From: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
---
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 c9aa4f3..77ed3da 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 <alexander.shishkin@xxxxxxxxxxxxxxx>
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@xxxxxxxxxxxxxxx>
+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 de80d45..9387f8c 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 1a79ed8..8369d8a 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,
--
1.9.1
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