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Message-ID: <1441730339.5459.8.camel@redhat.com>
Date: Tue, 08 Sep 2015 12:38:59 -0400
From: Mark Salter <msalter@...hat.com>
To: Leif Lindholm <leif.lindholm@...aro.org>,
linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
linux-serial@...r.kernel.org, linux-acpi@...r.kernel.org,
linux-kernel@...r.kernel.org
Cc: linaro-acpi@...ts.linaro.org, jcm@...hat.com, torez@...hat.com,
lv.zheng@...el.com
Subject: Re: [Linaro-acpi] [RFC 3/5] acpi/serial: add DBG2 earlycon support
On Tue, 2015-09-08 at 13:43 +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@...aro.org>
> ---
> arch/arm64/kernel/acpi.c | 2 +
> drivers/acpi/Makefile | 1 +
> drivers/acpi/console.c | 103 ++++++++++++++++++++++++++++++++++++++++++
> drivers/of/fdt.c | 2 +-
> drivers/tty/serial/earlycon.c | 16 ++++---
> include/linux/acpi.h | 4 ++
> include/linux/serial_core.h | 9 ++--
> 7 files changed, 126 insertions(+), 11 deletions(-)
> create mode 100644 drivers/acpi/console.c
>
> diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
> index b9a5623..be7600a 100644
> --- a/arch/arm64/kernel/acpi.c
> +++ b/arch/arm64/kernel/acpi.c
> @@ -207,6 +207,8 @@ void __init acpi_boot_table_init(void)
> if (!param_acpi_force)
> disable_acpi();
> }
> +
> + acpi_early_console_probe();
> }
>
> void __init acpi_gic_init(void)
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index b5e7cd8..a89587d 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -10,6 +10,7 @@ ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT
> #
> obj-y += tables.o
> obj-$(CONFIG_X86) += blacklist.o
> +obj-y += console.o
obj-$(CONFIG_SERIAL_EARLYCON) += console.o
to eliminate whole-file #ifdef
>
> #
> # ACPI Core Subsystem (Interpreter)
> 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
> +#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))
> +
> +#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);
> +
> +extern struct earlycon_id __earlycon_table[];
> +
> +static __initdata struct {
> + int id;
> + const char *name;
> +} subtypes[] = {
> + {0, "uart8250"},
> + {1, "uart8250"},
> + {2, NULL},
> + {3, "pl011"},
> +};
Instead of having a table here, why not have an ACPI_EARLYCON_DECLARE()
where individual drivers can provide an id similar to OF_EARLYCON_DECLARE()
providing compatible strings?
> +
> +static int __init acpi_setup_earlycon(unsigned long addr, const char *driver)
> +{
> + const struct earlycon_id *match;
> +
> + for (match = __earlycon_table; match->name[0]; match++)
> + if (strcmp(driver, match->name) == 0)
> + return setup_earlycon_driver(addr, match->setup);
> +
> + return -ENODEV;
> +}
> +
> +static int __init acpi_parse_dbg2(struct acpi_table_header *table)
> +{
> + struct acpi_table_dbg2 *dbg2;
> + struct acpi_dbg2_device *entry;
> + void *tbl_end;
> +
> + dbg2 = (struct acpi_table_dbg2 *)table;
> + if (!dbg2) {
> + pr_debug("DBG2 not present.\n");
> + return -ENODEV;
> + }
> +
> + tbl_end = (void *)table + table->length;
> +
> + entry = (struct acpi_dbg2_device *)((void *)dbg2 + dbg2->info_offset);
> +
> + while (((void *)entry) + sizeof(struct acpi_dbg2_device) < tbl_end) {
> + struct acpi_generic_address *addr;
> +
> + if (entry->revision != 0) {
> + pr_debug("DBG2 revision %d not supported.\n",
> + entry->revision);
> + return -ENODEV;
> + }
> +
> + addr = (void *)entry + entry->base_address_offset;
> +
> + pr_debug("DBG2 PROBE - console (%04x:%04x).\n",
> + entry->port_type, entry->port_subtype);
> +
> + if (use_earlycon &&
> + (entry->port_type == ACPI_DBG2_SERIAL_PORT) &&
> + (entry->port_subtype < NUM_ELEMS(subtypes)))
> + acpi_setup_earlycon(addr->address,
> + subtypes[entry->port_subtype].name);
Don't we need to handle space_id (and bit width) as well as address?
> +
> + entry = (struct acpi_dbg2_device *)
> + ((void *)entry + entry->length);
> + }
> +
> + return 0;
> +}
> +
> +int __init acpi_early_console_probe(void)
> +{
> + acpi_table_parse(ACPI_SIG_DBG2, acpi_parse_dbg2);
> +
> + return 0;
> +}
> +#endif /* CONFIG_SERIAL_EARLYCON */
> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
> index fcfc4c7..a96209f 100644
> --- a/drivers/of/fdt.c
> +++ b/drivers/of/fdt.c
> @@ -829,7 +829,7 @@ int __init early_init_dt_scan_chosen_serial(void)
> if (!addr)
> return -ENXIO;
>
> - of_setup_earlycon(addr, match->data);
> + setup_earlycon_driver(addr, match->data);
> return 0;
> }
> return -ENODEV;
> 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)
How do we know for sure that "acpi" has been parsed before "earlycon"?
> + return 0;
> + else if (IS_ENABLED(CONFIG_OF_FLATTREE))
> return early_init_dt_scan_chosen_serial();
> + }
>
> err = setup_earlycon(buf);
> if (err == -ENOENT || err == -EALREADY)
> @@ -198,8 +203,7 @@ static int __init param_setup_earlycon(char *buf)
> }
> early_param("earlycon", param_setup_earlycon);
>
> -int __init of_setup_earlycon(unsigned long addr,
> - int (*setup)(struct earlycon_device *, const char *))
> +int __init setup_earlycon_driver(unsigned long addr, earlycon_initfunc_t setup)
> {
> int err;
> struct uart_port *port = &early_console_dev.port;
> diff --git a/include/linux/acpi.h b/include/linux/acpi.h
> index 7235c48..88cb9c1 100644
> --- a/include/linux/acpi.h
> +++ b/include/linux/acpi.h
> @@ -811,4 +811,8 @@ static inline struct acpi_device *acpi_get_next_child(struct device *dev,
>
> #endif
>
> +#if defined(CONFIG_ACPI) && defined(CONFIG_SERIAL_EARLYCON)
> +int __init acpi_early_console_probe(void);
> +#endif
> +
> #endif /*_LINUX_ACPI_H*/
> diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
> index 297d4fa..39e99b0 100644
> --- a/include/linux/serial_core.h
> +++ b/include/linux/serial_core.h
> @@ -339,14 +339,15 @@ struct earlycon_device {
> unsigned int baud;
> };
>
> +typedef int (*earlycon_initfunc_t)(struct earlycon_device *, const char *);
> +
> struct earlycon_id {
> - char name[16];
> - int (*setup)(struct earlycon_device *, const char *options);
> + char name[16];
> + earlycon_initfunc_t setup;
> } __aligned(32);
>
> extern int setup_earlycon(char *buf);
> -extern int of_setup_earlycon(unsigned long addr,
> - int (*setup)(struct earlycon_device *, const char *));
> +extern int setup_earlycon_driver(unsigned long addr, earlycon_initfunc_t setup);
>
> #define EARLYCON_DECLARE(_name, func) \
> static const struct earlycon_id __earlycon_##_name \
--
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