[PATCH v4 1/2] ACPI: Add early console framework for DBGP/DBG2.

From: Lv Zheng
Date: Thu Sep 27 2012 - 22:40:57 EST

Microsoft Debug Port Table (DBGP or DBG2) is required for Windows SoC
platforms. This patch is introduced to fix the gap between Windows
and Linux.

Signed-off-by: Lv Zheng <lv.zheng@xxxxxxxxx>
---
Documentation/kernel-parameters.txt | 1 +
arch/x86/Kconfig.debug | 15 +++
arch/x86/kernel/acpi/boot.c | 1 +
arch/x86/kernel/early_printk.c | 13 +++
drivers/acpi/Makefile | 2 +
drivers/acpi/early_printk.c | 201 +++++++++++++++++++++++++++++++++++
include/linux/acpi.h | 24 +++++
7 files changed, 257 insertions(+)
create mode 100644 drivers/acpi/early_printk.c

Index: linux-acpi/Documentation/kernel-parameters.txt
===================================================================
--- linux-acpi.orig/Documentation/kernel-parameters.txt 2012-09-27 22:35:07.000000000 +0800
+++ linux-acpi/Documentation/kernel-parameters.txt 2012-09-27 22:35:44.000000000 +0800
@@ -763,6 +763,7 @@
earlyprintk=serial[,ttySn[,baudrate]]
earlyprintk=ttySn[,baudrate]
earlyprintk=dbgp[debugController#]
+ earlyprintk=acpi[debugController#]

Append ",keep" to not disable it when the real console
takes over.
Index: linux-acpi/arch/x86/Kconfig.debug
===================================================================
--- linux-acpi.orig/arch/x86/Kconfig.debug 2012-09-27 22:35:07.000000000 +0800
+++ linux-acpi/arch/x86/Kconfig.debug 2012-09-27 22:35:44.000000000 +0800
@@ -59,6 +59,21 @@
with klogd/syslogd or the X server. You should normally N here,
unless you want to debug such a crash. You need usb debug device.

+config EARLY_PRINTK_ACPI
+ bool "Early printk launcher via ACPI debug port tables"
+ depends on EARLY_PRINTK && ACPI
+ ---help---
+ Write kernel log output directly into the debug ports described
+ in the ACPI tables known as DBGP and DBG2.
+
+ To enable such debugging facilities, you need to enable this
+ configuration option and append the "earlyprintk=acpi" kernel
+ parameter through the boot loaders. Please refer the
+ "Documentation/kernel-parameters.txt" for details. Since this
+ is an early console launcher, you still need to enable actual
+ early console drivers that are suitable for your platform.
+ If in doubt, say "N".
+
config DEBUG_STACKOVERFLOW
bool "Check for stack overflows"
depends on DEBUG_KERNEL
Index: linux-acpi/arch/x86/kernel/acpi/boot.c
===================================================================
--- linux-acpi.orig/arch/x86/kernel/acpi/boot.c 2012-09-27 22:35:07.000000000 +0800
+++ linux-acpi/arch/x86/kernel/acpi/boot.c 2012-09-27 22:35:13.000000000 +0800
@@ -1518,6 +1518,7 @@
return;
}

+ acpi_early_console_parse();
acpi_table_parse(ACPI_SIG_BOOT, acpi_parse_sbf);

/*
Index: linux-acpi/arch/x86/kernel/early_printk.c
===================================================================
--- linux-acpi.orig/arch/x86/kernel/early_printk.c 2012-09-27 22:35:07.000000000 +0800
+++ linux-acpi/arch/x86/kernel/early_printk.c 2012-09-27 22:35:44.000000000 +0800
@@ -200,6 +200,15 @@
register_console(early_console);
}

+#ifdef CONFIG_EARLY_PRINTK_ACPI
+#include <linux/acpi.h>
+
+int __init acpi_early_console_setup(struct acpi_debug_port *info)
+{
+ return 0;
+}
+#endif
+
static int __init setup_early_printk(char *buf)
{
int keep;
@@ -236,6 +245,10 @@
if (!strncmp(buf, "dbgp", 4) && !early_dbgp_init(buf + 4))
early_console_register(&early_dbgp_console, keep);
#endif
+#ifdef CONFIG_EARLY_PRINTK_ACPI
+ if (!strncmp(buf, "acpi", 4))
+ acpi_early_console_init(buf + 4, keep);
+#endif
#ifdef CONFIG_HVC_XEN
if (!strncmp(buf, "xen", 3))
early_console_register(&xenboot_console, keep);
Index: linux-acpi/drivers/acpi/Makefile
===================================================================
--- linux-acpi.orig/drivers/acpi/Makefile 2012-09-27 22:35:07.000000000 +0800
+++ linux-acpi/drivers/acpi/Makefile 2012-09-27 22:35:36.000000000 +0800
@@ -46,6 +46,8 @@
acpi-y += video_detect.o
endif

+obj-$(CONFIG_EARLY_PRINTK_ACPI) += early_printk.o
+
# These are (potentially) separate modules
obj-$(CONFIG_ACPI_AC) += ac.o
obj-$(CONFIG_ACPI_BUTTON) += button.o
Index: linux-acpi/drivers/acpi/early_printk.c
===================================================================
--- /dev/null 1970-01-01 00:00:00.000000000 +0000
+++ linux-acpi/drivers/acpi/early_printk.c 2012-09-27 22:35:13.000000000 +0800
@@ -0,0 +1,201 @@
+/*
+ * acpi/early_printk.c - ACPI Boot-Time Debug Ports
+ *
+ * Copyright (C) 2012 Lv Zheng <lv.zheng@xxxxxxxxx>
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ *
+ */
+
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/acpi.h>
+#include <linux/bootmem.h>
+
+#define ACPI_EARLY_DISABLED 0x0000
+#define ACPI_EARLY_ENABLED 0x0001
+#define ACPI_EARLY_KEEP 0x0002
+#define ACPI_EARLY_PORT_MSK 0xFF00
+#define ACPI_EARLY_PORT_OFF 8
+
+u16 acpi_early_flags = ACPI_EARLY_DISABLED;
+
+static inline bool acpi_early_enabled(void)
+{
+ return acpi_early_flags & ACPI_EARLY_ENABLED;
+}
+
+static inline u8 acpi_early_port_index(void)
+{
+ return (acpi_early_flags & ACPI_EARLY_PORT_MSK) >> ACPI_EARLY_PORT_OFF;
+}
+
+int __init acpi_early_console_keep(void)
+{
+ return acpi_early_flags & ACPI_EARLY_KEEP ? 1 : 0;
+}
+
+static inline int acpi_table_parse_dbg2(acpi_early_console_handler handler)
+{
+ struct acpi_table_header *table_header = NULL;
+ struct acpi_dbg2_device *entry;
+ unsigned int count = 0;
+ unsigned long table_end;
+ acpi_size tbl_size;
+ unsigned int max_entries;
+ struct acpi_debug_port devinfo;
+
+ if (acpi_disabled)
+ return -ENODEV;
+
+ if (!handler)
+ return -EINVAL;
+
+ acpi_get_table(ACPI_SIG_DBG2, 0, &table_header);
+ if (!table_header) {
+ pr_warn("DBG2 not present\n");
+ return -ENODEV;
+ }
+ tbl_size = table_header->length;
+ table_end = (unsigned long)table_header + table_header->length;
+
+ entry = (struct acpi_dbg2_device *)
+ ((unsigned long)table_header +
+ ((struct acpi_table_dbg2 *)table_header)->info_offset);
+ max_entries = ((struct acpi_table_dbg2 *)table_header)->info_count;
+
+ while (((unsigned long)entry) + sizeof(struct acpi_dbg2_device) <
+ table_end) {
+ if (entry->revision != 0) {
+ pr_warn("DBG2 revision %d not supported\n",
+ entry->revision);
+ count = -ENODEV;
+ goto fail;
+ }
+ if (!max_entries || count++ < max_entries) {
+ devinfo.port_index = (u8)count;
+ devinfo.port_type = entry->port_type;
+ devinfo.port_subtype = entry->port_subtype;
+ devinfo.register_count = entry->register_count;
+ devinfo.registers = (struct acpi_generic_address *)
+ ((unsigned long)entry + entry->base_address_offset);
+ devinfo.namepath_length = entry->namepath_length;
+ devinfo.namepath = (char *)
+ ((unsigned long)entry + entry->namepath_offset);
+ devinfo.oem_data_length = entry->oem_data_length;
+ devinfo.oem_data = (u8 *)
+ ((unsigned long)entry + entry->oem_data_offset);
+
+ if (handler(&devinfo, table_end)) {
+ count = -ENODEV;
+ goto fail;
+ }
+ }
+
+ entry = (struct acpi_dbg2_device *)
+ ((unsigned long)entry + entry->length);
+ }
+
+fail:
+ early_acpi_os_unmap_memory((char *)table_header, tbl_size);
+ return count;
+}
+
+static int __init acpi_parse_early_console(struct acpi_debug_port *info,
+ const unsigned long end)
+{
+ pr_info("early: DBG2 console %d detected: %04x:%04x.\n",
+ info->port_index, info->port_type, info->port_subtype);
+
+ if (acpi_early_port_index() != 0 &&
+ acpi_early_port_index() != info->port_index)
+ return 0;
+
+ acpi_early_console_setup(info);
+
+ return 0;
+}
+
+static int __init acpi_parse_dbgp(struct acpi_table_header *table)
+{
+ struct acpi_table_dbgp *dbgp;
+ struct acpi_debug_port devinfo;
+
+ if (acpi_early_port_index() != 0 &&
+ acpi_early_port_index() != 1)
+ return 0;
+
+ dbgp = (struct acpi_table_dbgp *)table;
+ if (!dbgp) {
+ pr_warn("Unable to map DBGP\n");
+ return -ENODEV;
+ }
+
+ pr_info("early: DBGP console detected: %04x.\n",
+ dbgp->type);
+
+ devinfo.port_index = 1;
+ devinfo.port_type = ACPI_DBG2_SERIAL_PORT;
+ devinfo.port_subtype = dbgp->type;
+ devinfo.register_count = 1;
+ devinfo.registers = (struct acpi_generic_address *)&dbgp->debug_port;
+ devinfo.namepath_length = 0;
+ devinfo.namepath = NULL;
+ devinfo.oem_data_length = 0;
+ devinfo.oem_data = NULL;
+
+ acpi_parse_early_console(&devinfo, 0);
+
+ return 0;
+}
+
+int __init acpi_early_console_parse(void)
+{
+ if (!acpi_early_enabled())
+ return -EINVAL;
+
+ if (acpi_table_parse_dbg2(acpi_parse_early_console) == 0)
+ acpi_table_parse(ACPI_SIG_DBGP, acpi_parse_dbgp);
+
+ return 0;
+}
+
+int __init acpi_early_console_init(char *s, int keep)
+{
+ acpi_early_flags = ACPI_EARLY_ENABLED;
+ if (keep)
+ acpi_early_flags |= ACPI_EARLY_KEEP;
+
+ if (*s) {
+ int ret;
+ unsigned long port;
+
+ ret = kstrtoul(s, 10, &port);
+ if (!ret)
+ acpi_early_flags |= ((u8)port) << ACPI_EARLY_PORT_OFF;
+ }
+
+ pr_info("early: debug port index %d.\n", acpi_early_port_index());
+
+ return 0;
+}
+
Index: linux-acpi/include/linux/acpi.h
===================================================================
--- linux-acpi.orig/include/linux/acpi.h 2012-09-27 22:35:07.000000000 +0800
+++ linux-acpi/include/linux/acpi.h 2012-09-27 22:35:41.000000000 +0800
@@ -430,4 +430,28 @@
#define acpi_os_set_prepare_sleep(func, pm1a_ctrl, pm1b_ctrl) do { } while (0)
#endif

+#ifdef CONFIG_EARLY_PRINTK_ACPI
+struct acpi_debug_port {
+ u8 port_index;
+ u16 port_type;
+ u16 port_subtype;
+ u16 register_count;
+ struct acpi_generic_address *registers;
+ u16 namepath_length;
+ char *namepath;
+ u16 oem_data_length;
+ u8 *oem_data;
+};
+
+typedef int (*acpi_early_console_handler)(struct acpi_debug_port *dev,
+ const unsigned long end);
+
+int __init acpi_early_console_keep(void);
+int __init acpi_early_console_init(char *s, int keep);
+int __init acpi_early_console_parse(void);
+int __init acpi_early_console_setup(struct acpi_debug_port *info);
+#else
+static int acpi_early_console_parse(void) { return 0; }
+#endif
+
#endif /*_LINUX_ACPI_H*/
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/