]> rtime.felk.cvut.cz Git - sojka/can-utils.git/blobdiff - can-calc-bit-timing.c
can-utils: AOSP build clean up
[sojka/can-utils.git] / can-calc-bit-timing.c
index 913b926d3798746c02aa782c834eabd3b5a787c6..a9fb992bf8129f2f568b20c29035a035eceea638 100644 (file)
  *   This software is released under the GPL-License.
  */
 
+#include <errno.h>
+#include <getopt.h>
+#include <stdint.h>
 #include <stdio.h>
 #include <stdlib.h>
-#include <stdint.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 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 */
+       __u32 ref_clk;          /* CAN system clock frequency in Hz */
+       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)
 {
        printf("Usage: %s [options] [<CAN-contoller-name>]\n"
@@ -32,36 +139,10 @@ static void print_usage(char* cmd)
               "\t-c <clock>   : real CAN system clock in Hz\n",
               cmd);
 
-       exit(1);
+       exit(EXIT_FAILURE);
 }
 
-struct can_bittime {
-       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)
+static void printf_btr_sja1000(struct can_bittiming *bt, int hdr)
 {
        uint8_t btr0, btr1;
 
@@ -75,10 +156,10 @@ 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) {
-               printf("CAN_BR");
+               printf("%10s", "CAN_BR");
        } else {
                uint32_t br = ((bt->phase_seg2 - 1) |
                               ((bt->phase_seg1 - 1) << 4) |
@@ -89,7 +170,22 @@ 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_flexcan(struct can_bittiming *bt, int 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, int hdr)
 {
        uint8_t cnf1, cnf2, cnf3;
 
@@ -103,90 +199,235 @@ 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_ti_hecc(struct can_bittiming *bt, int hdr)
 {
-       uint16_t bcr0, bcr1;
-
        if (hdr) {
-               printf("__BCR0 __BCR1");
+               printf("%10s", "CANBTC");
        } else {
-               bcr1 = ((((bt->prop_seg + bt->phase_seg1 - 1) & 0x0F) << 12) |
-                       (((bt->phase_seg2 - 1) & 0x07) << 8) |
-                       (((bt->sjw - 1) & 0x03) << 4));
-               bcr0 =  ((bt->brp - 1) & 0xFF);
-               printf("0x%04x 0x%04x", bcr0, bcr1);
+               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);
        }
 }
 
-struct can_bittiming_const can_calc_consts[] = {
+static struct can_bittiming_const can_calc_consts[] = {
        {
-               "sja1000",
-               /* Note: only prop_seg + bt->phase_seg1 matters */
-               .phase_seg1_min = 1,
-               .phase_seg1_max = 16,
-               .phase_seg2_min = 1,
-               .phase_seg2_max = 8,
+               .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 = 8000000,
                .printf_btr = printf_btr_sja1000,
        },
        {
-               "mscan",
-               /* Note: only prop_seg + bt->phase_seg1 matters */
-               .phase_seg1_min = 4,
-               .phase_seg1_max = 16,
-               .phase_seg2_min = 2,
-               .phase_seg2_max = 8,
+               .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 = 32000000,
                .printf_btr = printf_btr_sja1000,
        },
        {
-               "at91",
-               .prop_seg_min = 1,
-               .prop_seg_max = 8,
-               .phase_seg1_min = 1,
-               .phase_seg1_max = 8,
-               .phase_seg2_min = 2,
-               .phase_seg2_max = 8,
+               .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 = 33000000,
+               .printf_btr = printf_btr_sja1000,
+       },
+       {
+               .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 = 33300000,
+               .printf_btr = printf_btr_sja1000,
+       },
+       {
+               .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 = 33333333,
+               .printf_btr = printf_btr_sja1000,
+       },
+       {
+               .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 = 66660000,    /* mpc5121 */
+               .printf_btr = printf_btr_sja1000,
+       },
+       {
+               .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 = 100000000,
+               .printf_btr = printf_btr_at91,
+       },
+       {
+               .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,
+
+               /* real world clock as found on the ronetix PM9263 */
+               .ref_clk = 99532800,
                .printf_btr = printf_btr_at91,
        },
        {
-               "mcp2510",
-               .prop_seg_min = 1,
-               .prop_seg_max = 8,
-               .phase_seg1_min = 1,
-               .phase_seg1_max = 8,
-               .phase_seg2_min = 2,
-               .phase_seg2_max = 8,
+               .name = "flexcan",
+               .tseg1_min = 4,
+               .tseg1_max = 16,
+               .tseg2_min = 2,
+               .tseg2_max = 8,
                .sjw_max = 4,
                .brp_min = 1,
-               .brp_max = 64,
+               .brp_max = 256,
                .brp_inc = 1,
-               .printf_btr = printf_btr_mcp2510,
+
+               .ref_clk = 24000000,    /* mx28 */
+               .printf_btr = printf_btr_flexcan,
        },
        {
-               "rtcantl1",
-               .prop_seg_min = 2,
-               .prop_seg_max = 8,
-               .phase_seg1_min = 2,
-               .phase_seg1_max = 8,
-               .phase_seg2_min = 2,
-               .phase_seg2_max = 8,
+               .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,
-               .printf_btr = printf_btr_rtcantl1,
+
+               .ref_clk = 49875000,
+               .printf_btr = printf_btr_flexcan,
        },
+       {
+               .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 = 66000000,
+               .printf_btr = printf_btr_flexcan,
+       },
+       {
+               .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 = 66500000,
+               .printf_btr = printf_btr_flexcan,
+       },
+       {
+               .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 = 8000000,
+               .printf_btr = printf_btr_mcp251x,
+       },
+       {
+               .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 = 16000000,
+               .printf_btr = printf_btr_mcp251x,
+       },
+       {
+               .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 = 13000000,
+               .printf_btr = printf_btr_ti_hecc,
+       }
 };
 
 static long common_bitrates[] = {
@@ -198,69 +439,66 @@ static long common_bitrates[] = {
        100000,
        50000,
        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,
                          int sampl_pt, int tseg, int *tseg1, int *tseg2)
 {
        *tseg2 = tseg + 1 - (sampl_pt * (tseg + 1)) / 1000;
-       if (*tseg2 < btc->phase_seg2_min)
-               *tseg2 = btc->phase_seg2_min;
-       if (*tseg2 > btc->phase_seg2_max)
-               *tseg2 = btc->phase_seg2_max;
+       if (*tseg2 < btc->tseg2_min)
+               *tseg2 = btc->tseg2_min;
+       if (*tseg2 > btc->tseg2_max)
+               *tseg2 = btc->tseg2_max;
        *tseg1 = tseg - *tseg2;
-       if (*tseg1 > btc->prop_seg_max + btc->phase_seg1_max) {
-               *tseg1 = btc->prop_seg_max + btc->phase_seg1_max;
+       if (*tseg1 > btc->tseg1_max) {
+               *tseg1 = btc->tseg1_max;
                *tseg2 = tseg - *tseg1;
        }
        return 1000 * (tseg + 1 - *tseg2) / (tseg + 1);
 }
 
-int can_calc_bittiming(struct can_bittime *bt, long bitrate,
-                      int sampl_pt, long clock,
-                      const struct can_bittiming_const *btc)
+static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt)
 {
-       long best_error = 1000000000, error;
+       struct can_priv *priv = netdev_priv(dev);
+       const struct can_bittiming_const *btc = priv->bittiming_const;
+       long rate = 0;
+       long best_error = 1000000000, error = 0;
        int best_tseg = 0, best_brp = 0, brp = 0;
-       int spt_error = 1000, spt = 0;
-       long rate, best_rate = 0;
-       int tseg = 0, tseg1 = 0, tseg2 = 0;
-       uint64_t v64;
-
-       if (sampl_pt == 0) {
-               /* Use CIA recommended sample points */
-               if (bitrate > 800000)
+       int tsegall, tseg = 0, tseg1 = 0, tseg2 = 0;
+       int spt_error = 1000, spt = 0, sampl_pt;
+       u64 v64;
+
+       if (!priv->bittiming_const)
+               return -ENOTSUPP;
+
+       /* Use CIA recommended sample points */
+       if (bt->sample_point) {
+               sampl_pt = bt->sample_point;
+       } else {
+               if (bt->bitrate > 800000)
                        sampl_pt = 750;
-               else if (bitrate > 500000)
+               else if (bt->bitrate > 500000)
                        sampl_pt = 800;
                else
                        sampl_pt = 875;
        }
 
-#ifdef DEBUG
-       printf("tseg brp bitrate biterror\n");
-#endif
-
        /* tseg even = round down, odd = round up */
-       for (tseg = (btc->prop_seg_max + btc->phase_seg1_max +
-                    btc->phase_seg2_max) * 2 + 1;
-            tseg >= (btc->prop_seg_min + btc->phase_seg1_min +
-                     btc->phase_seg2_min) * 2; tseg--) {
-               /* Compute all posibilities of tseg choices (tseg=tseg1+tseg2) */
-               brp = clock / ((1 + tseg / 2) * bitrate) + tseg % 2;
+       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 = clock / (brp * (1 + tseg / 2));
-               error = bitrate - rate;
+               rate = priv->clock.freq / (brp * tsegall);
+               error = bt->bitrate - rate;
                /* 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)
                        error = -error;
                if (error > best_error)
@@ -270,94 +508,140 @@ int can_calc_bittiming(struct can_bittime *bt, long bitrate,
                        spt = can_update_spt(btc, sampl_pt, tseg / 2,
                                             &tseg1, &tseg2);
                        error = sampl_pt - spt;
-                       //printf("%d %d %d\n", sampl_pt, error, spt_error);
                        if (error < 0)
                                error = -error;
                        if (error > spt_error)
                                continue;
                        spt_error = error;
-                       //printf("%d\n", spt_error);
                }
-               //printf("error=%d\n", best_error);
                best_tseg = tseg / 2;
                best_brp = brp;
-               best_rate = rate;
                if (error == 0)
                        break;
        }
 
-       if (best_error && (bitrate / best_error < 10))
-               return -1;
+       if (best_error) {
+               /* 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,
-                            &tseg1, &tseg2);
+       /* real sample point */
+       bt->sample_point = can_update_spt(btc, sampl_pt, best_tseg,
+                                         &tseg1, &tseg2);
 
-       if (tseg2 > tseg1) {
-               /* sample point < 50% */
-               bt->phase_seg1 = tseg1 / 2;
-       } else {
-               /* 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;
-       }
+       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;
        bt->sjw = 1;
        bt->brp = best_brp;
-       bt->error = best_error;
-       bt->sampl_pt = spt;
-       v64 = (uint64_t)bt->brp * 1000000000UL;
-       v64 /= clock;
-       bt->tq = (int)v64;
+
+       /* real bit-rate */
+       bt->bitrate = priv->clock.freq / (bt->brp * (tseg1 + tseg2 + 1));
 
        return 0;
 }
 
-void print_bit_timing(const struct can_bittiming_const *btc,
-                     long bitrate, int sampl_pt, long ref_clk, int quiet)
+static __u32 get_cia_sample_point(__u32 bitrate)
 {
-       struct can_bittime bt;
+       __u32 sampl_pt;
+
+       if (bitrate > 800000)
+               sampl_pt = 750;
+       else if (bitrate > 500000)
+               sampl_pt = 800;
+       else
+               sampl_pt = 875;
 
-       memset(&bt, 0, sizeof(bt));
+       return sampl_pt;
+}
+
+static void print_bit_timing(const struct can_bittiming_const *btc,
+                            __u32 bitrate, __u32 sample_point, __u32 ref_clk,
+                            int quiet)
+{
+       struct net_device dev = {
+               .priv.bittiming_const = btc,
+               .priv.clock.freq = ref_clk,
+       };
+       struct can_bittiming bt = {
+               .bitrate = bitrate,
+               .sample_point = sample_point,
+       };
+       long rate_error, spt_error;
 
        if (!quiet) {
-               printf("Bit timing parameters for %s using %ldHz\n",
-                      btc->name, ref_clk);
-               printf("Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP SampP Error ");
+               printf("Bit timing parameters for %s with %.6f MHz ref clock\n"
+                      "nominal                                 real Bitrt   nom  real SampP\n"
+                      "Bitrate TQ[ns] PrS PhS1 PhS2 SJW BRP Bitrate Error SampP SampP Error ",
+                      btc->name,
+                      ref_clk / 1000000.0);
+
                btc->printf_btr(&bt, 1);
                printf("\n");
        }
 
-       if (can_calc_bittiming(&bt, bitrate, sampl_pt, ref_clk, btc)) {
-               printf("%7ld ***bitrate not possible***\n", bitrate);
+       if (can_calc_bittiming(&dev, &bt)) {
+               printf("%7d ***bitrate not possible***\n", bitrate);
                return;
        }
 
-       printf("%7ld %6d %3d %4d %4d %3d %3d %2d.%d%% %4.1f%% ",
-              bitrate, bt.tq, bt.prop_seg, bt.phase_seg1,
-              bt.phase_seg2, bt.sjw, bt.brp,
-              bt.sampl_pt / 10, bt.sampl_pt % 10,
-              (double)100 * bt.error / bitrate);
+       /* get nominal sample point */
+       if (!sample_point)
+               sample_point = get_cia_sample_point(bitrate);
+
+       rate_error = abs((__s32)(bitrate - bt.bitrate));
+       spt_error = abs((__s32)(sample_point - bt.sample_point));
+
+       printf("%7d "
+              "%6d %3d %4d %4d "
+              "%3d %3d "
+              "%7d %4.1f%% "
+              "%4.1f%% %4.1f%% %4.1f%% ",
+              bitrate,
+              bt.tq, bt.prop_seg, bt.phase_seg1, bt.phase_seg2,
+              bt.sjw, bt.brp,
+
+              bt.bitrate,
+              100.0 * rate_error / bitrate,
+
+              sample_point / 10.0,
+              bt.sample_point / 10.0,
+              100.0 * spt_error / sample_point);
+
        btc->printf_btr(&bt, 0);
        printf("\n");
 }
 
+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].name);
+}
+
 int main(int argc, char *argv[])
 {
-       long bitrate = 0;
-       long ref_clk = 8000000;
+       __u32 bitrate = 0;
+       __u32 opt_ref_clk = 0, ref_clk;
        int sampl_pt = 0;
        int quiet = 0;
        int list = 0;
        char *name = NULL;
-       int i, opt;
+       unsigned int i, j;
+       int opt, found = 0;
 
        const struct can_bittiming_const *btc = NULL;
 
@@ -368,7 +652,7 @@ int main(int argc, char *argv[])
                        break;
 
                case 'c':
-                       ref_clk = atoi(optarg);
+                       opt_ref_clk = atoi(optarg);
                        break;
 
                case 'l':
@@ -396,37 +680,40 @@ int main(int argc, char *argv[])
                name = argv[optind];
 
        if (list) {
-               for (i = 0; i < sizeof(can_calc_consts) /
-                            sizeof(struct can_bittiming_const); i++)
-                       printf("%s\n", can_calc_consts[i].name);
-               return 0;
+               do_list();
+               exit(EXIT_SUCCESS);
        }
 
        if (sampl_pt && (sampl_pt >= 1000 || sampl_pt < 100))
                print_usage(argv[0]);
 
-       if (name) {
-               for (i = 0; i < sizeof(can_calc_consts) /
-                            sizeof(struct can_bittiming_const); i++) {
-                       if (!strcmp(can_calc_consts[i].name, name)) {
-                               btc = &can_calc_consts[i];
-                               break;
-                       }
-               }
-               if (!btc)
-                       print_usage(argv[0]);
+       for (i = 0; i < ARRAY_SIZE(can_calc_consts); i++) {
+               if (name && strcmp(can_calc_consts[i].name, name))
+                       continue;
 
-       } else {
-               btc = &can_calc_consts[0];
+               found = 1;
+               btc = &can_calc_consts[i];
+
+               if (opt_ref_clk)
+                       ref_clk = opt_ref_clk;
+               else
+                       ref_clk = btc->ref_clk;
+
+               if (bitrate) {
+                       print_bit_timing(btc, bitrate, sampl_pt, ref_clk, quiet);
+               } else {
+                       for (j = 0; j < ARRAY_SIZE(common_bitrates); j++)
+                               print_bit_timing(btc, common_bitrates[j],
+                                                sampl_pt, ref_clk, j);
+               }
+               printf("\n");
        }
 
-       if (bitrate) {
-               print_bit_timing(btc, bitrate, sampl_pt, ref_clk, quiet);
-       } else {
-               for (i = 0; i < sizeof(common_bitrates) / sizeof(long); i++)
-                       print_bit_timing(btc, common_bitrates[i], sampl_pt,
-                                        ref_clk, i);
+       if (!found) {
+               printf("error: unknown CAN controller '%s', try one of these:\n\n", name);
+               do_list();
+               exit(EXIT_FAILURE);
        }
 
-       return 0;
+       exit(EXIT_SUCCESS);
 }