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@xxxxxxxxxx>
---
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
#
# 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"},
+};
+
+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);
+
+ 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)
+ 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 \
--
2.1.4
--
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