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-rw-r--r--sound/usb/helper.c132
1 files changed, 132 insertions, 0 deletions
diff --git a/sound/usb/helper.c b/sound/usb/helper.c
new file mode 100644
index 0000000000..bf80e55d01
--- /dev/null
+++ b/sound/usb/helper.c
@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ */
+
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/usb.h>
+
+#include "usbaudio.h"
+#include "helper.h"
+#include "quirks.h"
+
+/*
+ * combine bytes and get an integer value
+ */
+unsigned int snd_usb_combine_bytes(unsigned char *bytes, int size)
+{
+ switch (size) {
+ case 1: return *bytes;
+ case 2: return combine_word(bytes);
+ case 3: return combine_triple(bytes);
+ case 4: return combine_quad(bytes);
+ default: return 0;
+ }
+}
+
+/*
+ * parse descriptor buffer and return the pointer starting the given
+ * descriptor type.
+ */
+void *snd_usb_find_desc(void *descstart, int desclen, void *after, u8 dtype)
+{
+ u8 *p, *end, *next;
+
+ p = descstart;
+ end = p + desclen;
+ for (; p < end;) {
+ if (p[0] < 2)
+ return NULL;
+ next = p + p[0];
+ if (next > end)
+ return NULL;
+ if (p[1] == dtype && (!after || (void *)p > after)) {
+ return p;
+ }
+ p = next;
+ }
+ return NULL;
+}
+
+/*
+ * find a class-specified interface descriptor with the given subtype.
+ */
+void *snd_usb_find_csint_desc(void *buffer, int buflen, void *after, u8 dsubtype)
+{
+ unsigned char *p = after;
+
+ while ((p = snd_usb_find_desc(buffer, buflen, p,
+ USB_DT_CS_INTERFACE)) != NULL) {
+ if (p[0] >= 3 && p[2] == dsubtype)
+ return p;
+ }
+ return NULL;
+}
+
+/*
+ * Wrapper for usb_control_msg().
+ * Allocates a temp buffer to prevent dmaing from/to the stack.
+ */
+int snd_usb_ctl_msg(struct usb_device *dev, unsigned int pipe, __u8 request,
+ __u8 requesttype, __u16 value, __u16 index, void *data,
+ __u16 size)
+{
+ int err;
+ void *buf = NULL;
+ int timeout;
+
+ if (usb_pipe_type_check(dev, pipe))
+ return -EINVAL;
+
+ if (size > 0) {
+ buf = kmemdup(data, size, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+ }
+
+ if (requesttype & USB_DIR_IN)
+ timeout = USB_CTRL_GET_TIMEOUT;
+ else
+ timeout = USB_CTRL_SET_TIMEOUT;
+
+ err = usb_control_msg(dev, pipe, request, requesttype,
+ value, index, buf, size, timeout);
+
+ if (size > 0) {
+ memcpy(data, buf, size);
+ kfree(buf);
+ }
+
+ snd_usb_ctl_msg_quirk(dev, pipe, request, requesttype,
+ value, index, data, size);
+
+ return err;
+}
+
+unsigned char snd_usb_parse_datainterval(struct snd_usb_audio *chip,
+ struct usb_host_interface *alts)
+{
+ switch (snd_usb_get_speed(chip->dev)) {
+ case USB_SPEED_HIGH:
+ case USB_SPEED_SUPER:
+ case USB_SPEED_SUPER_PLUS:
+ if (get_endpoint(alts, 0)->bInterval >= 1 &&
+ get_endpoint(alts, 0)->bInterval <= 4)
+ return get_endpoint(alts, 0)->bInterval - 1;
+ break;
+ default:
+ break;
+ }
+ return 0;
+}
+
+struct usb_host_interface *
+snd_usb_get_host_interface(struct snd_usb_audio *chip, int ifnum, int altsetting)
+{
+ struct usb_interface *iface;
+
+ iface = usb_ifnum_to_if(chip->dev, ifnum);
+ if (!iface)
+ return NULL;
+ return usb_altnum_to_altsetting(iface, altsetting);
+}