From 289ea9e4ae595545e736a63ccaadba65f880e9a4 Mon Sep 17 00:00:00 2001 From: Vincent Mailhol Date: Wed, 24 Feb 2021 09:20:04 +0900 Subject: can: add new CAN FD bittiming parameters: Transmitter Delay Compensation (TDC) At high bit rates, the propagation delay from the TX pin to the RX pin of the transceiver causes measurement errors: the sample point on the RX pin might occur on the previous bit. This issue is addressed in ISO 11898-1 section 11.3.3 "Transmitter delay compensation" (TDC). This patch adds two new structures: can_tdc and can_tdc_const in order to implement this TDC. The structures are then added to can_priv. A controller supports TDC if an only if can_priv::tdc_const is not NULL. TDC is active if and only if: - fd flag is on - can_priv::tdc.tdco is not zero. It is the driver responsibility to check those two conditions are met. No new controller modes are introduced (i.e. no CAN_CTRL_MODE_TDC) in order not to be redundant with above logic. The names of the parameters are chosen to match existing CAN controllers specification. References: - Bosch C_CAN FD8: https://www.bosch-semiconductors.com/media/ip_modules/pdf_2/c_can_fd8/users_manual_c_can_fd8_r210_1.pdf - Microchip CAN FD Controller Module: http://ww1.microchip.com/downloads/en/DeviceDoc/MCP251XXFD-CAN-FD-Controller-Module-Family-Reference-Manual-20005678B.pdf - SAM E701/S70/V70/V71 Family: https://www.mouser.com/datasheet/2/268/60001527A-1284321.pdf Link: https://lore.kernel.org/r/20210224002008.4158-2-mailhol.vincent@wanadoo.fr Signed-off-by: Vincent Mailhol Signed-off-by: Marc Kleine-Budde --- include/linux/can/dev.h | 3 +++ 1 file changed, 3 insertions(+) (limited to 'include/linux/can/dev.h') diff --git a/include/linux/can/dev.h b/include/linux/can/dev.h index ac4d83a1ab81..4795da0eb949 100644 --- a/include/linux/can/dev.h +++ b/include/linux/can/dev.h @@ -42,6 +42,9 @@ struct can_priv { struct can_bittiming bittiming, data_bittiming; const struct can_bittiming_const *bittiming_const, *data_bittiming_const; + struct can_tdc tdc; + const struct can_tdc_const *tdc_const; + const u16 *termination_const; unsigned int termination_const_cnt; u16 termination; -- cgit v1.2.3