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usb: device_next: cdc_acm: allow setting the interface description

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Add a interface-name string for the CDC-ACM node, this allow setting a
string that is then set as iInterface, which can then be used downstream
in an udev rule such as:

SUBSYSTEM=="tty", ACTION=="add",
ATTRS{interface}=="my interface descriptor",
SYMLINK+="tty-my-device"

To create known aliases for these ports.

Signed-off-by: Fabio Baltieri <fabiobaltieri@google.com>
This commit is contained in:
Fabio Baltieri 2025-01-15 23:12:54 +00:00 • committed by Benjamin Cabé
commit b0791400f6
3 changed files with 26 additions and 0 deletions
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5
dts/bindings/serial/zephyr,cdc-acm-uart.yaml
View file

@ -21,3 +21,8 @@ properties:
default: 1024
description: |
Size of the virtual CDC ACM UART RX FIFO
label:
description: |
The string defined by the label property is also used for the USB
interface string descriptor.

1
samples/subsys/usb/cdc_acm/app.overlay
View file

@ -7,5 +7,6 @@
&zephyr_udc0 {
cdc_acm_uart0 {
compatible = "zephyr,cdc-acm-uart";
label = "Zephyr USB CDC-ACM";
};
};

20
subsys/usb/device_next/class/usbd_cdc_acm.c
View file

@ -83,6 +83,8 @@ struct usbd_cdc_acm_desc {
struct cdc_acm_uart_data {
/* Pointer to the associated USBD class node */
struct usbd_class_data *c_data;
/* Pointer to the interface description node or NULL */
struct usbd_desc_node *const if_desc_data;
/* Pointer to the class interface descriptors */
struct usbd_cdc_acm_desc *const desc;
const struct usb_desc_header **const fs_desc;
@ -488,6 +490,7 @@ static int usbd_cdc_acm_ctd(struct usbd_class_data *const c_data,
static int usbd_cdc_acm_init(struct usbd_class_data *const c_data)
{
struct usbd_context *uds_ctx = usbd_class_get_ctx(c_data);
const struct device *dev = usbd_class_get_private(c_data);
struct cdc_acm_uart_data *data = dev->data;
struct usbd_cdc_acm_desc *desc = data->desc;
@ -495,6 +498,14 @@ static int usbd_cdc_acm_init(struct usbd_class_data *const c_data)
desc->if0_union.bControlInterface = desc->if0.bInterfaceNumber;
desc->if0_union.bSubordinateInterface0 = desc->if1.bInterfaceNumber;
if (data->if_desc_data != NULL) {
if (usbd_add_descriptor(uds_ctx, data->if_desc_data)) {
LOG_ERR("Failed to add interface string descriptor");
} else {
desc->if0.iInterface = usbd_str_desc_get_idx(data->if_desc_data);
}
}
return 0;
}
@ -1259,12 +1270,21 @@ const static struct usb_desc_header *cdc_acm_hs_desc_##n[] = { \
&usbd_cdc_acm_api, \
(void *)DEVICE_DT_GET(DT_DRV_INST(n)), NULL); \
\
IF_ENABLED(DT_INST_NODE_HAS_PROP(n, label), ( \
USBD_DESC_STRING_DEFINE(cdc_acm_if_desc_data_##n, \
DT_INST_PROP(n, label), \
USBD_DUT_STRING_INTERFACE); \
)) \
\
RING_BUF_DECLARE(cdc_acm_rb_rx_##n, DT_INST_PROP(n, rx_fifo_size)); \
RING_BUF_DECLARE(cdc_acm_rb_tx_##n, DT_INST_PROP(n, tx_fifo_size)); \
\
static struct cdc_acm_uart_data uart_data_##n = { \
.line_coding = CDC_ACM_DEFAULT_LINECODING, \
.c_data = &cdc_acm_##n, \
IF_ENABLED(DT_INST_NODE_HAS_PROP(n, label), ( \
.if_desc_data = &cdc_acm_if_desc_data_##n, \
)) \
.rx_fifo.rb = &cdc_acm_rb_rx_##n, \
.tx_fifo.rb = &cdc_acm_rb_tx_##n, \
.flow_ctrl = DT_INST_PROP(n, hw_flow_control), \