linux-kernel - Re: [PATCH v2] power: reset: at91-shdwc: add new shutdown controller driver

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Date:	Thu, 24 Sep 2015 13:06:52 +0200
From:	Alexandre Belloni <alexandre.belloni@...e-electrons.com>
To:	Nicolas Ferre <nicolas.ferre@...el.com>
Cc:	sre@...nel.org, linux@...ck-us.net,
	Maxime Ripard <maxime.ripard@...e-electrons.com>,
	robh+dt@...nel.org, mark.rutland@....com,
	ijc+devicetree@...lion.org.uk,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	Jean-Christophe PLAGNIOL-VILLARD <plagnioj@...osoft.com>
Subject: Re: [PATCH v2] power: reset: at91-shdwc: add new shutdown controller
 driver

On 22/09/2015 at 17:57:52 +0200, Nicolas Ferre wrote :
> +config POWER_RESET_AT91_SHDWC

Maybe we should start numbering, at91-poweroff is already a driver for
an shdwc.

> +#define SLOW_CLOCK_FREQ	32768
> +

The slow clock is an input to the shdwc, then you have to get it,
prepare and enable it. The you could use clk_get_rate.
By duplicating the driver, you are repeating mistakes from the past ;)


> +static void at91_poweroff(void)
> +{
> +	BUG_ON(!at91_shdwc);

Is that condition even possible?

> +
> +	writel(AT91_SHDW_KEY | AT91_SHDW_SHDW,
> +			at91_shdwc->at91_shdwc_base + AT91_SHDW_CR);

This is not properly aligned.

> +}
> +
> +static u32 at91_shdwc_debouncer_value(struct platform_device *pdev,
> +				      u32 in_period_us)
> +{
> +	int i;
> +	int max_idx = ARRAY_SIZE(sdwc_dbc_period) - 1;
> +	unsigned long long period_us;
> +	unsigned long long max_period_us = DBC_PERIOD_US(sdwc_dbc_period[max_idx]);
> +
> +	if (in_period_us > max_period_us) {
> +		dev_warn(&pdev->dev,
> +			 "debouncer period %u too big, reduced to %llu us\n",
> +			 in_period_us, max_period_us);
> +		return max_idx;
> +	}
> +
> +	for (i = max_idx - 1; i > 0; i--) {
> +		period_us = DBC_PERIOD_US(sdwc_dbc_period[i]);
> +		dev_dbg(&pdev->dev, "%s: ref[%d] = %llu\n",
> +						__func__, i, period_us);
ditto


> +		if (in_period_us > period_us)
> +			break;
> +	}
> +
> +	return i + 1;
> +}
> +
> +static u32 at91_shdwc_get_wakeup_input(struct platform_device *pdev,
> +				       struct device_node *np)
> +{
> +	struct device_node *cnp;
> +	const char *pm;
> +	u32 wk_input_mask;
> +	u32 wuir = 0;
> +	u32 wk_input;
> +
> +	for_each_child_of_node(np, cnp) {
> +		if (of_property_read_u32(cnp, "reg", &wk_input)) {
> +			dev_warn(&pdev->dev, "reg property is missing for %s\n",
> +				 cnp->full_name);
> +			continue;
> +		}
> +
> +		wk_input_mask = 1 << wk_input;
> +		if (!(wk_input_mask & AT91_SHDW_WKUPEN_MASK)) {
> +			dev_warn(&pdev->dev,
> +				 "wake-up input %d out of bounds ignore\n",
> +				 wk_input);
> +			continue;
> +		}
> +		wuir |= wk_input_mask;
> +
> +		if (!of_property_read_string(cnp, "atmel,wakeup-type", &pm)) {
> +			if (!strcasecmp(pm, "high"))
> +				/*
> +				 * only add a type if "high" is specified. Low
> +				 * is the default.
> +				 */
> +				wuir |= AT91_SHDW_WKUPT(wk_input);
> +		}
> +		dev_dbg(&pdev->dev, "%s: (child %d) wuir = %#x\n",
> +						__func__, wk_input, wuir);

ditto

> +static int at91_shdwc_probe(struct platform_device *pdev)
> +{
> +	struct resource *res;
> +	const struct of_device_id *match;
> +
> +	if (!pdev->dev.of_node)
> +		return -ENODEV;
> +
> +	at91_shdwc = devm_kzalloc(&pdev->dev, sizeof(*at91_shdwc), GFP_KERNEL);
> +	if (!at91_shdwc)
> +		return -ENOMEM;
> +
> +	platform_set_drvdata(pdev, at91_shdwc);
> +
> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +	at91_shdwc->at91_shdwc_base = devm_ioremap_resource(&pdev->dev, res);
> +	if (IS_ERR(at91_shdwc->at91_shdwc_base)) {
> +		dev_err(&pdev->dev, "Could not map reset controller address\n");
> +		return PTR_ERR(at91_shdwc->at91_shdwc_base);
> +	}
> +
> +	match = of_match_node(at91_shdwc_of_match, pdev->dev.of_node);
> +	if (match != NULL)

match will never be NULL, else you wouldn't be probed. You can remove that test.

-- 
Alexandre Belloni, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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