'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.
Defer initialization of DT earlycon until ACPI/DT decision is made. Parse the ACPI SPCR table, setup earlycon if required, enable specified console. Thanks to Peter Hurley for explaining how this should work. [1] http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.den0044a/index.html [2] https://msdn.microsoft.com/en-us/library/windows/hardware/dn639132(v=vs.85).aspx Signed-off-by: Aleksey Makarov <aleksey.maka...@linaro.org> Acked-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com> Reviewed-by: Peter Hurley <pe...@hurleysoftware.com> Tested-by: Kefeng Wang <wangkefeng.w...@huawei.com> Tested-by: Christopher Covington <c...@codeaurora.org> --- drivers/acpi/Kconfig | 3 ++ drivers/acpi/Makefile | 1 + drivers/acpi/spcr.c | 111 ++++++++++++++++++++++++++++++++++++++++++ drivers/tty/serial/earlycon.c | 19 +++++++- include/linux/acpi.h | 6 +++ include/linux/serial_core.h | 9 +++- 6 files changed, 146 insertions(+), 3 deletions(-) create mode 100644 drivers/acpi/spcr.c diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig index 6cef2d1..4a269f9 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 e5ada78..d799593 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..e8d7bc7 --- /dev/null +++ b/drivers/acpi/spcr.c @@ -0,0 +1,111 @@ +/* + * 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> + +/** + * parse_spcr() - parse ACPI SPCR table and add preferred console + * + * @earlycon: set up earlycon for the console specified by the table + * + * For the architectures with support for ACPI, CONFIG_ACPI_SPCR_TABLE may be + * defined to parse ACPI SPCR table. As a result of the parsing preferred + * console is registered and if @earlycon is true, earlycon is set up. + * + * When CONFIG_ACPI_SPCR_TABLE is defined, this function should be called + * from arch inintialization code as soon as the DT/ACPI decision is made. + * + */ +int __init parse_spcr(bool earlycon) +{ + static char opts[64]; + struct acpi_table_spcr *table; + acpi_size table_size; + acpi_status status; + char *uart; + char *iotype; + int baud_rate; + int err; + + if (acpi_disabled) + return -ENODEV; + + status = acpi_get_table_with_size(ACPI_SIG_SPCR, 0, + (struct acpi_table_header **)&table, + &table_size); + + if (ACPI_FAILURE(status)) + return -ENOENT; + + if (table->header.revision < 2) { + err = -ENOENT; + pr_err("wrong table version\n"); + goto done; + } + + iotype = table->serial_port.space_id == ACPI_ADR_SPACE_SYSTEM_MEMORY ? + "mmio" : "io"; + + switch (table->interface_type) { + case ACPI_DBG2_ARM_SBSA_32BIT: + iotype = "mmio32"; + /* fall through */ + case ACPI_DBG2_ARM_PL011: + case ACPI_DBG2_ARM_SBSA_GENERIC: + case ACPI_DBG2_BCM2835: + uart = "pl011"; + break; + case ACPI_DBG2_16550_COMPATIBLE: + case ACPI_DBG2_16550_SUBSET: + uart = "uart"; + break; + default: + err = -ENOENT; + goto done; + } + + switch (table->baud_rate) { + case 3: + baud_rate = 9600; + break; + case 4: + baud_rate = 19200; + break; + case 6: + baud_rate = 57600; + break; + case 7: + baud_rate = 115200; + break; + default: + err = -ENOENT; + goto done; + } + + snprintf(opts, sizeof(opts), "%s,%s,0x%llx,%d", uart, iotype, + table->serial_port.address, baud_rate); + + pr_info("console: %s\n", opts); + + if (earlycon) + setup_earlycon(opts); + + err = add_preferred_console(uart, 0, opts + strlen(uart) + 1); + +done: + early_acpi_os_unmap_memory((void __iomem *)table, table_size); + return err; +} diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c index 7aae655..ea00b9f 100644 --- a/drivers/tty/serial/earlycon.c +++ b/drivers/tty/serial/earlycon.c @@ -21,6 +21,7 @@ #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> @@ -199,6 +200,14 @@ int __init setup_earlycon(char *buf) return -ENOENT; } +/* + * When CONFIG_ACPI_SPCR_TABLE is defined, "earlycon" without parameters in + * command line does not start DT earlycon immediately, instead it defers + * starting it until DT/ACPI decision is made. At that time if ACPI is enabled + * call parse_spcr(), else call early_init_dt_scan_chosen_stdout() + */ +bool earlycon_init_is_deferred __initdata; + /* early_param wrapper for setup_earlycon() */ static int __init param_setup_earlycon(char *buf) { @@ -208,8 +217,14 @@ static int __init param_setup_earlycon(char *buf) * Just 'earlycon' is a valid param for devicetree earlycons; * don't generate a warning from parse_early_params() in that case */ - if (!buf || !buf[0]) - return early_init_dt_scan_chosen_stdout(); + if (!buf || !buf[0]) { + if (IS_ENABLED(CONFIG_ACPI_SPCR_TABLE)) { + earlycon_init_is_deferred = true; + return 0; + } else { + return early_init_dt_scan_chosen_stdout(); + } + } err = setup_earlycon(buf); if (err == -ENOENT || err == -EALREADY) diff --git a/include/linux/acpi.h b/include/linux/acpi.h index c5eaf2f..2353827 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -1074,4 +1074,10 @@ void acpi_table_upgrade(void); static inline void acpi_table_upgrade(void) { } #endif +#ifdef CONFIG_ACPI_SPCR_TABLE +int parse_spcr(bool earlycon); +#else +static inline int parse_spcr(bool earlycon) { return 0; } +#endif + #endif /*_LINUX_ACPI_H*/ diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h index 2f44e20..9e84cff 100644 --- a/include/linux/serial_core.h +++ b/include/linux/serial_core.h @@ -367,11 +367,18 @@ extern const struct earlycon_id __earlycon_table_end[]; #define EARLYCON_DECLARE(_name, fn) OF_EARLYCON_DECLARE(_name, "", fn) -extern int setup_earlycon(char *buf); extern int of_setup_earlycon(const struct earlycon_id *match, unsigned long node, const char *options); +#ifdef CONFIG_SERIAL_EARLYCON +extern bool earlycon_init_is_deferred __initdata; +int setup_earlycon(char *buf); +#else +static const bool earlycon_init_is_deferred; +static inline int setup_earlycon(char *buf) { return 0; } +#endif + struct uart_port *uart_get_console(struct uart_port *ports, int nr, struct console *c); int uart_parse_earlycon(char *p, unsigned char *iotype, unsigned long *addr, -- 2.10.0
