1 // SPDX-License-Identifier: GPL-2.0-only
2 /* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
3 * Copyright (C) 2006 Andrey Volkov, Varma Electronics
4 * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
5 */
6
7 #include <linux/can/dev.h>
8
can_sjw_set_default(struct can_bittiming * bt)9 void can_sjw_set_default(struct can_bittiming *bt)
10 {
11 if (bt->sjw)
12 return;
13
14 /* If user space provides no sjw, use sane default of phase_seg2 / 2 */
15 bt->sjw = max(1U, min(bt->phase_seg1, bt->phase_seg2 / 2));
16 }
17
can_sjw_check(const struct net_device * dev,const struct can_bittiming * bt,const struct can_bittiming_const * btc,struct netlink_ext_ack * extack)18 int can_sjw_check(const struct net_device *dev, const struct can_bittiming *bt,
19 const struct can_bittiming_const *btc, struct netlink_ext_ack *extack)
20 {
21 if (bt->sjw > btc->sjw_max) {
22 NL_SET_ERR_MSG_FMT(extack, "sjw: %u greater than max sjw: %u",
23 bt->sjw, btc->sjw_max);
24 return -EINVAL;
25 }
26
27 if (bt->sjw > bt->phase_seg1) {
28 NL_SET_ERR_MSG_FMT(extack,
29 "sjw: %u greater than phase-seg1: %u",
30 bt->sjw, bt->phase_seg1);
31 return -EINVAL;
32 }
33
34 if (bt->sjw > bt->phase_seg2) {
35 NL_SET_ERR_MSG_FMT(extack,
36 "sjw: %u greater than phase-seg2: %u",
37 bt->sjw, bt->phase_seg2);
38 return -EINVAL;
39 }
40
41 return 0;
42 }
43
44 /* Checks the validity of the specified bit-timing parameters prop_seg,
45 * phase_seg1, phase_seg2 and sjw and tries to determine the bitrate
46 * prescaler value brp. You can find more information in the header
47 * file linux/can/netlink.h.
48 */
can_fixup_bittiming(const struct net_device * dev,struct can_bittiming * bt,const struct can_bittiming_const * btc,struct netlink_ext_ack * extack)49 static int can_fixup_bittiming(const struct net_device *dev, struct can_bittiming *bt,
50 const struct can_bittiming_const *btc,
51 struct netlink_ext_ack *extack)
52 {
53 const unsigned int tseg1 = bt->prop_seg + bt->phase_seg1;
54 const struct can_priv *priv = netdev_priv(dev);
55 u64 brp64;
56 int err;
57
58 if (tseg1 < btc->tseg1_min) {
59 NL_SET_ERR_MSG_FMT(extack, "prop-seg + phase-seg1: %u less than tseg1-min: %u",
60 tseg1, btc->tseg1_min);
61 return -EINVAL;
62 }
63 if (tseg1 > btc->tseg1_max) {
64 NL_SET_ERR_MSG_FMT(extack, "prop-seg + phase-seg1: %u greater than tseg1-max: %u",
65 tseg1, btc->tseg1_max);
66 return -EINVAL;
67 }
68 if (bt->phase_seg2 < btc->tseg2_min) {
69 NL_SET_ERR_MSG_FMT(extack, "phase-seg2: %u less than tseg2-min: %u",
70 bt->phase_seg2, btc->tseg2_min);
71 return -EINVAL;
72 }
73 if (bt->phase_seg2 > btc->tseg2_max) {
74 NL_SET_ERR_MSG_FMT(extack, "phase-seg2: %u greater than tseg2-max: %u",
75 bt->phase_seg2, btc->tseg2_max);
76 return -EINVAL;
77 }
78
79 can_sjw_set_default(bt);
80
81 err = can_sjw_check(dev, bt, btc, extack);
82 if (err)
83 return err;
84
85 brp64 = (u64)priv->clock.freq * (u64)bt->tq;
86 if (btc->brp_inc > 1)
87 do_div(brp64, btc->brp_inc);
88 brp64 += 500000000UL - 1;
89 do_div(brp64, 1000000000UL); /* the practicable BRP */
90 if (btc->brp_inc > 1)
91 brp64 *= btc->brp_inc;
92 bt->brp = (u32)brp64;
93
94 if (bt->brp < btc->brp_min) {
95 NL_SET_ERR_MSG_FMT(extack, "resulting brp: %u less than brp-min: %u",
96 bt->brp, btc->brp_min);
97 return -EINVAL;
98 }
99 if (bt->brp > btc->brp_max) {
100 NL_SET_ERR_MSG_FMT(extack, "resulting brp: %u greater than brp-max: %u",
101 bt->brp, btc->brp_max);
102 return -EINVAL;
103 }
104
105 bt->bitrate = priv->clock.freq / (bt->brp * can_bit_time(bt));
106 bt->sample_point = ((CAN_SYNC_SEG + tseg1) * 1000) / can_bit_time(bt);
107 bt->tq = DIV_U64_ROUND_CLOSEST(mul_u32_u32(bt->brp, NSEC_PER_SEC),
108 priv->clock.freq);
109
110 return 0;
111 }
112
113 /* Checks the validity of predefined bitrate settings */
114 static int
can_validate_bitrate(const struct net_device * dev,const struct can_bittiming * bt,const u32 * bitrate_const,const unsigned int bitrate_const_cnt,struct netlink_ext_ack * extack)115 can_validate_bitrate(const struct net_device *dev, const struct can_bittiming *bt,
116 const u32 *bitrate_const,
117 const unsigned int bitrate_const_cnt,
118 struct netlink_ext_ack *extack)
119 {
120 unsigned int i;
121
122 for (i = 0; i < bitrate_const_cnt; i++) {
123 if (bt->bitrate == bitrate_const[i])
124 return 0;
125 }
126
127 NL_SET_ERR_MSG_FMT(extack, "bitrate %u bps not supported",
128 bt->brp);
129
130 return -EINVAL;
131 }
132
can_get_bittiming(const struct net_device * dev,struct can_bittiming * bt,const struct can_bittiming_const * btc,const u32 * bitrate_const,const unsigned int bitrate_const_cnt,struct netlink_ext_ack * extack)133 int can_get_bittiming(const struct net_device *dev, struct can_bittiming *bt,
134 const struct can_bittiming_const *btc,
135 const u32 *bitrate_const,
136 const unsigned int bitrate_const_cnt,
137 struct netlink_ext_ack *extack)
138 {
139 /* Depending on the given can_bittiming parameter structure the CAN
140 * timing parameters are calculated based on the provided bitrate OR
141 * alternatively the CAN timing parameters (tq, prop_seg, etc.) are
142 * provided directly which are then checked and fixed up.
143 */
144 if (!bt->tq && bt->bitrate && btc)
145 return can_calc_bittiming(dev, bt, btc, extack);
146 if (bt->tq && !bt->bitrate && btc)
147 return can_fixup_bittiming(dev, bt, btc, extack);
148 if (!bt->tq && bt->bitrate && bitrate_const)
149 return can_validate_bitrate(dev, bt, bitrate_const,
150 bitrate_const_cnt, extack);
151
152 return -EINVAL;
153 }
154
