metag: Add JTAG Debug Adapter (DA) support

Add basic JTAG Debug Adapter (DA) support so that drivers which
communicate with the DA can detect whether one is actually present
(otherwise the target will halt indefinitely).

This allows the metag_da TTY driver and imgdafs filesystem driver to be
built, updates defconfigs, and sets up the metag_da console early if
it's configured in.

Signed-off-by: James Hogan <james.hogan@imgtec.com>

9 files changed, 105 insertions, 0 deletions

diff --git a/MAINTAINERS b/MAINTAINERS
index 9b2b769..a6a0c35 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5042,6 +5042,8 @@ F:	Documentation/devicetree/bindings/metag/
 F:	drivers/clocksource/metag_generic.c
 F:	drivers/irqchip/irq-metag.c
 F:	drivers/irqchip/irq-metag-ext.c
+F:	drivers/tty/metag_da.c
+F:	fs/imgdafs/
 
 MICROBLAZE ARCHITECTURE
 M:	Michal Simek <monstr@monstr.eu>
diff --git a/arch/metag/Kconfig b/arch/metag/Kconfig
index f6846ad..30adc78 100644
--- a/arch/metag/Kconfig
+++ b/arch/metag/Kconfig
@@ -214,6 +214,18 @@ config METAG_PERFCOUNTER_IRQS
 	  When disabled, Performance Counters information will be collected
 	  based on Timer Interrupt.
 
+config METAG_DA
+	bool "DA support"
+	help
+	  Say Y if you plan to use a DA debug adapter with Linux. The presence
+	  of the DA will be detected automatically at boot, so it is safe to say
+	  Y to this option even when booting without a DA.
+
+	  This enables support for services provided by DA JTAG debug adapters,
+	  such as:
+	  - communication over DA channels (such as the console driver).
+	  - use of the DA filesystem.
+
 menu "Boot options"
 
 config METAG_BUILTIN_DTB
diff --git a/arch/metag/configs/meta1_defconfig b/arch/metag/configs/meta1_defconfig
index 837c235..ad663ca 100644
--- a/arch/metag/configs/meta1_defconfig
+++ b/arch/metag/configs/meta1_defconfig
@@ -14,6 +14,7 @@ CONFIG_PARTITION_ADVANCED=y
 # CONFIG_IOSCHED_CFQ is not set
 CONFIG_FLATMEM_MANUAL=y
 CONFIG_META12_FPGA=y
+CONFIG_METAG_DA=y
 CONFIG_HZ_100=y
 CONFIG_DEVTMPFS=y
 CONFIG_DEVTMPFS_MOUNT=y
@@ -27,6 +28,8 @@ CONFIG_BLK_DEV_RAM_SIZE=16384
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
 # CONFIG_LEGACY_PTYS is not set
+CONFIG_DA_TTY=y
+CONFIG_DA_CONSOLE=y
 # CONFIG_DEVKMEM is not set
 # CONFIG_HW_RANDOM is not set
 # CONFIG_HWMON is not set
diff --git a/arch/metag/configs/meta2_defconfig b/arch/metag/configs/meta2_defconfig
index e5bada8..47922e93 100644
--- a/arch/metag/configs/meta2_defconfig
+++ b/arch/metag/configs/meta2_defconfig
@@ -16,6 +16,7 @@ CONFIG_PARTITION_ADVANCED=y
 CONFIG_METAG_L2C=y
 CONFIG_FLATMEM_MANUAL=y
 CONFIG_METAG_HALT_ON_PANIC=y
+CONFIG_METAG_DA=y
 CONFIG_HZ_100=y
 CONFIG_DEVTMPFS=y
 # CONFIG_STANDALONE is not set
@@ -28,6 +29,8 @@ CONFIG_BLK_DEV_RAM_SIZE=16384
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
 # CONFIG_LEGACY_PTYS is not set
+CONFIG_DA_TTY=y
+CONFIG_DA_CONSOLE=y
 # CONFIG_DEVKMEM is not set
 # CONFIG_HW_RANDOM is not set
 # CONFIG_HWMON is not set
diff --git a/arch/metag/configs/meta2_smp_defconfig b/arch/metag/configs/meta2_smp_defconfig
index 41983a2..f508250 100644
--- a/arch/metag/configs/meta2_smp_defconfig
+++ b/arch/metag/configs/meta2_smp_defconfig
@@ -17,6 +17,7 @@ CONFIG_METAG_L2C=y
 CONFIG_FLATMEM_MANUAL=y
 CONFIG_METAG_HALT_ON_PANIC=y
 CONFIG_SMP=y
+CONFIG_METAG_DA=y
 CONFIG_HZ_100=y
 CONFIG_DEVTMPFS=y
 # CONFIG_STANDALONE is not set
@@ -29,6 +30,8 @@ CONFIG_BLK_DEV_RAM_SIZE=16384
 # CONFIG_SERIO is not set
 # CONFIG_VT is not set
 # CONFIG_LEGACY_PTYS is not set
+CONFIG_DA_TTY=y
+CONFIG_DA_CONSOLE=y
 # CONFIG_DEVKMEM is not set
 # CONFIG_HW_RANDOM is not set
 # CONFIG_HWMON is not set
diff --git a/arch/metag/include/asm/da.h b/arch/metag/include/asm/da.h
new file mode 100644
index 0000000..81bd521
--- /dev/null
+++ b/arch/metag/include/asm/da.h
@@ -0,0 +1,43 @@
+/*
+ * Meta DA JTAG debugger control.
+ *
+ * Copyright 2012 Imagination Technologies Ltd.
+ */
+
+#ifndef _METAG_DA_H_
+#define _METAG_DA_H_
+
+#ifdef CONFIG_METAG_DA
+
+#include <linux/init.h>
+#include <linux/types.h>
+
+extern bool _metag_da_present;
+
+/**
+ * metag_da_enabled() - Find whether a DA is currently enabled.
+ *
+ * Returns:	true if a DA was detected, false if not.
+ */
+static inline bool metag_da_enabled(void)
+{
+	return _metag_da_present;
+}
+
+/**
+ * metag_da_probe() - Try and detect a connected DA.
+ *
+ * This is used at start up to detect whether a DA is active.
+ *
+ * Returns:	0 on detection, -err otherwise.
+ */
+int __init metag_da_probe(void);
+
+#else /* !CONFIG_METAG_DA */
+
+#define metag_da_enabled() false
+#define metag_da_probe() do {} while (0)
+
+#endif
+
+#endif /* _METAG_DA_H_ */
diff --git a/arch/metag/kernel/Makefile b/arch/metag/kernel/Makefile
index a5e4ba6..d7675f4 100644
--- a/arch/metag/kernel/Makefile
+++ b/arch/metag/kernel/Makefile
@@ -28,6 +28,7 @@ obj-y	+= user_gateway.o
 obj-$(CONFIG_PERF_EVENTS)		+= perf/
 
 obj-$(CONFIG_METAG_COREMEM)		+= coremem.o
+obj-$(CONFIG_METAG_DA)			+= da.o
 obj-$(CONFIG_DYNAMIC_FTRACE)		+= ftrace.o
 obj-$(CONFIG_FUNCTION_TRACER)		+= ftrace_stub.o
 obj-$(CONFIG_MODULES)			+= metag_ksyms.o
diff --git a/arch/metag/kernel/da.c b/arch/metag/kernel/da.c
new file mode 100644
index 0000000..52aabb6
--- /dev/null
+++ b/arch/metag/kernel/da.c
@@ -0,0 +1,23 @@
+/*
+ * Meta DA JTAG debugger control.
+ *
+ * Copyright 2012 Imagination Technologies Ltd.
+ */
+
+
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <asm/da.h>
+#include <asm/metag_mem.h>
+
+bool _metag_da_present;
+
+int __init metag_da_probe(void)
+{
+	_metag_da_present = (metag_in32(T0VECINT_BHALT) == 1);
+	if (_metag_da_present)
+		pr_info("DA present\n");
+	else
+		pr_info("DA not present\n");
+	return 0;
+}
diff --git a/arch/metag/kernel/setup.c b/arch/metag/kernel/setup.c
index 74e2c1f..89f9cdc 100644
--- a/arch/metag/kernel/setup.c
+++ b/arch/metag/kernel/setup.c
@@ -37,6 +37,7 @@
 #include <asm/hwthread.h>
 #include <asm/mmzone.h>
 #include <asm/l2cache.h>
+#include <asm/da.h>
 #include <asm/prom.h>
 #include <asm/mach/arch.h>
 #include <asm/core_reg.h>
@@ -60,6 +61,11 @@ extern char _heap_start[];
 extern u32 __dtb_start[];
 #endif
 
+#ifdef CONFIG_DA_CONSOLE
+/* Our early channel based console driver */
+extern struct console dash_console;
+#endif
+
 struct machine_desc *machine_desc __initdata;
 
 /*
@@ -180,6 +186,15 @@ void __init setup_arch(char **cmdline_p)
 
 	metag_cache_probe();
 
+	metag_da_probe();
+#ifdef CONFIG_DA_CONSOLE
+	if (metag_da_enabled()) {
+		/* An early channel based console driver */
+		register_console(&dash_console);
+		add_preferred_console("ttyDA", 1, NULL);
+	}
+#endif
+
 	/* try interpreting the argument as a device tree */
 	machine_desc = setup_machine_fdt(original_cmd_line);
 	/* if it doesn't look like a device tree it must be a command line */