/* * Helper function to walk the array of sample rate triplets reported by * the device. The problem is that we need to parse whole array first to * get to know how many sample rates we have to expect. * Then fp->rate_table can be allocated and filled. */ static int parse_uac2_sample_rate_range(struct snd_usb_audio *chip, struct audioformat *fp, int nr_triplets, const unsigned char *data) { int i, nr_rates = 0; fp->rates = fp->rate_min = fp->rate_max = 0; for (i = 0; i < nr_triplets; i++) { int min = combine_quad(&data[2 + 12 * i]); int max = combine_quad(&data[6 + 12 * i]); int res = combine_quad(&data[10 + 12 * i]); unsigned int rate; if ((max < 0) || (min < 0) || (res < 0) || (max < min)) continue; /* * for ranges with res == 1, we announce a continuous sample * rate range, and this function should return 0 for no further * parsing. */ if (res == 1) { fp->rate_min = min; fp->rate_max = max; fp->rates = SNDRV_PCM_RATE_CONTINUOUS; return 0; } for (rate = min; rate <= max; rate += res) { if (fp->rate_table) fp->rate_table[nr_rates] = rate; if (!fp->rate_min || rate < fp->rate_min) fp->rate_min = rate; if (!fp->rate_max || rate > fp->rate_max) fp->rate_max = rate; fp->rates |= snd_pcm_rate_to_rate_bit(rate); nr_rates++; if (nr_rates >= MAX_NR_RATES) { usb_audio_err(chip, "invalid uac2 rates\n"); break; } /* avoid endless loop */ if (res == 0) break; } } return nr_rates; }
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 the format descriptor and stores the possible sample rates * on the audioformat table (audio class v2). */ static int parse_audio_format_rates_v2(struct snd_usb_audio *chip, struct audioformat *fp, struct usb_host_interface *iface) { struct usb_device *dev = chip->dev; unsigned char tmp[2], *data; int i, nr_rates, data_size, ret = 0; /* get the number of sample rates first by only fetching 2 bytes */ ret = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_RANGE, USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN, UAC2_CS_CONTROL_SAM_FREQ << 8, chip->clock_id << 8, tmp, sizeof(tmp), 1000); if (ret < 0) { snd_printk(KERN_ERR "unable to retrieve number of sample rates\n"); goto err; } nr_rates = (tmp[1] << 8) | tmp[0]; data_size = 2 + 12 * nr_rates; data = kzalloc(data_size, GFP_KERNEL); if (!data) { ret = -ENOMEM; goto err; } /* now get the full information */ ret = snd_usb_ctl_msg(dev, usb_rcvctrlpipe(dev, 0), UAC2_CS_RANGE, USB_TYPE_CLASS | USB_RECIP_INTERFACE | USB_DIR_IN, UAC2_CS_CONTROL_SAM_FREQ << 8, chip->clock_id << 8, data, data_size, 1000); if (ret < 0) { snd_printk(KERN_ERR "unable to retrieve sample rate range\n"); ret = -EINVAL; goto err_free; } fp->rate_table = kmalloc(sizeof(int) * nr_rates, GFP_KERNEL); if (!fp->rate_table) { ret = -ENOMEM; goto err_free; } fp->nr_rates = 0; fp->rate_min = fp->rate_max = 0; for (i = 0; i < nr_rates; i++) { int rate = combine_quad(&data[2 + 12 * i]); fp->rate_table[fp->nr_rates] = rate; if (!fp->rate_min || rate < fp->rate_min) fp->rate_min = rate; if (!fp->rate_max || rate > fp->rate_max) fp->rate_max = rate; fp->rates |= snd_pcm_rate_to_rate_bit(rate); fp->nr_rates++; } err_free: kfree(data); err: return ret; }