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can-calc-bit-timing: use algorithm from the kernel 

This patch copies the algorithm functions (can_update_spt and
can_calc_bittiming) from the kernel. Then some glue code is added that
these functions compile in userspace.

Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>
pull/7/head
Marc Kleine-Budde 2010-07-20 13:43:08 +00:00
parent daed6be029
commit ccd199739e
1 changed files with 223 additions and 144 deletions
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359
can-calc-bit-timing.c
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@ -12,14 +12,120 @@
* This software is released under the GPL-License. * This software is released under the GPL-License.
*/ */
#include <errno.h>
#include <getopt.h>
#include <stdint.h>
#include <stdio.h> #include <stdio.h>
#include <stdlib.h> #include <stdlib.h>
#include <stdint.h>
#include <string.h> #include <string.h>
#include <getopt.h>
#include <linux/types.h>
/* seems not to be defined in errno.h */
#ifndef ENOTSUPP
#define ENOTSUPP 524 /* Operation is not supported */
#endif
/* usefull defines */
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
#define do_div(a,b) a = (a) / (b) #define do_div(a,b) a = (a) / (b)
#define abs(x) ({ \
long __x = (x); \
(__x < 0) ? -__x : __x; \
})
/**
* clamp - return a value clamped to a given range with strict typechecking
* @val: current value
* @min: minimum allowable value
* @max: maximum allowable value
*
* This macro does strict typechecking of min/max to make sure they are of the
* same type as val. See the unnecessary pointer comparisons.
*/
#define clamp(val, min, max) ({ \
typeof(val) __val = (val); \
typeof(min) __min = (min); \
typeof(max) __max = (max); \
(void) (&__val == &__min); \
(void) (&__val == &__max); \
__val = __val < __min ? __min: __val; \
__val > __max ? __max: __val; })
/* we don't want to see these prints */
#define dev_err(dev, format, arg...) do { } while (0)
#define dev_warn(dev, format, arg...) do { } while (0)
/* define in-kernel-types */
typedef __u64 u64;
typedef __u32 u32;
/*
* CAN bit-timing parameters
*
* For futher information, please read chapter "8 BIT TIMING
* REQUIREMENTS" of the "Bosch CAN Specification version 2.0"
* at http://www.semiconductors.bosch.de/pdf/can2spec.pdf.
*/
struct can_bittiming {
__u32 bitrate; /* Bit-rate in bits/second */
__u32 sample_point; /* Sample point in one-tenth of a percent */
__u32 tq; /* Time quanta (TQ) in nanoseconds */
__u32 prop_seg; /* Propagation segment in TQs */
__u32 phase_seg1; /* Phase buffer segment 1 in TQs */
__u32 phase_seg2; /* Phase buffer segment 2 in TQs */
__u32 sjw; /* Synchronisation jump width in TQs */
__u32 brp; /* Bit-rate prescaler */
};
/*
* CAN harware-dependent bit-timing constant
*
* Used for calculating and checking bit-timing parameters
*/
struct can_bittiming_const {
char name[16]; /* Name of the CAN controller hardware */
__u32 tseg1_min; /* Time segement 1 = prop_seg + phase_seg1 */
__u32 tseg1_max;
__u32 tseg2_min; /* Time segement 2 = phase_seg2 */
__u32 tseg2_max;
__u32 sjw_max; /* Synchronisation jump width */
__u32 brp_min; /* Bit-rate prescaler */
__u32 brp_max;
__u32 brp_inc;
/* added for can-calc-bit-timing utility */
void (*printf_btr)(struct can_bittiming *bt, int hdr);
};
/*
* CAN clock parameters
*/
struct can_clock {
__u32 freq; /* CAN system clock frequency in Hz */
};
/*
* minimal structs, just enough to be source level compatible
*/
struct can_priv {
const struct can_bittiming_const *bittiming_const;
struct can_clock clock;
};
struct net_device {
struct can_priv priv;
};
static inline void *netdev_priv(const struct net_device *dev)
{
return (void *)&dev->priv;
}
static void print_usage(char* cmd) static void print_usage(char* cmd)
{ {
printf("Usage: %s [options] [<CAN-contoller-name>]\n" printf("Usage: %s [options] [<CAN-contoller-name>]\n"
@ -35,33 +141,7 @@ static void print_usage(char* cmd)
exit(1); exit(1);
} }
struct can_bittime { static void printf_btr_sja1000(struct can_bittiming *bt, int hdr)
uint32_t brp;
uint8_t prop_seg;
uint8_t phase_seg1;
uint8_t phase_seg2;
uint8_t sjw;
uint32_t tq;
uint32_t error;
int sampl_pt;
};
struct can_bittiming_const {
char name[32];
int prop_seg_min;
int prop_seg_max;
int phase_seg1_min;
int phase_seg1_max;
int phase_seg2_min;
int phase_seg2_max;
int sjw_max;
int brp_min;
int brp_max;
int brp_inc;
void (*printf_btr)(struct can_bittime *bt, int hdr);
};
static void printf_btr_sja1000(struct can_bittime *bt, int hdr)
{ {
uint8_t btr0, btr1; uint8_t btr0, btr1;
@ -75,7 +155,7 @@ static void printf_btr_sja1000(struct can_bittime *bt, int hdr)
} }
} }
static void printf_btr_at91(struct can_bittime *bt, int hdr) static void printf_btr_at91(struct can_bittiming *bt, int hdr)
{ {
if (hdr) { if (hdr) {
printf("CAN_BR"); printf("CAN_BR");
@ -89,7 +169,7 @@ static void printf_btr_at91(struct can_bittime *bt, int hdr)
} }
} }
static void printf_btr_mcp2510(struct can_bittime *bt, int hdr) static void printf_btr_mcp251x(struct can_bittiming *bt, int hdr)
{ {
uint8_t cnf1, cnf2, cnf3; uint8_t cnf1, cnf2, cnf3;
@ -103,7 +183,7 @@ static void printf_btr_mcp2510(struct can_bittime *bt, int hdr)
} }
} }
static void printf_btr_rtcantl1(struct can_bittime *bt, int hdr) static void printf_btr_rtcantl1(struct can_bittiming *bt, int hdr)
{ {
uint16_t bcr0, bcr1; uint16_t bcr0, bcr1;
@ -118,73 +198,70 @@ static void printf_btr_rtcantl1(struct can_bittime *bt, int hdr)
} }
} }
struct can_bittiming_const can_calc_consts[] = { static struct can_bittiming_const can_calc_consts[] = {
{ {
"sja1000", .name = "sja1000",
/* Note: only prop_seg + bt->phase_seg1 matters */ .tseg1_min = 1,
.phase_seg1_min = 1, .tseg1_max = 16,
.phase_seg1_max = 16, .tseg2_min = 1,
.phase_seg2_min = 1, .tseg2_max = 8,
.phase_seg2_max = 8,
.sjw_max = 4, .sjw_max = 4,
.brp_min = 1, .brp_min = 1,
.brp_max = 64, .brp_max = 64,
.brp_inc = 1, .brp_inc = 1,
.printf_btr = printf_btr_sja1000, .printf_btr = printf_btr_sja1000,
}, },
{ {
"mscan", .name = "mscan",
/* Note: only prop_seg + bt->phase_seg1 matters */ .tseg1_min = 4,
.phase_seg1_min = 4, .tseg1_max = 16,
.phase_seg1_max = 16, .tseg2_min = 2,
.phase_seg2_min = 2, .tseg2_max = 8,
.phase_seg2_max = 8,
.sjw_max = 4, .sjw_max = 4,
.brp_min = 1, .brp_min = 1,
.brp_max = 64, .brp_max = 64,
.brp_inc = 1, .brp_inc = 1,
.printf_btr = printf_btr_sja1000, .printf_btr = printf_btr_sja1000,
}, },
{ {
"at91", .name = "at91",
.prop_seg_min = 1, .tseg1_min = 4,
.prop_seg_max = 8, .tseg1_max = 16,
.phase_seg1_min = 1, .tseg2_min = 2,
.phase_seg1_max = 8, .tseg2_max = 8,
.phase_seg2_min = 2,
.phase_seg2_max = 8,
.sjw_max = 4, .sjw_max = 4,
.brp_min = 1, .brp_min = 2,
.brp_max = 128, .brp_max = 128,
.brp_inc = 1, .brp_inc = 1,
.printf_btr = printf_btr_at91, .printf_btr = printf_btr_at91,
}, },
{ {
"mcp2510", .name = "mcp251x",
.prop_seg_min = 1, .tseg1_min = 3,
.prop_seg_max = 8, .tseg1_max = 16,
.phase_seg1_min = 1, .tseg2_min = 2,
.phase_seg1_max = 8, .tseg2_max = 8,
.phase_seg2_min = 2,
.phase_seg2_max = 8,
.sjw_max = 4, .sjw_max = 4,
.brp_min = 1, .brp_min = 1,
.brp_max = 64, .brp_max = 64,
.brp_inc = 1, .brp_inc = 1,
.printf_btr = printf_btr_mcp2510,
.printf_btr = printf_btr_mcp251x,
}, },
{ {
"rtcantl1", .name = "rtcantl1",
.prop_seg_min = 2, .tseg1_min = 4,
.prop_seg_max = 8, .tseg1_max = 16,
.phase_seg1_min = 2, .tseg2_min = 2,
.phase_seg1_max = 8, .tseg2_max = 8,
.phase_seg2_min = 2,
.phase_seg2_max = 8,
.sjw_max = 4, .sjw_max = 4,
.brp_min = 1, .brp_min = 1,
.brp_max = 256, .brp_max = 256,
.brp_inc = 1, .brp_inc = 1,
.printf_btr = printf_btr_rtcantl1, .printf_btr = printf_btr_rtcantl1,
}, },
}; };
@ -198,69 +275,66 @@ static long common_bitrates[] = {
100000, 100000,
50000, 50000,
20000, 20000,
10000 10000,
}; };
#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
static int can_update_spt(const struct can_bittiming_const *btc, static int can_update_spt(const struct can_bittiming_const *btc,
int sampl_pt, int tseg, int *tseg1, int *tseg2) int sampl_pt, int tseg, int *tseg1, int *tseg2)
{ {
*tseg2 = tseg + 1 - (sampl_pt * (tseg + 1)) / 1000; *tseg2 = tseg + 1 - (sampl_pt * (tseg + 1)) / 1000;
if (*tseg2 < btc->phase_seg2_min) if (*tseg2 < btc->tseg2_min)
*tseg2 = btc->phase_seg2_min; *tseg2 = btc->tseg2_min;
if (*tseg2 > btc->phase_seg2_max) if (*tseg2 > btc->tseg2_max)
*tseg2 = btc->phase_seg2_max; *tseg2 = btc->tseg2_max;
*tseg1 = tseg - *tseg2; *tseg1 = tseg - *tseg2;
if (*tseg1 > btc->prop_seg_max + btc->phase_seg1_max) { if (*tseg1 > btc->tseg1_max) {
*tseg1 = btc->prop_seg_max + btc->phase_seg1_max; *tseg1 = btc->tseg1_max;
*tseg2 = tseg - *tseg1; *tseg2 = tseg - *tseg1;
} }
return 1000 * (tseg + 1 - *tseg2) / (tseg + 1); return 1000 * (tseg + 1 - *tseg2) / (tseg + 1);
} }
int can_calc_bittiming(struct can_bittime *bt, long bitrate, static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt)
int sampl_pt, long clock,
const struct can_bittiming_const *btc)
{ {
long best_error = 1000000000, error; struct can_priv *priv = netdev_priv(dev);
int best_tseg = 0, best_brp = 0, brp = 0; const struct can_bittiming_const *btc = priv->bittiming_const;
int spt_error = 1000, spt = 0;
long rate, best_rate = 0; long rate, best_rate = 0;
int tseg = 0, tseg1 = 0, tseg2 = 0; long best_error = 1000000000, error = 0;
uint64_t v64; int best_tseg = 0, best_brp = 0, brp = 0;
int tsegall, tseg = 0, tseg1 = 0, tseg2 = 0;
int spt_error = 1000, spt = 0, sampl_pt;
u64 v64;
if (!priv->bittiming_const)
return -ENOTSUPP;
if (sampl_pt == 0) {
/* Use CIA recommended sample points */ /* Use CIA recommended sample points */
if (bitrate > 800000) if (bt->sample_point) {
sampl_pt = bt->sample_point;
} else {
if (bt->bitrate > 800000)
sampl_pt = 750; sampl_pt = 750;
else if (bitrate > 500000) else if (bt->bitrate > 500000)
sampl_pt = 800; sampl_pt = 800;
else else
sampl_pt = 875; sampl_pt = 875;
} }
#ifdef DEBUG
printf("tseg brp bitrate biterror\n");
#endif
/* tseg even = round down, odd = round up */ /* tseg even = round down, odd = round up */
for (tseg = (btc->prop_seg_max + btc->phase_seg1_max + for (tseg = (btc->tseg1_max + btc->tseg2_max) * 2 + 1;
btc->phase_seg2_max) * 2 + 1; tseg >= (btc->tseg1_min + btc->tseg2_min) * 2; tseg--) {
tseg >= (btc->prop_seg_min + btc->phase_seg1_min + tsegall = 1 + tseg / 2;
btc->phase_seg2_min) * 2; tseg--) { /* Compute all possible tseg choices (tseg=tseg1+tseg2) */
/* Compute all posibilities of tseg choices (tseg=tseg1+tseg2) */ brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;
brp = clock / ((1 + tseg / 2) * bitrate) + tseg % 2;
/* chose brp step which is possible in system */ /* chose brp step which is possible in system */
brp = (brp / btc->brp_inc) * btc->brp_inc; brp = (brp / btc->brp_inc) * btc->brp_inc;
if ((brp < btc->brp_min) || (brp > btc->brp_max)) if ((brp < btc->brp_min) || (brp > btc->brp_max))
continue; continue;
rate = clock / (brp * (1 + tseg / 2)); rate = priv->clock.freq / (brp * tsegall);
error = bitrate - rate; error = bt->bitrate - rate;
/* tseg brp biterror */ /* tseg brp biterror */
#if DEBUG
printf("%4d %3d %7ld %8ld %03d\n", tseg, brp, rate, error,
can_update_spt(btc, sampl_pt, tseg / 2,
&tseg1, &tseg2));
#endif
if (error < 0) if (error < 0)
error = -error; error = -error;
if (error > best_error) if (error > best_error)
@ -270,15 +344,12 @@ int can_calc_bittiming(struct can_bittime *bt, long bitrate,
spt = can_update_spt(btc, sampl_pt, tseg / 2, spt = can_update_spt(btc, sampl_pt, tseg / 2,
&tseg1, &tseg2); &tseg1, &tseg2);
error = sampl_pt - spt; error = sampl_pt - spt;
//printf("%d %d %d\n", sampl_pt, error, spt_error);
if (error < 0) if (error < 0)
error = -error; error = -error;
if (error > spt_error) if (error > spt_error)
continue; continue;
spt_error = error; spt_error = error;
//printf("%d\n", spt_error);
} }
//printf("error=%d\n", best_error);
best_tseg = tseg / 2; best_tseg = tseg / 2;
best_brp = brp; best_brp = brp;
best_rate = rate; best_rate = rate;
@ -286,65 +357,73 @@ int can_calc_bittiming(struct can_bittime *bt, long bitrate,
break; break;
} }
if (best_error && (bitrate / best_error < 10)) if (best_error) {
return -1; /* Error in one-tenth of a percent */
error = (best_error * 1000) / bt->bitrate;
if (error > CAN_CALC_MAX_ERROR) {
dev_err(dev->dev.parent,
"bitrate error %ld.%ld%% too high\n",
error / 10, error % 10);
return -EDOM;
} else {
dev_warn(dev->dev.parent, "bitrate error %ld.%ld%%\n",
error / 10, error % 10);
}
}
spt = can_update_spt(btc, sampl_pt, best_tseg, /* real sample point */
bt->sample_point = can_update_spt(btc, sampl_pt, best_tseg,
&tseg1, &tseg2); &tseg1, &tseg2);
if (tseg2 > tseg1) { v64 = (u64)best_brp * 1000000000UL;
/* sample point < 50% */ do_div(v64, priv->clock.freq);
bt->phase_seg1 = tseg1 / 2; bt->tq = (u32)v64;
} else { bt->prop_seg = tseg1 / 2;
/* keep phase_seg{1,2} equal around the sample point */
bt->phase_seg1 = tseg2;
}
bt->prop_seg = tseg1 - bt->phase_seg1;
/* Check prop_seg range if necessary */
if (btc->prop_seg_min || btc->prop_seg_max) {
if (bt->prop_seg < btc->prop_seg_min)
bt->prop_seg = btc->prop_seg_min;
else if (bt->prop_seg > btc->prop_seg_max)
bt->prop_seg = btc->prop_seg_max;
bt->phase_seg1 = tseg1 - bt->prop_seg; bt->phase_seg1 = tseg1 - bt->prop_seg;
}
bt->phase_seg2 = tseg2; bt->phase_seg2 = tseg2;
bt->sjw = 1; bt->sjw = 1;
bt->brp = best_brp; bt->brp = best_brp;
bt->error = best_error;
bt->sampl_pt = spt; /* real bit-rate */
v64 = (uint64_t)bt->brp * 1000000000UL; bt->bitrate = priv->clock.freq / (bt->brp * (tseg1 + tseg2 + 1));
v64 /= clock;
bt->tq = (int)v64;
return 0; return 0;
} }
void print_bit_timing(const struct can_bittiming_const *btc, static void print_bit_timing(const struct can_bittiming_const *btc,
long bitrate, int sampl_pt, long ref_clk, int quiet) __u32 bitrate, __u32 sample_point, __u32 ref_clk,
int quiet)
{ {
struct can_bittime bt; struct net_device dev = {
.priv.bittiming_const = btc,
memset(&bt, 0, sizeof(bt)); .priv.clock.freq = ref_clk,
};
struct can_bittiming bt = {
.bitrate = bitrate,
.sample_point = sample_point,
};
long rate_error;
if (!quiet) { if (!quiet) {
printf("Bit timing parameters for %s using %ldHz\n", printf("Bit timing parameters for %s using %dHz\n",
btc->name, ref_clk); btc->name, ref_clk);
printf("Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP SampP Error "); printf("Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP SampP Error ");
btc->printf_btr(&bt, 1); btc->printf_btr(&bt, 1);
printf("\n"); printf("\n");
} }
if (can_calc_bittiming(&bt, bitrate, sampl_pt, ref_clk, btc)) { if (can_calc_bittiming(&dev, &bt)) {
printf("%7ld ***bitrate not possible***\n", bitrate); printf("%7d ***bitrate not possible***\n", bitrate);
return; return;
} }
printf("%7ld %6d %3d %4d %4d %3d %3d %2d.%d%% %4.1f%% ", rate_error = abs((__s32)(bitrate - bt.bitrate));
printf("%7d %6d %3d %4d %4d %3d %3d %2d.%d%% %4.1f%% ",
bitrate, bt.tq, bt.prop_seg, bt.phase_seg1, bitrate, bt.tq, bt.prop_seg, bt.phase_seg1,
bt.phase_seg2, bt.sjw, bt.brp, bt.phase_seg2, bt.sjw, bt.brp,
bt.sampl_pt / 10, bt.sampl_pt % 10, bt.sample_point / 10, bt.sample_point % 10,
(double)100 * bt.error / bitrate); 100.0 * rate_error / bitrate);
btc->printf_btr(&bt, 0); btc->printf_btr(&bt, 0);
printf("\n"); printf("\n");
} }