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2016-11-22stm: Mark the functions of writing STM with notraceChunyan Zhang
If CONFIG_STM_SOURCE_FTRACE is selected, Function trace data can be writen to sink via STM, all functions that related to writing data packets to STM should be marked 'notrace' to avoid being traced by Ftrace, otherwise the program would stall into an endless loop. Link: http://lkml.kernel.org/r/1479715043-6534-7-git-send-email-zhang.chunyan@linaro.org Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org> Acked-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
2016-05-03stm class: Support devices that override software assigned mastersAlexander Shishkin
Some STM devices adjust software assigned master numbers depending on the trace source and its runtime state and whatnot. This patch adds a sysfs attribute to inform the trace-side software that master numbers assigned to software sources will not match those in the STP stream, so that, for example, master/channel allocation policy can be adjusted accordingly. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-20stm class: Plug stm device's unlink callbackAlexander Shishkin
STM device's unlink callback is never actually called from anywhere in the stm class code. This patch adds calls to stm driver's unlink method after the unlinking has succeeded. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2016-02-20stm class: Use driver's packet callback return valueAlexander Shishkin
STM drivers provide a callback to generate/send individual STP packets; it also tells the stm core how many bytes of payload it has consumed. However, we would also need to use the negative space of this return value to communicate errors that occur during the packet generation, in which case the stm core will have to take appropriate action. For now, we need to account for the possibility that the stm driver may not support certain combinations of packet type/flags, in which case it is expected to signal an error. Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2015-10-04stm class: Introduce an abstraction for System Trace Module devicesAlexander Shishkin
A System Trace Module (STM) is a device exporting data in System Trace Protocol (STP) format as defined by MIPI STP standards. Examples of such devices are Intel(R) Trace Hub and Coresight STM. This abstraction provides a unified interface for software trace sources to send their data over an STM device to a debug host. In order to do that, such a trace source needs to be assigned a pair of master/channel identifiers that all the data from this source will be tagged with. The STP decoder on the debug host side will use these master/channel tags to distinguish different trace streams from one another inside one STP stream. This abstraction provides a configfs-based policy management mechanism for dynamic allocation of these master/channel pairs based on trace source-supplied string identifier. It has the flexibility of being defined at runtime and at the same time (provided that the policy definition is aligned with the decoding end) consistency. For userspace trace sources, this abstraction provides write()-based and mmap()-based (if the underlying stm device allows this) output mechanism. For kernel-side trace sources, we provide "stm_source" device class that can be connected to an stm device at run time. Cc: linux-api@vger.kernel.org Reviewed-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Alexander Shishkin <alexander.shishkin@linux.intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>