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@xxxxxxxxxx>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx>
---
.../ABI/testing/sysfs-bus-coresight-devices-tmc | 8 ++++++
.../devicetree/bindings/arm/coresight.txt | 3 +-
drivers/hwtracing/coresight/coresight-tmc.c | 33 ++++++++++++++++++++++
3 files changed, 43 insertions(+), 1 deletion(-)
diff --git a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc
index 4fe677e..ea78714 100644
--- a/Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc
+++ b/Documentation/ABI/testing/sysfs-bus-coresight-devices-tmc
@@ -83,3 +83,11 @@ KernelVersion: 4.7
Contact: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
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: August 2018
+KernelVersion: 4.18
+Contact: Mathieu Poirier <mathieu.poirier@xxxxxxxxxx>
+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.
diff --git a/Documentation/devicetree/bindings/arm/coresight.txt b/Documentation/devicetree/bindings/arm/coresight.txt
index 603d3c6..9aa30a1 100644
--- a/Documentation/devicetree/bindings/arm/coresight.txt
+++ b/Documentation/devicetree/bindings/arm/coresight.txt
@@ -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 This property is obsolete.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.
diff --git a/drivers/hwtracing/coresight/coresight-tmc.c b/drivers/hwtracing/coresight/coresight-tmc.c
index bc8fc86..1b817ec 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.c
+++ b/drivers/hwtracing/coresight/coresight-tmc.c
@@ -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,
};
--
2.7.4
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