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authorAleksey Makarov <aleksey.makarov@linaro.org>2016-05-20 16:03:21 +0300
committerGraeme Gregory <graeme.gregory@linaro.org>2016-06-07 13:47:00 +0100
commitc297c27354afe1b13fdceb647f97556878779914 (patch)
treeced38023beb4801240bada07b9e0d881f63da540 /drivers
parent3df2702192e42678129edfbab75cc0326e7e0651 (diff)
downloadleg-kernel-c297c27354afe1b13fdceb647f97556878779914.tar.gz
ACPI: parse SPCR and enable matching console
'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.makarov@linaro.org> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/acpi/Kconfig3
-rw-r--r--drivers/acpi/Makefile1
-rw-r--r--drivers/acpi/spcr.c111
-rw-r--r--drivers/tty/serial/earlycon.c19
4 files changed, 132 insertions, 2 deletions
diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
index b7e2e776397d..89218ea0e00b 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 251ce85a66fb..43cde68b00dc 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 000000000000..f4cfc5ca78d1
--- /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", 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 7aae655d9338..ea00b9fde04f 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)