static int etm4_config_timestamp_event()

in coresight/coresight-etm4x-core.c [535:605]

• 42 lines of code
• 8 McCabe index (conditional complexity)

static int etm4_config_timestamp_event(struct etmv4_drvdata *drvdata)
{
	int ctridx, ret = -EINVAL;
	int counter, rselector;
	u32 val = 0;
	struct etmv4_config *config = &drvdata->config;

	/* No point in trying if we don't have at least one counter */
	if (!drvdata->nr_cntr)
		goto out;

	/* Find a counter that hasn't been initialised */
	for (ctridx = 0; ctridx < drvdata->nr_cntr; ctridx++)
		if (config->cntr_val[ctridx] == 0)
			break;

	/* All the counters have been configured already, bail out */
	if (ctridx == drvdata->nr_cntr) {
		pr_debug("%s: no available counter found\n", __func__);
		ret = -ENOSPC;
		goto out;
	}

	/*
	 * Searching for an available resource selector to use, starting at
	 * '2' since every implementation has at least 2 resource selector.
	 * ETMIDR4 gives the number of resource selector _pairs_,
	 * hence multiply by 2.
	 */
	for (rselector = 2; rselector < drvdata->nr_resource * 2; rselector++)
		if (!config->res_ctrl[rselector])
			break;

	if (rselector == drvdata->nr_resource * 2) {
		pr_debug("%s: no available resource selector found\n",
			 __func__);
		ret = -ENOSPC;
		goto out;
	}

	/* Remember what counter we used */
	counter = 1 << ctridx;

	/*
	 * Initialise original and reload counter value to the smallest
	 * possible value in order to get as much precision as we can.
	 */
	config->cntr_val[ctridx] = 1;
	config->cntrldvr[ctridx] = 1;

	/* Set the trace counter control register */
	val =  0x1 << 16	|  /* Bit 16, reload counter automatically */
	       0x0 << 7		|  /* Select single resource selector */
	       0x1;		   /* Resource selector 1, i.e always true */

	config->cntr_ctrl[ctridx] = val;

	val = 0x2 << 16		| /* Group 0b0010 - Counter and sequencers */
	      counter << 0;	  /* Counter to use */

	config->res_ctrl[rselector] = val;

	val = 0x0 << 7		| /* Select single resource selector */
	      rselector;	  /* Resource selector */

	config->ts_ctrl = val;

	ret = 0;
out:
	return ret;
}