On 18.09.2022 22:23:48, Marc Kleine-Budde wrote: > 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 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> [...] > +static int gs_usb_get_termination(struct net_device *netdev, u16 *term) > +{ > + struct gs_can *dev = netdev_priv(netdev); > + struct gs_termination_state 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, > + &state, sizeof(state), 1000, > + GFP_KERNEL); > + > + return rc; > +} > + > +static int gs_usb_set_termination(struct net_device *netdev, u16 term) > +{ > + struct gs_can *dev = netdev_priv(netdev); > + struct gs_termination_state state; > + u16 actual_term; > + int rc; > + > + if (term == GS_USB_TERMINATION_ENABLED) > + state.state = cpu_to_le32(GS_CAN_TERMINATION_STATE_ON); > + else > + state.state = cpu_to_le32(GS_CAN_TERMINATION_STATE_OFF); > + > + rc = 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, > + &state, sizeof(state), 1000, > + GFP_KERNEL); > + > + if (rc) > + return rc; > + > + rc = gs_usb_get_termination(netdev, &actual_term); I'm not sure if we need this. The usb_control_msg_send() should only return if the request succeeds. I'll add a gs_usb_get_termination() call to the probe function, so that the driver knows the termination state. > + if (rc) > + return rc; > + > + if (term != actual_term) > + return -EIO; > + > + return rc; > +} > + regards, 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: +49-5121-206917-5555 |
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