This patch introduces a new NCM tx engine, able to operate in standard-
and huawei-style mode.
In the first case, the NDP is disposed after the initial headers and
before any datagram.
What works:
- is able to communicate with compliant NCM devices:
I tested this with a board running the Linux g_ncm gadget driver.
What doesn't work:
- After some packets I start gettint LOTS of EVENT_RX_MEMORY from usbnet,
which fails to allocate an RX SKB in rx_submit(). Don't understand why,
any suggestion would be very welcome.
The tx_fixup function given here, even if actually working, should be
considered as an example: the NCM manager is used here simulating the
cdc_ncm.c behaviour.
Signed-off-by: Enrico Mioso <mrkiko...@gmail.com>
---
drivers/net/usb/huawei_cdc_ncm.c | 187 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 185 insertions(+), 2 deletions(-)
diff --git a/drivers/net/usb/huawei_cdc_ncm.c b/drivers/net/usb/huawei_cdc_ncm.c
index 735f7da..217802a 100644
--- a/drivers/net/usb/huawei_cdc_ncm.c
+++ b/drivers/net/usb/huawei_cdc_ncm.c
@@ -29,6 +29,35 @@
#include <linux/usb/cdc-wdm.h>
#include <linux/usb/cdc_ncm.h>
+/* NCM management operations: */
+
+/* NCM_INIT_FRAME: prepare for a new frame.
+ * NTH16 header is written to output SKB, NDP data is reset and last
+ * committed NDP pointer set to NULL.
+ * Now, data may be added to this NCM package.
+ */
+#define NCM_INIT_FRAME 1
+
+/* NCM_UPDATE_NDP: adds data to an NDP structure, hence updating it.
+ * Some checks are performed to be sure data fits in, respecting device and
+ * spec constrains.
+ * Normally the NDP is kept in memory and committed to the SKB only when
+ * requested. However, calling this "method" after NCM_COMMIT_NDP, causes it to
+ * work directly on the already committed SKB copy. this allows for flexibility
+ * in frame ordering.
+ */
+#define NCM_UPDATE_NDP 2
+
+/* Write NDP: commits NDP to output SKB.
+ * This method should be called only once per frame.
+ */
+#define NCM_COMMIT_NDP 3
+
+/* Finalizes NTH16 header: to be called when working in
+ * update-already-committed mode.
+ */
+#define NCM_FINALIZE_NTH 5
+
/* Driver data */
struct huawei_cdc_ncm_state {
struct cdc_ncm_ctx *ctx;
@@ -36,6 +65,16 @@ struct huawei_cdc_ncm_state {
struct usb_driver *subdriver;
struct usb_interface *control;
struct usb_interface *data;
+
+ /* Keeps track of where data starts and ends in SKBs. */
+ int data_start;
+ int data_len;
+
+ /* Last committed NDP for post-commit operations. */
+ struct usb_cdc_ncm_ndp16 *skb_ndp;
+
+ /* Non-committed NDP */
+ struct usb_cdc_ncm_ndp16 *ndp;
};
static int huawei_cdc_ncm_manage_power(struct usbnet *usbnet_dev, int on)
@@ -53,6 +92,149 @@ static int huawei_cdc_ncm_manage_power(struct usbnet
*usbnet_dev, int on)
return 0;
}
+/* huawei_ncm_mgmt: flexible TX NCM manager.
+ *
+ * Once a non-zero status value is rturned, current frame should be discarded
+ * and operations restarted from scratch.
+ */
+int
+huawei_ncm_mgmt(struct usbnet *dev,
+ struct huawei_cdc_ncm_state *drvstate, struct sk_buff *skb_out,
int mode) {
+ struct usb_cdc_ncm_nth16 *nth16 = (struct usb_cdc_ncm_nth16
*)skb_out->data;
+ struct cdc_ncm_ctx *ctx = drvstate->ctx;
+ struct usb_cdc_ncm_ndp16 *ndp16 = NULL;
+ int ret = -EINVAL;
+ u16 ndplen, index;
+
+ switch (mode) {
+ case NCM_INIT_FRAME:
+
+ /* Write a new NTH16 header */
+ nth16 = (struct usb_cdc_ncm_nth16 *)memset(skb_put(skb_out,
sizeof(struct usb_cdc_ncm_nth16)), 0, sizeof(struct usb_cdc_ncm_nth16));
+ if (!nth16) {
+ ret = -EINVAL;
+ goto error;
+ }
+
+ /* NTH16 signature and header length are known a-priori. */
+ nth16->dwSignature = cpu_to_le32(USB_CDC_NCM_NTH16_SIGN);
+ nth16->wHeaderLength = cpu_to_le16(sizeof(struct
usb_cdc_ncm_nth16));
+
+ /* TX sequence numbering */
+ nth16->wSequence = cpu_to_le16(ctx->tx_seq++);
+
+ /* Forget about previous SKB NDP */
+ drvstate->skb_ndp = NULL;
+
+ /* Allocate a new NDP */
+ ndp16 = kzalloc(ctx->max_ndp_size, GFP_NOIO);
+ if (!ndp16)
+ return ret;
+
+ /* Prepare a new NDP to add data on subsequent calls. */
+ drvstate->ndp = memset(ndp16, 0, ctx->max_ndp_size);
+
+ /* Initial NDP length */
+ ndp16->wLength = cpu_to_le16(sizeof(struct usb_cdc_ncm_ndp16) +
sizeof(struct usb_cdc_ncm_dpe16));
+
+ /* Frame signature: to be reworked in general. */
+ ndp16->dwSignature =
cpu_to_le32(USB_CDC_NCM_NDP16_NOCRC_SIGN);
+
+ ret = 0;
+ break;
+
+ case NCM_UPDATE_NDP:
+
+ if (drvstate->skb_ndp) {
+ ndp16 = drvstate->skb_ndp;
+ } else {
+ ndp16 = drvstate->ndp;
+
+ /* Do we have enough space for the data? */
+ if (skb_out->len + ctx->max_ndp_size > ctx->tx_max)
+ goto error;
+ }
+
+ /* Calculate frame number within this NDP */
+ ndplen = le16_to_cpu(ndp16->wLength);
+ index = (ndplen - sizeof(struct usb_cdc_ncm_ndp16)) /
sizeof(struct usb_cdc_ncm_dpe16) - 1;
+
+ if (index >= CDC_NCM_DPT_DATAGRAMS_MAX)
+ goto error;
+
+ /* tx_max shouldn't be exceeded after committing. */
+ if (ndplen + sizeof(struct usb_cdc_ncm_dpe16) > ctx->tx_max)
+ goto error;
+
+ /* Adding a DPT entry. */
+ ndp16->dpe16[index].wDatagramLength =
cpu_to_le16(drvstate->data_len);
+ ndp16->dpe16[index].wDatagramIndex =
cpu_to_le16(drvstate->data_start);
+ ndp16->wLength = cpu_to_le16(ndplen + sizeof(struct
usb_cdc_ncm_dpe16));
+
+ ret = 0;
+ break;
+
+ case NCM_COMMIT_NDP:
+
+ if (drvstate->skb_ndp)
+ goto error; /* Call this only once please. */
+
+ ndp16 = drvstate->ndp;
+
+ nth16->wNdpIndex = cpu_to_le16(skb_out->len);
+
+ /* "commit" NDP */
+ drvstate->skb_ndp = memcpy(skb_put(skb_out, ctx->max_ndp_size),
ndp16, ctx->max_ndp_size);
+
+ kfree(ndp16);
+ ndp16 = NULL;
+ drvstate->ndp = NULL;
+
+ case NCM_FINALIZE_NTH:
+
+ /* Finalize NTH16 header, setting it's block length */
+ nth16->wBlockLength = cpu_to_le16(skb_out->len);
+
+ ret = 0;
+ break;
+ default:
+ break;
+ }
+
+error:
+ if (ret)
+ kfree(drvstate->ndp);
+ return ret;
+}
+
+/* XXX rewrite, not multipacket */
+struct sk_buff *
+huawei_ncm_tx_fixup(struct usbnet *dev, struct sk_buff *skb_in, gfp_t flags) {
+ struct huawei_cdc_ncm_state *drvstate = (void *)&dev->data;
+ struct cdc_ncm_ctx *ctx = drvstate->ctx;
+ struct sk_buff *skb_out;
+ int status;
+
+ skb_out = alloc_skb(ctx->tx_max, GFP_ATOMIC);
+
+ status = huawei_ncm_mgmt(dev, drvstate, skb_out, NCM_INIT_FRAME);
+
+ cdc_ncm_align_tail(skb_out, ctx->tx_ndp_modulus, 0, ctx->tx_max);
+ status = huawei_ncm_mgmt(dev, drvstate, skb_out, NCM_COMMIT_NDP);
+
+ cdc_ncm_align_tail(skb_out, ctx->tx_modulus, ctx->tx_remainder,
ctx->tx_max);
+ drvstate->data_start = skb_out->len;
+ memcpy(skb_put(skb_out, skb_in->len), skb_in->data, skb_in->len);
+ drvstate->data_len = skb_out->len - drvstate->data_start;
+
+ status = huawei_ncm_mgmt(dev, drvstate, skb_out, NCM_UPDATE_NDP);
+
+ status = huawei_ncm_mgmt(dev, drvstate, skb_out, NCM_FINALIZE_NTH);
+
+ kfree_skb(skb_in);
+ return skb_out;
+}
+
static int huawei_cdc_ncm_wdm_manage_power(struct usb_interface *intf,
int status)
{
@@ -175,12 +357,13 @@ err:
static const struct driver_info huawei_cdc_ncm_info = {
.description = "Huawei CDC NCM device",
- .flags = FLAG_NO_SETINT | FLAG_MULTI_PACKET | FLAG_WWAN,
+ /* .flags = FLAG_NO_SETINT | FLAG_MULTI_PACKET | FLAG_WWAN, */
+ .flags = FLAG_NO_SETINT | FLAG_WWAN,
.bind = huawei_cdc_ncm_bind,
.unbind = huawei_cdc_ncm_unbind,
.manage_power = huawei_cdc_ncm_manage_power,
.rx_fixup = cdc_ncm_rx_fixup,
- .tx_fixup = cdc_ncm_tx_fixup,
+ .tx_fixup = huawei_ncm_tx_fixup,
};
static const struct usb_device_id huawei_cdc_ncm_devs[] = {
--
2.4.4
--
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