can: gs_usb: use union and FLEX_ARRAY for data in struct gs_host_frame

Modify struct gs_host_frame to make use of a union and
DECLARE_FLEX_ARRAY to be able to store different data (lengths), which
will be added in later commits.

Store the gs_host_frame length in TX direction (host -> device) in
struct gs_can::hf_size_tx and RX direction (device -> host) in struct
gs_usb::hf_size_rx so it must be calculated only once.

Link: https://lore.kernel.org/all/20220309124132.291861-15-mkl@pengutronix.de
Signed-off-by: Peter Fink <pfink@christ-es.de>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

diff --git a/drivers/net/can/usb/gs_usb.c b/drivers/net/can/usb/gs_usb.c
index 4bc10264005b30c9373b77f0f8f1c54062b40274..1fe9d9f08c17d997b497647e1ac6672a993aa94f 100644 (file)
--- a/drivers/net/can/usb/gs_usb.c
+++ b/drivers/net/can/usb/gs_usb.c
@@ -146,6 +146,10 @@ struct gs_device_bt_const {
 
 #define GS_CAN_FLAG_OVERFLOW BIT(0)
 
+struct classic_can {
+       u8 data[8];
+} __packed;
+
 struct gs_host_frame {
        u32 echo_id;
        __le32 can_id;
@@ -155,7 +159,9 @@ struct gs_host_frame {
        u8 flags;
        u8 reserved;
 
-       u8 data[8];
+       union {
+               DECLARE_FLEX_ARRAY(struct classic_can, classic_can);
+       };
 } __packed;
 /* The GS USB devices make use of the same flags and masks as in
  * linux/can.h and linux/can/error.h, and no additional mapping is necessary.
@@ -187,6 +193,8 @@ struct gs_can {
        struct can_bittiming_const bt_const;
        unsigned int channel;   /* channel number */
 
+       unsigned int hf_size_tx;
+
        /* This lock prevents a race condition between xmit and receive. */
        spinlock_t tx_ctx_lock;
        struct gs_tx_context tx_context[GS_MAX_TX_URBS];
@@ -200,6 +208,7 @@ struct gs_usb {
        struct gs_can *canch[GS_MAX_INTF];
        struct usb_anchor rx_submitted;
        struct usb_device *udev;
+       unsigned int hf_size_rx;
        u8 active_channels;
 };
 
@@ -343,7 +352,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
                cf->can_id = le32_to_cpu(hf->can_id);
 
                can_frame_set_cc_len(cf, hf->can_dlc, dev->can.ctrlmode);
-               memcpy(cf->data, hf->data, 8);
+               memcpy(cf->data, hf->classic_can->data, 8);
 
                /* ERROR frames tell us information about the controller */
                if (le32_to_cpu(hf->can_id) & CAN_ERR_FLAG)
@@ -398,7 +407,7 @@ static void gs_usb_receive_bulk_callback(struct urb *urb)
  resubmit_urb:
        usb_fill_bulk_urb(urb, usbcan->udev,
                          usb_rcvbulkpipe(usbcan->udev, GSUSB_ENDPOINT_IN),
-                         hf, sizeof(struct gs_host_frame),
+                         hf, dev->parent->hf_size_rx,
                          gs_usb_receive_bulk_callback, usbcan);
 
        rc = usb_submit_urb(urb, GFP_ATOMIC);
@@ -485,7 +494,7 @@ static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
        if (!urb)
                goto nomem_urb;
 
-       hf = usb_alloc_coherent(dev->udev, sizeof(*hf), GFP_ATOMIC,
+       hf = usb_alloc_coherent(dev->udev, dev->hf_size_tx, GFP_ATOMIC,
                                &urb->transfer_dma);
        if (!hf) {
                netdev_err(netdev, "No memory left for USB buffer\n");
@@ -509,11 +518,11 @@ static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
        hf->can_id = cpu_to_le32(cf->can_id);
        hf->can_dlc = can_get_cc_dlc(cf, dev->can.ctrlmode);
 
-       memcpy(hf->data, cf->data, cf->len);
+       memcpy(hf->classic_can->data, cf->data, cf->len);
 
        usb_fill_bulk_urb(urb, dev->udev,
                          usb_sndbulkpipe(dev->udev, GSUSB_ENDPOINT_OUT),
-                         hf, sizeof(*hf),
+                         hf, dev->hf_size_tx,
                          gs_usb_xmit_callback, txc);
 
        urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
@@ -531,8 +540,8 @@ static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
                gs_free_tx_context(txc);
 
                usb_unanchor_urb(urb);
-               usb_free_coherent(dev->udev,
-                                 sizeof(*hf), hf, urb->transfer_dma);
+               usb_free_coherent(dev->udev, urb->transfer_buffer_length,
+                                 urb->transfer_buffer, urb->transfer_dma);
 
                if (rc == -ENODEV) {
                        netif_device_detach(netdev);
@@ -552,7 +561,8 @@ static netdev_tx_t gs_can_start_xmit(struct sk_buff *skb,
        return NETDEV_TX_OK;
 
  badidx:
-       usb_free_coherent(dev->udev, sizeof(*hf), hf, urb->transfer_dma);
+       usb_free_coherent(dev->udev, urb->transfer_buffer_length,
+                         urb->transfer_buffer, urb->transfer_dma);
  nomem_hf:
        usb_free_urb(urb);
 
@@ -569,6 +579,7 @@ static int gs_can_open(struct net_device *netdev)
        struct gs_usb *parent = dev->parent;
        int rc, i;
        struct gs_device_mode *dm;
+       struct gs_host_frame *hf;
        u32 ctrlmode;
        u32 flags = 0;
 
@@ -576,6 +587,8 @@ static int gs_can_open(struct net_device *netdev)
        if (rc)
                return rc;
 
+       dev->hf_size_tx = struct_size(hf, classic_can, 1);
+
        if (!parent->active_channels) {
                for (i = 0; i < GS_MAX_RX_URBS; i++) {
                        struct urb *urb;
@@ -588,7 +601,7 @@ static int gs_can_open(struct net_device *netdev)
 
                        /* alloc rx buffer */
                        buf = usb_alloc_coherent(dev->udev,
-                                                sizeof(struct gs_host_frame),
+                                                dev->parent->hf_size_rx,
                                                 GFP_KERNEL,
                                                 &urb->transfer_dma);
                        if (!buf) {
@@ -604,7 +617,7 @@ static int gs_can_open(struct net_device *netdev)
                                          usb_rcvbulkpipe(dev->udev,
                                                          GSUSB_ENDPOINT_IN),
                                          buf,
-                                         sizeof(struct gs_host_frame),
+                                         dev->parent->hf_size_rx,
                                          gs_usb_receive_bulk_callback, parent);
                        urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
 
@@ -886,6 +899,7 @@ static int gs_usb_probe(struct usb_interface *intf,
                        const struct usb_device_id *id)
 {
        struct usb_device *udev = interface_to_usbdev(intf);
+       struct gs_host_frame *hf;
        struct gs_usb *dev;
        int rc = -ENOMEM;
        unsigned int icount, i;
@@ -947,6 +961,7 @@ static int gs_usb_probe(struct usb_interface *intf,
        }
 
        init_usb_anchor(&dev->rx_submitted);
+       dev->hf_size_rx = struct_size(hf, classic_can, 1);
 
        usb_set_intfdata(intf, dev);
        dev->udev = udev;