linux-kernel - Re: [PATCH v7 1/2] rtc: tps6594: Add driver for TPS6594 RTC

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Date:   Sun, 1 Oct 2023 23:20:49 +0200
From:   Alexandre Belloni <alexandre.belloni@...tlin.com>
To:     Esteban Blanc <eblanc@...libre.com>
Cc:     linus.walleij@...aro.org, a.zummo@...ertech.it,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-rtc@...r.kernel.org, jpanis@...libre.com,
        jneanne@...libre.com, aseketeli@...libre.com, u-kumar1@...com
Subject: Re: [PATCH v7 1/2] rtc: tps6594: Add driver for TPS6594 RTC

Hello,

What is the status of this series?

On 28/06/2023 15:30:20+0200, Esteban Blanc wrote:
> +static int tps6594_rtc_read_offset(struct device *dev, long *offset)
> +{
> +	int calibration;
> +	s64 tmp;
> +	int ret;
> +
> +	ret = tps6594_rtc_get_calibration(dev, &calibration);
> +	if (ret < 0)
> +		return ret;
> +
> +	// Convert from RTC calibration register format to ppb format.
> +	tmp = calibration * PPB_MULT;
> +
> +	if (tmp < 0)
> +		tmp -= TICKS_PER_HOUR / 2LL;
> +	else
> +		tmp += TICKS_PER_HOUR / 2LL;
> +	tmp = div_s64(tmp, TICKS_PER_HOUR);
> +
> +	/*
> +	 * SAFETY:
> +	 * Compution is the reverse operation of the one done in

Small typo -^

> +	 * `tps6594_rtc_set_offset`. The safety remarks applie here too.
> +	 */
> +
> +	/*
> +	 * Offset value operates in negative way, so swap sign.
> +	 * See 8.3.10.5, (32768 - COMP_REG).
> +	 */
> +	*offset = (long)-tmp;
> +
> +	return 0;
> +}
> +
> +static int tps6594_rtc_set_offset(struct device *dev, long offset)
> +{
> +	int calibration;
> +	s64 tmp;
> +
> +	// Make sure offset value is within supported range.
> +	if (offset < MIN_OFFSET || offset > MAX_OFFSET)
> +		return -ERANGE;
> +
> +	// Convert from ppb format to RTC calibration register format.
> +
> +	tmp = offset * TICKS_PER_HOUR;
> +	if (tmp < 0)
> +		tmp -= PPB_MULT / 2LL;
> +	else
> +		tmp += PPB_MULT / 2LL;
> +	tmp = div_s64(tmp, PPB_MULT);
> +
> +	/*
> +	 * SAFETY:
> +	 * - tmp = offset * TICK_PER_HOUR :
> +	 *	`offset` can't be more than 277774, so `tmp` can't exceed 277774000000000
> +	 *	which is lower than the maximum value in an `s64` (2^63-1). No overflow here.
> +	 *
> +	 * - tmp += TICK_PER_HOUR / 2LL :
> +	 *	tmp will have a maximum value of 277774117964800 which is still inferior to 2^63-1.
> +	 */
> +
> +	// Offset value operates in negative way, so swap sign.
> +	calibration = (int)-tmp;
> +
> +	return tps6594_rtc_set_calibration(dev, calibration);
> +}
> +
> +static irqreturn_t tps6594_rtc_interrupt(int irq, void *rtc)
> +{
> +	struct device *dev = rtc;
> +	unsigned long events = 0;
> +	struct tps6594 *tps = dev_get_drvdata(dev->parent);
> +	struct rtc_device *rtc_dev = dev_get_drvdata(dev);
> +	int ret;
> +	u32 rtc_reg;
> +
> +	ret = regmap_read(tps->regmap, TPS6594_REG_RTC_STATUS, &rtc_reg);
> +	if (ret)
> +		return IRQ_NONE;
> +
> +	if (rtc_reg & TPS6594_BIT_ALARM)
> +		events = RTC_IRQF | RTC_AF;
> +
> +	// Notify RTC core on event.

Nit: I don't feel like the events varialbe and the comment are
necessary.

> +	rtc_update_irq(rtc_dev, 1, events);
> +
> +	return IRQ_HANDLED;
> +}
> +

If you resend, you can add:

Acked-by: Alexandre Belloni <alexandre.belloni@...tlin.com>


-- 
Alexandre Belloni, co-owner and COO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com