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usb: device_next: uac2: Support multiple sample rates
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Add callbacks for setting and getting the sample rate. The callbacks are
optional if all Clock Source entities support only one sample rate.

This commit results in working High-Speed operation with Windows UAC2
driver when the Clock Source is host-programmable. Windows UAC2 driver
won't work if setting sample rate fails even if Clock Source supports
only one sample rate.

Signed-off-by: Tomasz Moń <[email protected]>
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@tmon-nordic @carlescufi
tmon-nordic authored and carlescufi committed Sep 13, 2024
1 parent 57666d3 commit 4c6b1e5
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Showing 2 changed files with 185 additions and 5 deletions.
33 changes: 33 additions & 0 deletions include/zephyr/usb/class/usbd_uac2.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -123,6 +123,39 @@ struct uac2_ops {
*/
uint32_t (*feedback_cb)(const struct device *dev, uint8_t terminal,
void *user_data);
/**
* @brief Get active sample rate
*
* USB stack calls this function when the host asks for active sample
* rate if the Clock Source entity supports more than one sample rate.
* This function won't ever be called (should be NULL) if all Clock
* Source entities support only one sample rate.
*
* @param dev USB Audio 2 device
* @param clock_id Clock Source ID whose sample rate should be returned
* @param user_data Opaque user data pointer
*
* @return Active sample rate in Hz
*/
uint32_t (*get_sample_rate)(const struct device *dev, uint8_t clock_id,
void *user_data);
/**
* @brief Set active sample rate
*
* USB stack calls this function when the host sets active sample rate.
* This callback may be NULL if all Clock Source entities have only one
* sample rate. USB stack sanitizes the sample rate to closest valid
* rate for given Clock Source entity.
*
* @param dev USB Audio 2 device
* @param clock_id Clock Source ID whose sample rate should be set
* @param rate Sample rate in Hz
* @param user_data Opaque user data pointer
*
* @return 0 on success, negative value on error
*/
int (*set_sample_rate)(const struct device *dev, uint8_t clock_id,
uint32_t rate, void *user_data);
};

/**
Expand Down
157 changes: 152 additions & 5 deletions subsys/usb/device_next/class/usbd_uac2.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -464,6 +464,49 @@ void uac2_update(struct usbd_class_data *const c_data,
}
}

/* 5.2.2 Control Request Layout: "As a general rule, when an attribute value
* is set, a Control will automatically adjust the passed value to the closest
* available valid value."
*
* The values array must be sorted ascending with at least 1 element.
*/
static uint32_t find_closest(const uint32_t input, const uint32_t *values,
const size_t values_count)
{
size_t i;

__ASSERT_NO_MSG(values_count);

for (i = 0; i < values_count; i++) {
if (input == values[i]) {
/* Exact match */
return input;
} else if (input < values[i]) {
break;
}
}

if (i == values_count) {
/* All values are smaller than input, return largest value */
return values[i - 1];
}

if (i == 0) {
/* All values are larger than input, return smallest value */
return values[i];
}

/* At this point values[i] is larger than input and values[i - 1] is
* smaller than input, find and return the one that is closer, favoring
* bigger value if input is exactly in the middle between the two.
*/
if ((values[i] - input) > (input - values[i - 1])) {
return values[i - 1];
} else {
return values[i];
}
}

/* Table 5-6: 4-byte Control CUR Parameter Block */
static void layout3_cur_response(struct net_buf *const buf, uint16_t length,
const uint32_t value)
Expand All @@ -475,6 +518,19 @@ static void layout3_cur_response(struct net_buf *const buf, uint16_t length,
net_buf_add_mem(buf, tmp, MIN(length, 4));
}

static int layout3_cur_request(const struct net_buf *const buf, uint32_t *out)
{
uint8_t tmp[4];

if (buf->len != 4) {
return -EINVAL;
}

memcpy(tmp, buf->data, sizeof(tmp));
*out = sys_get_le32(tmp);
return 0;
}

/* Table 5-7: 4-byte Control RANGE Parameter Block */
static void layout3_range_response(struct net_buf *const buf, uint16_t length,
const uint32_t *min, const uint32_t *max,
Expand Down Expand Up @@ -522,7 +578,10 @@ static int get_clock_source_request(struct usbd_class_data *const c_data,
const struct usb_setup_packet *const setup,
struct net_buf *const buf)
{
const struct device *dev = usbd_class_get_private(c_data);
struct uac2_ctx *ctx = dev->data;
const uint32_t *frequencies;
const uint32_t clock_id = CONTROL_ENTITY_ID(setup);
size_t count;

/* Channel Number must be zero */
Expand All @@ -533,7 +592,7 @@ static int get_clock_source_request(struct usbd_class_data *const c_data,
return 0;
}

count = clock_frequencies(c_data, CONTROL_ENTITY_ID(setup), &frequencies);
count = clock_frequencies(c_data, clock_id, &frequencies);

if (CONTROL_SELECTOR(setup) == CS_SAM_FREQ_CONTROL) {
if (CONTROL_ATTRIBUTE(setup) == CUR) {
Expand All @@ -542,10 +601,15 @@ static int get_clock_source_request(struct usbd_class_data *const c_data,
frequencies[0]);
return 0;
}
/* TODO: If there is more than one frequency supported,
* call registered application API to determine active
* sample rate.
*/

if (ctx->ops->get_sample_rate) {
uint32_t hz;

hz = ctx->ops->get_sample_rate(dev, clock_id,
ctx->user_data);
layout3_cur_response(buf, setup->wLength, hz);
return 0;
}
} else if (CONTROL_ATTRIBUTE(setup) == RANGE) {
layout3_range_response(buf, setup->wLength, frequencies,
frequencies, NULL, count);
Expand All @@ -560,6 +624,88 @@ static int get_clock_source_request(struct usbd_class_data *const c_data,
return 0;
}

static int set_clock_source_request(struct usbd_class_data *const c_data,
const struct usb_setup_packet *const setup,
const struct net_buf *const buf)
{
const struct device *dev = usbd_class_get_private(c_data);
struct uac2_ctx *ctx = dev->data;
const uint32_t *frequencies;
const uint32_t clock_id = CONTROL_ENTITY_ID(setup);
size_t count;

/* Channel Number must be zero */
if (CONTROL_CHANNEL_NUMBER(setup) != 0) {
LOG_DBG("Clock source control with channel %d",
CONTROL_CHANNEL_NUMBER(setup));
errno = -EINVAL;
return 0;
}

count = clock_frequencies(c_data, clock_id, &frequencies);

if (CONTROL_SELECTOR(setup) == CS_SAM_FREQ_CONTROL) {
if (CONTROL_ATTRIBUTE(setup) == CUR) {
uint32_t requested, hz;
int err;

err = layout3_cur_request(buf, &requested);
if (err) {
errno = err;
return 0;
}

hz = find_closest(requested, frequencies, count);

if (ctx->ops->set_sample_rate == NULL) {
/* The set_sample_rate() callback is optional
* if there is only one supported sample rate.
*/
if (count > 1) {
errno = -ENOTSUP;
}
return 0;
}

err = ctx->ops->set_sample_rate(dev, clock_id, hz,
ctx->user_data);
if (err) {
errno = err;
}

return 0;
}
} else {
LOG_DBG("Unhandled clock control selector 0x%02x",
CONTROL_SELECTOR(setup));
}

errno = -ENOTSUP;
return 0;
}

static int uac2_control_to_dev(struct usbd_class_data *const c_data,
const struct usb_setup_packet *const setup,
const struct net_buf *const buf)
{
entity_type_t entity_type;

if (CONTROL_ATTRIBUTE(setup) != CUR) {
errno = -ENOTSUP;
return 0;
}

if (setup->bmRequestType == SET_CLASS_REQUEST_TYPE) {
entity_type = id_type(c_data, CONTROL_ENTITY_ID(setup));
if (entity_type == ENTITY_TYPE_CLOCK_SOURCE) {
return set_clock_source_request(c_data, setup, buf);
}
}

errno = -ENOTSUP;
return 0;
}

static int uac2_control_to_host(struct usbd_class_data *const c_data,
const struct usb_setup_packet *const setup,
struct net_buf *const buf)
Expand Down Expand Up @@ -720,6 +866,7 @@ static int uac2_init(struct usbd_class_data *const c_data)

struct usbd_class_api uac2_api = {
.update = uac2_update,
.control_to_dev = uac2_control_to_dev,
.control_to_host = uac2_control_to_host,
.request = uac2_request,
.sof = uac2_sof,
Expand Down

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