/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2014 Daniel Thompson <daniel@redfelineninja.org.uk>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <stdlib.h>
#include <libopencm3/usb/usbd.h>
#include <libopencm3/usb/audio.h>
#include <libopencm3/usb/midi.h>
#include <libopencm3/cm3/scb.h>
#include <libopencm3/stm32/desig.h>
#include <libopencm3/stm32/rcc.h>
#include <libopencm3/stm32/gpio.h>

/*
 * All references in this file come from Universal Serial Bus Device Class
 * Definition for MIDI Devices, release 1.0.
 */

/*
 * Table B-1: MIDI Adapter Device Descriptor
 */
static const struct usb_device_descriptor dev = {
	.bLength = USB_DT_DEVICE_SIZE,
	.bDescriptorType = USB_DT_DEVICE,
	.bcdUSB = 0x0200,    /* was 0x0110 in Table B-1 example descriptor */
	.bDeviceClass = 0,   /* device defined at interface level */
	.bDeviceSubClass = 0,
	.bDeviceProtocol = 0,
	.bMaxPacketSize0 = 64,
	.idVendor = 0x6666,  /* Prototype product vendor ID */
	.idProduct = 0x5119, /* dd if=/dev/random bs=2 count=1 | hexdump */
	.bcdDevice = 0x0100,
	.iManufacturer = 1,  /* index to string desc */
	.iProduct = 2,       /* index to string desc */
	.iSerialNumber = 3,  /* index to string desc */
	.bNumConfigurations = 1,
};

/*
 * Midi specific endpoint descriptors.
 */
static const struct usb_midi_endpoint_descriptor midi_bulk_endp[] = {{
	/* Table B-12: MIDI Adapter Class-specific Bulk OUT Endpoint
	 * Descriptor
	 */
	.head = {
		.bLength = sizeof(struct usb_midi_endpoint_descriptor),
		.bDescriptorType = USB_AUDIO_DT_CS_ENDPOINT,
		.bDescriptorSubType = USB_MIDI_SUBTYPE_MS_GENERAL,
		.bNumEmbMIDIJack = 1,
	},
	.jack[0] = {
		.baAssocJackID = 0x01,
	},
}, {
	/* Table B-14: MIDI Adapter Class-specific Bulk IN Endpoint
	 * Descriptor
	 */
	.head = {
		.bLength = sizeof(struct usb_midi_endpoint_descriptor),
		.bDescriptorType = USB_AUDIO_DT_CS_ENDPOINT,
		.bDescriptorSubType = USB_MIDI_SUBTYPE_MS_GENERAL,
		.bNumEmbMIDIJack = 1,
	},
	.jack[0] = {
		.baAssocJackID = 0x03,
	},
} };

/*
 * Standard endpoint descriptors
 */
static const struct usb_endpoint_descriptor bulk_endp[] = {{
	/* Table B-11: MIDI Adapter Standard Bulk OUT Endpoint Descriptor */
	.bLength = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType = USB_DT_ENDPOINT,
	.bEndpointAddress = 0x01,
	.bmAttributes = USB_ENDPOINT_ATTR_BULK,
	.wMaxPacketSize = 0x40,
	.bInterval = 0x00,

	.extra = &midi_bulk_endp[0],
	.extralen = sizeof(midi_bulk_endp[0])
}, {
	.bLength = USB_DT_ENDPOINT_SIZE,
	.bDescriptorType = USB_DT_ENDPOINT,
	.bEndpointAddress = 0x81,
	.bmAttributes = USB_ENDPOINT_ATTR_BULK,
	.wMaxPacketSize = 0x40,
	.bInterval = 0x00,

	.extra = &midi_bulk_endp[1],
	.extralen = sizeof(midi_bulk_endp[1])
} };

/*
 * Table B-4: MIDI Adapter Class-specific AC Interface Descriptor
 */
static const struct {
	struct usb_audio_header_descriptor_head header_head;
	struct usb_audio_header_descriptor_body header_body;
} __attribute__((packed)) audio_control_functional_descriptors = {
	.header_head = {
		.bLength = sizeof(struct usb_audio_header_descriptor_head) +
		           1 * sizeof(struct usb_audio_header_descriptor_body),
		.bDescriptorType = USB_AUDIO_DT_CS_INTERFACE,
		.bDescriptorSubtype = USB_AUDIO_TYPE_HEADER,
		.bcdADC = 0x0100,
		.wTotalLength =
			   sizeof(struct usb_audio_header_descriptor_head) +
			   1 * sizeof(struct usb_audio_header_descriptor_body),
		.binCollection = 1,
	},
	.header_body = {
		.baInterfaceNr = 0x01,
	},
};

/*
 * Table B-3: MIDI Adapter Standard AC Interface Descriptor
 */
static const struct usb_interface_descriptor audio_control_iface[] = {{
	.bLength = USB_DT_INTERFACE_SIZE,
	.bDescriptorType = USB_DT_INTERFACE,
	.bInterfaceNumber = 0,
	.bAlternateSetting = 0,
	.bNumEndpoints = 0,
	.bInterfaceClass = USB_CLASS_AUDIO,
	.bInterfaceSubClass = USB_AUDIO_SUBCLASS_CONTROL,
	.bInterfaceProtocol = 0,
	.iInterface = 0,

	.extra = &audio_control_functional_descriptors,
	.extralen = sizeof(audio_control_functional_descriptors)
} };

/*
 * Class-specific MIDI streaming interface descriptor
 */
static const struct {
	struct usb_midi_header_descriptor header;
	struct usb_midi_in_jack_descriptor in_embedded;
	struct usb_midi_in_jack_descriptor in_external;
	struct usb_midi_out_jack_descriptor out_embedded;
	struct usb_midi_out_jack_descriptor out_external;
} __attribute__((packed)) midi_streaming_functional_descriptors = {
	/* Table B-6: Midi Adapter Class-specific MS Interface Descriptor */
	.header = {
		.bLength = sizeof(struct usb_midi_header_descriptor),
		.bDescriptorType = USB_AUDIO_DT_CS_INTERFACE,
		.bDescriptorSubtype = USB_MIDI_SUBTYPE_MS_HEADER,
		.bcdMSC = 0x0100,
		.wTotalLength = sizeof(midi_streaming_functional_descriptors),
	},
	/* Table B-7: MIDI Adapter MIDI IN Jack Descriptor (Embedded) */
	.in_embedded = {
		.bLength = sizeof(struct usb_midi_in_jack_descriptor),
		.bDescriptorType = USB_AUDIO_DT_CS_INTERFACE,
		.bDescriptorSubtype = USB_MIDI_SUBTYPE_MIDI_IN_JACK,
		.bJackType = USB_MIDI_JACK_TYPE_EMBEDDED,
		.bJackID = 0x01,
		.iJack = 0x00,
	},
	/* Table B-8: MIDI Adapter MIDI IN Jack Descriptor (External) */
	.in_external = {
		.bLength = sizeof(struct usb_midi_in_jack_descriptor),
		.bDescriptorType = USB_AUDIO_DT_CS_INTERFACE,
		.bDescriptorSubtype = USB_MIDI_SUBTYPE_MIDI_IN_JACK,
		.bJackType = USB_MIDI_JACK_TYPE_EXTERNAL,
		.bJackID = 0x02,
		.iJack = 0x00,
	},
	/* Table B-9: MIDI Adapter MIDI OUT Jack Descriptor (Embedded) */
	.out_embedded = {
		.head = {
			.bLength = sizeof(struct usb_midi_out_jack_descriptor),
			.bDescriptorType = USB_AUDIO_DT_CS_INTERFACE,
			.bDescriptorSubtype = USB_MIDI_SUBTYPE_MIDI_OUT_JACK,
			.bJackType = USB_MIDI_JACK_TYPE_EMBEDDED,
			.bJackID = 0x03,
			.bNrInputPins = 1,
		},
		.source[0] = {
			.baSourceID = 0x02,
			.baSourcePin = 0x01,
		},
		.tail = {
			.iJack = 0x00,
		}
	},
	/* Table B-10: MIDI Adapter MIDI OUT Jack Descriptor (External) */
	.out_external = {
		.head = {
			.bLength = sizeof(struct usb_midi_out_jack_descriptor),
			.bDescriptorType = USB_AUDIO_DT_CS_INTERFACE,
			.bDescriptorSubtype = USB_MIDI_SUBTYPE_MIDI_OUT_JACK,
			.bJackType = USB_MIDI_JACK_TYPE_EXTERNAL,
			.bJackID = 0x04,
			.bNrInputPins = 1,
		},
		.source[0] = {
			.baSourceID = 0x01,
			.baSourcePin = 0x01,
		},
		.tail = {
			.iJack = 0x00,
		},
	},
};

/*
 * Table B-5: MIDI Adapter Standard MS Interface Descriptor
 */
static const struct usb_interface_descriptor midi_streaming_iface[] = {{
	.bLength = USB_DT_INTERFACE_SIZE,
	.bDescriptorType = USB_DT_INTERFACE,
	.bInterfaceNumber = 1,
	.bAlternateSetting = 0,
	.bNumEndpoints = 2,
	.bInterfaceClass = USB_CLASS_AUDIO,
	.bInterfaceSubClass = USB_AUDIO_SUBCLASS_MIDISTREAMING,
	.bInterfaceProtocol = 0,
	.iInterface = 0,

	.endpoint = bulk_endp,

	.extra = &midi_streaming_functional_descriptors,
	.extralen = sizeof(midi_streaming_functional_descriptors)
} };

static const struct usb_interface ifaces[] = {{
	.num_altsetting = 1,
	.altsetting = audio_control_iface,
}, {
	.num_altsetting = 1,
	.altsetting = midi_streaming_iface,
} };

/*
 * Table B-2: MIDI Adapter Configuration Descriptor
 */
static const struct usb_config_descriptor config = {
	.bLength = USB_DT_CONFIGURATION_SIZE,
	.bDescriptorType = USB_DT_CONFIGURATION,
	.wTotalLength = 0, /* can be anything, it is updated automatically
			      when the usb code prepares the descriptor */
	.bNumInterfaces = 2, /* control and data */
	.bConfigurationValue = 1,
	.iConfiguration = 0,
	.bmAttributes = 0x80, /* bus powered */
	.bMaxPower = 0x32,

	.interface = ifaces,
};

static char usb_serial_number[25]; /* 12 bytes of desig and a \0 */

static const char * usb_strings[] = {
	"libopencm3.org",
	"MIDI demo",
	usb_serial_number
};

/* Buffer to be used for control requests. */
uint8_t usbd_control_buffer[128];

/* SysEx identity message, preformatted with correct USB framing information */
const uint8_t sysex_identity[] = {
	0x04,	/* USB Framing (3 byte SysEx) */
	0xf0,	/* SysEx start */
	0x7e,	/* non-realtime */
	0x00,	/* Channel 0 */
	0x04,	/* USB Framing (3 byte SysEx) */
	0x7d,	/* Educational/prototype manufacturer ID */
	0x66,	/* Family code (byte 1) */
	0x66,	/* Family code (byte 2) */
	0x04,	/* USB Framing (3 byte SysEx) */
	0x51,	/* Model number (byte 1) */
	0x19,	/* Model number (byte 2) */
	0x00,	/* Version number (byte 1) */
	0x04,	/* USB Framing (3 byte SysEx) */
	0x00,	/* Version number (byte 2) */
	0x01,	/* Version number (byte 3) */
	0x00,	/* Version number (byte 4) */
	0x05,	/* USB Framing (1 byte SysEx) */
	0xf7,	/* SysEx end */
	0x00,	/* Padding */
	0x00,	/* Padding */
};

static void usbmidi_data_rx_cb(usbd_device *usbd_dev, uint8_t ep)
{
	(void)ep;

	char buf[64];
	int len = usbd_ep_read_packet(usbd_dev, 0x01, buf, 64);

	/* This implementation treats any message from the host as a SysEx
	 * identity request. This works well enough providing the host
	 * packs the identify request in a single 8 byte USB message.
	 */
	if (len) {
		while (usbd_ep_write_packet(usbd_dev, 0x81, sysex_identity,
					    sizeof(sysex_identity)) == 0);
	}

	gpio_toggle(GPIOC, GPIO5);
}

static void usbmidi_set_config(usbd_device *usbd_dev, uint16_t wValue)
{
	(void)wValue;

	usbd_ep_setup(usbd_dev, 0x01, USB_ENDPOINT_ATTR_BULK, 64,
			usbmidi_data_rx_cb);
	usbd_ep_setup(usbd_dev, 0x81, USB_ENDPOINT_ATTR_BULK, 64, NULL);
}

static void button_send_event(usbd_device *usbd_dev, int pressed)
{
	char buf[4] = { 0x08, /* USB framing: virtual cable 0, note on */
			0x80, /* MIDI command: note on, channel 1 */
			60,   /* Note 60 (middle C) */
			64,   /* "Normal" velocity */
	};

	buf[0] |= pressed;
	buf[1] |= pressed << 4;

	while (usbd_ep_write_packet(usbd_dev, 0x81, buf, sizeof(buf)) == 0);
}

static void button_poll(usbd_device *usbd_dev)
{
	static uint32_t button_state = 0;

	/* This is a simple shift based debounce. It's simplistic because
	 * although this implements debounce adequately it does not have any
	 * noise suppression. It is also very wide (32-bits) because it can
	 * be polled in a very tight loop (no debounce timer).
	 */
	uint32_t old_button_state = button_state;
	button_state = (button_state << 1) | (GPIOA_IDR & 1);
	if ((0 == button_state) != (0 == old_button_state)) {
		button_send_event(usbd_dev, !!button_state);
	}
}

int main(void)
{
	usbd_device *usbd_dev;

	rcc_clock_setup_hse_3v3(&rcc_hse_8mhz_3v3[RCC_CLOCK_3V3_168MHZ]);

	rcc_periph_clock_enable(RCC_GPIOA);
	rcc_periph_clock_enable(RCC_OTGFS);

	/* USB pins */
	gpio_mode_setup(GPIOA, GPIO_MODE_AF, GPIO_PUPD_NONE, GPIO11 | GPIO12);
	gpio_set_af(GPIOA, GPIO_AF10, GPIO11 | GPIO12);

	desig_get_unique_id_as_string(usb_serial_number, sizeof(usb_serial_number));

	/* Button pin */
	gpio_mode_setup(GPIOA, GPIO_MODE_INPUT, GPIO_PUPD_NONE, GPIO0);

	usbd_dev = usbd_init(&otgfs_usb_driver, &dev, &config,
			usb_strings, 3,
			usbd_control_buffer, sizeof(usbd_control_buffer));

	usbd_register_set_config_callback(usbd_dev, usbmidi_set_config);

	while (1) {
		usbd_poll(usbd_dev);
		button_poll(usbd_dev);
	}
}