On 15.09.2022 01:39:43, Matej Vasilevski wrote:
[...]
> /* Check for big-endianity and set according IO-accessors */
> if ((ctucan_read32(priv, CTUCANFD_DEVICE_ID) & 0xFFFF) != CTUCANFD_ID) {
> @@ -1425,6 +1582,49 @@ int ctucan_probe_common(struct device *dev, void __iomem *addr, int irq, unsigne
>
> priv->can.clock.freq = can_clk_rate;
>
> + /* Obtain timestamping counter bit size */
> + timestamp_bit_size = FIELD_GET(REG_ERR_CAPT_TS_BITS,
> + ctucan_read32(priv, CTUCANFD_ERR_CAPT));
> +
> + /* The register value is actually bit_size - 1 */
> + if (timestamp_bit_size) {
> + timestamp_bit_size += 1;
> + } else {
> + /* For 2.x versions of the IP core, we will assume 64-bit counter
> + * if there was a 0 in the register.
> + */
> + u32 version_reg = ctucan_read32(priv, CTUCANFD_DEVICE_ID);
> + u32 major = FIELD_GET(REG_DEVICE_ID_VER_MAJOR, version_reg);
> +
> + if (major == 2)
> + timestamp_bit_size = 64;
> + else
> + priv->timestamp_possible = false;
> + }
> +
> + /* Setup conversion constants and work delay */
> + priv->cc.mask = CYCLECOUNTER_MASK(timestamp_bit_size);
> + if (priv->timestamp_possible) {
> + u64 max_cycles;
> + u64 work_delay_ns;
> + u32 maxsec = min_t(u32, CTUCANFD_MAX_WORK_DELAY_SEC,
> + div_u64(priv->cc.mask, timestamp_freq));
> +
> + priv->cc.read = ctucan_read_timestamp_cc_wrapper;
> + clocks_calc_mult_shift(&priv->cc.mult, &priv->cc.shift,
> + timestamp_freq, NSEC_PER_SEC, maxsec);
> +
> + /* shortened copy of clocks_calc_max_nsecs() */
> + max_cycles = div_u64(ULLONG_MAX, priv->cc.mult);
> + max_cycles = min(max_cycles, priv->cc.mask);
> + work_delay_ns = clocksource_cyc2ns(max_cycles, priv->cc.mult,
> + priv->cc.shift) >> 1;
I just ported the code to another driver with dynamic frequency and
width. I noticed that the shift of 1 is not enough. With 2 it works.
regards,
MArc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
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