drivers: udc_dwc2: fix interpretation of NUMDEVEPS and INEPS fields

The NUMDEVEPS field provides the number of endpoints in addition to the
control endpoint. It is used to iterate over GHWCFG1 register value to
get correct number of configured IN/OUT endpoints. To get it correctly,
we need to use it internally as number including control endpoint.

Interpretation of INEPS misses +1 because value 0 means 1 IN endpoint
and so on.

Signed-off-by: Johann Fischer <johann.fischer@nordicsemi.no>

Author: jfischer-no

drivers/usb/udc/udc_dwc2.c

@@ -69,7 +69,7 @@ struct udc_dwc2_data {
 	uint32_t max_pktcnt;
 	uint32_t tx_len[16];
 	unsigned int dynfifosizing : 1;
-	/* Number of endpoints in addition to control endpoint */
+	/* Number of endpoints including control endpoint */
 	uint8_t numdeveps;
 	/* Number of IN endpoints including control endpoint */
 	uint8_t ineps;
@@ -948,7 +948,7 @@ static void dwc2_unset_unused_fifo(const struct device *dev)
 	struct udc_dwc2_data *const priv = udc_get_private(dev);
 	struct udc_ep_config *tmp;
 
-	for (uint8_t i = priv->ineps; i > 0; i--) {
+	for (uint8_t i = priv->ineps - 1U; i > 0; i--) {
 		tmp = udc_get_ep_cfg(dev, i | USB_EP_DIR_IN);
 
 		if (tmp->stat.enabled && (priv->txf_set & BIT(i))) {
@@ -1396,10 +1396,10 @@ static int udc_dwc2_init_controller(const struct device *dev)
 	}
 
 	/* Get the number or endpoints and IN endpoints we can use later */
-	priv->numdeveps = usb_dwc2_get_ghwcfg2_numdeveps(ghwcfg2);
-	priv->ineps = usb_dwc2_get_ghwcfg4_ineps(ghwcfg4);
-	LOG_DBG("Number of endpoints (NUMDEVEPS) %u", priv->numdeveps);
-	LOG_DBG("Number of IN endpoints (INEPS) %u", priv->ineps);
+	priv->numdeveps = usb_dwc2_get_ghwcfg2_numdeveps(ghwcfg2) + 1U;
+	priv->ineps = usb_dwc2_get_ghwcfg4_ineps(ghwcfg4) + 1U;
+	LOG_DBG("Number of endpoints (NUMDEVEPS + 1) %u", priv->numdeveps);
+	LOG_DBG("Number of IN endpoints (INEPS + 1) %u", priv->ineps);
 
 	LOG_DBG("Number of periodic IN endpoints (NUMDEVPERIOEPS) %u",
 		usb_dwc2_get_ghwcfg4_numdevperioeps(ghwcfg4));