drivers: usb: udc: stm32: clean up handling of USB buffer table

The ST USB controller (compatible 'st,stm32-usb') is fitted with private
SRAM called the Private Memory Area or PMA. This is primarily used to hold
data transfered over USB, but it also contains the so-called 'buffer table'
(a.k.a. BTABLE) which holds the base address and size of buffers in the PMA
allocated to each endpoint. The BTABLE is placed by the driver at the start
of the PMA and occupies a fixed size ('USB_BTABLE_SIZE'), which was stored
in the driver configuration field 'pma_offset'. This mechanism is unused on
non-ST USB controllers from STM32 microcontrollers, but USB_BTABLE_SIZE is
still defined (to a dummy value) and stored in the 'pma_offset' field which
becomes unused.

Remove the 'USB_BTABLE_SIZE' definition and the 'pma_offset' field from the
driver configuration, and update the ST USB controller-specific verison of
'udc_stm32_mem_init' to derive the BTABLE size from the number of endpoints
that the controller has instead.

Signed-off-by: Mathieu Choplain <[email protected]>

Author: mathieuchopstm

drivers/usb/udc/udc_stm32.c

@@ -157,7 +157,6 @@ struct udc_stm32_data  {
 
 struct udc_stm32_config {
 	uint32_t num_endpoints;
-	uint32_t pma_offset;
 	uint32_t dram_size;
 	uint16_t ep_mps;
 	/* PHY selected for use by instance */
@@ -608,7 +607,12 @@ static inline void udc_stm32_mem_init(const struct device *dev)
 	struct udc_stm32_data *priv = udc_get_private(dev);
 	const struct udc_stm32_config *cfg = dev->config;
 
-	priv->occupied_mem = cfg->pma_offset;
+	/**
+	 * Endpoint configuration table is placed at the
+	 * beginning of Private Memory Area and consumes
+	 * 8 bytes for each endpoint.
+	 */
+	priv->occupied_mem = (8 * cfg->num_endpoints);
 }
 
 static int udc_stm32_ep_mem_config(const struct device *dev,
@@ -1074,7 +1078,6 @@ static const struct udc_api udc_stm32_api = {
 
 #if defined(USB) || defined(USB_DRD_FS)
 #define EP_MPS 64U
-#define USB_BTABLE_SIZE  (8 * USB_NUM_BIDIR_ENDPOINTS)
 #define USB_RAM_SIZE	DT_INST_PROP(0, ram_size)
 #else /* USB_OTG_FS */
 #if DT_HAS_COMPAT_STATUS_OKAY(st_stm32_otghs)
@@ -1083,7 +1086,6 @@ static const struct udc_api udc_stm32_api = {
 #define EP_MPS USB_OTG_FS_MAX_PACKET_SIZE
 #endif
 #define USB_RAM_SIZE	DT_INST_PROP(0, ram_size)
-#define USB_BTABLE_SIZE 0
 #endif /* USB */
 
 static struct udc_stm32_data udc0_priv;
@@ -1096,7 +1098,6 @@ static struct udc_data udc0_data = {
 static const struct udc_stm32_config udc0_cfg  = {
 	.num_endpoints = USB_NUM_BIDIR_ENDPOINTS,
 	.dram_size = USB_RAM_SIZE,
-	.pma_offset = USB_BTABLE_SIZE,
 	.ep_mps = EP_MPS,
 	.selected_phy = UDC_STM32_NODE_PHY_ITFACE(DT_DRV_INST(0)),
 	.selected_speed = UDC_STM32_NODE_SPEED(DT_DRV_INST(0)),