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drivers: can: calculate a default SJW value

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Change the CAN timing calculation APIs to automatically calculate a default
(Re-)Synchronization Jump Width (SJW) value. The calculated value can be
overwritten by the caller if desired.

This allows automatically scaling the SJW according to the number of Time
Quanta (TQ) used for phase segment 2 instead of relying on a compile-time
fallback value defined in devicetree.

This reduces the can_set_timing()/can_set_timing_data() API functions to
simple setters (with validation).

Fixes: #63033

Signed-off-by: Henrik Brix Andersen <hebad@vestas.com>
This commit is contained in:
Henrik Brix Andersen 2023-09-22 11:58:16 +02:00 • committed by Carles Cufí
commit e397b85eb8
3 changed files with 39 additions and 57 deletions
Download patch file Download diff file Expand all files Collapse all files

26
drivers/can/can_common.c
View file

@ -170,7 +170,7 @@ static int can_calc_timing_int(uint32_t core_clock, struct can_timing *res,
CAN_SYNC_SEG;
uint16_t sp_err_min = UINT16_MAX;
int sp_err;
struct can_timing tmp_res;
struct can_timing tmp_res = { 0 };
if (bitrate == 0 || sp >= 1000) {
return -EINVAL;
@ -209,6 +209,10 @@ static int can_calc_timing_int(uint32_t core_clock, struct can_timing *res,
LOG_DBG("SP error: %d 1/1000", sp_err_min);
}
/* Calculate default sjw as phase_seg2 / 2 and clamp the result */
res->sjw = MIN(res->phase_seg1, res->phase_seg2 / 2);
res->sjw = CLAMP(res->sjw, min->sjw, max->sjw);
return sp_err_min == UINT16_MAX ? -ENOTSUP : (int)sp_err_min;
}
@ -300,18 +304,18 @@ static int check_timing_in_range(const struct can_timing *timing,
const struct can_timing *min,
const struct can_timing *max)
{
if (timing->sjw != CAN_SJW_NO_CHANGE &&
!IN_RANGE(timing->sjw, min->sjw, max->sjw)) {
return -ENOTSUP;
}
if (!IN_RANGE(timing->prop_seg, min->prop_seg, max->prop_seg) ||
if (!IN_RANGE(timing->sjw, min->sjw, max->sjw) ||
!IN_RANGE(timing->prop_seg, min->prop_seg, max->prop_seg) ||
!IN_RANGE(timing->phase_seg1, min->phase_seg1, max->phase_seg1) ||
!IN_RANGE(timing->phase_seg2, min->phase_seg2, max->phase_seg2) ||
!IN_RANGE(timing->prescaler, min->prescaler, max->prescaler)) {
return -ENOTSUP;
}
if ((timing->sjw > timing->phase_seg1) || (timing->sjw > timing->phase_seg2)) {
return -ENOTSUP;
}
return 0;
}
@ -333,7 +337,7 @@ int z_impl_can_set_timing(const struct device *dev,
int z_impl_can_set_bitrate(const struct device *dev, uint32_t bitrate)
{
struct can_timing timing;
struct can_timing timing = { 0 };
uint32_t max_bitrate;
uint16_t sample_pnt;
int ret;
@ -360,8 +364,6 @@ int z_impl_can_set_bitrate(const struct device *dev, uint32_t bitrate)
return -ERANGE;
}
timing.sjw = CAN_SJW_NO_CHANGE;
return can_set_timing(dev, &timing);
}
@ -388,7 +390,7 @@ int z_impl_can_set_timing_data(const struct device *dev,
int z_impl_can_set_bitrate_data(const struct device *dev, uint32_t bitrate_data)
{
struct can_timing timing_data;
struct can_timing timing_data = { 0 };
uint32_t max_bitrate;
uint16_t sample_pnt;
int ret;
@ -415,8 +417,6 @@ int z_impl_can_set_bitrate_data(const struct device *dev, uint32_t bitrate_data)
return -ERANGE;
}
timing_data.sjw = CAN_SJW_NO_CHANGE;
return can_set_timing_data(dev, &timing_data);
}
#endif /* CONFIG_CAN_FD_MODE */

66
drivers/can/can_shell.c
View file

@ -368,7 +368,7 @@ static int cmd_can_show(const struct shell *sh, size_t argc, char **argv)
static int cmd_can_bitrate_set(const struct shell *sh, size_t argc, char **argv)
{
const struct device *dev = device_get_binding(argv[1]);
struct can_timing timing;
struct can_timing timing = { 0 };
uint16_t sample_pnt;
uint32_t bitrate;
char *endptr;
@ -392,16 +392,6 @@ static int cmd_can_bitrate_set(const struct shell *sh, size_t argc, char **argv)
return -EINVAL;
}
if (argc >= 5) {
timing.sjw = (uint16_t)strtoul(argv[4], &endptr, 10);
if (*endptr != '\0') {
shell_error(sh, "failed to parse SJW");
return -EINVAL;
}
} else {
timing.sjw = CAN_SJW_NO_CHANGE;
}
err = can_calc_timing(dev, &timing, bitrate, sample_pnt);
if (err < 0) {
shell_error(sh, "failed to calculate timing for "
@ -410,17 +400,20 @@ static int cmd_can_bitrate_set(const struct shell *sh, size_t argc, char **argv)
return err;
}
if (timing.sjw == CAN_SJW_NO_CHANGE) {
shell_print(sh, "setting bitrate to %d bps, sample point %d.%d%% "
"(+/- %d.%d%%)",
bitrate, sample_pnt / 10, sample_pnt % 10, err / 10, err % 10);
} else {
shell_print(sh, "setting bitrate to %d bps, sample point %d.%d%% "
"(+/- %d.%d%%), sjw %d",
bitrate, sample_pnt / 10, sample_pnt % 10, err / 10, err % 10,
timing.sjw);
if (argc >= 5) {
/* Overwrite calculated default SJW with user-provided value */
timing.sjw = (uint16_t)strtoul(argv[4], &endptr, 10);
if (*endptr != '\0') {
shell_error(sh, "failed to parse SJW");
return -EINVAL;
}
}
shell_print(sh, "setting bitrate to %d bps, sample point %d.%d%% "
"(+/- %d.%d%%), sjw %d",
bitrate, sample_pnt / 10, sample_pnt % 10, err / 10, err % 10,
timing.sjw);
LOG_DBG("sjw %u, prop_seg %u, phase_seg1 %u, phase_seg2 %u, prescaler %u",
timing.sjw, timing.prop_seg, timing.phase_seg1, timing.phase_seg2,
timing.prescaler);
@ -446,7 +439,7 @@ static int cmd_can_bitrate_set(const struct shell *sh, size_t argc, char **argv)
static int cmd_can_dbitrate_set(const struct shell *sh, size_t argc, char **argv)
{
const struct device *dev = device_get_binding(argv[1]);
struct can_timing timing;
struct can_timing timing = { 0 };
uint16_t sample_pnt;
uint32_t bitrate;
char *endptr;
@ -470,16 +463,6 @@ static int cmd_can_dbitrate_set(const struct shell *sh, size_t argc, char **argv
return -EINVAL;
}
if (argc >= 5) {
timing.sjw = (uint16_t)strtoul(argv[4], &endptr, 10);
if (*endptr != '\0') {
shell_error(sh, "failed to parse SJW");
return -EINVAL;
}
} else {
timing.sjw = CAN_SJW_NO_CHANGE;
}
err = can_calc_timing_data(dev, &timing, bitrate, sample_pnt);
if (err < 0) {
shell_error(sh, "failed to calculate timing for "
@ -488,17 +471,20 @@ static int cmd_can_dbitrate_set(const struct shell *sh, size_t argc, char **argv
return err;
}
if (timing.sjw == CAN_SJW_NO_CHANGE) {
shell_print(sh, "setting data bitrate to %d bps, sample point %d.%d%% "
"(+/- %d.%d%%)",
bitrate, sample_pnt / 10, sample_pnt % 10, err / 10, err % 10);
} else {
shell_print(sh, "setting data bitrate to %d bps, sample point %d.%d%% "
"(+/- %d.%d%%), sjw %d",
bitrate, sample_pnt / 10, sample_pnt % 10, err / 10, err % 10,
timing.sjw);
if (argc >= 5) {
/* Overwrite calculated default SJW with user-provided value */
timing.sjw = (uint16_t)strtoul(argv[4], &endptr, 10);
if (*endptr != '\0') {
shell_error(sh, "failed to parse SJW");
return -EINVAL;
}
}
shell_print(sh, "setting data bitrate to %d bps, sample point %d.%d%% "
"(+/- %d.%d%%), sjw %d",
bitrate, sample_pnt / 10, sample_pnt % 10, err / 10, err % 10,
timing.sjw);
LOG_DBG("sjw %u, prop_seg %u, phase_seg1 %u, phase_seg2 %u, prescaler %u",
timing.sjw, timing.prop_seg, timing.phase_seg1, timing.phase_seg2,
timing.prescaler);

4
include/zephyr/drivers/can.h
View file

@ -865,8 +865,6 @@ __syscall int can_calc_timing_data(const struct device *dev, struct can_timing *
/**
* @brief Configure the bus timing for the data phase of a CAN-FD controller.
*
* If the sjw equals CAN_SJW_NO_CHANGE, the sjw parameter is not changed.
*
* @note @kconfig{CONFIG_CAN_FD_MODE} must be selected for this function to be
* available.
*
@ -936,8 +934,6 @@ int can_calc_prescaler(const struct device *dev, struct can_timing *timing,
/**
* @brief Configure the bus timing of a CAN controller.
*
* If the sjw equals CAN_SJW_NO_CHANGE, the sjw parameter is not changed.
*
* @see can_set_timing_data()
*
* @param dev Pointer to the device structure for the driver instance.