coresight: tmc: Hide trace buffer handling for file read

At the moment we adjust the buffer pointers for reading the trace
data via misc device in the common code for ETF/ETB and ETR. Since
we are going to change how we manage the buffer for ETR, let us
move the buffer manipulation to the respective driver files, hiding
it from the common code. We do so by adding type specific helpers
for finding the length of data and the pointer to the buffer,
for a given length at a file position.

Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 23 insertions, 18 deletions

diff --git a/drivers/hwtracing/coresight/coresight-tmc.c b/drivers/hwtracing/coresight/coresight-tmc.c
index 456f122df74f..bb57e7f57eb5 100644
--- a/drivers/hwtracing/coresight/coresight-tmc.c
+++ b/drivers/hwtracing/coresight/coresight-tmc.c
@@ -123,35 +123,40 @@ static int tmc_open(struct inode *inode, struct file *file)
 	return 0;
 }
 
+static inline ssize_t tmc_get_sysfs_trace(struct tmc_drvdata *drvdata,
+					  loff_t pos, size_t len, char **bufpp)
+{
+	switch (drvdata->config_type) {
+	case TMC_CONFIG_TYPE_ETB:
+	case TMC_CONFIG_TYPE_ETF:
+		return tmc_etb_get_sysfs_trace(drvdata, pos, len, bufpp);
+	case TMC_CONFIG_TYPE_ETR:
+		return tmc_etr_get_sysfs_trace(drvdata, pos, len, bufpp);
+	}
+
+	return -EINVAL;
+}
+
 static ssize_t tmc_read(struct file *file, char __user *data, size_t len,
 			loff_t *ppos)
 {
+	char *bufp;
+	ssize_t actual;
 	struct tmc_drvdata *drvdata = container_of(file->private_data,
 						   struct tmc_drvdata, miscdev);
-	char *bufp = drvdata->buf + *ppos;
-
-	if (*ppos + len > drvdata->len)
-		len = drvdata->len - *ppos;
-
-	if (drvdata->config_type == TMC_CONFIG_TYPE_ETR) {
-		if (bufp == (char *)(drvdata->vaddr + drvdata->size))
-			bufp = drvdata->vaddr;
-		else if (bufp > (char *)(drvdata->vaddr + drvdata->size))
-			bufp -= drvdata->size;
-		if ((bufp + len) > (char *)(drvdata->vaddr + drvdata->size))
-			len = (char *)(drvdata->vaddr + drvdata->size) - bufp;
-	}
+	actual = tmc_get_sysfs_trace(drvdata, *ppos, len, &bufp);
+	if (actual <= 0)
+		return 0;
 
-	if (copy_to_user(data, bufp, len)) {
+	if (copy_to_user(data, bufp, actual)) {
 		dev_dbg(drvdata->dev, "%s: copy_to_user failed\n", __func__);
 		return -EFAULT;
 	}
 
-	*ppos += len;
+	*ppos += actual;
+	dev_dbg(drvdata->dev, "%zu bytes copied\n", actual);
 
-	dev_dbg(drvdata->dev, "%s: %zu bytes copied, %d bytes left\n",
-		__func__, len, (int)(drvdata->len - *ppos));
-	return len;
+	return actual;
 }
 
 static int tmc_release(struct inode *inode, struct file *file)