'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, setup earlycon and enable the 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.makarov@xxxxxxxxxx> --- drivers/acpi/Kconfig | 3 ++ drivers/acpi/Makefile | 1 + drivers/acpi/spcr.c | 102 ++++++++++++++++++++++++++++++++++++++++++ drivers/tty/serial/earlycon.c | 13 ++++-- include/linux/acpi.h | 8 ++++ 5 files changed, 123 insertions(+), 4 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 7395928..f70ae14 100644 --- a/drivers/acpi/Makefile +++ b/drivers/acpi/Makefile @@ -82,6 +82,7 @@ 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..1ec82f9 --- /dev/null +++ b/drivers/acpi/spcr.c @@ -0,0 +1,102 @@ +/* + * 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 bool init_earlycon; + +void __init init_spcr_earlycon(void) +{ + init_earlycon = true; +} + +int __init parse_spcr(void) +{ + 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 = 0; + + 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 = -EINVAL; + 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; + } + + sprintf(opts, "%s,%s,0x%llx,%d", uart, iotype, + table->serial_port.address, baud_rate); + + pr_info("console: %s", opts); + + if (init_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 d217366..ec030c9 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> @@ -206,11 +207,15 @@ 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 and ACPI SPCR + * earlycons; don't generate a warning from parse_early_params() + * in that case */ - if (!buf || !buf[0]) - return early_init_dt_scan_chosen_serial(); + if (!buf || !buf[0]) { + init_spcr_earlycon(); + early_init_dt_scan_chosen_serial(); + return 0; + } err = setup_earlycon(buf); if (err == -ENOENT || err == -EALREADY) diff --git a/include/linux/acpi.h b/include/linux/acpi.h index 06ed7e5..ebbb212 100644 --- a/include/linux/acpi.h +++ b/include/linux/acpi.h @@ -1004,4 +1004,12 @@ static inline struct fwnode_handle *acpi_get_next_subnode(struct device *dev, #define acpi_probe_device_table(t) ({ int __r = 0; __r;}) #endif +#ifdef CONFIG_ACPI_SPCR_TABLE +int parse_spcr(void); +void init_spcr_earlycon(void); +#else +static inline int parse_spcr(void) { return 0; } +static inline void init_spcr_earlycon(void) {} +#endif + #endif /*_LINUX_ACPI_H*/ -- 2.7.4 -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
