From: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
To: linux-kernel@vger.kernel.org, netdev@vger.kernel.org,
linux-can@vger.kernel.org,
Wolfgang Grandegger <wg@grandegger.com>,
Marc Kleine-Budde <mkl@pengutronix.de>,
"David S . Miller" <davem@davemloft.net>
Cc: Vincent Mailhol <mailhol.vincent@wanadoo.fr>,
Jakub Kicinski <kuba@kernel.org>
Subject: [PATCH 4/6] can: dev: add a helper function to calculate the duration of one bit
Date: Sun, 27 Sep 2020 02:57:54 +0900 [thread overview]
Message-ID: <20200926175810.278529-5-mailhol.vincent@wanadoo.fr> (raw)
In-Reply-To: <20200926175810.278529-1-mailhol.vincent@wanadoo.fr>
Rename macro CAN_CALC_SYNC_SEG to CAN_SYNC_SEG and make it available
through include/linux/can/dev.h
Add an helper function can_bit_time() which returns the duration (in
time quanta) of one CAN bit.
Rationale for this patch: the sync segment and the bit time are two
concepts which are defined in the CAN ISO standard. Device drivers for
CAN might need those.
Please refer to ISO 11898-1:2015, section 11.3.1.1 "Bit time" for
additional information.
Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
---
drivers/net/can/dev.c | 13 ++++++-------
include/linux/can/dev.h | 15 +++++++++++++++
2 files changed, 21 insertions(+), 7 deletions(-)
diff --git a/drivers/net/can/dev.c b/drivers/net/can/dev.c
index 8c3e11820e03..6070b4ab3bd8 100644
--- a/drivers/net/can/dev.c
+++ b/drivers/net/can/dev.c
@@ -60,7 +60,6 @@ EXPORT_SYMBOL_GPL(can_len2dlc);
#ifdef CONFIG_CAN_CALC_BITTIMING
#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
-#define CAN_CALC_SYNC_SEG 1
/* Bit-timing calculation derived from:
*
@@ -86,8 +85,8 @@ can_update_sample_point(const struct can_bittiming_const *btc,
int i;
for (i = 0; i <= 1; i++) {
- tseg2 = tseg + CAN_CALC_SYNC_SEG -
- (sample_point_nominal * (tseg + CAN_CALC_SYNC_SEG)) /
+ tseg2 = tseg + CAN_SYNC_SEG -
+ (sample_point_nominal * (tseg + CAN_SYNC_SEG)) /
1000 - i;
tseg2 = clamp(tseg2, btc->tseg2_min, btc->tseg2_max);
tseg1 = tseg - tseg2;
@@ -96,8 +95,8 @@ can_update_sample_point(const struct can_bittiming_const *btc,
tseg2 = tseg - tseg1;
}
- sample_point = 1000 * (tseg + CAN_CALC_SYNC_SEG - tseg2) /
- (tseg + CAN_CALC_SYNC_SEG);
+ sample_point = 1000 * (tseg + CAN_SYNC_SEG - tseg2) /
+ (tseg + CAN_SYNC_SEG);
sample_point_error = abs(sample_point_nominal - sample_point);
if (sample_point <= sample_point_nominal &&
@@ -145,7 +144,7 @@ static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
/* 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;
+ tsegall = CAN_SYNC_SEG + tseg / 2;
/* Compute all possible tseg choices (tseg=tseg1+tseg2) */
brp = priv->clock.freq / (tsegall * bt->bitrate) + tseg % 2;
@@ -223,7 +222,7 @@ static int can_calc_bittiming(struct net_device *dev, struct can_bittiming *bt,
/* real bitrate */
bt->bitrate = priv->clock.freq /
- (bt->brp * (CAN_CALC_SYNC_SEG + tseg1 + tseg2));
+ (bt->brp * (CAN_SYNC_SEG + tseg1 + tseg2));
return 0;
}
diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h
index 72a8a60c0094..30b327f1a4bd 100644
--- a/include/linux/can/dev.h
+++ b/include/linux/can/dev.h
@@ -82,6 +82,21 @@ struct can_priv {
#endif
};
+#define CAN_SYNC_SEG 1
+
+/*
+ * can_bit_time() - Duration of one bit
+ *
+ * Please refer to ISO 11898-1:2015, section 11.3.1.1 "Bit time" for
+ * additional information.
+ *
+ * Return: the number of time quanta in one bit.
+ */
+static inline int can_bit_time(struct can_bittiming *bt)
+{
+ return CAN_SYNC_SEG + bt->prop_seg + bt->phase_seg1 + bt->phase_seg2;
+}
+
/*
* get_can_dlc(value) - helper macro to cast a given data length code (dlc)
* to __u8 and ensure the dlc value to be max. 8 bytes.
--
2.26.2
next prev parent reply other threads:[~2020-09-26 17:59 UTC|newest]
Thread overview: 33+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-26 17:57 [PATCH 0/6] can: add support for ETAS ES58X CAN USB Vincent Mailhol
2020-09-26 17:57 ` [PATCH 1/6] can: dev: can_get_echo_skb(): prevent call to kfree_skb() in hard IRQ context Vincent Mailhol
2020-09-26 17:57 ` [PATCH 2/6] can: dev: add a helper function to get the correct length of Classical frames Vincent Mailhol
2020-09-26 17:57 ` [PATCH 3/6] can: dev: __can_get_echo_skb(): fix the return length Vincent Mailhol
2020-09-26 17:57 ` Vincent Mailhol [this message]
2020-09-26 17:57 ` [PATCH 6/6] USB: cdc-acm: blacklist ETAS ES58X device Vincent Mailhol
2020-09-27 5:45 ` Greg Kroah-Hartman
2020-09-27 5:52 ` Greg Kroah-Hartman
2020-09-29 2:15 ` Vincent Mailhol
2020-09-30 14:45 ` [PATCH v2 0/6] can: add support for ETAS ES58X CAN USB Vincent Mailhol
2020-09-30 14:45 ` [PATCH v2 1/6] can: dev: can_get_echo_skb(): prevent call to kfree_skb() in hard IRQ context Vincent Mailhol
2020-09-30 14:45 ` [PATCH v2 2/6] can: dev: add a helper function to get the correct length of Classical frames Vincent Mailhol
2020-09-30 15:21 ` Marc Kleine-Budde
2020-10-01 15:45 ` [PATCH v2 2/6] can: dev: add a helper function Vincent Mailhol
2020-10-01 15:51 ` Marc Kleine-Budde
2020-09-30 14:45 ` [PATCH v2 3/6] can: dev: __can_get_echo_skb(): fix the return length Vincent Mailhol
2020-09-30 14:45 ` [PATCH v2 4/6] can: dev: add a helper function to calculate the duration of one bit Vincent Mailhol
2020-09-30 14:45 ` [PATCH v2 6/6] usb: cdc-acm: add quirk to blacklist ETAS ES58X devices Vincent Mailhol
[not found] ` <20200930144602.10290-6-mailhol.vincent@wanadoo.fr>
2020-09-30 16:18 ` [PATCH v2 5/6] can: usb: etas_es58X: add support for ETAS ES58X CAN USB interfaces Greg Kroah-Hartman
2020-10-01 15:56 ` Vincent Mailhol
2020-10-02 15:41 ` [PATCH v3 0/7] can: add support for ETAS ES58X CAN USB Vincent Mailhol
2020-10-02 15:41 ` [PATCH v3 1/7] can: dev: can_get_echo_skb(): prevent call to kfree_skb() in hard IRQ context Vincent Mailhol
2020-10-02 15:41 ` [PATCH v3 2/7] can: dev: fix type of get_can_dlc() and get_canfd_dlc() macros Vincent Mailhol
2020-10-02 15:41 ` [PATCH v3 3/7] can: dev: add a helper function to get the correct length of Classical frames Vincent Mailhol
2020-10-02 15:41 ` [PATCH v3 4/7] can: dev: __can_get_echo_skb(): fix the return length Vincent Mailhol
2020-10-02 15:41 ` [PATCH v3 5/7] can: dev: add a helper function to calculate the duration of one bit Vincent Mailhol
2020-10-04 11:06 ` Marc Kleine-Budde
2020-10-04 11:10 ` Marc Kleine-Budde
2020-10-02 15:41 ` [PATCH v3 7/7] usb: cdc-acm: add quirk to blacklist ETAS ES58X devices Vincent Mailhol
2020-10-05 11:14 ` Greg Kroah-Hartman
[not found] ` <20201002154219.4887-7-mailhol.vincent@wanadoo.fr>
2020-10-04 12:06 ` [PATCH v3 6/7] can: usb: etas_es58X: add support for ETAS ES58X CAN USB interfaces Marc Kleine-Budde
2020-10-10 8:12 ` Vincent Mailhol
-- strict thread matches above, loose matches on Subject: below --
2020-09-26 17:45 [PATCH 0/6] can: add support for ETAS ES58X CAN USB Vincent Mailhol
2020-09-26 17:45 ` [PATCH 4/6] can: dev: add a helper function to calculate the duration of one bit Vincent Mailhol
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