPP;
>> +
>> + switch (table->baud_rate) {
>
> You don't need 'options' if your big condition returns false,
> so you can evaluate it inside conditional block.
>
>> + case 3:
>> + options = "9600";
>> + break;
>> + case 4:
>> + options = "19200";
>> + break;
>> + case 6:
>> + options = "57600";
>> + break;
>> + case 7:
>> + options = "115200";
>> + break;
>> + default:
>> + options = "";
>> + break;
>
> 'break' isnot needed here
... except for this.
No, it is not, but C language style guides tell us to have it here.
Also see the first example from Documentation/CodingStyle
where they have it.
Thank you
Aleksey Makarov
>
>> + }
>> +
>> + if ((table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY &&
>
> Nitpick: just for better readability, I'd split it onto a set of
> separated checks:
>
> foo() {
> if (!cond1)
> return 0;
>
> if (!cond2)
> return 0;
> ...
>
> switch () {
> case 1:
> ...
> case 2:
> ...
> case 3:
> ...
> default:
> ...
> }
>
> return 1;
> }
>
>> + 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);
>> + }
>>
>> 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*/
>> --
>> 2.7.1
>>
>>
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