[PATCH 1/2] coresight: etb10: Refactor etb_drvdata::mode handling

Mathieu Poirier
2018-08-14T22:14:32Z

This patch moves the etb_drvdata::mode from a locat_t to a simple u32,
as it is for the ETF and ETR drivers. This streamlines the code and adds
commonality with the other drivers when dealing with similar operations.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
---
drivers/hwtracing/coresight/coresight-etb10.c | 62 +++++++++++++++------------
1 file changed, 34 insertions(+), 28 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-etb10.c b/drivers/hwtracing/coresight/coresight-etb10.c
index 9fd77fdc1244..69287163ce4e 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -5,7 +5,6 @@
* Description: CoreSight Embedded Trace Buffer driver
*/

-#include <asm/local.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/types.h>
@@ -72,8 +71,8 @@
* @miscdev: specifics to handle "/dev/xyz.etb" entry.
* @spinlock: only one at a time pls.
* @reading: synchronise user space access to etb buffer.
- * @mode: this ETB is being used.
* @buf: area of memory where ETB buffer content gets sent.
+ * @mode: this ETB is being used.
* @buffer_depth: size of @buf.
* @trigger_cntr: amount of words to store after a trigger.
*/
@@ -85,8 +84,8 @@ struct etb_drvdata {
struct miscdevice miscdev;
spinlock_t spinlock;
local_t reading;
- local_t mode;
u8 *buf;
+ u32 mode;
u32 buffer_depth;
u32 trigger_cntr;
};
@@ -138,44 +137,48 @@ static void etb_enable_hw(struct etb_drvdata *drvdata)
static int etb_enable(struct coresight_device *csdev, u32 mode, void *data)
{
int ret = 0;
- u32 val;
unsigned long flags;
struct etb_drvdata *drvdata = dev_get_drvdata(csdev->dev.parent);

- /*
- * We don't have an internal state to clean up if we fail to setup
- * the perf buffer. So we can perform the step before we turn the
- * ETB on and leave without cleaning up.
- */
- if (mode == CS_MODE_PERF) {
- ret = etb_set_buffer(csdev, (struct perf_output_handle *)data);
- if (ret)
- goto out;
- }
+ spin_lock_irqsave(&drvdata->spinlock, flags);

- val = local_cmpxchg(&drvdata->mode,
- CS_MODE_DISABLED, mode);
/*
* When accessing from Perf, a HW buffer can be handled
* by a single trace entity. In sysFS mode many tracers
* can be logging to the same HW buffer.
*/
- if (val == CS_MODE_PERF)
- return -EBUSY;
+ if (drvdata->mode == CS_MODE_PERF) {
+ ret = -EBUSY;
+ goto out;
+ }

/* Don't let perf disturb sysFS sessions */
- if (val == CS_MODE_SYSFS && mode == CS_MODE_PERF)
- return -EBUSY;
+ if (drvdata->mode == CS_MODE_SYSFS && mode == CS_MODE_PERF) {
+ ret = -EBUSY;
+ goto out;
+ }

/* Nothing to do, the tracer is already enabled. */
- if (val == CS_MODE_SYSFS)
+ if (drvdata->mode == CS_MODE_SYSFS && mode == CS_MODE_SYSFS)
goto out;

- spin_lock_irqsave(&drvdata->spinlock, flags);
+ /*
+ * We don't have an internal state to clean up if we fail to setup
+ * the perf buffer. So we can perform the step before we turn the
+ * ETB on and leave without cleaning up.
+ */
+ if (mode == CS_MODE_PERF) {
+ ret = etb_set_buffer(csdev, (struct perf_output_handle *)data);
+ if (ret)
+ goto out;
+ }
+
+ drvdata->mode = mode;
etb_enable_hw(drvdata);
- spin_unlock_irqrestore(&drvdata->spinlock, flags);

out:
+ spin_unlock_irqrestore(&drvdata->spinlock, flags);
+
if (!ret)
dev_dbg(drvdata->dev, "ETB enabled\n");
return ret;
@@ -277,11 +280,14 @@ static void etb_disable(struct coresight_device *csdev)
unsigned long flags;

spin_lock_irqsave(&drvdata->spinlock, flags);
- etb_disable_hw(drvdata);
- etb_dump_hw(drvdata);
- spin_unlock_irqrestore(&drvdata->spinlock, flags);

- local_set(&drvdata->mode, CS_MODE_DISABLED);
+ /* Disable the ETB only if it needs to */
+ if (drvdata->mode != CS_MODE_DISABLED) {
+ etb_disable_hw(drvdata);
+ etb_dump_hw(drvdata);
+ drvdata->mode = CS_MODE_DISABLED;
+ }
+ spin_unlock_irqrestore(&drvdata->spinlock, flags);

dev_dbg(drvdata->dev, "ETB disabled\n");
}
@@ -488,7 +494,7 @@ static void etb_dump(struct etb_drvdata *drvdata)
unsigned long flags;

spin_lock_irqsave(&drvdata->spinlock, flags);
- if (local_read(&drvdata->mode) == CS_MODE_SYSFS) {
+ if (drvdata->mode == CS_MODE_SYSFS) {
etb_disable_hw(drvdata);
etb_dump_hw(drvdata);
etb_enable_hw(drvdata);
--
2.7.4