Add terminating resistor support

The mcba_usb kernel driver in linux has support for configurable terminating
resistors. This patch adds similar support to this firmware which the
gs_usb USB driver would then activate via the netlink interface.

Signed-off-by: Daniel Trevitz <daniel.trevitz@wika.com>

include/config.h

@@ -206,6 +206,11 @@ THE SOFTWARE.
 	#define USB_Pin_DM		 GPIO_PIN_11
 	#define USB_Pin_DP		 GPIO_PIN_12
 
+	#define PIN_TERM_GPIO_Port		GPIOB
+	#define PIN_TERM_Pin			GPIO_PIN_3
+	#define PIN_TERM_Mode			GPIO_MODE_OUTPUT_PP
+	#define PIN_TERM_Active_High	1
+
 #else
 	#error please define BOARD
 #endif

include/gpio.h

@@ -27,3 +27,14 @@ THE SOFTWARE.
 #pragma once
 
 void gpio_init(void);
+
+
+enum terminator_status {
+	term_unsupported = -1,
+	term_inactive,
+	term_active
+};
+
+enum terminator_status set_term(unsigned int channel, enum terminator_status state);
+
+enum terminator_status get_term(unsigned int channel);

include/gs_usb.h

@@ -64,6 +64,7 @@ THE SOFTWARE.
  * GS_USB_BREQ_BT_CONST_EXT and struct gs_device_bt_const_extended
  */
 #define GS_CAN_FEATURE_BT_CONST_EXT             (1<<10)
+#define GS_CAN_FEATURE_TERMINATION              (1<<11)
 
 #define GS_CAN_FLAG_OVERFLOW                    (1<<0)
 #define GS_CAN_FLAG_FD                          (1<<1) /* is a CAN-FD frame */
@@ -163,6 +164,8 @@ 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 {

src/gpio.c

@@ -25,6 +25,7 @@ THE SOFTWARE.
 */
 
 #include "config.h"
+#include "gpio.h"
 #include "hal_include.h"
 
 // must run before can_init
@@ -70,6 +71,19 @@ void gpio_init(void)
 	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
 	HAL_GPIO_Init(LEDTX_GPIO_Port, &GPIO_InitStruct);
 
+#ifdef PIN_TERM_Pin
+#if (PIN_TERM_Active_High == 1)
+	HAL_GPIO_WritePin(PIN_TERM_GPIO_Port, PIN_TERM_Pin, GPIO_PIN_RESET);
+#else
+	HAL_GPIO_WritePin(PIN_TERM_GPIO_Port, PIN_TERM_Pin, GPIO_PIN_SET);
+#endif
+	GPIO_InitStruct.Pin = PIN_TERM_Pin;
+	GPIO_InitStruct.Mode = PIN_TERM_Mode;
+	GPIO_InitStruct.Pull = GPIO_NOPULL;
+	GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
+	HAL_GPIO_Init(PIN_TERM_GPIO_Port, &GPIO_InitStruct);
+#endif
+
 #if defined(BOARD_cannette)
 	HAL_GPIO_WritePin(nCANSTBY_Port, nCANSTBY_Pin, GPIO_PIN_RESET);
 	GPIO_InitStruct.Pin = nCANSTBY_Pin;
@@ -104,3 +118,50 @@ void gpio_init(void)
 	HAL_GPIO_Init(USB_GPIO_Port, &GPIO_InitStruct);
 #endif
 }
+
+#ifdef PIN_TERM_Pin
+static int term_state = 0;
+
+enum terminator_status set_term(unsigned int channel, enum terminator_status state)
+{
+	// TODO add support for multiple channels
+	if (state == term_active) {
+		term_state |= 1 << channel;
+	} else {
+		term_state &= ~(1 << channel);
+	}
+
+#if (PIN_TERM_Active_High == 1)
+	#define TERM_ON  GPIO_PIN_SET
+	#define TERM_OFF GPIO_PIN_RESET
+#else
+	#define TERM_ON  GPIO_PIN_RESET
+	#define TERM_OFF GPIO_PIN_SET
+#endif
+
+	HAL_GPIO_WritePin(PIN_TERM_GPIO_Port, PIN_TERM_Pin, state ? TERM_ON : TERM_OFF);
+
+	return state;
+}
+
+enum terminator_status get_term(unsigned int channel)
+{
+	return !!(term_state & (1 << channel));
+}
+
+#else
+
+enum terminator_status set_term(unsigned int channel, enum terminator_status state)
+{
+	(void)state;
+	(void)channel;
+	return term_unsupported;
+}
+
+enum terminator_status get_term(unsigned int channel)
+{
+	(void)channel;
+	return term_unsupported;
+}
+
+#endif

src/usbd_gs_can.c

@@ -34,6 +34,7 @@ THE SOFTWARE.
 #include "usbd_ioreq.h"
 #include "gs_usb.h"
 #include "can.h"
+#include "gpio.h"
 #include "timer.h"
 #include "flash.h"
 
@@ -272,7 +273,11 @@ static const struct gs_device_bt_const USBD_GS_CAN_btconst = {
 	| GS_CAN_FEATURE_HW_TIMESTAMP
 	| GS_CAN_FEATURE_IDENTIFY
 	| GS_CAN_FEATURE_USER_ID
-	| GS_CAN_FEATURE_PAD_PKTS_TO_MAX_PKT_SIZE,
+	| GS_CAN_FEATURE_PAD_PKTS_TO_MAX_PKT_SIZE
+#ifdef PIN_TERM_Pin
+	| GS_CAN_FEATURE_TERMINATION
+#endif
+	,
 	CAN_CLOCK_SPEED, // can timing base clock
 	1, // tseg1 min
 	16, // tseg1 max
@@ -383,6 +388,12 @@ static uint8_t USBD_GS_CAN_EP0_RxReady(USBD_HandleTypeDef *pdev) {
 			}
 			break;
 
+		case GS_USB_BREQ_SET_TERMINATION:
+			memcpy(&param_u32, hcan->ep0_buf, sizeof(param_u32));
+			if (set_term(req->wValue, param_u32) == term_unsupported)
+				USBD_CtlError(pdev, req);
+			break;
+
 		case GS_USB_BREQ_SET_USER_ID:
 			memcpy(&param_u32, hcan->ep0_buf, sizeof(param_u32));
 			if (flash_set_user_id(req->wValue, param_u32)) {
@@ -468,6 +479,7 @@ static uint8_t USBD_GS_CAN_DFU_Request(USBD_HandleTypeDef *pdev, USBD_SetupReqTy
 static uint8_t USBD_GS_CAN_Config_Request(USBD_HandleTypeDef *pdev, USBD_SetupReqTypedef *req)
 {
 	USBD_GS_CAN_HandleTypeDef *hcan = (USBD_GS_CAN_HandleTypeDef*) pdev->pClassData;
+	enum terminator_status term_state;
 	uint32_t d32;
 
 	switch (req->bRequest) {
@@ -477,10 +489,24 @@ static uint8_t USBD_GS_CAN_Config_Request(USBD_HandleTypeDef *pdev, USBD_SetupRe
 		case GS_USB_BREQ_BITTIMING:
 		case GS_USB_BREQ_IDENTIFY:
 		case GS_USB_BREQ_SET_USER_ID:
+		case GS_USB_BREQ_SET_TERMINATION:
 			hcan->last_setup_request = *req;
 			USBD_CtlPrepareRx(pdev, hcan->ep0_buf, req->wLength);
 			break;
 
+		case GS_USB_BREQ_GET_TERMINATION:
+			term_state = get_term(req->wValue);
+
+			if(term_state == term_unsupported) {
+				USBD_CtlError(pdev, req);
+			} else {
+				d32 = (uint32_t)term_state;
+				memcpy(hcan->ep0_buf, &d32, sizeof(d32));
+				USBD_CtlSendData(pdev, hcan->ep0_buf, req->wLength);
+			}
+
+			break;
+
 		case GS_USB_BREQ_DEVICE_CONFIG:
 			memcpy(hcan->ep0_buf, &USBD_GS_CAN_dconf, sizeof(USBD_GS_CAN_dconf));
 			USBD_CtlSendData(pdev, hcan->ep0_buf, req->wLength);
@@ -738,7 +764,7 @@ void USBD_GS_CAN_SuspendCallback(USBD_HandleTypeDef  *pdev)
 
 	if(hcan != NULL && hcan->leds != NULL)
 		led_set_mode(hcan->leds, led_mode_off);
-	
+
 	is_usb_suspend_cb = true;
 }