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wasm3/platforms/embedded/fomu/src/usb-epfifo.c  view on Meta::CPAN

#include <usb.h>
#include <irq.h>
#include <generated/csr.h>
#include <string.h>
#include <usb.h>

#ifdef CSR_USB_EP_0_OUT_EV_PENDING_ADDR

static volatile uint8_t usb_rx_fifo[64];
static volatile uint8_t usb_rx_fifo_rd;
static volatile uint8_t usb_rx_fifo_wr;

static volatile int have_new_address;
static volatile uint8_t new_address;

// Firmware versions < 1.9 didn't have usb_address_write()
static inline void usb_set_address_wrapper(uint8_t address) {
    if (version_major_read() < 1)
        return;
    if (version_minor_read() < 9)
        return;
    usb_address_write(address);
}

// Note that our PIDs are only bits 2 and 3 of the token,
// since all other bits are effectively redundant at this point.
enum USB_PID {
    USB_PID_OUT   = 0,
    USB_PID_SOF   = 1,
    USB_PID_IN    = 2,
    USB_PID_SETUP = 3,
};

enum epfifo_response {
    EPF_ACK = 0,
    EPF_NAK = 1,
    EPF_NONE = 2,
    EPF_STALL = 3,
};

#define USB_EV_ERROR 1
#define USB_EV_PACKET 2

void usb_disconnect(void) {
    usb_ep_0_out_ev_enable_write(0);
    usb_ep_0_in_ev_enable_write(0);
    irq_setmask(irq_getmask() & ~(1 << USB_INTERRUPT));
    usb_pullup_out_write(0);
    usb_set_address_wrapper(0);
}

void usb_connect(void) {

    usb_set_address_wrapper(0);
    usb_ep_0_out_ev_pending_write(usb_ep_0_out_ev_enable_read());
    usb_ep_0_in_ev_pending_write(usb_ep_0_in_ev_pending_read());
    usb_ep_0_out_ev_enable_write(USB_EV_PACKET | USB_EV_ERROR);
    usb_ep_0_in_ev_enable_write(USB_EV_PACKET | USB_EV_ERROR);

    usb_ep_1_in_ev_pending_write(usb_ep_1_in_ev_enable_read());
    usb_ep_1_in_ev_enable_write(USB_EV_PACKET | USB_EV_ERROR);

    usb_ep_2_out_ev_pending_write(usb_ep_2_out_ev_enable_read());
    usb_ep_2_in_ev_pending_write(usb_ep_2_in_ev_pending_read());
    usb_ep_2_out_ev_enable_write(USB_EV_PACKET | USB_EV_ERROR);
    usb_ep_2_in_ev_enable_write(USB_EV_PACKET | USB_EV_ERROR);

    // Accept incoming data by default.
    usb_ep_0_out_respond_write(EPF_ACK);
    usb_ep_2_out_respond_write(EPF_ACK);

    // Reject outgoing data, since we have none to give yet.
    usb_ep_0_in_respond_write(EPF_NAK);
    usb_ep_1_in_respond_write(EPF_NAK);
    usb_ep_2_in_respond_write(EPF_NAK);

    usb_pullup_out_write(1);

	irq_setmask(irq_getmask() | (1 << USB_INTERRUPT));
}

void usb_init(void) {
    usb_pullup_out_write(0);
    return;
}

#define EP0OUT_BUFFERS 4
__attribute__((aligned(4)))
static uint8_t volatile usb_ep0out_buffer[EP0OUT_BUFFERS][256];
static uint8_t volatile usb_ep0out_buffer_len[EP0OUT_BUFFERS];
static uint8_t volatile usb_ep0out_last_tok[EP0OUT_BUFFERS];
static volatile uint8_t usb_ep0out_wr_ptr;
static volatile uint8_t usb_ep0out_rd_ptr;
static const int max_byte_length = 64;

static const uint8_t * volatile current_data;
static volatile int current_length;
static volatile int data_offset;
static volatile int data_to_send;
static int next_packet_is_empty;
static volatile uint8_t ep2_fifo_bytes;

__attribute__((section(".ramtext")))
static void process_tx(void) {

    // Don't allow requeueing -- only queue more data if we're
    // currently set up to respond NAK.
    if (usb_ep_0_in_respond_read() != EPF_NAK) {
        return;
    }

    // Prevent us from double-filling the buffer.
    if (!usb_ep_0_in_ibuf_empty_read()) {
        return;
    }

    if (!current_data || !current_length) {
        return;
    }

    data_offset += data_to_send;

    data_to_send = current_length - data_offset;

    // Clamp the data to the maximum packet length
    if (data_to_send > max_byte_length) {
        data_to_send = max_byte_length;
        next_packet_is_empty = 0;
    }
    else if (data_to_send == max_byte_length) {
        next_packet_is_empty = 1;
    }
    else if (next_packet_is_empty) {
        next_packet_is_empty = 0;
        data_to_send = 0;
    }
    else if (current_data == NULL || data_to_send <= 0) {
        next_packet_is_empty = 0;
        current_data = NULL;