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Date: Tue, 1 Mar 2016 19:57:25 +0300
From: Aleksey Makarov <aleksey.makarov@...aro.org>
To: Peter Hurley <peter@...leysoftware.com>, linux-acpi@...r.kernel.org
Cc: linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-arm-kernel@...ts.infradead.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>,
Graeme Gregory <graeme.gregory@...aro.org>,
Al Stone <ahs3@...hat.com>,
Christopher Covington <cov@...eaurora.org>,
Matthias Brugger <mbrugger@...e.com>,
Jonathan Corbet <corbet@....net>, Jiri Slaby <jslaby@...e.com>,
linux-doc@...r.kernel.org
Subject: Re: [PATCH v3 5/7] ACPI: serial: implement earlycon on ACPI DBG2 port
On 03/01/2016 06:53 PM, Peter Hurley wrote:
> On 02/29/2016 04:42 AM, Aleksey Makarov wrote:
>> Add ACPI_DBG2_EARLYCON_DECLARE() macros that declares
>> an earlycon on the serial port specified in the DBG2 ACPI table.
>>
>> Pass the string "earlycon=acpi_dbg2" to the kernel to activate it.
>>
>> Callbacks for EARLYCON_DECLARE() and OF_EARLYCON_DECLARE()
>> can also be used for this macros.
>>
>> Signed-off-by: Aleksey Makarov <aleksey.makarov@...aro.org>
>> ---
>> Documentation/kernel-parameters.txt | 3 ++
>> drivers/tty/serial/earlycon.c | 60 +++++++++++++++++++++++++++++++++++++
>> include/linux/acpi_dbg2.h | 20 +++++++++++++
>> 3 files changed, 83 insertions(+)
>>
>> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
>> index e0a21e4..19b947b 100644
>> --- a/Documentation/kernel-parameters.txt
>> +++ b/Documentation/kernel-parameters.txt
>> @@ -1072,6 +1072,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>> A valid base address must be provided, and the serial
>> port must already be setup and configured.
>>
>> + acpi_dbg2
>> + Use serial port specified by the DBG2 ACPI table.
>> +
>> earlyprintk= [X86,SH,BLACKFIN,ARM,M68k]
>> earlyprintk=vga
>> earlyprintk=efi
>> diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
>> index d217366..9ba3a04 100644
>> --- a/drivers/tty/serial/earlycon.c
>> +++ b/drivers/tty/serial/earlycon.c
>> @@ -22,6 +22,7 @@
>> #include <linux/sizes.h>
>> #include <linux/of.h>
>> #include <linux/of_fdt.h>
>> +#include <linux/acpi.h>
>>
>> #ifdef CONFIG_FIX_EARLYCON_MEM
>> #include <asm/fixmap.h>
>> @@ -200,6 +201,8 @@ int __init setup_earlycon(char *buf)
>> return -ENOENT;
>> }
>>
>> +static bool setup_dbg2_earlycon;
>> +
>> /* early_param wrapper for setup_earlycon() */
>> static int __init param_setup_earlycon(char *buf)
>> {
>> @@ -212,6 +215,11 @@ static int __init param_setup_earlycon(char *buf)
>> if (!buf || !buf[0])
>> return early_init_dt_scan_chosen_serial();
>>
>> + if (!strcmp(buf, "acpi_dbg2")) {
>> + setup_dbg2_earlycon = true;
>> + return 0;
>> + }
>
> So this series doesn't start an ACPI earlycon at early_param time?
> That doesn't seem very useful.
>
> When does the ACPI earlycon actually start?
> And don't say "when the DBG2 table is probed"; that much is obvious.
ACPI earlycon starts as soon as ACPI tables become accessible (setup_arch()).
I think that is still quite early.
>> +
>> err = setup_earlycon(buf);
>> if (err == -ENOENT || err == -EALREADY)
>> return 0;
>> @@ -286,3 +294,55 @@ int __init of_setup_earlycon(const struct earlycon_id *match,
>> }
>>
>> #endif /* CONFIG_OF_EARLY_FLATTREE */
>> +
>> +#ifdef CONFIG_ACPI_DBG2_TABLE
>> +
>> +int __init acpi_setup_earlycon(struct acpi_dbg2_device *device, void *d)
>> +{
>> + int err;
>> + struct uart_port *port = &early_console_dev.port;
>> + int (*setup)(struct earlycon_device *, const char *) = d;
>> + struct acpi_generic_address *reg;
>> +
>> + if (!setup_dbg2_earlycon)
>> + return -ENODEV;
>> +
>> + if (device->register_count < 1)
>> + return -ENODEV;
>> +
>> + if (device->base_address_offset >= device->length)
>> + return -EINVAL;
>> +
>> + reg = (void *)device + device->base_address_offset;
>> +
>> + if (reg->space_id != ACPI_ADR_SPACE_SYSTEM_MEMORY &&
>> + reg->space_id != ACPI_ADR_SPACE_SYSTEM_IO)
>> + return -EINVAL;
>> +
>> + spin_lock_init(&port->lock);
>> + port->uartclk = BASE_BAUD * 16;
>> +
>> + if (reg->space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY) {
>> + if (device->port_type == ACPI_DBG2_ARM_SBSA_32BIT)
>> + port->iotype = UPIO_MEM32;
>> + else
>> + port->iotype = UPIO_MEM;
>> + port->mapbase = reg->address;
>> + port->membase = earlycon_map(reg->address, SZ_4K);
>> + } else {
>> + port->iotype = UPIO_PORT;
>> + port->iobase = reg->address;
>> + }
>> +
>> + early_console_dev.con->data = &early_console_dev;
>> + err = setup(&early_console_dev, NULL);
>> + if (err < 0)
>> + return err;
>> + if (!early_console_dev.con->write)
>> + return -ENODEV;
>> +
>> + register_console(early_console_dev.con);
>> + return 0;
>> +}
>> +
>> +#endif /* CONFIG_ACPI_DBG2_TABLE */
>> diff --git a/include/linux/acpi_dbg2.h b/include/linux/acpi_dbg2.h
>> index 125ae7e..b653752 100644
>> --- a/include/linux/acpi_dbg2.h
>> +++ b/include/linux/acpi_dbg2.h
>> @@ -37,12 +37,32 @@ int acpi_dbg2_setup(struct acpi_table_header *header, const void *data);
>> ACPI_DECLARE_PROBE_ENTRY(dbg2, name, ACPI_SIG_DBG2, \
>> acpi_dbg2_setup, &__acpi_dbg2_data_##name)
>>
>> +int acpi_setup_earlycon(struct acpi_dbg2_device *device, void *d);
>> +
>> +/**
>> + * ACPI_DBG2_EARLYCON_DECLARE() - Define handler for ACPI GDB2 serial port
>> + * @name: Identifier to compose name of table data
>> + * @subtype: Subtype of the port
>> + * @console_setup: Function to be called to setup the port
>> + *
>> + * Type of the console_setup() callback is
>> + * int (*setup)(struct earlycon_device *, const char *)
>> + * It's the type of callback of of_setup_earlycon().
>> + */
>> +#define ACPI_DBG2_EARLYCON_DECLARE(name, subtype, console_setup) \
>> + ACPI_DBG2_DECLARE(name, ACPI_DBG2_SERIAL_PORT, subtype, \
>> + acpi_setup_earlycon, console_setup)
>> +
>> #else
>>
>> #define ACPI_DBG2_DECLARE(name, type, subtype, setup_fn, data_ptr) \
>> static const void *__acpi_dbg_data_##name[] \
>> __used __initdata = { (void *)setup_fn, (void *)data_ptr }
>>
>> +#define ACPI_DBG2_EARLYCON_DECLARE(name, subtype, console_setup) \
>> + static const void *__acpi_dbg_data_serial_##name[] \
>> + __used __initdata = { (void *)console_setup }
>> +
>> #endif
>>
>> #endif
>>
>
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