netdev - Re: [PATCH net-next v1 1/4] net: phy: broadcom: Add PTP support for some Broadcom PHYs.

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Date:   Sun, 24 Apr 2022 18:38:00 -0700
From:   Richard Cochran <richardcochran@...il.com>
To:     Jonathan Lemon <jonathan.lemon@...il.com>
Cc:     f.fainelli@...il.com, bcm-kernel-feedback-list@...adcom.com,
        andrew@...n.ch, hkallweit1@...il.com, linux@...linux.org.uk,
        netdev@...r.kernel.org, kernel-team@...com
Subject: Re: [PATCH net-next v1 1/4] net: phy: broadcom: Add PTP support for
 some Broadcom PHYs.

On Sat, Apr 23, 2022 at 07:23:53PM -0700, Jonathan Lemon wrote:

> +static bool bcm_ptp_get_tstamp(struct bcm_ptp_private *priv,
> +			       struct bcm_ptp_capture *capts)
> +{
> +	struct phy_device *phydev = priv->phydev;
> +	u16 ts[4], reg;
> +	u32 sec, nsec;
> +
> +	mutex_lock(&priv->mutex);
> +
> +	reg = bcm_phy_read_exp(phydev, INTR_STATUS);
> +	if ((reg & INTC_SOP) == 0) {
> +		mutex_unlock(&priv->mutex);
> +		return false;
> +	}
> +
> +	bcm_phy_write_exp(phydev, TS_READ_CTRL, TS_READ_START);
> +
> +	ts[0] = bcm_phy_read_exp(phydev, TS_REG_0);
> +	ts[1] = bcm_phy_read_exp(phydev, TS_REG_1);
> +	ts[2] = bcm_phy_read_exp(phydev, TS_REG_2);
> +	ts[3] = bcm_phy_read_exp(phydev, TS_REG_3);
> +
> +	/* not in be32 format for some reason */
> +	capts->seq_id = bcm_phy_read_exp(priv->phydev, TS_INFO_0);
> +
> +	reg = bcm_phy_read_exp(phydev, TS_INFO_1);
> +	capts->msgtype = reg >> 12;
> +	capts->tx_dir = !!(reg & BIT(11));

Okay, so now I am sad.  The 541xx has:

  TIMESTAMP_INFO_1 0xA8C  bit 0 DIR, bits 1-2 msg_type, etc
  TIMESTAMP_INFO_2 0xA8D  sequence ID

It is the same info, but randomly shuffled among the two registers in
a different way.

So much for supporting multiple devices with a common code base.  :(

> +	bcm_phy_write_exp(phydev, TS_READ_CTRL, TS_READ_END);
> +	bcm_phy_write_exp(phydev, TS_READ_CTRL, 0);
> +
> +	mutex_unlock(&priv->mutex);
> +
> +	sec = (ts[3] << 16) | ts[2];
> +	nsec = (ts[1] << 16) | ts[0];
> +	capts->hwtstamp = ktime_set(sec, nsec);
> +
> +	return true;
> +}

Thanks,
Richard