Commit 8e996a28 authored by Alexander Shishkin's avatar Alexander Shishkin Committed by Greg Kroah-Hartman
Browse files

stm class: Support devices that override software assigned masters 



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: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 6327a454

Documentation/ABI/testing/sysfs-class-stm

+10 −0
Original line number Diff line number Diff line
@@ -12,3 +12,13 @@ KernelVersion: 4.3 
Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>

Description:

		Shows the number of channels per master on this STM device.



What:		/sys/class/stm/<stm>/hw_override

Date:		March 2016

KernelVersion:	4.7

Contact:	Alexander Shishkin <alexander.shishkin@linux.intel.com>

Description:

		Reads as 0 if master numbers in the STP stream produced by

		this stm device will match the master numbers assigned by

		the software or 1 if the stm hardware overrides software

		assigned masters.

drivers/hwtracing/stm/core.c

+15 −0
Original line number Diff line number Diff line
@@ -67,9 +67,24 @@ static ssize_t channels_show(struct device *dev, 


static DEVICE_ATTR_RO(channels);



static ssize_t hw_override_show(struct device *dev,

				struct device_attribute *attr,

				char *buf)

{

	struct stm_device *stm = to_stm_device(dev);

	int ret;



	ret = sprintf(buf, "%u\n", stm->data->hw_override);



	return ret;

}



static DEVICE_ATTR_RO(hw_override);



static struct attribute *stm_attrs[] = {

	&dev_attr_masters.attr,

	&dev_attr_channels.attr,

	&dev_attr_hw_override.attr,

	NULL,

};

include/linux/stm.h

+3 −0
Original line number Diff line number Diff line
@@ -50,6 +50,8 @@ struct stm_device; 
 * @sw_end:		last STP master available to software

 * @sw_nchannels:	number of STP channels per master

 * @sw_mmiosz:		size of one channel's IO space, for mmap, optional

 * @hw_override:	masters in the STP stream will not match the ones

 *			assigned by software, but are up to the STM hardware

 * @packet:		callback that sends an STP packet

 * @mmio_addr:		mmap callback, optional

 * @link:		called when a new stm_source gets linked to us, optional
@@ -85,6 +87,7 @@ struct stm_data { 
	unsigned int		sw_end;

	unsigned int		sw_nchannels;

	unsigned int		sw_mmiosz;

	unsigned int		hw_override;

	ssize_t			(*packet)(struct stm_data *, unsigned int,

					  unsigned int, unsigned int,

					  unsigned int, unsigned int,

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