linux-kernel - Re: [RFC Patch net-next v2 8/8] net: dsa: microchip: ptp: add periodic output signal

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Message-ID: <Y3zegX68J7Mfbrbr@hoboy.vegasvil.org>
Date:   Tue, 22 Nov 2022 06:36:49 -0800
From:   Richard Cochran <richardcochran@...il.com>
To:     Arun Ramadoss <arun.ramadoss@...rochip.com>
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        woojung.huh@...rochip.com, UNGLinuxDriver@...rochip.com,
        andrew@...n.ch, vivien.didelot@...il.com, f.fainelli@...il.com,
        olteanv@...il.com, davem@...emloft.net, edumazet@...gle.com,
        kuba@...nel.org, pabeni@...hat.com, linux@...linux.org.uk,
        Tristram.Ha@...rochip.com
Subject: Re: [RFC Patch net-next v2 8/8] net: dsa: microchip: ptp: add
 periodic output signal

On Mon, Nov 21, 2022 at 09:11:50PM +0530, Arun Ramadoss wrote:

> +static int ksz_ptp_enable_perout(struct ksz_device *dev,
> +				 struct ptp_perout_request const *perout_request,
> +				 int on)
> +{
> +	struct ksz_ptp_data *ptp_data = &dev->ptp_data;
> +	u64 cycle_width_ns;
> +	u64 pulse_width_ns;
> +	int ret;
> +
> +	if (perout_request->flags & ~KSZ_PEROUT_VALID_FLAGS)
> +		return -EINVAL;
> +
> +	if (ptp_data->tou_mode != KSZ_PTP_TOU_PEROUT &&
> +	    ptp_data->tou_mode != KSZ_PTP_TOU_IDLE)
> +		return -EBUSY;
> +
> +	ret = ksz_ptp_tou_reset(dev, KSZ_PER_OUT_TOU);
> +	if (ret)
> +		return ret;
> +
> +	if (!on) {
> +		ptp_data->tou_mode = KSZ_PTP_TOU_IDLE;
> +		return 0;  /* success */
> +	}
> +
> +	ptp_data->perout_target_time_first.tv_sec  = perout_request->start.sec;
> +	ptp_data->perout_target_time_first.tv_nsec = perout_request->start.nsec;
> +
> +	ptp_data->perout_period.tv_sec = perout_request->period.sec;
> +	ptp_data->perout_period.tv_nsec = perout_request->period.nsec;
> +
> +	cycle_width_ns = timespec64_to_ns(&ptp_data->perout_period);
> +	if ((cycle_width_ns & TRIG_CYCLE_WIDTH_M) != cycle_width_ns)
> +		return -EINVAL;
> +
> +	if (perout_request->flags & PTP_PEROUT_DUTY_CYCLE)
> +		pulse_width_ns = perout_request->on.sec * NSEC_PER_SEC +
> +			perout_request->on.nsec;
> +
> +	else
> +		/* Use a duty cycle of 50%. Maximum pulse width supported by the
> +		 * hardware is a little bit more than 125 ms.
> +		 */
> +		pulse_width_ns = min_t(u64,
> +				       (perout_request->period.sec * NSEC_PER_SEC
> +					+ perout_request->period.nsec) / 2
> +				       / 8 * 8,
> +				       125000000LL);

CodyStyle nit: if/else bodies need {} because of two lines in 'else'.

Thanks,
Richard


> +
> +	ret = ksz_ptp_tou_pulse_verify(pulse_width_ns);
> +	if (ret)
> +		return ret;
> +
> +	ret = ksz_ptp_configure_perout(dev, cycle_width_ns,
> +				       pulse_width_ns,
> +				       &ptp_data->perout_target_time_first);
> +	if (ret)
> +		return ret;
> +
> +	/* Activate trigger unit */
> +	ret = ksz9477_ptp_tou_start(dev);
> +	if (ret)
> +		return ret;
> +
> +	ptp_data->tou_mode = KSZ_PTP_TOU_PEROUT;
> +
> +	return 0;
> +}