On Tue, Sep 08, 2015 at 01:43:35PM +0100, Leif Lindholm wrote:
The ACPI DBG2 table defines a debug console. Add support for parsing it and using it to select earlycon destination when no arguments provided.
Signed-off-by: Leif Lindholm leif.lindholm@linaro.org
[...]
diff --git a/drivers/acpi/console.c b/drivers/acpi/console.c new file mode 100644 index 0000000..a985890 --- /dev/null +++ b/drivers/acpi/console.c @@ -0,0 +1,103 @@ +/*
- Copyright (c) 2012, Intel Corporation
- Copyright (c) 2015, 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 DEBUG
Why?
+#define pr_fmt(fmt) "ACPI: " KBUILD_MODNAME ": " fmt
+#include <linux/acpi.h> +#include <linux/kernel.h> +#include <linux/serial_core.h>
+#define NUM_ELEMS(x) (sizeof(x) / sizeof(*x))
Use ARRAY_SIZE (from kernel.h).
+#ifdef CONFIG_SERIAL_EARLYCON +static int use_earlycon __initdata; +static int __init setup_acpi_earlycon(char *buf) +{
- if (!buf)
use_earlycon = 1;
- return 0;
+} +early_param("earlycon", setup_acpi_earlycon);
It seems a shame to add this after folding the OF case into the earlycon code. What necessitates this being a separate early_param? Why is it too early to parse DBG2?
[...]
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c index 2bda09a..c063cbb 100644 --- a/drivers/tty/serial/earlycon.c +++ b/drivers/tty/serial/earlycon.c @@ -13,6 +13,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include <linux/acpi.h> #include <linux/console.h> #include <linux/kernel.h> #include <linux/init.h> @@ -184,12 +185,16 @@ static int __init param_setup_earlycon(char *buf) int err; /*
* Just 'earlycon' is a valid param for devicetree earlycons;
* don't generate a warning from parse_early_params() in that case
* Just 'earlycon' is a valid param for devicetree or ACPI earlycons;
* ACPI cannot be parsed yet, so return without action if enabled.
*/* Otherwise, attempt initialization using DT.
- if (!buf || !buf[0])
if (IS_ENABLED(CONFIG_OF_FLATTREE))
- if (!buf || !buf[0]) {
if (!acpi_disabled)
return 0;
else if (IS_ENABLED(CONFIG_OF_FLATTREE)) return early_init_dt_scan_chosen_serial();
- }
It would be much nicer if we could handle the ACPI earlycon parsing in the same place. As above, I assume I'm missing something that prevents that.
Mark.