1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 */ 4 5 #include <linux/init.h> 6 #include <linux/slab.h> 7 #include <linux/usb.h> 8 9 #include "usbaudio.h" 10 #include "helper.h" 11 #include "quirks.h" 12 13 /* 14 * combine bytes and get an integer value 15 */ 16 unsigned int snd_usb_combine_bytes(unsigned char *bytes, int size) 17 { 18 switch (size) { 19 case 1: return *bytes; 20 case 2: return combine_word(bytes); 21 case 3: return combine_triple(bytes); 22 case 4: return combine_quad(bytes); 23 default: return 0; 24 } 25 } 26 27 /* 28 * parse descriptor buffer and return the pointer starting the given 29 * descriptor type. 30 */ 31 void *snd_usb_find_desc(void *descstart, int desclen, void *after, u8 dtype) 32 { 33 u8 *p, *end, *next; 34 35 p = descstart; 36 end = p + desclen; 37 for (; p < end;) { 38 if (p[0] < 2) 39 return NULL; 40 next = p + p[0]; 41 if (next > end) 42 return NULL; 43 if (p[1] == dtype && (!after || (void *)p > after)) { 44 return p; 45 } 46 p = next; 47 } 48 return NULL; 49 } 50 51 /* 52 * find a class-specified interface descriptor with the given subtype. 53 */ 54 void *snd_usb_find_csint_desc(void *buffer, int buflen, void *after, u8 dsubtype) 55 { 56 unsigned char *p = after; 57 58 while ((p = snd_usb_find_desc(buffer, buflen, p, 59 USB_DT_CS_INTERFACE)) != NULL) { 60 if (p[0] >= 3 && p[2] == dsubtype) 61 return p; 62 } 63 return NULL; 64 } 65 66 /* 67 * Wrapper for usb_control_msg(). 68 * Allocates a temp buffer to prevent dmaing from/to the stack. 69 */ 70 int snd_usb_ctl_msg(struct usb_device *dev, unsigned int pipe, __u8 request, 71 __u8 requesttype, __u16 value, __u16 index, void *data, 72 __u16 size) 73 { 74 int err; 75 void *buf = NULL; 76 int timeout; 77 78 if (usb_pipe_type_check(dev, pipe)) 79 return -EINVAL; 80 81 if (size > 0) { 82 buf = kmemdup(data, size, GFP_KERNEL); 83 if (!buf) 84 return -ENOMEM; 85 } 86 87 if (requesttype & USB_DIR_IN) 88 timeout = USB_CTRL_GET_TIMEOUT; 89 else 90 timeout = USB_CTRL_SET_TIMEOUT; 91 92 err = usb_control_msg(dev, pipe, request, requesttype, 93 value, index, buf, size, timeout); 94 95 if (size > 0) { 96 memcpy(data, buf, size); 97 kfree(buf); 98 } 99 100 snd_usb_ctl_msg_quirk(dev, pipe, request, requesttype, 101 value, index, data, size); 102 103 return err; 104 } 105 106 unsigned char snd_usb_parse_datainterval(struct snd_usb_audio *chip, 107 struct usb_host_interface *alts) 108 { 109 switch (snd_usb_get_speed(chip->dev)) { 110 case USB_SPEED_HIGH: 111 case USB_SPEED_SUPER: 112 case USB_SPEED_SUPER_PLUS: 113 if (get_endpoint(alts, 0)->bInterval >= 1 && 114 get_endpoint(alts, 0)->bInterval <= 4) 115 return get_endpoint(alts, 0)->bInterval - 1; 116 break; 117 default: 118 break; 119 } 120 return 0; 121 } 122 123 struct usb_host_interface * 124 snd_usb_get_host_interface(struct snd_usb_audio *chip, int ifnum, int altsetting) 125 { 126 struct usb_interface *iface; 127 128 iface = usb_ifnum_to_if(chip->dev, ifnum); 129 if (!iface) 130 return NULL; 131 return usb_altnum_to_altsetting(iface, altsetting); 132 } 133