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

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/* SPDX-License-Identifier: GPL-2.0-only */
/* can-calc-bit-timing.c: Calculate CAN bit timing parameters
*
* Copyright (C) 2008 Wolfgang Grandegger <wg@grandegger.com>
* Copyright (C) 2016, 2021, 2022 Marc Kleine-Budde <mkl@pengutronix.de>
*
* Derived from:
* can_baud.c - CAN baudrate calculation
* 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
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the version 2 of the GNU General Public License
* as published by the Free Software Foundation
*/
#include <errno.h>
#include <getopt.h>
#include <libgen.h>
#include <limits.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <linux/can/netlink.h>
#include <linux/types.h>
enum {
OPT_TQ = UCHAR_MAX + 1,
OPT_PROP_SEG,
OPT_PHASE_SEG1,
OPT_PHASE_SEG2,
OPT_SJW,
OPT_BRP,
OPT_TSEG1,
OPT_TSEG2,
OPT_ALG,
};
/* imported from kernel */
/**
* abs - return absolute value of an argument
* @x: the value. If it is unsigned type, it is converted to signed type first.
* char is treated as if it was signed (regardless of whether it really is)
* but the macro's return type is preserved as char.
*
* Return: an absolute value of x.
*/
#define abs(x) __abs_choose_expr(x, long long, \
__abs_choose_expr(x, long, \
__abs_choose_expr(x, int, \
__abs_choose_expr(x, short, \
__abs_choose_expr(x, char, \
__builtin_choose_expr( \
__builtin_types_compatible_p(typeof(x), char), \
(char)({ signed char __x = (x); __x < 0 ? -__x:__x; }), \
((void)0)))))))
#define __abs_choose_expr(x, type, other) __builtin_choose_expr( \
__builtin_types_compatible_p(typeof(x), signed type) || \
__builtin_types_compatible_p(typeof(x), unsigned type), \
({ signed type __x = (x); __x < 0 ? -__x : __x; }), other)
/*
* min()/max()/clamp() macros that also do
* strict type-checking.. See the
* "unnecessary" pointer comparison.
*/
#define min(x, y) ({ \
typeof(x) _min1 = (x); \
typeof(y) _min2 = (y); \
(void) (&_min1 == &_min2); \
_min1 < _min2 ? _min1 : _min2; })
#define max(x, y) ({ \
typeof(x) _max1 = (x); \
typeof(y) _max2 = (y); \
(void) (&_max1 == &_max2); \
_max1 > _max2 ? _max1 : _max2; })
/**
* clamp - return a value clamped to a given range with strict typechecking
* @val: current value
* @lo: lowest allowable value
* @hi: highest allowable value
*
* This macro does strict typechecking of lo/hi to make sure they are of the
* same type as val. See the unnecessary pointer comparisons.
*/
#define clamp(val, lo, hi) min((typeof(val))max(val, lo), hi)
#define do_div(n, base) ({ \
uint32_t __base = (base); \
uint32_t __rem; \
__rem = ((uint64_t)(n)) % __base; \
(n) = ((uint64_t)(n)) / __base; \
__rem; \
})
/* */
#define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]))
/* 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 in-kernel-types */
typedef __u64 u64;
typedef __u32 u32;
struct calc_ref_clk {
__u32 clk; /* CAN system clock frequency in Hz */
const char *name;
};
/*
* minimal structs, just enough to be source level compatible
*/
struct can_priv {
struct can_clock clock;
};
struct net_device {
struct can_priv priv;
};
struct calc_bittiming_const {
const struct can_bittiming_const bittiming_const;
const struct can_bittiming_const data_bittiming_const;
const struct calc_ref_clk ref_clk[16];
const void (*printf_btr)(struct can_bittiming *bt, bool hdr);
const void (*printf_data_btr)(struct can_bittiming *bt, bool hdr);
};
struct can_calc_bittiming {
int (*alg)(struct net_device *dev, struct can_bittiming *bt,
const struct can_bittiming_const *btc);
const char *name;
};
struct calc_data {
const struct can_bittiming_const *bittiming_const;
const struct can_calc_bittiming *calc_bittiming;
const void (*printf_btr)(struct can_bittiming *bt, bool hdr);
const char *name;
const struct calc_ref_clk *ref_clks;
const unsigned int *bitrates;
unsigned int sample_point;
const struct calc_ref_clk *opt_ref_clk;
const unsigned int *opt_bitrates;
const unsigned int *opt_data_bitrates;
const struct can_bittiming *opt_bt;
bool quiet;
};
static inline void *netdev_priv(const struct net_device *dev)
{
return (void *)&dev->priv;
}
static void print_usage(char *cmd)
{
printf("%s - calculate CAN bit timing parameters.\n", cmd);
printf("Usage: %s [options] [<CAN-contoller-name>]\n"
"Options:\n"
"\t-q don't print header line\n"
"\t-l list all support CAN controller names\n"
"\t-b <bitrate> arbitration bit-rate in bits/sec\n"
"\t-d <bitrate> data bit-rate in bits/sec\n"
"\t-s <samp_pt> sample-point in one-tenth of a percent\n"
"\t or 0 for CIA recommended sample points\n"
"\t-c <clock> real CAN system clock in Hz\n"
"\t--alg <alg> choose specified algorithm for bit-timing calculation\n"
"\n"
"Or supply low level bit timing parameters to decode them:\n"
"\n"
"\t--prop-seg Propagation segment in TQs\n"
"\t--phase-seg1 Phase buffer segment 1 in TQs\n"
"\t--phase-seg2 Phase buffer segment 2 in TQs\n"
"\t--sjw Synchronisation jump width in TQs\n"
"\t--brp Bit-rate prescaler\n"
"\t--tseg1 Time segment 1 = prop-seg + phase-seg1\n"
"\t--tseg2 Time segment 2 = phase_seg2\n",
cmd);
}
static void printf_btr_nop(struct can_bittiming *bt, bool hdr)
{
}
static void printf_btr_sja1000(struct can_bittiming *bt, bool hdr)
{
uint8_t btr0, btr1;
if (hdr) {
printf("%9s", "BTR0 BTR1");
} else {
btr0 = ((bt->brp - 1) & 0x3f) | (((bt->sjw - 1) & 0x3) << 6);
btr1 = ((bt->prop_seg + bt->phase_seg1 - 1) & 0xf) |
(((bt->phase_seg2 - 1) & 0x7) << 4);
printf("0x%02x 0x%02x", btr0, btr1);
}
}
static void printf_btr_at91(struct can_bittiming *bt, bool hdr)
{
if (hdr) {
printf("%10s", "CAN_BR");
} else {
uint32_t br = ((bt->phase_seg2 - 1) |
((bt->phase_seg1 - 1) << 4) |
((bt->prop_seg - 1) << 8) |
((bt->sjw - 1) << 12) |
((bt->brp - 1) << 16));
printf("0x%08x", br);
}
}
static void printf_btr_flexcan(struct can_bittiming *bt, bool hdr)
{
if (hdr) {
printf("%10s", "CAN_CTRL");
} else {
uint32_t ctrl = (((bt->brp - 1) << 24) |
((bt->sjw - 1) << 22) |
((bt->phase_seg1 - 1) << 19) |
((bt->phase_seg2 - 1) << 16) |
((bt->prop_seg - 1) << 0));
printf("0x%08x", ctrl);
}
}
static void printf_btr_mcp251x(struct can_bittiming *bt, bool hdr)
{
uint8_t cnf1, cnf2, cnf3;
if (hdr) {
printf("CNF1 CNF2 CNF3");
} else {
cnf1 = ((bt->sjw - 1) << 6) | (bt->brp - 1);
cnf2 = 0x80 | ((bt->phase_seg1 - 1) << 3) | (bt->prop_seg - 1);
cnf3 = bt->phase_seg2 - 1;
printf("0x%02x 0x%02x 0x%02x", cnf1, cnf2, cnf3);
}
}
static void printf_btr_mcp251xfd(struct can_bittiming *bt, bool hdr)
{
if (hdr) {
printf("%10s", "NBTCFG");
} else {
uint32_t nbtcfg = ((bt->brp - 1) << 24) |
((bt->prop_seg + bt->phase_seg1 - 1) << 16) |
((bt->phase_seg2 - 1) << 8) |
(bt->sjw - 1);
printf("0x%08x", nbtcfg);
}
}
static void printf_btr_ti_hecc(struct can_bittiming *bt, bool hdr)
{
if (hdr) {
printf("%10s", "CANBTC");
} else {
uint32_t can_btc;
can_btc = (bt->phase_seg2 - 1) & 0x7;
can_btc |= ((bt->phase_seg1 + bt->prop_seg - 1)
& 0xF) << 3;
can_btc |= ((bt->sjw - 1) & 0x3) << 8;
can_btc |= ((bt->brp - 1) & 0xFF) << 16;
printf("0x%08x", can_btc);
}
}
#define RCAR_CAN_BCR_TSEG1(x) (((x) & 0x0f) << 20)
#define RCAR_CAN_BCR_BPR(x) (((x) & 0x3ff) << 8)
#define RCAR_CAN_BCR_SJW(x) (((x) & 0x3) << 4)
#define RCAR_CAN_BCR_TSEG2(x) ((x) & 0x07)
static void printf_btr_rcar_can(struct can_bittiming *bt, bool hdr)
{
if (hdr) {
printf("%10s", "CiBCR");
} else {
uint32_t bcr;
bcr = RCAR_CAN_BCR_TSEG1(bt->phase_seg1 + bt->prop_seg - 1) |
RCAR_CAN_BCR_BPR(bt->brp - 1) |
RCAR_CAN_BCR_SJW(bt->sjw - 1) |
RCAR_CAN_BCR_TSEG2(bt->phase_seg2 - 1);
printf("0x%08x", bcr << 8);
}
}
static void printf_btr_bxcan(struct can_bittiming *bt, bool hdr)
{
if (hdr) {
printf("%10s", "CAN_BTR");
} else {
uint32_t btr;
btr = (((bt->brp -1) & 0x3ff) << 0) |
(((bt->prop_seg + bt->phase_seg1 -1) & 0xf) << 16) |
(((bt->phase_seg2 -1) & 0x7) << 20) |
(((bt->sjw -1) & 0x3) << 24);
printf("0x%08x", btr);
}
}
static void printf_btr_c_can(struct can_bittiming *bt, bool hdr)
{
if (hdr) {
printf("%13s", "BTR BRPEXT");
} else {
uint32_t btr;
uint32_t brpext;
btr = (((bt->brp -1) & 0x3f) << 0) |
(((bt->sjw -1) & 0x3) << 6) |
(((bt->prop_seg + bt->phase_seg1 -1) & 0xf) << 8) |
(((bt->phase_seg2 -1) & 0x7) << 12);
brpext = ((bt->brp -1) >> 6) & 0xf;
printf("0x%04x 0x%04x", btr, brpext);
}
}
static void printf_btr_mcan(struct can_bittiming *bt, bool hdr)
{
if (hdr) {
printf("%10s", "NBTP");
} else {
uint32_t nbtp;
nbtp = (((bt->brp -1) & 0x1ff) << 16) |
(((bt->sjw -1) & 0x7f) << 25) |
(((bt->prop_seg + bt->phase_seg1 -1) & 0xff) << 8) |
(((bt->phase_seg2 -1) & 0x7f) << 0);
printf("0x%08x", nbtp);
}
}
static const struct calc_bittiming_const can_calc_consts[] = {
{
.bittiming_const = {
.name = "sja1000",
.tseg1_min = 1,
.tseg1_max = 16,
.tseg2_min = 1,
.tseg2_max = 8,
.sjw_max = 4,
.brp_min = 1,
.brp_max = 64,
.brp_inc = 1,
},
.ref_clk = {
{ .clk = 8000000, },
},
.printf_btr = printf_btr_sja1000,
}, {
.bittiming_const = {
.name = "mscan",
.tseg1_min = 4,
.tseg1_max = 16,
.tseg2_min = 2,
.tseg2_max = 8,
.sjw_max = 4,
.brp_min = 1,
.brp_max = 64,
.brp_inc = 1,
},
.ref_clk = {
{ .clk = 32000000, },
{ .clk = 33000000, },
{ .clk = 33300000, },
{ .clk = 33333333, },
{ .clk = 66660000, .name = "mpc5121", },
{ .clk = 66666666, .name = "mpc5121" },
},
}, {
.bittiming_const = {
.name = "at91",
.tseg1_min = 4,
.tseg1_max = 16,
.tseg2_min = 2,
.tseg2_max = 8,
.sjw_max = 4,
.brp_min = 2,
.brp_max = 128,
.brp_inc = 1,
},
.ref_clk = {
{ .clk = 99532800, .name = "ronetix PM9263", },
{ .clk = 100000000, },
},
.printf_btr = printf_btr_at91,
}, {
.bittiming_const = {
.name = "flexcan",
.tseg1_min = 4,
.tseg1_max = 16,
.tseg2_min = 2,
.tseg2_max = 8,
.sjw_max = 4,
.brp_min = 1,
.brp_max = 256,
.brp_inc = 1,
},
.ref_clk = {
{ .clk = 24000000, .name = "mx28" },
{ .clk = 30000000, .name = "mx6" },
{ .clk = 49875000, },
{ .clk = 66000000, },
{ .clk = 66500000, },
{ .clk = 66666666, },
{ .clk = 83368421, .name = "vybrid" },
},
.printf_btr = printf_btr_flexcan,
}, {
.bittiming_const = {
.name = "mcp251x",
.tseg1_min = 3,
.tseg1_max = 16,
.tseg2_min = 2,
.tseg2_max = 8,
.sjw_max = 4,
.brp_min = 1,
.brp_max = 64,
.brp_inc = 1,
},
.ref_clk = {
/* The mcp251x uses half of the external OSC clock as the base clock */
{ .clk = 8000000 / 2, .name = "8 MHz OSC" },
{ .clk = 16000000 / 2, .name = "16 MHz OSC" },
{ .clk = 20000000 / 2, .name = "20 MHz OSC" },
},
.printf_btr = printf_btr_mcp251x,
}, {
.bittiming_const = {
.name = "mcp251xfd",
.tseg1_min = 2,
.tseg1_max = 256,
.tseg2_min = 1,
.tseg2_max = 128,
.sjw_max = 128,
.brp_min = 1,
.brp_max = 256,
.brp_inc = 1,
},
.ref_clk = {
{ .clk = 20000000, },
{ .clk = 40000000, },
},
.printf_btr = printf_btr_mcp251xfd,
}, {
.bittiming_const = {
.name = "ti_hecc",
.tseg1_min = 1,
.tseg1_max = 16,
.tseg2_min = 1,
.tseg2_max = 8,
.sjw_max = 4,
.brp_min = 1,
.brp_max = 256,
.brp_inc = 1,
},
.ref_clk = {
{ .clk = 13000000, },
},
.printf_btr = printf_btr_ti_hecc,
}, {
.bittiming_const = {
.name = "rcar_can",
.tseg1_min = 4,
.tseg1_max = 16,
.tseg2_min = 2,
.tseg2_max = 8,
.sjw_max = 4,
.brp_min = 1,
.brp_max = 1024,
.brp_inc = 1,
},
.ref_clk = {
{ .clk = 65000000, },
},
.printf_btr = printf_btr_rcar_can,
}, {
.bittiming_const = {
.name = "bxcan",
.tseg1_min = 1,
.tseg1_max = 16,
.tseg2_min = 1,
.tseg2_max = 8,
.sjw_max = 4,
.brp_min = 1,
.brp_max = 1024,
.brp_inc = 1,
},
.ref_clk = {
{ .clk = 48000000, },
},
.printf_btr = printf_btr_bxcan,
}, {
.bittiming_const = {
.name = "c_can",
.tseg1_min = 2,
.tseg1_max = 16,
.tseg2_min = 1,
.tseg2_max = 8,
.sjw_max = 4,
.brp_min = 1,
.brp_max = 1024,
.brp_inc = 1,
},
.ref_clk = {
{ .clk = 24000000, },
},
.printf_btr = printf_btr_c_can,
}, {
.bittiming_const = {
.name = "mcan-v3.1+",
.tseg1_min = 2,
.tseg1_max = 256,
.tseg2_min = 2,
.tseg2_max = 128,
.sjw_max = 128,
.brp_min = 1,
.brp_max = 512,
.brp_inc = 1,
},
.ref_clk = {
{ .clk = 40000000, },
},
.printf_btr = printf_btr_mcan,
},
};
static const unsigned int common_bitrates[] = {
1000000,
800000,
500000,
250000,
125000,
100000,
50000,
20000,
10000,
0
};
static const unsigned int common_data_bitrates[] = {
12000000,
10000000,
8000000,
5000000,
4000000,
2000000,
1000000,
0
};
#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
#define CAN_CALC_SYNC_SEG 1
/*
* 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.
*/
/*
* imported from v3.18-rc1~52^2~248^2~1
*
* b25a437206ed can: dev: remove unused variable from can_calc_bittiming() function
*/
#undef can_calc_bittiming
#undef can_update_spt
#define can_calc_bittiming can_calc_bittiming_v3_18
#define can_update_spt can_update_spt_v3_18
static int can_update_spt(const struct can_bittiming_const *btc,
int sampl_pt, int tseg, int *tseg1, int *tseg2)
{
*tseg2 = tseg + 1 - (sampl_pt * (tseg + 1)) / 1000;
if (*tseg2 < btc->tseg2_min)
*tseg2 = btc->tseg2_min;
if (*tseg2 > btc->tseg2_max)
*tseg2 = btc->tseg2_max;
*tseg1 = tseg - *tseg2;
if (*tseg1 > btc->tseg1_max) {
*tseg1 = btc->tseg1_max;
*tseg2 = tseg - *tseg1;
}
return 1000 * (tseg + 1 - *tseg2) / (tseg + 1);
}
static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
const struct can_bittiming_const *btc)
{
struct can_priv *priv = netdev_priv(dev);
long best_error = 1000000000, error = 0;
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;
long rate;
u64 v64;
/* Use CIA recommended sample points */
if (bt->sample_point) {
sampl_pt = bt->sample_point;
} else {
if (bt->bitrate > 800000)
sampl_pt = 750;
else if (bt->bitrate > 500000)
sampl_pt = 800;
else
sampl_pt = 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 = 1 + tseg / 2;
/* Compute all possible tseg choices (tseg=tseg1+tseg2) */
brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;
/* chose 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;
rate = priv->clock.freq / (brp * tsegall);
error = bt->bitrate - rate;
/* tseg brp biterror */
if (error < 0)
error = -error;
if (error > best_error)
continue;
best_error = error;
if (error == 0) {
spt = can_update_spt(btc, sampl_pt, tseg / 2,
&tseg1, &tseg2);
error = sampl_pt - spt;
if (error < 0)
error = -error;
if (error > spt_error)
continue;
spt_error = error;
}
best_tseg = tseg / 2;
best_brp = brp;
if (error == 0)
break;
}
if (best_error) {
/* Error in one-tenth of a percent */
error = (best_error * 1000) / bt->bitrate;
if (error > CAN_CALC_MAX_ERROR) {
netdev_err(dev,
"bitrate error %ld.%ld%% too high\n",
error / 10, error % 10);
return -EDOM;
} else {
netdev_warn(dev, "bitrate error %ld.%ld%%\n",
error / 10, error % 10);
}
}
/* real sample point */
bt->sample_point = can_update_spt(btc, sampl_pt, best_tseg,
&tseg1, &tseg2);
v64 = (u64)best_brp * 1000000000UL;
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;
/* check for sjw user settings */
if (!bt->sjw || !btc->sjw_max)
bt->sjw = 1;
else {
/* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */
if (bt->sjw > btc->sjw_max)
bt->sjw = btc->sjw_max;
/* bt->sjw must not be higher than tseg2 */
if (tseg2 < bt->sjw)
bt->sjw = tseg2;
}
bt->brp = best_brp;
/* real bit-rate */
bt->bitrate = priv->clock.freq / (bt->brp * (tseg1 + tseg2 + 1));
return 0;
}
/*
* imported from v4.8-rc1~140^2~304^2~11
*
* 7da29f97d6c8 can: dev: can-calc-bit-timing(): better sample point calculation
*/
#undef can_update_spt
#undef can_calc_bittiming
#define can_update_spt can_update_spt_v4_8
#define can_calc_bittiming can_calc_bittiming_v4_8
static int can_update_spt(const struct can_bittiming_const *btc,
unsigned int spt_nominal, unsigned int tseg,
unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
unsigned int *spt_error_ptr)
{
unsigned int spt_error, best_spt_error = UINT_MAX;
unsigned int spt, best_spt = 0;
unsigned int tseg1, tseg2;
int i;
for (i = 0; i <= 1; i++) {
tseg2 = tseg + CAN_CALC_SYNC_SEG - (spt_nominal * (tseg + CAN_CALC_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;
}
spt = 1000 * (tseg + CAN_CALC_SYNC_SEG - tseg2) / (tseg + CAN_CALC_SYNC_SEG);
spt_error = abs(spt_nominal - spt);
if ((spt <= spt_nominal) && (spt_error < best_spt_error)) {
best_spt = spt;
best_spt_error = spt_error;
*tseg1_ptr = tseg1;
*tseg2_ptr = tseg2;
}
}
if (spt_error_ptr)
*spt_error_ptr = best_spt_error;
return best_spt;
}
static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
const struct can_bittiming_const *btc)
{
struct can_priv *priv = netdev_priv(dev);
unsigned int rate; /* current bitrate */
unsigned int rate_error; /* difference between current and nominal value */
unsigned int best_rate_error = UINT_MAX;
unsigned int spt_error; /* difference between current and nominal value */
unsigned int best_spt_error = UINT_MAX;
unsigned int spt_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;
/* Use CiA recommended sample points */
if (bt->sample_point) {
spt_nominal = bt->sample_point;
} else {
if (bt->bitrate > 800000)
spt_nominal = 750;
else if (bt->bitrate > 500000)
spt_nominal = 800;
else
spt_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_CALC_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;
rate = priv->clock.freq / (brp * tsegall);
rate_error = abs(bt->bitrate - rate);
/* tseg brp biterror */
if (rate_error > best_rate_error)
continue;
/* reset sample point error if we have a better bitrate */
if (rate_error < best_rate_error)
best_spt_error = UINT_MAX;
can_update_spt(btc, spt_nominal, tseg / 2, &tseg1, &tseg2, &spt_error);
if (spt_error > best_spt_error)
continue;
best_spt_error = spt_error;
best_rate_error = rate_error;
best_tseg = tseg / 2;
best_brp = brp;
if (rate_error == 0 && spt_error == 0)
break;
}
if (best_rate_error) {
/* Error in one-tenth of a percent */
rate_error = (best_rate_error * 1000) / bt->bitrate;
if (rate_error > CAN_CALC_MAX_ERROR) {
netdev_err(dev,
"bitrate error %ld.%ld%% too high\n",
rate_error / 10, rate_error % 10);
return -EDOM;
}
netdev_warn(dev, "bitrate error %ld.%ld%%\n",
rate_error / 10, rate_error % 10);
}
/* real sample point */
bt->sample_point = can_update_spt(btc, spt_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;
/* check for sjw user settings */
if (!bt->sjw || !btc->sjw_max) {
bt->sjw = 1;
} else {
/* bt->sjw is at least 1 -> sanitize upper bound to sjw_max */
if (bt->sjw > btc->sjw_max)
bt->sjw = btc->sjw_max;
/* bt->sjw must not be higher than tseg2 */
if (tseg2 < bt->sjw)
bt->sjw = tseg2;
}
bt->brp = best_brp;
/* real bit-rate */
bt->bitrate = priv->clock.freq / (bt->brp * (CAN_CALC_SYNC_SEG + tseg1 + tseg2));
return 0;
}
#undef can_calc_bittiming
#undef can_update_spt
static const struct can_calc_bittiming calc_bittiming_list[] = {
/* 1st will be default */
{
.alg = can_calc_bittiming_v4_8,
.name = "v4.8",
}, {
.alg = can_calc_bittiming_v3_18,
.name = "v3.18",
},
};
static int can_fixup_bittiming(struct net_device *dev, struct can_bittiming *bt,
const struct can_bittiming_const *btc)
{
struct can_priv *priv = netdev_priv(dev);
unsigned int tseg1, alltseg;
u64 brp64, v64;
tseg1 = bt->prop_seg + bt->phase_seg1;
if (!bt->sjw)
bt->sjw = 1;
if (bt->sjw > btc->sjw_max ||
tseg1 < btc->tseg1_min || tseg1 > btc->tseg1_max ||
bt->phase_seg2 < btc->tseg2_min || bt->phase_seg2 > btc->tseg2_max)
return -ERANGE;
if (!bt->brp) {
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 = brp64;
}
v64 = bt->brp * 1000 * 1000 * 1000;
do_div(v64, priv->clock.freq);
bt->tq = v64;
if (bt->brp < btc->brp_min || bt->brp > btc->brp_max)
return -EINVAL;
alltseg = CAN_CALC_SYNC_SEG + bt->prop_seg + bt->phase_seg1 + bt->phase_seg2;
bt->bitrate = priv->clock.freq / (bt->brp * alltseg);
bt->sample_point = ((CAN_CALC_SYNC_SEG + tseg1) * 1000) / alltseg;
return 0;
}
static __u32 get_cia_sample_point(__u32 bitrate)
{
__u32 sampl_pt;
if (bitrate > 800000)
sampl_pt = 750;
else if (bitrate > 500000)
sampl_pt = 800;
else
sampl_pt = 875;
return sampl_pt;
}
static void print_bittiming_one(const struct can_calc_bittiming *calc_bittiming,
const struct can_bittiming_const *bittiming_const,
const struct can_bittiming *ref_bt,
const struct calc_ref_clk *ref_clk,
unsigned int bitrate_nominal,
unsigned int sample_point_nominal,
void (*printf_btr)(struct can_bittiming *bt, bool hdr),
bool quiet)
{
struct net_device dev = {
.priv.clock.freq = ref_clk->clk,
};
struct can_bittiming bt = {
.bitrate = bitrate_nominal,
.sample_point = sample_point_nominal,
};
unsigned int bitrate_error, sample_point_error;
if (!quiet) {
printf("Bit timing parameters for %s with %.6f MHz ref clock %s%s%susing algo '%s'\n"
" nominal real Bitrt nom real SampP\n"
" Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP Bitrate Error SampP SampP Error ",
bittiming_const->name,
ref_clk->clk / 1000000.0,
ref_clk->name ? "(" : "",
ref_clk->name ? ref_clk->name : "",
ref_clk->name ? ") " : "",
calc_bittiming->name);
printf_btr(&bt, true);
printf("\n");
}
if (ref_bt) {
bt = *ref_bt;
if (can_fixup_bittiming(&dev, &bt, bittiming_const)) {
printf("%8d ***parameters exceed controller's range***\n", bitrate_nominal);
return;
}
} else {
if (calc_bittiming->alg(&dev, &bt, bittiming_const)) {
printf("%8d ***bitrate not possible***\n", bitrate_nominal);
return;
}
}
bitrate_error = abs(bitrate_nominal - bt.bitrate);
sample_point_error = abs(sample_point_nominal - bt.sample_point);
printf("%8d " /* Bitrate */
"%6d %3d %4d %4d " /* TQ[ns], PrS, PhS1, PhS2 */
"%3d %3d " /* SJW, BRP */
"%8d ", /* real Bitrate */
bitrate_nominal,
bt.tq, bt.prop_seg, bt.phase_seg1, bt.phase_seg2,
bt.sjw, bt.brp,
bt.bitrate);
if (100.0 * bitrate_error / bitrate_nominal > 99.9)
printf("≥100%% ");
else
printf("%4.1f%% ", /* Bitrate Error */
100.0 * bitrate_error / bitrate_nominal);
printf("%4.1f%% %4.1f%% ", /* nom Sample Point, real Sample Point */
sample_point_nominal / 10.0,
bt.sample_point / 10.0);
if (100.0 * sample_point_error / sample_point_nominal > 99.9)
printf("≥100%% ");
else
printf("%4.1f%% ", /* Sample Point Error */
100.0 * sample_point_error / sample_point_nominal);
printf_btr(&bt, false);
printf("\n");
}
static void print_bittiming(const struct calc_data *data)
{
const struct calc_ref_clk *ref_clks = data->ref_clks;
if (!ref_clks->clk && !data->quiet)
printf("Skipping bit timing parameter calculation for %s, no ref clock defined\n\n",
data->bittiming_const->name);
while (ref_clks->clk) {
void (*printf_btr)(struct can_bittiming *bt, bool hdr);
unsigned int const *bitrates = data->bitrates;
bool quiet = data->quiet;
if (data->printf_btr)
printf_btr = data->printf_btr;
else
printf_btr = printf_btr_nop;
while (*bitrates) {
unsigned int sample_point;
/* get nominal sample point */
if (data->sample_point)
sample_point = data->sample_point;
else
sample_point = get_cia_sample_point(*bitrates);
print_bittiming_one(data->calc_bittiming,
data->bittiming_const,
data->opt_bt,
ref_clks,
*bitrates,
sample_point,
printf_btr,
quiet);
bitrates++;
quiet = true;
}
printf("\n");
ref_clks++;
}
}
static void do_list_calc_bittiming_list(void)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(calc_bittiming_list); i++)
printf(" %s\n", calc_bittiming_list[i].name);
}
static void do_list(void)
{
unsigned int i;
for (i = 0; i < ARRAY_SIZE(can_calc_consts); i++)
printf("%s\n", can_calc_consts[i].bittiming_const.name);
}
static void do_calc(struct calc_data *data)
{
unsigned int i;
bool found = false;
for (i = 0; i < ARRAY_SIZE(can_calc_consts); i++) {
const struct calc_bittiming_const *btc;
btc = &can_calc_consts[i];
if (data->name &&
strcmp(data->name, btc->bittiming_const.name) &&
strcmp(data->name, btc->data_bittiming_const.name))
continue;
found = true;
if (btc->bittiming_const.name[0]) {
data->bittiming_const = &btc->bittiming_const;
data->printf_btr = btc->printf_btr;
if (data->opt_ref_clk)
data->ref_clks = data->opt_ref_clk;
else
data->ref_clks = btc->ref_clk;
if (data->opt_bitrates)
data->bitrates = data->opt_bitrates;
else
data->bitrates = common_bitrates;
print_bittiming(data);
}
if (btc->data_bittiming_const.name[0]) {
data->bittiming_const = &btc->data_bittiming_const;
if (btc->printf_data_btr)
data->printf_btr = btc->printf_data_btr;
else
data->printf_btr = btc->printf_btr;
if (data->opt_ref_clk)
data->ref_clks = data->opt_ref_clk;
else
data->ref_clks = btc->ref_clk;
if (data->opt_data_bitrates)
data->bitrates = data->opt_data_bitrates;
else if (data->opt_bitrates)
data->bitrates = data->opt_bitrates;
else
data->bitrates = common_data_bitrates;
print_bittiming(data);
}
}
if (!found) {
printf("error: unknown CAN controller '%s', try one of these:\n\n", data->name);
do_list();
exit(EXIT_FAILURE);
}
}
int main(int argc, char *argv[])
{
struct calc_ref_clk opt_ref_clk[] = {
{ .name = "cmd-line" },
{ /* sentinel */ }
};
struct can_bittiming opt_bt[1] = { };
unsigned int opt_bitrate[] = {
0,
0 /* sentinel */
};
unsigned int opt_data_bitrate[] = {
0,
0 /* sentinel */
};
struct calc_data data[] = {
{
.calc_bittiming = calc_bittiming_list,
}
};
const char *opt_alg_name = NULL;
bool list = false;
int opt;
const struct option long_options[] = {
{ "tq", required_argument, 0, OPT_TQ, },
{ "prop-seg", required_argument, 0, OPT_PROP_SEG, },
{ "phase-seg1", required_argument, 0, OPT_PHASE_SEG1, },
{ "phase-seg2", required_argument, 0, OPT_PHASE_SEG2, },
{ "sjw", required_argument, 0, OPT_SJW, },
{ "brp", required_argument, 0, OPT_BRP, },
{ "tseg1", required_argument, 0, OPT_TSEG1, },
{ "tseg2", required_argument, 0, OPT_TSEG2, },
{ "alg", optional_argument, 0, OPT_ALG, },
{ 0, 0, 0, 0 },
};
while ((opt = getopt_long(argc, argv, "b:c:d:lqs:?", long_options, NULL)) != -1) {
switch (opt) {
case 'b':
opt_bitrate[0] = strtoul(optarg, NULL, 10);
break;
case 'c':
opt_ref_clk->clk = strtoul(optarg, NULL, 10);
break;
case 'd':
opt_data_bitrate[0] = strtoul(optarg, NULL, 10);
break;
case 'l':
list = true;
break;
case 'q':
data->quiet = true;
break;
case 's':
data->sample_point = strtoul(optarg, NULL, 10);
break;
case '?':
print_usage(basename(argv[0]));
exit(EXIT_SUCCESS);
break;
case OPT_TQ:
opt_bt->tq = strtoul(optarg, NULL, 10);
break;
case OPT_PROP_SEG:
opt_bt->prop_seg = strtoul(optarg, NULL, 10);
break;
case OPT_PHASE_SEG1:
opt_bt->phase_seg1 = strtoul(optarg, NULL, 10);
break;
case OPT_PHASE_SEG2:
opt_bt->phase_seg2 = strtoul(optarg, NULL, 10);
break;
case OPT_SJW:
opt_bt->sjw = strtoul(optarg, NULL, 10);
break;
case OPT_BRP:
opt_bt->brp = strtoul(optarg, NULL, 10);
break;
case OPT_TSEG1: {
__u32 tseg1;
tseg1 = strtoul(optarg, NULL, 10);
opt_bt->prop_seg = tseg1 / 2;
opt_bt->phase_seg1 = tseg1 - opt_bt->prop_seg;
break;
}
case OPT_TSEG2:
opt_bt->phase_seg2 = strtoul(optarg, NULL, 10);
break;
case OPT_ALG:
if (!optarg) {
printf("Supported CAN calc bit timing algorithms:\n\n");
do_list_calc_bittiming_list();
printf("\n");
exit(EXIT_SUCCESS);
}
opt_alg_name = optarg;
break;
default:
print_usage(basename(argv[0]));
exit(EXIT_FAILURE);
break;
}
}
if (argc > optind + 1) {
print_usage(argv[0]);
exit(EXIT_FAILURE);
}
if (argc == optind + 1)
data->name = argv[optind];
if (list) {
do_list();
exit(EXIT_SUCCESS);
}
if (data->sample_point && (data->sample_point >= 1000 || data->sample_point < 100))
print_usage(argv[0]);
if (opt_alg_name) {
bool alg_found = false;
unsigned int i;
for (i = 0; i < ARRAY_SIZE(calc_bittiming_list); i++) {
if (!strcmp(opt_alg_name, calc_bittiming_list[i].name)) {
data->calc_bittiming = &calc_bittiming_list[i];
alg_found = true;
}
}
if (!alg_found) {
printf("error: unknown CAN calc bit timing algorithm '%s', try one of these:\n\n", opt_alg_name);
do_list_calc_bittiming_list();
exit(EXIT_FAILURE);
}
}
if (opt_ref_clk->clk)
data->opt_ref_clk = opt_ref_clk;
if (opt_bitrate[0])
data->opt_bitrates = opt_bitrate;
if (opt_data_bitrate[0])
data->opt_data_bitrates = opt_data_bitrate;
if (opt_bt->prop_seg)
data->opt_bt = opt_bt;
do_calc(data);
exit(EXIT_SUCCESS);
}
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