This patch adds a driver that models itself as an stm_source and who's sole purpose is to export an interface to the rest of the kernel. Once the stm and stm_source have been linked via sysfs, everything that is passed to the interface will endup in the STM trace engine.
Signed-off-by: Chunyan Zhang <[email protected]> --- drivers/hwtracing/stm/Kconfig | 9 +++++++ drivers/hwtracing/stm/Makefile | 2 ++ drivers/hwtracing/stm/stm_ftrace.c | 54 ++++++++++++++++++++++++++++++++++++++ 3 files changed, 65 insertions(+) create mode 100644 drivers/hwtracing/stm/stm_ftrace.c diff --git a/drivers/hwtracing/stm/Kconfig b/drivers/hwtracing/stm/Kconfig index 847a39b..a36633a 100644 --- a/drivers/hwtracing/stm/Kconfig +++ b/drivers/hwtracing/stm/Kconfig @@ -39,4 +39,13 @@ config STM_SOURCE_HEARTBEAT If you want to send heartbeat messages over STM devices, say Y. +config STM_FTRACE + tristate "Redirect/copy the output from kernel Ftrace to STM engine" + help + This option can be used to redirect or copy the output from kernel Ftrace + to STM engine. Enabling this option will introduce a slight timing effect. + + If you want to send kernel Ftrace messages over STM devices, + say Y. + endif diff --git a/drivers/hwtracing/stm/Makefile b/drivers/hwtracing/stm/Makefile index a9ce3d4..5eef041 100644 --- a/drivers/hwtracing/stm/Makefile +++ b/drivers/hwtracing/stm/Makefile @@ -9,3 +9,5 @@ obj-$(CONFIG_STM_SOURCE_HEARTBEAT) += stm_heartbeat.o stm_console-y := console.o stm_heartbeat-y := heartbeat.o + +obj-$(CONFIG_STM_FTRACE) += stm_ftrace.o diff --git a/drivers/hwtracing/stm/stm_ftrace.c b/drivers/hwtracing/stm/stm_ftrace.c new file mode 100644 index 0000000..0b4eb70 --- /dev/null +++ b/drivers/hwtracing/stm/stm_ftrace.c @@ -0,0 +1,54 @@ +/* + * 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. + */ + +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/slab.h> +#include <linux/console.h> +#include <linux/stm.h> + +static struct stm_source_data stm_ftrace_data = { + .name = "stm_ftrace", + .nr_chans = 1, +}; + +/** + * stm_ftrace_write() - write data to STM via 'stm_ftrace' source + * @buf: buffer containing the data packet + * @len: length of the data packet + * @chan: offset above the start channel number allocated to 'stm_ftrace' + */ +void notrace stm_ftrace_write(const char *buf, unsigned int len, + unsigned int chan) +{ + stm_source_write(&stm_ftrace_data, chan, buf, len); +} +EXPORT_SYMBOL_GPL(stm_ftrace_write); + +static int __init stm_ftrace_init(void) +{ + return stm_source_register_device(NULL, &stm_ftrace_data); +} + +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 <[email protected]>"); -- 1.9.1
