The candleLight community is working on switchable termination support for the candleLight firmware. As the the Linux CAN framework supports switchable termination add this feature to the gs_usb driver. Devices supporting the feature should set the GS_CAN_FEATURE_TERMINATION and implement the GS_USB_BREQ_SET_TERMINATION and GS_USB_BREQ_GET_TERMINATION control messages. For now the driver assumes for activated termination the standard termination value of 120Ω. Link: https://github.com/candle-usb/candleLight_fw/issues/92 Link: https://github.com/candle-usb/candleLight_fw/pull/108 Cc: Daniel Trevitz <daniel.trevitz@xxxxxxxx> Cc: Ryan Edwards <ryan.edwards@xxxxxxxxx> Signed-off-by: Marc Kleine-Budde <mkl@xxxxxxxxxxxxxx> --- changes since v1 https://lore.kernel.org/all/20220918211802.692405-4-mkl@xxxxxxxxxxxxxx: - renamed struct gs_termination_state -> struct gs_device_termination_state - gs_make_candev(): don't fail with error, if initial gs_usb_get_termination() fails, only disable termination support. (Suggested by Daniel Trevitz) drivers/net/can/usb/gs_usb.c | 79 +++++++++++++++++++++++++++++++++++- 1 file changed, 78 insertions(+), 1 deletion(-) diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c index 9400993ae717..f0065d40eb24 100644 --- a/drivers/net/can/usb/gs_usb.c +++ b/drivers/net/can/usb/gs_usb.c @@ -64,6 +64,8 @@ enum gs_usb_breq { GS_USB_BREQ_SET_USER_ID, GS_USB_BREQ_DATA_BITTIMING, GS_USB_BREQ_BT_CONST_EXT, + GS_USB_BREQ_SET_TERMINATION, + GS_USB_BREQ_GET_TERMINATION, }; enum gs_can_mode { @@ -87,6 +89,14 @@ enum gs_can_identify_mode { GS_CAN_IDENTIFY_ON }; +enum gs_can_termination_state { + GS_CAN_TERMINATION_STATE_OFF = 0, + GS_CAN_TERMINATION_STATE_ON +}; + +#define GS_USB_TERMINATION_DISABLED CAN_TERMINATION_DISABLED +#define GS_USB_TERMINATION_ENABLED 120 + /* data types passed between host and device */ /* The firmware on the original USB2CAN by Geschwister Schneider @@ -123,6 +133,7 @@ struct gs_device_config { #define GS_CAN_MODE_FD BIT(8) /* GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX BIT(9) */ /* GS_CAN_FEATURE_BT_CONST_EXT BIT(10) */ +/* GS_CAN_FEATURE_TERMINATION BIT(11) */ struct gs_device_mode { __le32 mode; @@ -147,6 +158,10 @@ struct gs_identify_mode { __le32 mode; } __packed; +struct gs_device_termination_state { + __le32 state; +} __packed; + #define GS_CAN_FEATURE_LISTEN_ONLY BIT(0) #define GS_CAN_FEATURE_LOOP_BACK BIT(1) #define GS_CAN_FEATURE_TRIPLE_SAMPLE BIT(2) @@ -158,7 +173,8 @@ struct gs_identify_mode { #define GS_CAN_FEATURE_FD BIT(8) #define GS_CAN_FEATURE_REQ_USB_QUIRK_LPC546XX BIT(9) #define GS_CAN_FEATURE_BT_CONST_EXT BIT(10) -#define GS_CAN_FEATURE_MASK GENMASK(10, 0) +#define GS_CAN_FEATURE_TERMINATION BIT(11) +#define GS_CAN_FEATURE_MASK GENMASK(11, 0) /* internal quirks - keep in GS_CAN_FEATURE space for now */ @@ -1053,6 +1069,52 @@ static const struct ethtool_ops gs_usb_ethtool_ops = { .get_ts_info = gs_usb_get_ts_info, }; +static int gs_usb_get_termination(struct net_device *netdev, u16 *term) +{ + struct gs_can *dev = netdev_priv(netdev); + struct gs_device_termination_state term_state; + int rc; + + rc = usb_control_msg_recv(interface_to_usbdev(dev->iface), 0, + GS_USB_BREQ_GET_TERMINATION, + USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_INTERFACE, + dev->channel, 0, + &term_state, sizeof(term_state), 1000, + GFP_KERNEL); + if (rc) + return rc; + + if (term_state.state == cpu_to_le32(GS_CAN_TERMINATION_STATE_ON)) + *term = GS_USB_TERMINATION_ENABLED; + else + *term = GS_USB_TERMINATION_DISABLED; + + return 0; +} + +static int gs_usb_set_termination(struct net_device *netdev, u16 term) +{ + struct gs_can *dev = netdev_priv(netdev); + struct gs_device_termination_state term_state; + + if (term == GS_USB_TERMINATION_ENABLED) + term_state.state = cpu_to_le32(GS_CAN_TERMINATION_STATE_ON); + else + term_state.state = cpu_to_le32(GS_CAN_TERMINATION_STATE_OFF); + + return usb_control_msg_send(interface_to_usbdev(dev->iface), 0, + GS_USB_BREQ_SET_TERMINATION, + USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_INTERFACE, + dev->channel, 0, + &term_state, sizeof(term_state), 1000, + GFP_KERNEL); +} + +static const u16 gs_usb_termination_const[] = { + GS_USB_TERMINATION_DISABLED, + GS_USB_TERMINATION_ENABLED +}; + static struct gs_can *gs_make_candev(unsigned int channel, struct usb_interface *intf, struct gs_device_config *dconf) @@ -1147,6 +1209,21 @@ static struct gs_can *gs_make_candev(unsigned int channel, dev->can.do_set_data_bittiming = gs_usb_set_data_bittiming; } + if (feature & GS_CAN_FEATURE_TERMINATION) { + rc = gs_usb_get_termination(netdev, &dev->can.termination); + if (rc) { + dev->feature &= ~GS_CAN_FEATURE_TERMINATION; + + dev_info(&intf->dev, + "Disabling termination support for channel %d (%pe)\n", + channel, ERR_PTR(rc)); + } else { + dev->can.termination_const = gs_usb_termination_const; + dev->can.termination_const_cnt = ARRAY_SIZE(gs_usb_termination_const); + dev->can.do_set_termination = gs_usb_set_termination; + } + } + /* The CANtact Pro from LinkLayer Labs is based on the * LPC54616 µC, which is affected by the NXP LPC USB transfer * erratum. However, the current firmware (version 2) doesn't -- 2.35.1
