diff options
Diffstat (limited to 'drivers/net/can/dev/calc_bittiming.c')
| -rw-r--r-- | drivers/net/can/dev/calc_bittiming.c | 114 |
1 files changed, 88 insertions, 26 deletions
diff --git a/drivers/net/can/dev/calc_bittiming.c b/drivers/net/can/dev/calc_bittiming.c index 394d6974f481..cc4022241553 100644 --- a/drivers/net/can/dev/calc_bittiming.c +++ b/drivers/net/can/dev/calc_bittiming.c @@ -2,6 +2,7 @@ /* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix * Copyright (C) 2006 Andrey Volkov, Varma Electronics * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com> + * Copyright (C) 2021-2025 Vincent Mailhol <mailhol@kernel.org> */ #include <linux/units.h> @@ -9,6 +10,33 @@ #define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */ +/* CiA recommended sample points for Non Return to Zero encoding. */ +static int can_calc_sample_point_nrz(const struct can_bittiming *bt) +{ + if (bt->bitrate > 800 * KILO /* BPS */) + return 750; + + if (bt->bitrate > 500 * KILO /* BPS */) + return 800; + + return 875; +} + +/* Sample points for Pulse-Width Modulation encoding. */ +static int can_calc_sample_point_pwm(const struct can_bittiming *bt) +{ + if (bt->bitrate > 15 * MEGA /* BPS */) + return 625; + + if (bt->bitrate > 9 * MEGA /* BPS */) + return 600; + + if (bt->bitrate > 4 * MEGA /* BPS */) + return 560; + + return 520; +} + /* Bit-timing calculation derived from: * * Code based on LinCAN sources and H8S2638 project @@ -23,7 +51,7 @@ */ static int can_update_sample_point(const struct can_bittiming_const *btc, - const unsigned int sample_point_nominal, const unsigned int tseg, + const unsigned int sample_point_reference, const unsigned int tseg, unsigned int *tseg1_ptr, unsigned int *tseg2_ptr, unsigned int *sample_point_error_ptr) { @@ -34,7 +62,7 @@ can_update_sample_point(const struct can_bittiming_const *btc, for (i = 0; i <= 1; i++) { tseg2 = tseg + CAN_SYNC_SEG - - (sample_point_nominal * (tseg + CAN_SYNC_SEG)) / + (sample_point_reference * (tseg + CAN_SYNC_SEG)) / 1000 - i; tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max); tseg1 = tseg - tseg2; @@ -45,9 +73,9 @@ can_update_sample_point(const struct can_bittiming_const *btc, sample_point = 1000 * (tseg + CAN_SYNC_SEG - tseg2) / (tseg + CAN_SYNC_SEG); - sample_point_error = abs(sample_point_nominal - sample_point); + sample_point_error = abs(sample_point_reference - sample_point); - if (sample_point <= sample_point_nominal && + if (sample_point <= sample_point_reference && sample_point_error < best_sample_point_error) { best_sample_point = sample_point; best_sample_point_error = sample_point_error; @@ -67,28 +95,24 @@ int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt, { struct can_priv *priv = netdev_priv(dev); unsigned int bitrate; /* current bitrate */ - unsigned int bitrate_error; /* difference between current and nominal value */ + unsigned int bitrate_error; /* diff between calculated and reference value */ unsigned int best_bitrate_error = UINT_MAX; - unsigned int sample_point_error; /* difference between current and nominal value */ + unsigned int sample_point_error; /* diff between calculated and reference value */ unsigned int best_sample_point_error = UINT_MAX; - unsigned int sample_point_nominal; /* nominal sample point */ + unsigned int sample_point_reference; /* reference sample point */ unsigned int best_tseg = 0; /* current best value for tseg */ unsigned int best_brp = 0; /* current best value for brp */ unsigned int brp, tsegall, tseg, tseg1 = 0, tseg2 = 0; u64 v64; int err; - /* Use CiA recommended sample points */ - if (bt->sample_point) { - sample_point_nominal = bt->sample_point; - } else { - if (bt->bitrate > 800 * KILO /* BPS */) - sample_point_nominal = 750; - else if (bt->bitrate > 500 * KILO /* BPS */) - sample_point_nominal = 800; - else - sample_point_nominal = 875; - } + if (bt->sample_point) + sample_point_reference = bt->sample_point; + else if (btc == priv->xl.data_bittiming_const && + (priv->ctrlmode & CAN_CTRLMODE_XL_TMS)) + sample_point_reference = can_calc_sample_point_pwm(bt); + else + sample_point_reference = can_calc_sample_point_nrz(bt); /* tseg even = round down, odd = round up */ for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1; @@ -114,7 +138,7 @@ int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt, if (bitrate_error < best_bitrate_error) best_sample_point_error = UINT_MAX; - can_update_sample_point(btc, sample_point_nominal, tseg / 2, + can_update_sample_point(btc, sample_point_reference, tseg / 2, &tseg1, &tseg2, &sample_point_error); if (sample_point_error >= best_sample_point_error) continue; @@ -129,23 +153,26 @@ int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt, } if (best_bitrate_error) { - /* Error in one-tenth of a percent */ - v64 = (u64)best_bitrate_error * 1000; + /* Error in one-hundredth of a percent */ + v64 = (u64)best_bitrate_error * 10000; do_div(v64, bt->bitrate); bitrate_error = (u32)v64; + /* print at least 0.01% if the error is smaller */ + bitrate_error = max(bitrate_error, 1U); if (bitrate_error > CAN_CALC_MAX_ERROR) { NL_SET_ERR_MSG_FMT(extack, - "bitrate error: %u.%u%% too high", - bitrate_error / 10, bitrate_error % 10); + "bitrate error: %u.%02u%% too high", + bitrate_error / 100, + bitrate_error % 100); return -EINVAL; } NL_SET_ERR_MSG_FMT(extack, - "bitrate error: %u.%u%%", - bitrate_error / 10, bitrate_error % 10); + "bitrate error: %u.%02u%%", + bitrate_error / 100, bitrate_error % 100); } /* real sample point */ - bt->sample_point = can_update_sample_point(btc, sample_point_nominal, + bt->sample_point = can_update_sample_point(btc, sample_point_reference, best_tseg, &tseg1, &tseg2, NULL); @@ -198,3 +225,38 @@ void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const, *ctrlmode |= tdc_auto; } } + +int can_calc_pwm(struct net_device *dev, struct netlink_ext_ack *extack) +{ + struct can_priv *priv = netdev_priv(dev); + const struct can_pwm_const *pwm_const = priv->xl.pwm_const; + struct can_pwm *pwm = &priv->xl.pwm; + u32 xl_tqmin = can_bit_time_tqmin(&priv->xl.data_bittiming); + u32 xl_ns = can_tqmin_to_ns(xl_tqmin, priv->clock.freq); + u32 nom_tqmin = can_bit_time_tqmin(&priv->bittiming); + int pwm_per_bit_max = xl_tqmin / (pwm_const->pwms_min + pwm_const->pwml_min); + int pwm_per_bit; + u32 pwm_tqmin; + + /* For 5 MB/s databitrate or greater, xl_ns < CAN_PWM_NS_MAX + * giving us a pwm_per_bit of 1 and the loop immediately breaks + */ + for (pwm_per_bit = DIV_ROUND_UP(xl_ns, CAN_PWM_NS_MAX); + pwm_per_bit <= pwm_per_bit_max; pwm_per_bit++) + if (xl_tqmin % pwm_per_bit == 0) + break; + + if (pwm_per_bit > pwm_per_bit_max) { + NL_SET_ERR_MSG_FMT(extack, + "Can not divide the XL data phase's bit time: %u tqmin into multiple PWM symbols", + xl_tqmin); + return -EINVAL; + } + + pwm_tqmin = xl_tqmin / pwm_per_bit; + pwm->pwms = DIV_ROUND_UP_POW2(pwm_tqmin, 4); + pwm->pwml = pwm_tqmin - pwm->pwms; + pwm->pwmo = nom_tqmin % pwm_tqmin; + + return 0; +} |