path: root/drivers/usb/gadget/function/f_acm.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * f_acm.c -- USB CDC serial (ACM) function driver
 *
 * Copyright (C) 2003 Al Borchers (alborchers@steinerpoint.com)
 * Copyright (C) 2008 by David Brownell
 * Copyright (C) 2008 by Nokia Corporation
 * Copyright (C) 2009 by Samsung Electronics
 * Author: Michal Nazarewicz (mina86@mina86.com)
 */

/* #define VERBOSE_DEBUG */

#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/err.h>

#include "u_serial.h"


/*
 * This CDC ACM function support just wraps control functions and
 * notifications around the generic serial-over-usb code.
 *
 * Because CDC ACM is standardized by the USB-IF, many host operating
 * systems have drivers for it.  Accordingly, ACM is the preferred
 * interop solution for serial-port type connections.  The control
 * models are often not necessary, and in any case don't do much in
 * this bare-bones implementation.
 *
 * Note that even MS-Windows has some support for ACM.  However, that
 * support is somewhat broken because when you use ACM in a composite
 * device, having multiple interfaces confuses the poor OS.  It doesn't
 * seem to understand CDC Union descriptors.  The new "association"
 * descriptors (roughly equivalent to CDC Unions) may sometimes help.
 */

struct f_acm {
	struct gserial			port;
	u8				ctrl_id, data_id;
	u8				port_num;

	u8				pending;

	/* lock is mostly for pending and notify_req ... they get accessed
	 * by callbacks both from tty (open/close/break) under its spinlock,
	 * and notify_req.complete() which can't use that lock.
	 */
	spinlock_t			lock;

	struct usb_ep			*notify;
	struct usb_request		*notify_req;

	struct usb_cdc_line_coding	port_line_coding;	/* 8-N-1 etc */

	/* SetControlLineState request -- CDC 1.1 section 6.2.14 (INPUT) */
	u16				port_handshake_bits;
#define ACM_CTRL_RTS	(1 << 1)	/* unused with full duplex */
#define ACM_CTRL_DTR	(1 << 0)	/* host is ready for data r/w */

	/* SerialState notification -- CDC 1.1 section 6.3.5 (OUTPUT) */
	u16				serial_state;
#define ACM_CTRL_OVERRUN	(1 << 6)
#define ACM_CTRL_PARITY		(1 << 5)
#define ACM_CTRL_FRAMING	(1 << 4)
#define ACM_CTRL_RI		(1 << 3)
#define ACM_CTRL_BRK		(1 << 2)
#define ACM_CTRL_DSR		(1 << 1)
#define ACM_CTRL_DCD		(1 << 0)
};

static inline struct f_acm *func_to_acm(struct usb_function *f)
{
	return container_of(f, struct f_acm, port.func);
}

static inline struct f_acm *port_to_acm(struct gserial *p)
{
	return container_of(p, struct f_acm, port);
}

/*-------------------------------------------------------------------------*/

/* notification endpoint uses smallish and infrequent fixed-size messages */

#define GS_NOTIFY_INTERVAL_MS		32
#define GS_NOTIFY_MAXPACKET		10	/* notification + 2 bytes */

/* interface and class descriptors: */

static struct usb_interface_assoc_descriptor
acm_iad_descriptor = {
	.bLength =		sizeof acm_iad_descriptor,
	.bDescriptorType =	USB_DT_INTERFACE_ASSOCIATION,

	/* .bFirstInterface =	DYNAMIC, */
	.bInterfaceCount = 	2,	// control + data
	.bFunctionClass =	USB_CLASS_COMM,
	.bFunctionSubClass =	USB_CDC_SUBCLASS_ACM,
	.bFunctionProtocol =	USB_CDC_ACM_PROTO_AT_V25TER,
	/* .iFunction =		DYNAMIC */
};


static struct usb_interface_descriptor acm_control_interface_desc = {
	.bLength =		USB_DT_INTERFACE_SIZE,
	.bDescriptorType =	USB_DT_INTERFACE,
	/* .bInterfaceNumber = DYNAMIC */
	.bNumEndpoints =	1,
	.bInterfaceClass =	USB_CLASS_COMM,
	.bInterfaceSubClass =	USB_CDC_SUBCLASS_ACM,
	.bInterfaceProtocol =	USB_CDC_ACM_PROTO_AT_V25TER,
	/* .iInterface = DYNAMIC */
};

static struct usb_interface_descriptor acm_data_interface_desc = {
	.bLength =		USB_DT_INTERFACE_SIZE,
	.bDescriptorType =	USB_DT_INTERFACE,
	/* .bInterfaceNumber = DYNAMIC */
	.bNumEndpoints =	2,
	.bInterfaceClass =	USB_CLASS_CDC_DATA,
	.bInterfaceSubClass =	0,
	.bInterfaceProtocol =	0,
	/* .iInterface = DYNAMIC */
};

static struct usb_cdc_header_desc acm_header_desc = {
	.bLength =		sizeof(acm_header_desc),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_HEADER_TYPE,
	.bcdCDC =		cpu_to_le16(0x0110),
};

static struct usb_cdc_call_mgmt_descriptor
acm_call_mgmt_descriptor = {
	.bLength =		sizeof(acm_call_mgmt_descriptor),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_CALL_MANAGEMENT_TYPE,
	.bmCapabilities =	0,
	/* .bDataInterface = DYNAMIC */
};

static struct usb_cdc_acm_descriptor acm_descriptor = {
	.bLength =		sizeof(acm_descriptor),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_ACM_TYPE,
	.bmCapabilities =	USB_CDC_CAP_LINE,
};

static struct usb_cdc_union_desc acm_union_desc = {
	.bLength =		sizeof(acm_union_desc),
	.bDescriptorType =	USB_DT_CS_INTERFACE,
	.bDescriptorSubType =	USB_CDC_UNION_TYPE,
	/* .bMasterInterface0 =	DYNAMIC */
	/* .bSlaveInterface0 =	DYNAMIC */
};

/* full speed support: */

static struct usb_endpoint_descriptor acm_fs_notify_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_INT,
	.wMaxPacketSize =	cpu_to_le16(GS_NOTIFY_MAXPACKET),
	.bInterval =		GS_NOTIFY_INTERVAL_MS,
};

static struct usb_endpoint_descriptor acm_fs_in_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_IN,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
};

static struct usb_endpoint_descriptor acm_fs_out_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT,
	.bEndpointAddress =	USB_DIR_OUT,
	.bmAttributes =		USB_ENDPOINT_XFER_BULK,
};

static struct usb_descriptor_header *acm_fs_function[] = {
	(struct usb_descriptor_header *) &acm_iad_descriptor,
	(struct usb_descriptor_header *) &acm_control_interface_desc,
	(struct usb_descriptor_header *) &acm_header_desc,
	(struct usb_descriptor_header *) &acm_call_mgmt_descriptor,
	(struct usb_descriptor_header *) &acm_descriptor,
	(struct usb_descriptor_header *) &acm_union_desc,
	(struct usb_descriptor_header *) &acm_fs_notify_desc,
	(struct usb_descriptor_header *) &acm_data_interface_desc,
	(struct usb_descriptor_header *) &acm_fs_in_desc,
	(struct usb_descriptor_header *) &acm_fs_out_desc,
	NULL,
};

/* high speed support: */
static struct usb_endpoint_descriptor acm_hs_notify_desc = {
	.bLength =		USB_DT_ENDPOINT_SIZE,
	.bDescriptorType =	USB_DT_ENDPOINT