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Subject[PATCH v4 3/7] can: bittiming: move bittiming calculation functions to calc_bittiming.c
Date
The canonical way to select or deselect an object during compilation
is to use this pattern in the relevant Makefile:

bar-$(CONFIG_FOO) := foo.o

bittiming.c instead uses some #ifdef CONFIG_CAN_CALC_BITTIMG.

Create a new file named calc_bittiming.c with all the functions which
are conditionally compiled with CONFIG_CAN_CALC_BITTIMG and modify the
Makefile according to above pattern.

Signed-off-by: Vincent Mailhol <mailhol.vincent@wanadoo.fr>
---
drivers/net/can/Kconfig | 4 +
drivers/net/can/dev/Makefile | 2 +
drivers/net/can/dev/bittiming.c | 197 --------------------------
drivers/net/can/dev/calc_bittiming.c | 202 +++++++++++++++++++++++++++
4 files changed, 208 insertions(+), 197 deletions(-)
create mode 100644 drivers/net/can/dev/calc_bittiming.c

diff --git a/drivers/net/can/Kconfig b/drivers/net/can/Kconfig
index b1e47f6c5586..8f3b97aea638 100644
--- a/drivers/net/can/Kconfig
+++ b/drivers/net/can/Kconfig
@@ -96,6 +96,10 @@ config CAN_CALC_BITTIMING
source clock frequencies. Disabling saves some space, but then the
bit-timing parameters must be specified directly using the Netlink
arguments "tq", "prop_seg", "phase_seg1", "phase_seg2" and "sjw".
+
+ The additional features selected by this option will be added to the
+ can-dev module.
+
If unsure, say Y.

config CAN_AT91
diff --git a/drivers/net/can/dev/Makefile b/drivers/net/can/dev/Makefile
index 919f87e36eed..b8a55b1d90cd 100644
--- a/drivers/net/can/dev/Makefile
+++ b/drivers/net/can/dev/Makefile
@@ -9,3 +9,5 @@ can-dev-$(CONFIG_CAN_NETLINK) += dev.o
can-dev-$(CONFIG_CAN_NETLINK) += length.o
can-dev-$(CONFIG_CAN_NETLINK) += netlink.o
can-dev-$(CONFIG_CAN_NETLINK) += rx-offload.o
+
+can-dev-$(CONFIG_CAN_CALC_BITTIMING) += calc_bittiming.o
diff --git a/drivers/net/can/dev/bittiming.c b/drivers/net/can/dev/bittiming.c
index c1e76f0a5064..7ae80763c960 100644
--- a/drivers/net/can/dev/bittiming.c
+++ b/drivers/net/can/dev/bittiming.c
@@ -4,205 +4,8 @@
* Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
*/

-#include <linux/units.h>
#include <linux/can/dev.h>

-#ifdef CONFIG_CAN_CALC_BITTIMING
-#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
-
-/* 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.
- */
-static int
-can_update_sample_point(const struct can_bittiming_const *btc,
- const unsigned int sample_point_nominal, const unsigned int tseg,
- unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
- unsigned int *sample_point_error_ptr)
-{
- unsigned int sample_point_error, best_sample_point_error = UINT_MAX;
- unsigned int sample_point, best_sample_point = 0;
- unsigned int tseg1, tseg2;
- int i;
-
- for (i = 0; i <= 1; i++) {
- 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;
- if (tseg1 > btc->tseg1_max) {
- tseg1 = btc->tseg1_max;
- tseg2 = tseg - tseg1;
- }
-
- 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 &&
- sample_point_error < best_sample_point_error) {
- best_sample_point = sample_point;
- best_sample_point_error = sample_point_error;
- *tseg1_ptr = tseg1;
- *tseg2_ptr = tseg2;
- }
- }
-
- if (sample_point_error_ptr)
- *sample_point_error_ptr = best_sample_point_error;
-
- return best_sample_point;
-}
-
-int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
- const struct can_bittiming_const *btc)
-{
- struct can_priv *priv = netdev_priv(dev);
- unsigned int bitrate; /* current bitrate */
- unsigned int bitrate_error; /* difference between current and nominal value */
- unsigned int best_bitrate_error = UINT_MAX;
- unsigned int sample_point_error; /* difference between current and nominal value */
- unsigned int best_sample_point_error = UINT_MAX;
- unsigned int sample_point_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) {
- sample_point_nominal = bt->sample_point;
- } else {
- if (bt->bitrate > 800 * KILO /* BPS */)
- sample_point_nominal = 750;
- else if (bt->bitrate > 500 * KILO /* BPS */)
- sample_point_nominal = 800;
- else
- sample_point_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_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;
-
- bitrate = priv->clock.freq / (brp * tsegall);
- bitrate_error = abs(bt->bitrate - bitrate);
-
- /* tseg brp biterror */
- if (bitrate_error > best_bitrate_error)
- continue;
-
- /* reset sample point error if we have a better bitrate */
- if (bitrate_error < best_bitrate_error)
- best_sample_point_error = UINT_MAX;
-
- can_update_sample_point(btc, sample_point_nominal, tseg / 2,
- &tseg1, &tseg2, &sample_point_error);
- if (sample_point_error >= best_sample_point_error)
- continue;
-
- best_sample_point_error = sample_point_error;
- best_bitrate_error = bitrate_error;
- best_tseg = tseg / 2;
- best_brp = brp;
-
- if (bitrate_error == 0 && sample_point_error == 0)
- break;
- }
-
- if (best_bitrate_error) {
- /* Error in one-tenth of a percent */
- v64 = (u64)best_bitrate_error * 1000;
- do_div(v64, bt->bitrate);
- bitrate_error = (u32)v64;
- if (bitrate_error > CAN_CALC_MAX_ERROR) {
- netdev_err(dev,
- "bitrate error %d.%d%% too high\n",
- bitrate_error / 10, bitrate_error % 10);
- return -EDOM;
- }
- netdev_warn(dev, "bitrate error %d.%d%%\n",
- bitrate_error / 10, bitrate_error % 10);
- }
-
- /* real sample point */
- bt->sample_point = can_update_sample_point(btc, sample_point_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 bitrate */
- bt->bitrate = priv->clock.freq /
- (bt->brp * (CAN_SYNC_SEG + tseg1 + tseg2));
-
- return 0;
-}
-
-void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
- const struct can_bittiming *dbt,
- u32 *ctrlmode, u32 ctrlmode_supported)
-
-{
- if (!tdc_const || !(ctrlmode_supported & CAN_CTRLMODE_TDC_AUTO))
- return;
-
- *ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
-
- /* As specified in ISO 11898-1 section 11.3.3 "Transmitter
- * delay compensation" (TDC) is only applicable if data BRP is
- * one or two.
- */
- if (dbt->brp == 1 || dbt->brp == 2) {
- /* Sample point in clock periods */
- u32 sample_point_in_tc = (CAN_SYNC_SEG + dbt->prop_seg +
- dbt->phase_seg1) * dbt->brp;
-
- if (sample_point_in_tc < tdc_const->tdco_min)
- return;
- tdc->tdco = min(sample_point_in_tc, tdc_const->tdco_max);
- *ctrlmode |= CAN_CTRLMODE_TDC_AUTO;
- }
-}
-#endif /* CONFIG_CAN_CALC_BITTIMING */
-
/* Checks the validity of the specified bit-timing parameters prop_seg,
* phase_seg1, phase_seg2 and sjw and tries to determine the bitrate
* prescaler value brp. You can find more information in the header
diff --git a/drivers/net/can/dev/calc_bittiming.c b/drivers/net/can/dev/calc_bittiming.c
new file mode 100644
index 000000000000..d3caa040614d
--- /dev/null
+++ b/drivers/net/can/dev/calc_bittiming.c
@@ -0,0 +1,202 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2005 Marc Kleine-Budde, Pengutronix
+ * Copyright (C) 2006 Andrey Volkov, Varma Electronics
+ * Copyright (C) 2008-2009 Wolfgang Grandegger <wg@grandegger.com>
+ */
+
+#include <linux/units.h>
+#include <linux/can/dev.h>
+
+#define CAN_CALC_MAX_ERROR 50 /* in one-tenth of a percent */
+
+/* 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.
+ */
+static int
+can_update_sample_point(const struct can_bittiming_const *btc,
+ const unsigned int sample_point_nominal, const unsigned int tseg,
+ unsigned int *tseg1_ptr, unsigned int *tseg2_ptr,
+ unsigned int *sample_point_error_ptr)
+{
+ unsigned int sample_point_error, best_sample_point_error = UINT_MAX;
+ unsigned int sample_point, best_sample_point = 0;
+ unsigned int tseg1, tseg2;
+ int i;
+
+ for (i = 0; i <= 1; i++) {
+ 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;
+ if (tseg1 > btc->tseg1_max) {
+ tseg1 = btc->tseg1_max;
+ tseg2 = tseg - tseg1;
+ }
+
+ 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 &&
+ sample_point_error < best_sample_point_error) {
+ best_sample_point = sample_point;
+ best_sample_point_error = sample_point_error;
+ *tseg1_ptr = tseg1;
+ *tseg2_ptr = tseg2;
+ }
+ }
+
+ if (sample_point_error_ptr)
+ *sample_point_error_ptr = best_sample_point_error;
+
+ return best_sample_point;
+}
+
+int can_calc_bittiming(const struct net_device *dev, struct can_bittiming *bt,
+ const struct can_bittiming_const *btc)
+{
+ struct can_priv *priv = netdev_priv(dev);
+ unsigned int bitrate; /* current bitrate */
+ unsigned int bitrate_error; /* difference between current and nominal value */
+ unsigned int best_bitrate_error = UINT_MAX;
+ unsigned int sample_point_error; /* difference between current and nominal value */
+ unsigned int best_sample_point_error = UINT_MAX;
+ unsigned int sample_point_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) {
+ sample_point_nominal = bt->sample_point;
+ } else {
+ if (bt->bitrate > 800 * KILO /* BPS */)
+ sample_point_nominal = 750;
+ else if (bt->bitrate > 500 * KILO /* BPS */)
+ sample_point_nominal = 800;
+ else
+ sample_point_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_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;
+
+ bitrate = priv->clock.freq / (brp * tsegall);
+ bitrate_error = abs(bt->bitrate - bitrate);
+
+ /* tseg brp biterror */
+ if (bitrate_error > best_bitrate_error)
+ continue;
+
+ /* reset sample point error if we have a better bitrate */
+ if (bitrate_error < best_bitrate_error)
+ best_sample_point_error = UINT_MAX;
+
+ can_update_sample_point(btc, sample_point_nominal, tseg / 2,
+ &tseg1, &tseg2, &sample_point_error);
+ if (sample_point_error >= best_sample_point_error)
+ continue;
+
+ best_sample_point_error = sample_point_error;
+ best_bitrate_error = bitrate_error;
+ best_tseg = tseg / 2;
+ best_brp = brp;
+
+ if (bitrate_error == 0 && sample_point_error == 0)
+ break;
+ }
+
+ if (best_bitrate_error) {
+ /* Error in one-tenth of a percent */
+ v64 = (u64)best_bitrate_error * 1000;
+ do_div(v64, bt->bitrate);
+ bitrate_error = (u32)v64;
+ if (bitrate_error > CAN_CALC_MAX_ERROR) {
+ netdev_err(dev,
+ "bitrate error %d.%d%% too high\n",
+ bitrate_error / 10, bitrate_error % 10);
+ return -EDOM;
+ }
+ netdev_warn(dev, "bitrate error %d.%d%%\n",
+ bitrate_error / 10, bitrate_error % 10);
+ }
+
+ /* real sample point */
+ bt->sample_point = can_update_sample_point(btc, sample_point_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 bitrate */
+ bt->bitrate = priv->clock.freq /
+ (bt->brp * (CAN_SYNC_SEG + tseg1 + tseg2));
+
+ return 0;
+}
+
+void can_calc_tdco(struct can_tdc *tdc, const struct can_tdc_const *tdc_const,
+ const struct can_bittiming *dbt,
+ u32 *ctrlmode, u32 ctrlmode_supported)
+
+{
+ if (!tdc_const || !(ctrlmode_supported & CAN_CTRLMODE_TDC_AUTO))
+ return;
+
+ *ctrlmode &= ~CAN_CTRLMODE_TDC_MASK;
+
+ /* As specified in ISO 11898-1 section 11.3.3 "Transmitter
+ * delay compensation" (TDC) is only applicable if data BRP is
+ * one or two.
+ */
+ if (dbt->brp == 1 || dbt->brp == 2) {
+ /* Sample point in clock periods */
+ u32 sample_point_in_tc = (CAN_SYNC_SEG + dbt->prop_seg +
+ dbt->phase_seg1) * dbt->brp;
+
+ if (sample_point_in_tc < tdc_const->tdco_min)
+ return;
+ tdc->tdco = min(sample_point_in_tc, tdc_const->tdco_max);
+ *ctrlmode |= CAN_CTRLMODE_TDC_AUTO;
+ }
+}
--
2.35.1
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