can-calc-bit-timing: improve printing of bit timing parameters

[sojka/can-utils.git] / can-calc-bit-timing.c

diff --git a/can-calc-bit-timing.c b/can-calc-bit-timing.c
index 9db79e8cae29a43eec03225b427736eac4208d5f..1070b2991bce9587fe38d257fe6d3660092e8ac0 100644 (file)
--- a/can-calc-bit-timing.c
+++ b/can-calc-bit-timing.c
@@ -158,7 +158,7 @@ static void printf_btr_sja1000(struct can_bittiming *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) |
@@ -390,6 +390,20 @@ static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt)
        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_bit_timing(const struct can_bittiming_const *btc,
                             __u32 bitrate, __u32 sample_point, __u32 ref_clk,
                             int quiet)
@@ -402,12 +416,15 @@ static void print_bit_timing(const struct can_bittiming_const *btc,
                .bitrate = bitrate,
                .sample_point = sample_point,
        };
-       long rate_error;
+       long rate_error, spt_error;
 
        if (!quiet) {
-               printf("Bit timing parameters for %s using %dHz\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");
        }
@@ -417,13 +434,29 @@ static void print_bit_timing(const struct can_bittiming_const *btc,
                return;
        }
 
+       /* 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);
 
-       printf("%7d %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.sample_point / 10, bt.sample_point % 10,
-              100.0 * rate_error / bitrate);
        btc->printf_btr(&bt, 0);
        printf("\n");
 }