Merge pull request #444 from marckleinebudde/can-calc-bittiming-v6.3

can-calc-bit-timing: import bit timing calculation algorithm from v6.3

GNUmakefile.am

@@ -49,7 +49,8 @@ EXTRA_DIST += \
 	calc-bit-timing/can-calc-bit-timing-v3_18.c \
 	calc-bit-timing/can-calc-bit-timing-v4_8.c \
 	calc-bit-timing/can-calc-bit-timing-v5_16.c \
-	calc-bit-timing/can-calc-bit-timing-v5_19.c
+	calc-bit-timing/can-calc-bit-timing-v5_19.c \
+	calc-bit-timing/can-calc-bit-timing-v6_3.c
 
 mcp251xfd_dump_SOURCES = \
 	mcp251xfd/mcp251xfd-dev-coredump.c \

calc-bit-timing/can-calc-bit-timing-v6_3.c

@@ -0,0 +1,290 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/*
+ * imported from v6.3-rc1~162^2~124^2^2~1
+ *
+ */
+
+void can_sjw_set_default(struct can_bittiming *bt)
+{
+	if (bt->sjw)
+		return;
+
+	/* If user space provides no sjw, use sane default of phase_seg2 / 2 */
+	bt->sjw = max(1U, min(bt->phase_seg1, bt->phase_seg2 / 2));
+}
+
+int can_sjw_check(const struct net_device *dev, const struct can_bittiming *bt,
+		  const struct can_bittiming_const *btc, struct netlink_ext_ack *extack)
+{
+	if (bt->sjw > btc->sjw_max) {
+		NL_SET_ERR_MSG_FMT(extack, "sjw: %u greater than max sjw: %u",
+				   bt->sjw, btc->sjw_max);
+		return -EINVAL;
+	}
+
+	if (bt->sjw > bt->phase_seg1) {
+		NL_SET_ERR_MSG_FMT(extack,
+				   "sjw: %u greater than phase-seg1: %u",
+				   bt->sjw, bt->phase_seg1);
+		return -EINVAL;
+	}
+
+	if (bt->sjw > bt->phase_seg2) {
+		NL_SET_ERR_MSG_FMT(extack,
+				   "sjw: %u greater than phase-seg2: %u",
+				   bt->sjw, bt->phase_seg2);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+/*
+ * can_bit_time() - Duration of one bit
+ *
+ * Please refer to ISO 11898-1:2015, section 11.3.1.1 "Bit time" for
+ * additional information.
+ *
+ * Return: the number of time quanta in one bit.
+ */
+static inline unsigned int can_bit_time(const struct can_bittiming *bt)
+{
+	return CAN_SYNC_SEG + bt->prop_seg + bt->phase_seg1 + bt->phase_seg2;
+}
+
+/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
+ * Copyright (C) 2006 Andrey Volkov, Varma Electronics
+ * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
+ */
+
+/* Bit-timing calculation derived from:
+ *
+ * Code based on LinCAN sources and H8S2638 project
+ * Copyright 2004-2006 Pavel Pisa - DCE FELK CVUT cz
+ * Copyright 2005      Stanislav Marek
+ * email: pisa@cmp.felk.cvut.cz
+ *
+ * Calculates proper bit-timing parameters for a specified bit-rate
+ * and sample-point, which can then be used to set the bit-timing
+ * registers of the CAN controller. You can find more information
+ * in the header file linux/can/netlink.h.
+ */
+static int
+can_update_sample_point(const struct can_bittiming_const *btc,
+			const unsigned int sample_point_nominal, const unsigned int tseg,
+			unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
+			unsigned int *sample_point_error_ptr)
+{
+	unsigned int sample_point_error, best_sample_point_error = UINT_MAX;
+	unsigned int sample_point, best_sample_point = 0;
+	unsigned int tseg1, tseg2;
+	int i;
+
+	for (i = 0; i <= 1; i++) {
+		tseg2 = tseg + CAN_SYNC_SEG -
+			(sample_point_nominal * (tseg + CAN_SYNC_SEG)) /
+			1000 - i;
+		tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max);
+		tseg1 = tseg - tseg2;
+		if (tseg1 > btc->tseg1_max) {
+			tseg1 = btc->tseg1_max;
+			tseg2 = tseg - tseg1;
+		}
+
+		sample_point = 1000 * (tseg + CAN_SYNC_SEG - tseg2) /
+			(tseg + CAN_SYNC_SEG);
+		sample_point_error = abs(sample_point_nominal - sample_point);
+
+		if (sample_point <= sample_point_nominal &&
+		    sample_point_error < best_sample_point_error) {
+			best_sample_point = sample_point;
+			best_sample_point_error = sample_point_error;
+			*tseg1_ptr = tseg1;
+			*tseg2_ptr = tseg2;
+		}
+	}
+
+	if (sample_point_error_ptr)
+		*sample_point_error_ptr = best_sample_point_error;
+
+	return best_sample_point;
+}
+
+int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
+		       const struct can_bittiming_const *btc, struct netlink_ext_ack *extack)
+{
+	struct can_priv *priv = netdev_priv(dev);
+	unsigned int bitrate;			/* current bitrate */
+	unsigned int bitrate_error;		/* difference between current and nominal value */
+	unsigned int best_bitrate_error = UINT_MAX;
+	unsigned int sample_point_error;	/* difference between current and nominal value */
+	unsigned int best_sample_point_error = UINT_MAX;
+	unsigned int sample_point_nominal;	/* nominal 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;
+	}
+
+	/* tseg even = round down, odd = round up */
+	for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;
+	     tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {
+		tsegall = CAN_SYNC_SEG + tseg / 2;
+
+		/* Compute all possible tseg choices (tseg=tseg1+tseg2) */
+		brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;
+
+		/* choose brp step which is possible in system */
+		brp = (brp / btc->brp_inc) * btc->brp_inc;
+		if (brp < btc->brp_min || brp > btc->brp_max)
+			continue;
+
+		bitrate = priv->clock.freq / (brp * tsegall);
+		bitrate_error = abs(bt->bitrate - bitrate);
+
+		/* tseg brp biterror */
+		if (bitrate_error > best_bitrate_error)
+			continue;
+
+		/* reset sample point error if we have a better bitrate */
+		if (bitrate_error < best_bitrate_error)
+			best_sample_point_error = UINT_MAX;
+
+		can_update_sample_point(btc, sample_point_nominal, tseg / 2,
+					&tseg1, &tseg2, &sample_point_error);
+		if (sample_point_error >= best_sample_point_error)
+			continue;
+
+		best_sample_point_error = sample_point_error;
+		best_bitrate_error = bitrate_error;
+		best_tseg = tseg / 2;
+		best_brp = brp;
+
+		if (bitrate_error == 0 && sample_point_error == 0)
+			break;
+	}
+
+	if (best_bitrate_error) {
+		/* Error in one-tenth of a percent */
+		v64 = (u64)best_bitrate_error * 1000;
+		do_div(v64, bt->bitrate);
+		bitrate_error = (u32)v64;
+		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);
+			return -EINVAL;
+		}
+		NL_SET_ERR_MSG_FMT(extack,
+				   "bitrate error: %u.%u%%",
+				   bitrate_error / 10, bitrate_error % 10);
+	}
+
+	/* real sample point */
+	bt->sample_point = can_update_sample_point(btc, sample_point_nominal,
+						   best_tseg, &tseg1, &tseg2,
+						   NULL);
+
+	v64 = (u64)best_brp * 1000 * 1000 * 1000;
+	do_div(v64, priv->clock.freq);
+	bt->tq = (u32)v64;
+	bt->prop_seg = tseg1 / 2;
+	bt->phase_seg1 = tseg1 - bt->prop_seg;
+	bt->phase_seg2 = tseg2;
+
+	can_sjw_set_default(bt);
+
+	err = can_sjw_check(dev, bt, btc, extack);
+	if (err)
+		return err;
+
+	bt->brp = best_brp;
+
+	/* real bitrate */
+	bt->bitrate = priv->clock.freq /
+		(bt->brp * can_bit_time(bt));
+
+	return 0;
+}
+
+/* Checks the validity of the specified bit-timing parameters prop_seg,
+ * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate
+ * prescaler value brp. You can find more information in the header
+ * file linux/can/netlink.h.
+ */
+static int can_fixup_bittiming(const struct net_device *dev, struct can_bittiming *bt,
+			       const struct can_bittiming_const *btc,
+			       struct netlink_ext_ack *extack)
+{
+	const unsigned int tseg1 = bt->prop_seg + bt->phase_seg1;
+	const struct can_priv *priv = netdev_priv(dev);
+	u64 brp64;
+	int err;
+
+	if (tseg1 < btc->tseg1_min) {
+		NL_SET_ERR_MSG_FMT(extack, "prop-seg + phase-seg1: %u less than tseg1-min: %u",
+				   tseg1, btc->tseg1_min);
+		return -EINVAL;
+	}
+	if (tseg1 > btc->tseg1_max) {
+		NL_SET_ERR_MSG_FMT(extack, "prop-seg + phase-seg1: %u greater than tseg1-max: %u",
+				   tseg1, btc->tseg1_max);
+		return -EINVAL;
+	}
+	if (bt->phase_seg2 < btc->tseg2_min) {
+		NL_SET_ERR_MSG_FMT(extack, "phase-seg2: %u less than tseg2-min: %u",
+				   bt->phase_seg2, btc->tseg2_min);
+		return -EINVAL;
+	}
+	if (bt->phase_seg2 > btc->tseg2_max) {
+		NL_SET_ERR_MSG_FMT(extack, "phase-seg2: %u greater than tseg2-max: %u",
+				   bt->phase_seg2, btc->tseg2_max);
+		return -EINVAL;
+	}
+
+	can_sjw_set_default(bt);
+
+	err = can_sjw_check(dev, bt, btc, extack);
+	if (err)
+		return err;
+
+	brp64 = (u64)priv->clock.freq * (u64)bt->tq;
+	if (btc->brp_inc > 1)
+		do_div(brp64, btc->brp_inc);
+	brp64 += 500000000UL - 1;
+	do_div(brp64, 1000000000UL); /* the practicable BRP */
+	if (btc->brp_inc > 1)
+		brp64 *= btc->brp_inc;
+	bt->brp = (u32)brp64;
+
+	if (bt->brp < btc->brp_min) {
+		NL_SET_ERR_MSG_FMT(extack, "resulting brp: %u less than brp-min: %u",
+				   bt->brp, btc->brp_min);
+		return -EINVAL;
+	}
+	if (bt->brp > btc->brp_max) {
+		NL_SET_ERR_MSG_FMT(extack, "resulting brp: %u greater than brp-max: %u",
+				   bt->brp, btc->brp_max);
+		return -EINVAL;
+	}
+
+	bt->bitrate = priv->clock.freq / (bt->brp * can_bit_time(bt));
+	bt->sample_point = ((CAN_SYNC_SEG + tseg1) * 1000) / can_bit_time(bt);
+	bt->tq = DIV_U64_ROUND_CLOSEST(mul_u32_u32(bt->brp, NSEC_PER_SEC),
+				       priv->clock.freq);
+
+	return 0;
+}

calc-bit-timing/can-calc-bit-timing.c

@@ -43,6 +43,12 @@ enum {
 
 /* imported from kernel */
 
+/* define in-kernel-types */
+typedef __u64 u64;
+typedef __u32 u32;
+
+#define NSEC_PER_SEC	1000000000L
+
 /**
  * abs - return absolute value of an argument
  * @x: the value.  If it is unsigned type, it is converted to signed type first.
@@ -102,6 +108,48 @@ enum {
 	__rem;							\
 })
 
+
+/**
+ * DIV_U64_ROUND_CLOSEST - unsigned 64bit divide with 32bit divisor rounded to nearest integer
+ * @dividend: unsigned 64bit dividend
+ * @divisor: unsigned 32bit divisor
+ *
+ * Divide unsigned 64bit dividend by unsigned 32bit divisor
+ * and round to closest integer.
+ *
+ * Return: dividend / divisor rounded to nearest integer
+ */
+#define DIV_U64_ROUND_CLOSEST(dividend, divisor)	\
+	({ u32 _tmp = (divisor); div_u64((u64)(dividend) + _tmp / 2, _tmp); })
+
+/**
+ * div_u64_rem - unsigned 64bit divide with 32bit divisor with remainder
+ * @dividend: unsigned 64bit dividend
+ * @divisor: unsigned 32bit divisor
+ * @remainder: pointer to unsigned 32bit remainder
+ *
+ * Return: sets ``*remainder``, then returns dividend / divisor
+ *
+ * This is commonly provided by 32bit archs to provide an optimized 64bit
+ * divide.
+ */
+static inline u64 div_u64_rem(u64 dividend, u32 divisor, u32 *remainder)
+{
+	*remainder = dividend % divisor;
+	return dividend / divisor;
+}
+
+static inline u64 div_u64(u64 dividend, u32 divisor)
+{
+	u32 remainder;
+	return div_u64_rem(dividend, divisor, &remainder);
+}
+
+static inline u64 mul_u32_u32(u32 a, u32 b)
+{
+	return (u64)a * b;
+}
+
 /* */
 
 #define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
@@ -109,10 +157,7 @@ enum {
 /* we don't want to see these prints */
 #define netdev_err(dev, format, arg...) do { } while (0)
 #define netdev_warn(dev, format, arg...) do { } while (0)
-
+#define NL_SET_ERR_MSG_FMT(dev, format, arg...) do { } while (0)
-/* define in-kernel-types */
-typedef __u64 u64;
-typedef __u32 u32;
 
 struct calc_ref_clk {
 	__u32 clk;	/* CAN system clock frequency in Hz */
@@ -130,6 +175,10 @@ struct net_device {
 	struct can_priv	priv;
 };
 
+struct netlink_ext_ack {
+	u32 __dummy;
+};
+
 struct calc_bittiming_const {
 	const struct can_bittiming_const bittiming_const;
 	const struct can_bittiming_const data_bittiming_const;
@@ -146,12 +195,18 @@ struct alg {
 				      const struct can_bittiming_const *btc);
 		int (*calc_bittiming_const)(const struct net_device *dev, struct can_bittiming *bt,
 					    const struct can_bittiming_const *btc);
+		int (*calc_bittiming_extack)(const struct net_device *dev, struct can_bittiming *bt,
+					     const struct can_bittiming_const *btc, struct netlink_ext_ack *extack);
 	};
 	union {
 		int (*fixup_bittiming)(struct net_device *dev, struct can_bittiming *bt,
 				       const struct can_bittiming_const *btc);
 		int (*fixup_bittiming_const)(const struct net_device *dev, struct can_bittiming *bt,
 					     const struct can_bittiming_const *btc);
+		int (*fixup_bittiming_extack)(const struct net_device *dev, struct can_bittiming *bt,
+					      const struct can_bittiming_const *btc,
+					      struct netlink_ext_ack *extack);
+
 	};
 	const char *name;
 };
@@ -1232,9 +1287,21 @@ static const unsigned int common_data_bitrates[] = {
 #undef can_calc_bittiming
 #undef can_fixup_bittiming
 
+#define can_update_sample_point can_update_sample_point_v6_3
+#define can_calc_bittiming can_calc_bittiming_v6_3
+#define can_fixup_bittiming can_fixup_bittiming_v6_3
+#include "can-calc-bit-timing-v6_3.c"
+#undef can_update_sample_point
+#undef can_calc_bittiming
+#undef can_fixup_bittiming
+
 static const struct alg alg_list[] = {
 	/* 1st will be default */
 	{
+		.calc_bittiming_extack = can_calc_bittiming_v6_3,
+		.fixup_bittiming_extack = can_fixup_bittiming_v6_3,
+		.name = "v6.3",
+	}, {
 		.calc_bittiming_const = can_calc_bittiming_v5_19,
 		.fixup_bittiming_const = can_fixup_bittiming_v5_19,
 		.name = "v5.19",