[PATCH v1 04/11] stm class: stm_console: Add kernel-console-over-stm driver

[Alexander Shishkin <alexander.shishkin@linux.intel.com>]

This is a simple stm_source class device driver (kernelspace stm trace
source) that registers a console and sends kernel messages over STM
devices.

Cc: Pratik Patel <pratikp@codeaurora.org>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com>
---
 drivers/hwtracing/stm/Kconfig   | 10 ++++++
 drivers/hwtracing/stm/Makefile  |  2 ++
 drivers/hwtracing/stm/console.c | 80 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 92 insertions(+)
 create mode 100644 drivers/hwtracing/stm/console.c

diff --git a/drivers/hwtracing/stm/Kconfig b/drivers/hwtracing/stm/Kconfig
index cb3a0d3c4c..6f2db709b1 100644
--- a/drivers/hwtracing/stm/Kconfig
+++ b/drivers/hwtracing/stm/Kconfig
@@ -15,3 +15,13 @@ config STM_DUMMY
 	  and discards your data. Use for stm class testing.
 
 	  If you don't know what this is, say N.
+
+config STM_SOURCE_CONSOLE
+        tristate "Kernel console over STM devices"
+	default N
+	help
+	  This is a kernel space trace source that sends kernel log
+	  messages to trace hosts over STM devices.
+
+	  If you want to send kernel console messages over STM devices,
+	  say Y.
diff --git a/drivers/hwtracing/stm/Makefile b/drivers/hwtracing/stm/Makefile
index 1b2725fd04..74baf592db 100644
--- a/drivers/hwtracing/stm/Makefile
+++ b/drivers/hwtracing/stm/Makefile
@@ -3,3 +3,5 @@ obj-$(CONFIG_STM)	+= stm_core.o
 stm_core-y		:= core.o policy.o
 
 obj-$(CONFIG_STM_DUMMY)	+= dummy_stm.o
+
+obj-$(CONFIG_STM_SOURCE_CONSOLE)	+= console.o
diff --git a/drivers/hwtracing/stm/console.c b/drivers/hwtracing/stm/console.c
new file mode 100644
index 0000000000..c9d9a8d2ff
--- /dev/null
+++ b/drivers/hwtracing/stm/console.c
@@ -0,0 +1,80 @@
+/*
+ * Simple kernel console driver for STM devices
+ * Copyright (c) 2014, Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms and conditions of the GNU General Public License,
+ * version 2, as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope 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.
+ *
+ * STM console will send kernel messages over STM devices to a trace host.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/console.h>
+#include <linux/slab.h>
+#include <linux/stm.h>
+
+static int stm_console_link(struct stm_source_data *data);
+static void stm_console_unlink(struct stm_source_data *data);
+
+static struct stm_console {
+	struct stm_source_data	data;
+	struct console		console;
+} stm_console = {
+	.data	= {
+		.name		= "console",
+		.nr_chans	= 1,
+		.link		= stm_console_link,
+		.unlink		= stm_console_unlink,
+	},
+};
+
+static void
+stm_console_write(struct console *con, const char *buf, unsigned len)
+{
+	struct stm_console *sc = container_of(con, struct stm_console, console);
+
+	stm_source_write(&sc->data, 0, buf, len);
+}
+
+static int stm_console_link(struct stm_source_data *data)
+{
+	struct stm_console *sc = container_of(data, struct stm_console, data);
+
+	strcpy(sc->console.name, "stm_console");
+	sc->console.write = stm_console_write;
+	sc->console.flags = CON_ENABLED | CON_PRINTBUFFER;
+	register_console(&sc->console);
+
+	return 0;
+}
+
+static void stm_console_unlink(struct stm_source_data *data)
+{
+	struct stm_console *sc = container_of(data, struct stm_console, data);
+
+	unregister_console(&sc->console);
+}
+
+static int stm_console_init(void)
+{
+	return stm_source_register_device(NULL, &stm_console.data);
+}
+
+static void stm_console_exit(void)
+{
+	stm_source_unregister_device(&stm_console.data);
+}
+
+module_init(stm_console_init);
+module_exit(stm_console_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("stm_console driver");
+MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");
-- 
2.1.4