usb: dwc3: gadget: dynamically re-size TxFifos

We need to dynamically re-size TxFifos for the
cases where default values will not do.

While at that, we create a simple function which,
for now, will just allocate one full packet fifo
space for each of the enabled endpoints.

This can be improved later in order to allow for
better throughput by allocating more space for
endpoints which could make good use of that like
isochronous and bulk.
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/core.c

@@ -48,6 +48,7 @@
 #include <linux/list.h>
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
+#include <linux/of.h>
 
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
@@ -404,6 +405,7 @@ static void dwc3_core_exit(struct dwc3 *dwc)
 
 static int __devinit dwc3_probe(struct platform_device *pdev)
 {
+	struct device_node	*node = pdev->dev.of_node;
 	struct resource		*res;
 	struct dwc3		*dwc;
 
@@ -469,6 +471,9 @@ static int __devinit dwc3_probe(struct platform_device *pdev)
 	else
 		dwc->maximum_speed = DWC3_DCFG_SUPERSPEED;
 
+	if (of_get_property(node, "tx-fifo-resize", NULL))
+		dwc->needs_fifo_resize = true;
+
 	pm_runtime_enable(&pdev->dev);
 	pm_runtime_get_sync(&pdev->dev);
 	pm_runtime_forbid(&pdev->dev);

drivers/usb/dwc3/core.h

@@ -172,6 +172,10 @@
 #define DWC3_GUSB3PIPECTL_PHYSOFTRST (1 << 31)
 #define DWC3_GUSB3PIPECTL_SUSPHY (1 << 17)
 
+/* Global TX Fifo Size Register */
+#define DWC3_GTXFIFOSIZ_TXFDEF(n) ((n) & 0xffff)
+#define DWC3_GTXFIFOSIZ_TXFSTADDR(n) ((n) & 0xffff0000)
+
 /* Global HWPARAMS1 Register */
 #define DWC3_GHWPARAMS1_EN_PWROPT(n)	((n & (3 << 24)) >> 24)
 #define DWC3_GHWPARAMS1_EN_PWROPT_NO	0
@@ -546,8 +550,13 @@ struct dwc3_hwparams {
 #define DWC3_MODE_DRD		2
 #define DWC3_MODE_HUB		3
 
+#define DWC3_MDWIDTH(n)		(((n) & 0xff00) >> 8)
+
 /* HWPARAMS1 */
-#define DWC3_NUM_INT(n)	(((n) & (0x3f << 15)) >> 15)
+#define DWC3_NUM_INT(n)		(((n) & (0x3f << 15)) >> 15)
+
+/* HWPARAMS7 */
+#define DWC3_RAM1_DEPTH(n)	((n) & 0xffff)
 
 struct dwc3_request {
 	struct usb_request	request;
@@ -594,6 +603,8 @@ struct dwc3_request {
  * @ep0_expect_in: true when we expect a DATA IN transfer
  * @start_config_issued: true when StartConfig command has been issued
  * @setup_packet_pending: true when there's a Setup Packet in FIFO. Workaround
+ * @needs_fifo_resize: not all users might want fifo resizing, flag it
+ * @resize_fifos: tells us it's ok to reconfigure our TxFIFO sizes.
  * @ep0_next_event: hold the next expected event
  * @ep0state: state of endpoint zero
  * @link_state: link state
@@ -651,6 +662,8 @@ struct dwc3 {
 	unsigned		start_config_issued:1;
 	unsigned		setup_packet_pending:1;
 	unsigned		delayed_status:1;
+	unsigned		needs_fifo_resize:1;
+	unsigned		resize_fifos:1;
 
 	enum dwc3_ep0_next	ep0_next_event;
 	enum dwc3_ep0_state	ep0state;
@@ -812,6 +825,7 @@ union dwc3_event {
 
 /* prototypes */
 void dwc3_set_mode(struct dwc3 *dwc, u32 mode);
+int dwc3_gadget_resize_tx_fifos(struct dwc3 *dwc);
 
 int dwc3_host_init(struct dwc3 *dwc);
 void dwc3_host_exit(struct dwc3 *dwc);

drivers/usb/dwc3/ep0.c

@@ -457,8 +457,11 @@ static int dwc3_ep0_set_config(struct dwc3 *dwc, struct usb_ctrlrequest *ctrl)
 	case DWC3_ADDRESS_STATE:
 		ret = dwc3_ep0_delegate_req(dwc, ctrl);
 		/* if the cfg matches and the cfg is non zero */
-		if (cfg && (!ret || (ret == USB_GADGET_DELAYED_STATUS)))
+		if (cfg && (!ret || (ret == USB_GADGET_DELAYED_STATUS))) {
 			dwc->dev_state = DWC3_CONFIGURED_STATE;
+			dwc->resize_fifos = true;
+			dev_dbg(dwc->dev, "resize fifos flag SET\n");
+		}
 		break;
 
 	case DWC3_CONFIGURED_STATE:
@@ -707,6 +710,12 @@ static void dwc3_ep0_do_control_status(struct dwc3 *dwc, u32 epnum)
 {
 	struct dwc3_ep		*dep = dwc->eps[epnum];
 
+	if (dwc->resize_fifos) {
+		dev_dbg(dwc->dev, "starting to resize fifos\n");
+		dwc3_gadget_resize_tx_fifos(dwc);
+		dwc->resize_fifos = 0;
+	}
+
 	WARN_ON(dwc3_ep0_start_control_status(dep));
 }
 

drivers/usb/dwc3/gadget.c

@@ -125,6 +125,80 @@ int dwc3_gadget_set_link_state(struct dwc3 *dwc, enum dwc3_link_state state)
 	return -ETIMEDOUT;
 }
 
+/**
+ * dwc3_gadget_resize_tx_fifos - reallocate fifo spaces for current use-case
+ * @dwc: pointer to our context structure
+ *
+ * This function will a best effort FIFO allocation in order
+ * to improve FIFO usage and throughput, while still allowing
+ * us to enable as many endpoints as possible.
+ *
+ * Keep in mind that this operation will be highly dependent
+ * on the configured size for RAM1 - which contains TxFifo -,
+ * the amount of endpoints enabled on coreConsultant tool, and
+ * the width of the Master Bus.
+ *
+ * In the ideal world, we would always be able to satisfy the
+ * following equation:
+ *
+ * ((512 + 2 * MDWIDTH-Bytes) + (Number of IN Endpoints - 1) * \
+ * (3 * (1024 + MDWIDTH-Bytes) + MDWIDTH-Bytes)) / MDWIDTH-Bytes
+ *
+ * Unfortunately, due to many variables that's not always the case.
+ */
+int dwc3_gadget_resize_tx_fifos(struct dwc3 *dwc)
+{
+	int		last_fifo_depth = 0;
+	int		ram1_depth;
+	int		fifo_size;
+	int		mdwidth;
+	int		num;
+
+	if (!dwc->needs_fifo_resize)
+		return 0;
+
+	ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+	mdwidth = DWC3_MDWIDTH(dwc->hwparams.hwparams0);
+
+	/* MDWIDTH is represented in bits, we need it in bytes */
+	mdwidth >>= 3;
+
+	/*
+	 * FIXME For now we will only allocate 1 wMaxPacketSize space
+	 * for each enabled endpoint, later patches will come to
+	 * improve this algorithm so that we better use the internal
+	 * FIFO space
+	 */
+	for (num = 0; num < DWC3_ENDPOINTS_NUM; num++) {
+		struct dwc3_ep	*dep = dwc->eps[num];
+		int		fifo_number = dep->number >> 1;
+		int		tmp;
+
+		if (!(dep->number & 1))
+			continue;
+
+		if (!(dep->flags & DWC3_EP_ENABLED))
+			continue;
+
+		tmp = dep->endpoint.maxpacket;
+		tmp += mdwidth;
+		tmp += mdwidth;
+
+		fifo_size = DIV_ROUND_UP(tmp, mdwidth);
+		fifo_size |= (last_fifo_depth << 16);
+
+		dev_vdbg(dwc->dev, "%s: Fifo Addr %04x Size %d\n",
+				dep->name, last_fifo_depth, fifo_size & 0xffff);
+
+		dwc3_writel(dwc->regs, DWC3_GTXFIFOSIZ(fifo_number),
+				fifo_size);
+
+		last_fifo_depth += (fifo_size & 0xffff);
+	}
+
+	return 0;
+}
+
 void dwc3_map_buffer_to_dma(struct dwc3_request *req)
 {
 	struct dwc3			*dwc = req->dep->dwc;