From 1525472db066e6d9a56b8b0f6ef040b43bdc3cbe Mon Sep 17 00:00:00 2001 From: Alexander Shishkin Date: Tue, 3 May 2016 11:33:37 -0600 Subject: 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: Alexander Shishkin Signed-off-by: Greg Kroah-Hartman (cherry picked from commit 8e996a2874bbbed30e8dfe881453825fc6b7654e) --- Documentation/ABI/testing/sysfs-class-stm | 10 ++++++++++ drivers/hwtracing/stm/core.c | 15 +++++++++++++++ include/linux/stm.h | 3 +++ 3 files changed, 28 insertions(+) diff --git a/Documentation/ABI/testing/sysfs-class-stm b/Documentation/ABI/testing/sysfs-class-stm index c9aa4f3fc9a7..77ed3da0f68e 100644 --- a/Documentation/ABI/testing/sysfs-class-stm +++ b/Documentation/ABI/testing/sysfs-class-stm @@ -12,3 +12,13 @@ KernelVersion: 4.3 Contact: Alexander Shishkin Description: Shows the number of channels per master on this STM device. + +What: /sys/class/stm//hw_override +Date: March 2016 +KernelVersion: 4.7 +Contact: Alexander Shishkin +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. diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c index d21eb53ba199..02095410cb33 100644 --- a/drivers/hwtracing/stm/core.c +++ b/drivers/hwtracing/stm/core.c @@ -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, }; diff --git a/include/linux/stm.h b/include/linux/stm.h index 1a79ed8e43da..8369d8a8cabd 100644 --- a/include/linux/stm.h +++ b/include/linux/stm.h @@ -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, -- cgit v1.2.3