usb: dwc2: gadget: Add new core parameter for low speed

Added new core param for low speed, which can be used only when SNPSID
is equal to DWC2_CORE_FS_IOT. When LS mode is enabled, we are
restricting ep types and providing to upper layer only INTR and CTRL
endpoints.
Signed-off-by: Vardan Mikayelyan <mvardan@synopsys.com>
Signed-off-by: John Youn <johnyoun@synopsys.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc2/core.h

@@ -467,6 +467,7 @@ struct dwc2_core_params {
 	int speed;
 #define DWC2_SPEED_PARAM_HIGH	0
 #define DWC2_SPEED_PARAM_FULL	1
+#define DWC2_SPEED_PARAM_LOW	2
 
 	int enable_dynamic_fifo;
 	int en_multiple_tx_fifo;

drivers/usb/dwc2/gadget.c

@@ -3175,7 +3175,8 @@ void dwc2_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,
 		GUSBCFG_HNPCAP);
 
 	if (hsotg->params.phy_type == DWC2_PHY_TYPE_PARAM_FS &&
-	    hsotg->params.speed == DWC2_SPEED_PARAM_FULL) {
+	    (hsotg->params.speed == DWC2_SPEED_PARAM_FULL ||
+	     hsotg->params.speed == DWC2_SPEED_PARAM_LOW)) {
 		/* FS/LS Dedicated Transceiver Interface */
 		usbcfg |= GUSBCFG_PHYSEL;
 	} else {
@@ -3192,14 +3193,21 @@ void dwc2_hsotg_core_init_disconnected(struct dwc2_hsotg *hsotg,
 		__orr32(hsotg->regs + DCTL, DCTL_SFTDISCON);
 
 	dcfg |= DCFG_EPMISCNT(1);
-	if (hsotg->params.speed == DWC2_SPEED_PARAM_FULL) {
+
+	switch (hsotg->params.speed) {
+	case DWC2_SPEED_PARAM_LOW:
+		dcfg |= DCFG_DEVSPD_LS;
+		break;
+	case DWC2_SPEED_PARAM_FULL:
 		if (hsotg->params.phy_type == DWC2_PHY_TYPE_PARAM_FS)
 			dcfg |= DCFG_DEVSPD_FS48;
 		else
 			dcfg |= DCFG_DEVSPD_FS;
-	} else {
+		break;
+	default:
 		dcfg |= DCFG_DEVSPD_HS;
 	}
+
 	dwc2_writel(dcfg,  hsotg->regs + DCFG);
 
 	/* Clear any pending OTG interrupts */
@@ -4388,14 +4396,21 @@ static void dwc2_hsotg_initep(struct dwc2_hsotg *hsotg,
 
 	hs_ep->parent = hsotg;
 	hs_ep->ep.name = hs_ep->name;
-	usb_ep_set_maxpacket_limit(&hs_ep->ep, epnum ? 1024 : EP0_MPS_LIMIT);
+
+	if (hsotg->params.speed == DWC2_SPEED_PARAM_LOW)
+		usb_ep_set_maxpacket_limit(&hs_ep->ep, 8);
+	else
+		usb_ep_set_maxpacket_limit(&hs_ep->ep,
+					   epnum ? 1024 : EP0_MPS_LIMIT);
 	hs_ep->ep.ops = &dwc2_hsotg_ep_ops;
 
 	if (epnum == 0) {
 		hs_ep->ep.caps.type_control = true;
 	} else {
+		if (hsotg->params.speed != DWC2_SPEED_PARAM_LOW) {
 			hs_ep->ep.caps.type_iso = true;
 			hs_ep->ep.caps.type_bulk = true;
+		}
 		hs_ep->ep.caps.type_int = true;
 	}
 

drivers/usb/dwc2/hcd.c

@@ -230,9 +230,10 @@ static int dwc2_phy_init(struct dwc2_hsotg *hsotg, bool select_phy)
 	u32 usbcfg;
 	int retval = 0;
 
-	if (hsotg->params.speed == DWC2_SPEED_PARAM_FULL &&
+	if ((hsotg->params.speed == DWC2_SPEED_PARAM_FULL ||
+	     hsotg->params.speed == DWC2_SPEED_PARAM_LOW) &&
 	    hsotg->params.phy_type == DWC2_PHY_TYPE_PARAM_FS) {
-		/* If FS mode with FS PHY */
+		/* If FS/LS mode with FS/LS PHY */
 		retval = dwc2_fs_phy_init(hsotg, select_phy);
 		if (retval)
 			return retval;
@@ -2277,7 +2278,8 @@ static void dwc2_core_host_init(struct dwc2_hsotg *hsotg)
 
 	/* Initialize Host Configuration Register */
 	dwc2_init_fs_ls_pclk_sel(hsotg);
-	if (hsotg->params.speed == DWC2_SPEED_PARAM_FULL) {
+	if (hsotg->params.speed == DWC2_SPEED_PARAM_FULL ||
+	    hsotg->params.speed == DWC2_SPEED_PARAM_LOW) {
 		hcfg = dwc2_readl(hsotg->regs + HCFG);
 		hcfg |= HCFG_FSLSSUPP;
 		dwc2_writel(hcfg, hsotg->regs + HCFG);

drivers/usb/dwc2/params.c

@@ -742,14 +742,18 @@ static void dwc2_set_param_speed(struct dwc2_hsotg *hsotg, int val)
 {
 	int valid = 1;
 
-	if (DWC2_OUT_OF_BOUNDS(val, 0, 1)) {
+	if (DWC2_OUT_OF_BOUNDS(val, 0, 2)) {
 		if (val >= 0) {
 			dev_err(hsotg->dev, "Wrong value for speed parameter\n");
-			dev_err(hsotg->dev, "max_speed parameter must be 0 or 1\n");
+			dev_err(hsotg->dev, "max_speed parameter must be 0, 1, or 2\n");
 		}
 		valid = 0;
 	}
 
+	if (dwc2_is_hs_iot(hsotg) &&
+	    val == DWC2_SPEED_PARAM_LOW)
+		valid = 0;
+
 	if (val == DWC2_SPEED_PARAM_HIGH &&
 	    dwc2_get_param_phy_type(hsotg) == DWC2_PHY_TYPE_PARAM_FS)
 		valid = 0;