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 /* check the validity of pipe and EP types */ 67 int snd_usb_pipe_sanity_check(struct usb_device *dev, unsigned int pipe) 68 { 69 static const int pipetypes[4] = { 70 PIPE_CONTROL, PIPE_ISOCHRONOUS, PIPE_BULK, PIPE_INTERRUPT 71 }; 72 struct usb_host_endpoint *ep; 73 74 ep = usb_pipe_endpoint(dev, pipe); 75 if (usb_pipetype(pipe) != pipetypes[usb_endpoint_type(&ep->desc)]) 76 return -EINVAL; 77 return 0; 78 } 79 80 /* 81 * Wrapper for usb_control_msg(). 82 * Allocates a temp buffer to prevent dmaing from/to the stack. 83 */ 84 int snd_usb_ctl_msg(struct usb_device *dev, unsigned int pipe, __u8 request, 85 __u8 requesttype, __u16 value, __u16 index, void *data, 86 __u16 size) 87 { 88 int err; 89 void *buf = NULL; 90 int timeout; 91 92 if (snd_usb_pipe_sanity_check(dev, pipe)) 93 return -EINVAL; 94 95 if (size > 0) { 96 buf = kmemdup(data, size, GFP_KERNEL); 97 if (!buf) 98 return -ENOMEM; 99 } 100 101 if (requesttype & USB_DIR_IN) 102 timeout = USB_CTRL_GET_TIMEOUT; 103 else 104 timeout = USB_CTRL_SET_TIMEOUT; 105 106 err = usb_control_msg(dev, pipe, request, requesttype, 107 value, index, buf, size, timeout); 108 109 if (size > 0) { 110 memcpy(data, buf, size); 111 kfree(buf); 112 } 113 114 snd_usb_ctl_msg_quirk(dev, pipe, request, requesttype, 115 value, index, data, size); 116 117 return err; 118 } 119 120 unsigned char snd_usb_parse_datainterval(struct snd_usb_audio *chip, 121 struct usb_host_interface *alts) 122 { 123 switch (snd_usb_get_speed(chip->dev)) { 124 case USB_SPEED_HIGH: 125 case USB_SPEED_WIRELESS: 126 case USB_SPEED_SUPER: 127 case USB_SPEED_SUPER_PLUS: 128 if (get_endpoint(alts, 0)->bInterval >= 1 && 129 get_endpoint(alts, 0)->bInterval <= 4) 130 return get_endpoint(alts, 0)->bInterval - 1; 131 break; 132 default: 133 break; 134 } 135 return 0; 136 } 137 138