[RFC 4/8] coresight: add CoreSight ETB driver

On Thu, Dec 20, 2012 at 11:49:03AM -0600, Jon Hunter wrote:

On 12/18/2012 01:19 PM, pratikp at codeaurora.org wrote:

quoted

From: Pratik Patel <redacted>

This driver manages CoreSight ETB (Embedded Trace Buffer) which
acts as a circular buffer sink collecting generated trace data.

Signed-off-by: Pratik Patel <redacted>
---
 drivers/coresight/Makefile        |    2 +-
 drivers/coresight/coresight-etb.c |  467 +++++++++++++++++++++++++++++++++++++
 2 files changed, 468 insertions(+), 1 deletions(-)

[snip]

quoted

+static int __devinit etb_probe(struct platform_device *pdev)
+{
+	int ret;
+	struct device *dev = &pdev->dev;
+	struct coresight_platform_data *pdata;
+	struct etb_drvdata *drvdata;
+	struct resource *res;
+	struct coresight_desc *desc;
+
+	if (pdev->dev.of_node) {
+		pdata = of_get_coresight_platform_data(dev, pdev->dev.of_node);
+		if (IS_ERR(pdata))
+			return PTR_ERR(pdata);
+		pdev->dev.platform_data = pdata;
+	}
+
+	drvdata = devm_kzalloc(dev, sizeof(*drvdata), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+	drvdata->dev = &pdev->dev;
+	platform_set_drvdata(pdev, drvdata);
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	drvdata->base = devm_ioremap(dev, res->start, resource_size(res));
+	if (!drvdata->base)
+		return -ENOMEM;
+
+	spin_lock_init(&drvdata->spinlock);
+
+	drvdata->clk = devm_clk_get(dev, "core_clk");
+	if (IS_ERR(drvdata->clk))
+		return PTR_ERR(drvdata->clk);
+
+	ret = clk_set_rate(drvdata->clk, CORESIGHT_CLK_RATE_TRACE);
+	if (ret)
+		return ret;
+
+	drvdata->buf = devm_kzalloc(dev, ETB_SIZE_WORDS * BYTES_PER_WORD,
+				    GFP_KERNEL);
+	if (!drvdata->buf)
+		return -ENOMEM;
+
+	desc = devm_kzalloc(dev, sizeof(*desc), GFP_KERNEL);
+	if (!desc)
+		return -ENOMEM;
+	desc->type = CORESIGHT_DEV_TYPE_SINK;
+	desc->subtype.sink_subtype = CORESIGHT_DEV_SUBTYPE_SINK_BUFFER;

Can a source be directly connected to a sink or do you need to have a
link in between?

The reason, I ask is because on some Cortex-A8 devices we have ETM
directly connected to ETB and there is no link per-se to configure.

Source can be directly connected to a sink. I believe the current
code should be able to take care of that but I haven't tried it
since we didn't have such a case.

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