[PATCH v3 5/7] can: dev: add a helper function to calculate the duration of one bit
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
---
Changes in v3: None
Changes in v2: None
---
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 791c452d98e1..77c3ea49b8fb 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
Re: [PATCH v3 5/7] can: dev: add a helper function to calculate the duration of one bit
On 10/2/20 5:41 PM, Vincent Mailhol wrote:
> 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
> ---
>
> Changes in v3: None
>
> Changes in v2: None
> ---
> 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 791c452d98e1..77c3ea49b8fb 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)
make it return an unsigned int
make the bt pointer const
> +{
> + 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.
>
tnx,
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917- |
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Description: OpenPGP digital signature
Re: [PATCH v3 5/7] can: dev: add a helper function to calculate the duration of one bit
On 10/4/20 1:06 PM, Marc Kleine-Budde wrote:
> On 10/2/20 5:41 PM, Vincent Mailhol wrote:
>> 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
[...]
>> index 791c452d98e1..77c3ea49b8fb 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)
>
> make it return an unsigned int
> make the bt pointer const
I'll change this while applying the patch.
Marc
--
Pengutronix e.K. | Marc Kleine-Budde |
Embedded Linux | https://www.pengutronix.de |
Vertretung West/Dortmund | Phone: +49-231-2826-924 |
Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917- |
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