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path: root/drivers/hwtracing/stm/ftrace.c
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Diffstat (limited to 'drivers/hwtracing/stm/ftrace.c')
-rw-r--r--drivers/hwtracing/stm/ftrace.c87
1 files changed, 87 insertions, 0 deletions
diff --git a/drivers/hwtracing/stm/ftrace.c b/drivers/hwtracing/stm/ftrace.c
new file mode 100644
index 000000000000..bd126a7c6da2
--- /dev/null
+++ b/drivers/hwtracing/stm/ftrace.c
@@ -0,0 +1,87 @@
+/*
+ * Simple kernel driver to link kernel Ftrace and an STM device
+ * Copyright (c) 2016, Linaro Ltd.
+ *
+ * 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 Ftrace will be registered as a trace_export.
+ */
+
+#include <linux/module.h>
+#include <linux/stm.h>
+#include <linux/trace.h>
+
+#define STM_FTRACE_NR_CHANNELS 1
+#define STM_FTRACE_CHAN 0
+
+static int stm_ftrace_link(struct stm_source_data *data);
+static void stm_ftrace_unlink(struct stm_source_data *data);
+
+static struct stm_ftrace {
+ struct stm_source_data data;
+ struct trace_export ftrace;
+} stm_ftrace = {
+ .data = {
+ .name = "ftrace",
+ .nr_chans = STM_FTRACE_NR_CHANNELS,
+ .link = stm_ftrace_link,
+ .unlink = stm_ftrace_unlink,
+ },
+};
+
+/**
+ * stm_ftrace_write() - write data to STM via 'stm_ftrace' source
+ * @buf: buffer containing the data packet
+ * @len: length of the data packet
+ */
+static void notrace
+stm_ftrace_write(const void *buf, unsigned int len)
+{
+ stm_source_write(&stm_ftrace.data, STM_FTRACE_CHAN, buf, len);
+}
+
+static int stm_ftrace_link(struct stm_source_data *data)
+{
+ struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);
+
+ sf->ftrace.write = stm_ftrace_write;
+
+ return register_ftrace_export(&sf->ftrace);
+}
+
+static void stm_ftrace_unlink(struct stm_source_data *data)
+{
+ struct stm_ftrace *sf = container_of(data, struct stm_ftrace, data);
+
+ unregister_ftrace_export(&sf->ftrace);
+}
+
+static int __init stm_ftrace_init(void)
+{
+ int ret;
+
+ ret = stm_source_register_device(NULL, &stm_ftrace.data);
+ if (ret)
+ pr_err("Failed to register stm_source - ftrace.\n");
+
+ return ret;
+}
+
+static void __exit stm_ftrace_exit(void)
+{
+ stm_source_unregister_device(&stm_ftrace.data);
+}
+
+module_init(stm_ftrace_init);
+module_exit(stm_ftrace_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("stm_ftrace driver");
+MODULE_AUTHOR("Chunyan Zhang <zhang.chunyan@linaro.org>");