path: root/arm64-ACPI-parse-SPCR-table.patch

From patchwork Fri Aug 12 11:07:14 2016
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Subject: [v9,1/4] of/serial: move earlycon early_param handling to serial
From: Aleksey Makarov <aleksey.makarov@linaro.org>
X-Patchwork-Id: 9276727
Message-Id: <20160812110717.12351-1-aleksey.makarov@linaro.org>
To: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-serial@vger.kernel.org, linux-acpi@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
 Aleksey Makarov <aleksey.makarov@linaro.org>,
 Russell King <linux@arm.linux.org.uk>, Len Brown <lenb@kernel.org>,
 Leif Lindholm <leif.lindholm@linaro.org>,
 Graeme Gregory <graeme.gregory@linaro.org>, Al Stone <ahs3@redhat.com>,
 Christopher Covington <cov@codeaurora.org>,
 Yury Norov <ynorov@caviumnetworks.com>,
 Peter Hurley <peter@hurleysoftware.com>,
 Andy Shevchenko <andy.shevchenko@gmail.com>,
 "Zheng, Lv" <lv.zheng@intel.com>, Mark Salter <msalter@redhat.com>,
 Kefeng Wang <wangkefeng.wang@huawei.com>,
 Rob Herring <robh+dt@kernel.org>, Frank Rowand <frowand.list@gmail.com>,
 Jiri Slaby <jslaby@suse.com>, devicetree@vger.kernel.org
Date: Fri, 12 Aug 2016 14:07:14 +0300

From: Leif Lindholm <leif.lindholm@linaro.org>

We have multiple "earlycon" early_param handlers - merge the DT one into
the main earlycon one.  It's a cleanup that also will be useful
to defer setting up DT console until ACPI/DT decision is made.

Rename the exported function to avoid clashing with the function from
arch/microblaze/kernel/prom.c

Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org>
Acked-by: Rob Herring <robh@kernel.org>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 drivers/of/fdt.c              | 11 +----------
 drivers/tty/serial/earlycon.c |  2 +-
 include/linux/of_fdt.h        |  3 +++
 3 files changed, 5 insertions(+), 11 deletions(-)

diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c
index 55f1b83..741cac53 100644
--- a/drivers/of/fdt.c
+++ b/drivers/of/fdt.c
@@ -924,7 +924,7 @@ static inline void early_init_dt_check_for_initrd(unsigned long node)
 
 #ifdef CONFIG_SERIAL_EARLYCON
 
-static int __init early_init_dt_scan_chosen_serial(void)
+int __init early_init_dt_scan_chosen_stdout(void)
 {
 	int offset;
 	const char *p, *q, *options = NULL;
@@ -968,15 +968,6 @@ static int __init early_init_dt_scan_chosen_serial(void)
 	}
 	return -ENODEV;
 }
-
-static int __init setup_of_earlycon(char *buf)
-{
-	if (buf)
-		return 0;
-
-	return early_init_dt_scan_chosen_serial();
-}
-early_param("earlycon", setup_of_earlycon);
 #endif
 
 /**
diff --git a/drivers/tty/serial/earlycon.c b/drivers/tty/serial/earlycon.c
index 067783f..7aae655 100644
--- a/drivers/tty/serial/earlycon.c
+++ b/drivers/tty/serial/earlycon.c
@@ -209,7 +209,7 @@ static int __init param_setup_earlycon(char *buf)
 	 * don't generate a warning from parse_early_params() in that case
 	 */
 	if (!buf || !buf[0])
-		return 0;
+		return early_init_dt_scan_chosen_stdout();
 
 	err = setup_earlycon(buf);
 	if (err == -ENOENT || err == -EALREADY)
diff --git a/include/linux/of_fdt.h b/include/linux/of_fdt.h
index 26c3302..4341f32 100644
--- a/include/linux/of_fdt.h
+++ b/include/linux/of_fdt.h
@@ -14,6 +14,7 @@
 
 #include <linux/types.h>
 #include <linux/init.h>
+#include <linux/errno.h>
 
 /* Definitions used by the flattened device tree */
 #define OF_DT_HEADER		0xd00dfeed	/* marker */
@@ -66,6 +67,7 @@ extern int early_init_dt_scan_chosen(unsigned long node, const char *uname,
 				     int depth, void *data);
 extern int early_init_dt_scan_memory(unsigned long node, const char *uname,
 				     int depth, void *data);
+extern int early_init_dt_scan_chosen_stdout(void);
 extern void early_init_fdt_scan_reserved_mem(void);
 extern void early_init_fdt_reserve_self(void);
 extern void early_init_dt_add_memory_arch(u64 base, u64 size);
@@ -94,6 +96,7 @@ extern void early_get_first_memblock_info(void *, phys_addr_t *);
 extern u64 of_flat_dt_translate_address(unsigned long node);
 extern void of_fdt_limit_memory(int limit);
 #else /* CONFIG_OF_FLATTREE */
+static inline int early_init_dt_scan_chosen_stdout(void) { return -ENODEV; }
 static inline void early_init_fdt_scan_reserved_mem(void) {}
 static inline void early_init_fdt_reserve_self(void) {}
 static inline const char *of_flat_dt_get_machine_name(void) { return NULL; }
From patchwork Thu Aug 11 15:31:39 2016
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Subject: [v9,2/4] ACPI: parse SPCR and enable matching console
From: Aleksey Makarov <aleksey.makarov@linaro.org>
X-Patchwork-Id: 9275443
Message-Id: <20160811153152.755-3-aleksey.makarov@linaro.org>
To: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-serial@vger.kernel.org, linux-acpi@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
 Aleksey Makarov <aleksey.makarov@linaro.org>,
 Russell King <linux@arm.linux.org.uk>, Len Brown <lenb@kernel.org>,
 Leif Lindholm <leif.lindholm@linaro.org>,
 Graeme Gregory <graeme.gregory@linaro.org>, Al Stone <ahs3@redhat.com>,
 Christopher Covington <cov@codeaurora.org>,
 Yury Norov <ynorov@caviumnetworks.com>,
 Peter Hurley <peter@hurleysoftware.com>,
 Andy Shevchenko <andy.shevchenko@gmail.com>,
 "Zheng, Lv" <lv.zheng@intel.com>, Mark Salter <msalter@redhat.com>,
 Kefeng Wang <wangkefeng.wang@huawei.com>, Jiri Slaby <jslaby@suse.com>
Date: Thu, 11 Aug 2016 18:31:39 +0300

'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>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
 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 4d8452c..32407e4 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..04b8cfb 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;
+extern 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,
From patchwork Thu Aug 11 15:31:40 2016
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MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: [v9,3/4] ARM64: ACPI: enable ACPI_SPCR_TABLE
From: Aleksey Makarov <aleksey.makarov@linaro.org>
X-Patchwork-Id: 9275457
Message-Id: <20160811153152.755-4-aleksey.makarov@linaro.org>
To: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-serial@vger.kernel.org, linux-acpi@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
 Aleksey Makarov <aleksey.makarov@linaro.org>,
 Russell King <linux@arm.linux.org.uk>, Len Brown <lenb@kernel.org>,
 Leif Lindholm <leif.lindholm@linaro.org>,
 Graeme Gregory <graeme.gregory@linaro.org>, Al Stone <ahs3@redhat.com>,
 Christopher Covington <cov@codeaurora.org>,
 Yury Norov <ynorov@caviumnetworks.com>,
 Peter Hurley <peter@hurleysoftware.com>,
 Andy Shevchenko <andy.shevchenko@gmail.com>,
 "Zheng, Lv" <lv.zheng@intel.com>, Mark Salter <msalter@redhat.com>,
 Kefeng Wang <wangkefeng.wang@huawei.com>,
 Catalin Marinas <catalin.marinas@arm.com>,
 Will Deacon <will.deacon@arm.com>
Date: Thu, 11 Aug 2016 18:31:40 +0300

SBBR mentions SPCR as a mandatory ACPI table.  So enable it for ARM64

Earlycon should be set up as early as possible.  ACPI boot tables are
mapped in arch/arm64/kernel/acpi.c:acpi_boot_table_init() that
is called from setup_arch() and that's where we parse SPCR.
So it has to be opted-in per-arch.

When ACPI_SPCR_TABLE is defined initialization of DT earlycon is
deferred until the DT/ACPI decision is done.  Initialize DT earlycon
if ACPI is disabled.

Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org>
Tested-by: Kefeng Wang <wangkefeng.wang@huawei.com>
---
 arch/arm64/Kconfig       |  1 +
 arch/arm64/kernel/acpi.c | 11 ++++++++++-
 2 files changed, 11 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index 69c8787..a54dfc0 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig
@@ -4,6 +4,7 @@ config ARM64
 	select ACPI_GENERIC_GSI if ACPI
 	select ACPI_REDUCED_HARDWARE_ONLY if ACPI
 	select ACPI_MCFG if ACPI
+	select ACPI_SPCR_TABLE if ACPI
 	select ARCH_HAS_DEVMEM_IS_ALLOWED
 	select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
 	select ARCH_HAS_ATOMIC64_DEC_IF_POSITIVE
diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c
index 3e4f1a4..252a6d9 100644
--- a/arch/arm64/kernel/acpi.c
+++ b/arch/arm64/kernel/acpi.c
@@ -24,6 +24,7 @@
 #include <linux/memblock.h>
 #include <linux/of_fdt.h>
 #include <linux/smp.h>
+#include <linux/serial_core.h>
 
 #include <asm/cputype.h>
 #include <asm/cpu_ops.h>
@@ -206,7 +207,7 @@ void __init acpi_boot_table_init(void)
 	if (param_acpi_off ||
 	    (!param_acpi_on && !param_acpi_force &&
 	     of_scan_flat_dt(dt_scan_depth1_nodes, NULL)))
-		return;
+		goto done;
 
 	/*
 	 * ACPI is disabled at this point. Enable it in order to parse
@@ -226,6 +227,14 @@ void __init acpi_boot_table_init(void)
 		if (!param_acpi_force)
 			disable_acpi();
 	}
+
+done:
+	if (acpi_disabled) {
+		if (earlycon_init_is_deferred)
+			early_init_dt_scan_chosen_stdout();
+	} else {
+		parse_spcr(earlycon_init_is_deferred);
+	}
 }
 
 #ifdef CONFIG_ACPI_APEI
From patchwork Mon Aug 15 13:35:03 2016
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MIME-Version: 1.0
Content-Transfer-Encoding: 7bit
Subject: [v9,4/4] serial: pl011: add console matching function
From: Aleksey Makarov <aleksey.makarov@linaro.org>
X-Patchwork-Id: 9280971
Message-Id: <20160815133505.15294-1-aleksey.makarov@linaro.org>
To: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
 Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-serial@vger.kernel.org, linux-acpi@vger.kernel.org,
 linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
 Aleksey Makarov <aleksey.makarov@linaro.org>,
 Russell King <linux@arm.linux.org.uk>, Len Brown <lenb@kernel.org>,
 Leif Lindholm <leif.lindholm@linaro.org>,
 Graeme Gregory <graeme.gregory@linaro.org>, Al Stone <ahs3@redhat.com>,
 Christopher Covington <cov@codeaurora.org>,
 Yury Norov <ynorov@caviumnetworks.com>,
 Peter Hurley <peter@hurleysoftware.com>,
 Andy Shevchenko <andy.shevchenko@gmail.com>,
 "Zheng, Lv" <lv.zheng@intel.com>, Mark Salter <msalter@redhat.com>,
 Kefeng Wang <wangkefeng.wang@huawei.com>,
 Russell King <linux@armlinux.org.uk>, Jiri Slaby <jslaby@suse.com>
Date: Mon, 15 Aug 2016 16:35:03 +0300

This patch adds function pl011_console_match() that implements
method match of struct console.  It allows to match consoles against
data specified in a string, for example taken from command line or
compiled by ACPI SPCR table handler.

Signed-off-by: Aleksey Makarov <aleksey.makarov@linaro.org>
Reviewed-by: Peter Hurley <peter@hurleysoftware.com>
Acked-by: Russell King <rmk+kernel@armlinux.org.uk>
---
 drivers/tty/serial/amba-pl011.c | 55 +++++++++++++++++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)

diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index 8a9e213..2f9af8a 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2288,12 +2288,67 @@ static int __init pl011_console_setup(struct console *co, char *options)
 	return uart_set_options(&uap->port, co, baud, parity, bits, flow);
 }
 
+/**
+ *	pl011_console_match - non-standard console matching
+ *	@co:	  registering console
+ *	@name:	  name from console command line
+ *	@idx:	  index from console command line
+ *	@options: ptr to option string from console command line
+ *
+ *	Only attempts to match console command lines of the form:
+ *	    console=pl011,mmio|mmio32,<addr>[,<options>]
+ *	    console=pl011,0x<addr>[,<options>]
+ *	This form is used to register an initial earlycon boot console and
+ *	replace it with the amba_console at pl011 driver init.
+ *
+ *	Performs console setup for a match (as required by interface)
+ *	If no <options> are specified, then assume the h/w is already setup.
+ *
+ *	Returns 0 if console matches; otherwise non-zero to use default matching
+ */
+static int __init pl011_console_match(struct console *co, char *name, int idx,
+				      char *options)
+{
+	unsigned char iotype;
+	unsigned long addr;
+	int i;
+
+	if (strcmp(name, "pl011") != 0)
+		return -ENODEV;
+
+	if (uart_parse_earlycon(options, &iotype, &addr, &options))
+		return -ENODEV;
+
+	if (iotype != UPIO_MEM && iotype != UPIO_MEM32)
+		return -ENODEV;
+
+	/* try to match the port specified on the command line */
+	for (i = 0; i < ARRAY_SIZE(amba_ports); i++) {
+		struct uart_port *port;
+
+		if (!amba_ports[i])
+			continue;
+
+		port = &amba_ports[i]->port;
+
+		if (port->mapbase != addr)
+			continue;
+
+		co->index = i;
+		port->cons = co;
+		return pl011_console_setup(co, options);
+	}
+
+	return -ENODEV;
+}
+
 static struct uart_driver amba_reg;
 static struct console amba_console = {
 	.name		= "ttyAMA",
 	.write		= pl011_console_write,
 	.device		= uart_console_device,
 	.setup		= pl011_console_setup,
+	.match		= pl011_console_match,
 	.flags		= CON_PRINTBUFFER,
 	.index		= -1,
 	.data		= &amba_reg,