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

From: [email-masked] (Jon Hunter)
Date: Thu, 20 Dec 2012 11:49:03 -0600

On 12/18/2012 01:19 PM, pratikp at codeaurora.org wrote:
> From: Pratik Patel <[email-masked]>
> 
> This driver manages CoreSight ETB (Embedded Trace Buffer) which
> acts as a circular buffer sink collecting generated trace data.
> 
> Signed-off-by: Pratik Patel <[email-masked]>
> ---
>  drivers/coresight/Makefile        |    2 +-
>  drivers/coresight/coresight-etb.c |  467 +++++++++++++++++++++++++++++++++++++
>  2 files changed, 468 insertions(+), 1 deletions(-)

[snip]

> +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.

Cheers
Jon