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coresight: tmc: Add configuration support for trace buffer size 

Now that we can dynamically switch between contiguous memory and
SG table depending on the trace buffer size, provide the support
for selecting an appropriate buffer size.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Suzuki K Poulose 2018-07-11 13:40:24 -06:00 committed by Greg Kroah-Hartman
parent e8e3b77139
commit c34cc23f1d
3 changed files with 43 additions and 1 deletions
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8
Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc
View File

@ -83,3 +83,11 @@ KernelVersion: 4.7
Contact: Mathieu Poirier <mathieu.poirier@linaro.org>
Description: (R) Indicates the capabilities of the Coresight TMC.
The value is read directly from the DEVID register, 0xFC8,
What: /sys/bus/coresight/devices/<memory_map>.tmc/buffer_size
Date: December 2018
KernelVersion: 4.19
Contact: Mathieu Poirier <mathieu.poirier@linaro.org>
Description: (RW) Size of the trace buffer for TMC-ETR when used in SYSFS
mode. Writable only for TMC-ETR configurations. The value
should be aligned to the kernel pagesize.

3
Documentation/devicetree/bindings/arm/coresight.txt
View File

@ -84,7 +84,8 @@ its hardware characteristcs.
* Optional property for TMC:
* arm,buffer-size: size of contiguous buffer space for TMC ETR
(embedded trace router)
(embedded trace router). This property is obsolete. The buffer size
can be configured dynamically via buffer_size property in sysfs.
* arm,scatter-gather: boolean. Indicates that the TMC-ETR can safely
use the SG mode on this system.

33
drivers/hwtracing/coresight/coresight-tmc.c
View File

@ -277,8 +277,41 @@ static ssize_t trigger_cntr_store(struct device *dev,
}
static DEVICE_ATTR_RW(trigger_cntr);
static ssize_t buffer_size_show(struct device *dev,
struct device_attribute *attr, char *buf)
{
struct tmc_drvdata *drvdata = dev_get_drvdata(dev->parent);
return sprintf(buf, "%#x\n", drvdata->size);
}
static ssize_t buffer_size_store(struct device *dev,
struct device_attribute *attr,
const char *buf, size_t size)
{
int ret;
unsigned long val;
struct tmc_drvdata *drvdata = dev_get_drvdata(dev->parent);
/* Only permitted for TMC-ETRs */
if (drvdata->config_type != TMC_CONFIG_TYPE_ETR)
return -EPERM;
ret = kstrtoul(buf, 0, &val);
if (ret)
return ret;
/* The buffer size should be page aligned */
if (val & (PAGE_SIZE - 1))
return -EINVAL;
drvdata->size = val;
return size;
}
static DEVICE_ATTR_RW(buffer_size);
static struct attribute *coresight_tmc_attrs[] = {
&dev_attr_trigger_cntr.attr,
&dev_attr_buffer_size.attr,
NULL,
};