[PATCH v2] usb: dwc3: gadget: Add TxFIFO resizing supports for single port RAM

From: Selvarasu Ganesan
Date: Mon Nov 11 2024 - 09:22:23 EST


The existing implementation of the TxFIFO resizing logic only supports
scenarios where more than one port RAM is used. However, there is a need
to resize the TxFIFO in USB2.0-only mode where only a single port RAM is
available. This commit introduces the necessary changes to support
TxFIFO resizing in such scenarios.

Cc: stable@xxxxxxxxxxxxxxx # 6.12.x: fad16c82: usb: dwc3: gadget: Refine the logic for resizing Tx FIFOs
Signed-off-by: Selvarasu Ganesan <selvarasu.g@xxxxxxxxxxx>
---

Changes in v2:
 - Removed the code change that limits the number of FIFOs for bulk EP,
as plan to address this issue in a separate patch.
- Renamed the variable spram_type to is_single_port_ram for better
understanding.
- Link to v1: https://lore.kernel.org/lkml/20241107104040.502-1-selvarasu.g@xxxxxxxxxxx/
---
drivers/usb/dwc3/core.h | 4 +++
drivers/usb/dwc3/gadget.c | 54 +++++++++++++++++++++++++++++++++------
2 files changed, 50 insertions(+), 8 deletions(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index eaa55c0cf62f..8306b39e5c64 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -915,6 +915,7 @@ struct dwc3_hwparams {
#define DWC3_MODE(n) ((n) & 0x7)

/* HWPARAMS1 */
+#define DWC3_SPRAM_TYPE(n) (((n) >> 23) & 1)
#define DWC3_NUM_INT(n) (((n) & (0x3f << 15)) >> 15)

/* HWPARAMS3 */
@@ -925,6 +926,9 @@ struct dwc3_hwparams {
#define DWC3_NUM_IN_EPS(p) (((p)->hwparams3 & \
(DWC3_NUM_IN_EPS_MASK)) >> 18)

+/* HWPARAMS6 */
+#define DWC3_RAM0_DEPTH(n) (((n) & (0xffff0000)) >> 16)
+
/* HWPARAMS7 */
#define DWC3_RAM1_DEPTH(n) ((n) & 0xffff)

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 2fed2aa01407..4f2e063c9091 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -687,6 +687,44 @@ static int dwc3_gadget_calc_tx_fifo_size(struct dwc3 *dwc, int mult)
return fifo_size;
}

+/**
+ * dwc3_gadget_calc_ram_depth - calculates the ram depth for txfifo
+ * @dwc: pointer to the DWC3 context
+ */
+static int dwc3_gadget_calc_ram_depth(struct dwc3 *dwc)
+{
+ int ram_depth;
+ int fifo_0_start;
+ bool is_single_port_ram;
+ int tmp;
+
+ /* Check supporting RAM type by HW */
+ is_single_port_ram = DWC3_SPRAM_TYPE(dwc->hwparams.hwparams1);
+
+ /*
+ * If a single port RAM is utilized, then allocate TxFIFOs from
+ * RAM0. otherwise, allocate them from RAM1.
+ */
+ ram_depth = is_single_port_ram ? DWC3_RAM0_DEPTH(dwc->hwparams.hwparams6) :
+ DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+
+
+ /*
+ * In a single port RAM configuration, the available RAM is shared
+ * between the RX and TX FIFOs. This means that the txfifo can begin
+ * at a non-zero address.
+ */
+ if (is_single_port_ram) {
+ /* Check if TXFIFOs start at non-zero addr */
+ tmp = dwc3_readl(dwc->regs, DWC3_GTXFIFOSIZ(0));
+ fifo_0_start = DWC3_GTXFIFOSIZ_TXFSTADDR(tmp);
+
+ ram_depth -= (fifo_0_start >> 16);
+ }
+
+ return ram_depth;
+}
+
/**
* dwc3_gadget_clear_tx_fifos - Clears txfifo allocation
* @dwc: pointer to the DWC3 context
@@ -753,7 +791,7 @@ static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
{
struct dwc3 *dwc = dep->dwc;
int fifo_0_start;
- int ram1_depth;
+ int ram_depth;
int fifo_size;
int min_depth;
int num_in_ep;
@@ -773,7 +811,7 @@ static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
if (dep->flags & DWC3_EP_TXFIFO_RESIZED)
return 0;

- ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
+ ram_depth = dwc3_gadget_calc_ram_depth(dwc);

switch (dwc->gadget->speed) {
case USB_SPEED_SUPER_PLUS:
@@ -809,7 +847,7 @@ static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)

/* Reserve at least one FIFO for the number of IN EPs */
min_depth = num_in_ep * (fifo + 1);
- remaining = ram1_depth - min_depth - dwc->last_fifo_depth;
+ remaining = ram_depth - min_depth - dwc->last_fifo_depth;
remaining = max_t(int, 0, remaining);
/*
* We've already reserved 1 FIFO per EP, so check what we can fit in
@@ -835,9 +873,9 @@ static int dwc3_gadget_resize_tx_fifos(struct dwc3_ep *dep)
dwc->last_fifo_depth += DWC31_GTXFIFOSIZ_TXFDEP(fifo_size);

/* Check fifo size allocation doesn't exceed available RAM size. */
- if (dwc->last_fifo_depth >= ram1_depth) {
+ if (dwc->last_fifo_depth >= ram_depth) {
dev_err(dwc->dev, "Fifosize(%d) > RAM size(%d) %s depth:%d\n",
- dwc->last_fifo_depth, ram1_depth,
+ dwc->last_fifo_depth, ram_depth,
dep->endpoint.name, fifo_size);
if (DWC3_IP_IS(DWC3))
fifo_size = DWC3_GTXFIFOSIZ_TXFDEP(fifo_size);
@@ -3090,7 +3128,7 @@ static int dwc3_gadget_check_config(struct usb_gadget *g)
struct dwc3 *dwc = gadget_to_dwc(g);
struct usb_ep *ep;
int fifo_size = 0;
- int ram1_depth;
+ int ram_depth;
int ep_num = 0;

if (!dwc->do_fifo_resize)
@@ -3113,8 +3151,8 @@ static int dwc3_gadget_check_config(struct usb_gadget *g)
fifo_size += dwc->max_cfg_eps;

/* Check if we can fit a single fifo per endpoint */
- ram1_depth = DWC3_RAM1_DEPTH(dwc->hwparams.hwparams7);
- if (fifo_size > ram1_depth)
+ ram_depth = dwc3_gadget_calc_ram_depth(dwc);
+ if (fifo_size > ram_depth)
return -ENOMEM;

return 0;
--
2.17.1