/* hw/w5500.c - libmisc/net.h implementation for the WIZnet W5500 chip
 *
 * Copyright (C) 2024  Luke T. Shumaker <lukeshu@lukeshu.com>
 * SPDX-Licence-Identifier: AGPL-3.0-or-later
 *
 * https://github.com/Wiznet/ioLibrary_Driver/blob/b981401e7f3d07015619adf44c13998e13e777f9/Ethernet/wizchip_conf.c
 * https://github.com/Wiznet/ioLibrary_Driver/blob/b981401e7f3d07015619adf44c13998e13e777f9/Ethernet/W5500/w5500.h
 * https://github.com/Wiznet/ioLibrary_Driver/blob/b981401e7f3d07015619adf44c13998e13e777f9/socket.c
 *
 * SPDX-Licence-Identifier: BSD-3-Clause
 *
 * Copyright (c)  2013, WIZnet Co., LTD.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the distribution.
 *     * Neither the name of the <ORGANIZATION> nor the names of its
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
 * THE POSSIBILITY OF SUCH DAMAGE.
 */

#include <pico/time.h>     /* for sleep_ms() */
#include <hardware/gpio.h> /* pico-sdk:hardware_gpio */

#include <libcr/coroutine.h>
#include <libmisc/vcall.h>

#include "hw/w5500_ll.h"
#include "hw/w5500.h"

/* Config *********************************************************************/

#include "config.h"

/* These are the default values of the Linux kernel's
 * net.ipv4.ip_local_port_range, so I figure they're probably good
 * values to use.  */
#ifndef CONFIG_W5500_LOCAL_PORT_MIN
#	define CONFIG_W5500_LOCAL_PORT_MIN 32768
#endif
#ifndef CONFIG_W5500_LOCAL_PORT_MAX
#	define CONFIG_W5500_LOCAL_PORT_MAX 60999
#endif

#ifndef CONFIG_W5500_NUM
#	error config.h must define CONFIG_W5500_NUM
#endif

/* C language *****************************************************************/

#define UNUSED(name)
#define ARRAY_LEN(ary) (sizeof(ary)/sizeof((ary)[0]))

/* mid-level utilities ********************************************************/

/*static uint16_t w5500_get_local_port(struct w5500 *self) {
 *	uint16_t ret = self->next_local_port++;
 *	if (self->next_local_port > CONFIG_W5500_LOCAL_PORT_MAX)
 *		self->next_local_port = CONFIG_W5500_LOCAL_PORT_MIN;
 *	return ret;
 *}
 */

static struct w5500 *w5500_sock_chip(struct _w5500_listener *listener) {
	assert(listener);
	assert(listener->socknum < 8);

	struct _w5500_listener *sock0 = &listener[-listener->socknum];
	assert(sock0);
	struct w5500 *chip =
		((void *)sock0) - offsetof(struct w5500, listeners);
	assert(chip);
	return chip;
}

static inline void w5500_sock_cmd(struct _w5500_listener *listener, uint8_t cmd) {
	assert(listener);
	struct w5500 *chip = w5500_sock_chip(listener);
	uint8_t socknum = listener->socknum;

	cr_mutex_lock(&listener->cmd_mu);
	w5500ll_write_sock_reg(chip->spidev, socknum, command, cmd);
	while (w5500ll_read_sock_reg(chip->spidev, socknum, command) != 0x00)
		cr_yield();
	cr_mutex_unlock(&listener->cmd_mu);
}

static void w5500_sock_cmd_close(struct _w5500_listener *listener) {
	assert(listener);
	struct w5500 *chip = w5500_sock_chip(listener);
	uint8_t socknum = listener->socknum;

	w5500_sock_cmd(listener, CMD_CLOSE);
	w5500ll_write_sock_reg(chip->spidev, socknum, interrupt, 0xFF);
	while (w5500ll_read_sock_reg(chip->spidev, socknum, state) != STATE_CLOSED)
		cr_yield();

	listener->active_conn.read_open = listener->active_conn.write_open = false;
}

static COROUTINE w5500_irq_cr(void *_chip) {
	struct w5500 *chip = _chip;
	cr_begin();

	for (;;) {
		cr_sema_wait(&chip->intr);
		if (w5500ll_read_common_reg(chip->spidev, chip_interrupt))
			w5500ll_write_common_reg(chip->spidev, chip_interrupt, 0xFF);

		uint8_t sockmask = w5500ll_read_common_reg(chip->spidev, sock_interrupt);
		for (uint8_t socknum = 0; socknum < 8; socknum++) {
			if (!(sockmask & (1<<socknum)))
				continue;
			struct _w5500_listener *listener = &chip->listeners[socknum];

			uint8_t sockintr = w5500ll_read_sock_reg(chip->spidev, socknum, interrupt);

			/* SOCKINTR_SEND_OK is useless.  */
			uint8_t listen_bits = sockintr & (SOCKINTR_TIMEOUT|SOCKINTR_CONN),
				read_bits   = sockintr & (SOCKINTR_TIMEOUT|SOCKINTR_RECV|SOCKINTR_FIN);

			if (listen_bits)
				cr_sema_signal(&listener->listen_sema);
			if (read_bits)
				cr_sema_signal(&listener->read_sema);

			w5500ll_write_sock_reg(chip->spidev, socknum, interrupt, sockintr);
		}
	}

	cr_end();
}

/* init() *********************************************************************/

static implements_net_conn *w5500_accept(implements_net_listener *_listener);
static ssize_t w5500_read(implements_net_conn *conn, void *buf, size_t count);
static ssize_t w5500_write(implements_net_conn *conn, void *buf, size_t count);
static int w5500_close(implements_net_conn *conn, bool rd, bool wr);

static struct net_listener_vtable w5500_listener_vtable = {
	.accept = w5500_accept,
};

static struct net_conn_vtable w5500_conn_vtable = {
	.read  = w5500_read,
	.write = w5500_write,
	.close = w5500_close,
};


static struct w5500 *w5500_chips[CONFIG_W5500_NUM] = {0};

static void w5500_intrhandler(uint gpio, uint32_t UNUSED(event_mask)) {
	for (size_t i = 0; i < ARRAY_LEN(w5500_chips); i++)
		if (w5500_chips[i] && w5500_chips[i]->pin_intr == gpio)
			cr_sema_signal_from_intrhandler(&w5500_chips[i]->intr);
}

void _w5500_init(struct w5500 *chip,
                 struct spi* spi, uint pin_intr, uint pin_reset,
                 struct net_eth_addr addr) {
	assert(chip);
	assert(spi);

	/* Initialize the data structures.  */
	*chip = (struct w5500){
		/* const-after-init */
		.spidev = spi,
		.pin_intr = pin_intr,
		.pin_reset = pin_reset,
		/* mutable */
		.next_local_port = CONFIG_W5500_LOCAL_PORT_MIN,
	};
	for (uint8_t i = 0; i < 8; i++) {
		chip->listeners[i] = (struct _w5500_listener){
			/* const-after-init */
			.vtable = &w5500_listener_vtable,
			.socknum = i,
			.active_conn = {
				/* const-after-init */
				.vtable = &w5500_conn_vtable,
				/* mutable */
				.read_open = false,
				.write_open = false,
			},
			/* mutable */
			.port = 0,
		};
	}

	/* Initialize the hardware.  */
	gpio_set_irq_enabled_with_callback(pin_intr, GPIO_IRQ_EDGE_FALL, true, w5500_intrhandler);
	gpio_set_dir(chip->pin_reset, GPIO_OUT);
	w5500_hard_reset(chip, addr);

	/* Finally, wire in the interrupt handler.  */
	cr_disable_interrupts();
	for (size_t i = 0; i < ARRAY_LEN(w5500_chips); i++) {
		if (w5500_chips[i] == NULL) {
			w5500_chips[i] = chip;
			break;
		}
	}
	cr_enable_interrupts();
	coroutine_add(w5500_irq_cr, chip);
}

/* chip methods ***************************************************************/

static inline void w5500_post_reset(struct w5500 *chip, struct net_eth_addr addr) {
	w5500ll_write_common_reg(chip->spidev, eth_addr, addr);

	/* The RP2040 needs a 1/sys_clk hysteresis between interrupts for us
	 * to notice them.  At the maximum-rated clock-rate of 133MHz, that
	 * means 7.5ns (but the sbc-harness overclocks the RP2040, so we
	 * could get away with even shorter).
	 *
	 * The hysteresis is (intlevel+1)*4/(150MHz) (if intlevel is
	 * non-zero), or (intlevel+1)*26.7ns; so even the shortest-possible
	 * hysteresis much larger than necessary for us.  */
	w5500ll_write_common_reg(chip->spidev, intlevel, encode_u16be(1));

	/* This implementation does not care about any of the chip-level
	 * interrupts.  */
	w5500ll_write_common_reg(chip->spidev, chip_interrupt_mask, 0);

	/* This implementation cares about interrupts for each socket.  */
	w5500ll_write_common_reg(chip->spidev, sock_interrupt_mask, 0xFF);
}

void w5500_hard_reset(struct w5500 *chip, struct net_eth_addr addr) {
	/* TODO: Replace blocking sleep_ms() with something libcr-friendly.  */
	gpio_put(chip->pin_reset, 0);
	sleep_ms(1); /* minimum of 500us */
	gpio_put(chip->pin_reset, 1);
	sleep_ms(2); /* minimum of 1ms */

	w5500_post_reset(chip, addr);
}

void w5500_soft_reset(struct w5500 *chip, struct net_eth_addr addr) {
	w5500ll_write_common_reg(chip->spidev, mode, CHIPMODE_RST);
	while (w5500ll_read_common_reg(chip->spidev, mode) & CHIPMODE_RST)
		cr_yield();

	w5500_post_reset(chip, addr);
}

void w5500_netcfg(struct w5500 *chip, struct w5500_netcfg cfg) {
	w5500ll_write_common_reg(chip->spidev, ip_gateway_addr, cfg.gateway_addr);
	w5500ll_write_common_reg(chip->spidev, ip_subnet_mask, cfg.subnet_mask);
	w5500ll_write_common_reg(chip->spidev, ip_addr, cfg.addr);
}

implements_net_listener *w5500_listen(struct w5500 *chip, uint8_t socknum,
                                      uint16_t port) {
	assert(chip);
	assert(socknum < 8);
	assert(port);

	assert(chip->listeners[socknum].port == 0);
	chip->listeners[socknum].port = port;

	return &chip->listeners[socknum];
}

/* listener methods ***********************************************************/

#define ASSERT_LISTENER()                                   \
	struct _w5500_listener *self =                      \
		VCALL_SELF(struct _w5500_listener,          \
		           implements_net_listener, _self); \
	struct w5500 *chip = w5500_sock_chip(self);         \
	uint8_t socknum = self->socknum;

static implements_net_conn *w5500_accept(implements_net_listener *_self) {
	ASSERT_LISTENER();

 restart:
	/* Mimics socket.c:socket().  */
	w5500_sock_cmd_close(self);
	w5500ll_write_sock_reg(chip->spidev, socknum, mode, SOCKMODE_TCP);
	w5500ll_write_sock_reg(chip->spidev, socknum, local_port, encode_u16be(self->port));
	w5500_sock_cmd(self, CMD_OPEN);
	while (w5500ll_read_sock_reg(chip->spidev, socknum, state) != STATE_TCP_INIT)
		cr_yield();

	/* Mimics socket.c:listen().  */
	w5500_sock_cmd(self, CMD_LISTEN);
	for (;;) {
		uint8_t state = w5500ll_read_sock_reg(chip->spidev, socknum, state);
		switch (state) {
		case STATE_TCP_LISTEN:
		case STATE_TCP_SYNRECV:
			cr_sema_wait(&self->listen_sema);
			break;
		case STATE_TCP_ESTABLISHED:
			self->active_conn.read_open = true;
			/* fall-through */
		case STATE_TCP_CLOSE_WAIT:
			self->active_conn.write_open = true;
			return &self->active_conn;
		default:
			goto restart;
		}
	}
}

/* conn methods ***************************************************************/

static struct _w5500_listener *w5500_conn_listener(struct _w5500_conn *conn) {
	assert(conn);

	struct _w5500_listener *list =
		((void *)conn) - offsetof(struct _w5500_listener, active_conn);
	return list;
}

#define ASSERT_CONN()                                                       \
	struct _w5500_conn *self =                                          \
		VCALL_SELF(struct _w5500_conn, implements_net_conn, _self); \
	struct _w5500_listener *listener = w5500_conn_listener(self);       \
	struct w5500 *chip = w5500_sock_chip(listener);                     \
	uint8_t socknum = listener->socknum;

static ssize_t w5500_write(implements_net_conn *_self, void *buf, size_t count) {
	ASSERT_CONN();
	assert(buf);
	assert(count);

	/* What we really want is to pause until we receive an ACK
	 * for some data we just queued, so that we can line up some
	 * new data to keep the buffer full.  But that's not what SEND_FINIAIUI, the
	 * SEND_FINISHED interrupt doesn't fire until we receive the
	 * *last* ACK for the data, when the buffer is entirely empty.
	 *
	 * Which means we basically have to busy-poll for space in the
	 * buffer becoming available.
	 *
	 * We'll add more data to the buffer whenever there is
	 * `min_free_space` in the buffer (or the rest of the data
	 * fits in the buffer).
	 *
	 * This `min_free_space` can probably stand to be tuned; must
	 * be >0, <=bufsize.  `1500-58` is the 100BaseT MTU minus the
	 * Ethernet+IP+TCP overhead.  */
	uint16_t bufsize = ((uint16_t)w5500ll_read_sock_reg(chip->spidev, socknum, tx_buf_size))*1024;
	uint16_t min_free_space = MIN(1500-58, bufsize/4);

	size_t done = 0;
	while (done < count) {
		if (!self->write_open)
			return -1;
		uint8_t state = w5500ll_read_sock_reg(chip->spidev, socknum, state);
		if (state != STATE_TCP_ESTABLISHED && state != STATE_TCP_CLOSE_WAIT)
			return -1;

		uint16_t freesize = decode_u16be(w5500ll_read_sock_reg(chip->spidev, socknum, tx_free_size));
		if (freesize < count-done && freesize < min_free_space) {
			/* Wait for more buffer space.  */
			cr_yield();
			continue;
		}

		/* Queue data to be sent.  */
		uint16_t ptr = decode_u16be(w5500ll_read_sock_reg(chip->spidev, socknum, tx_write_pointer));
		w5500ll_write(chip->spidev, ptr, CTL_BLOCK_SOCK(socknum, TX), &((char *)buf)[done], freesize);
		w5500ll_write_sock_reg(chip->spidev, socknum, tx_write_pointer, encode_u16be(ptr+freesize));

		/* Submit the queue.  */
		w5500_sock_cmd(listener, CMD_SEND);
		done += freesize;
	}
	return done;
}

static ssize_t w5500_read(implements_net_conn *_self, void *buf, size_t count) {
	ASSERT_CONN();
	assert(buf);
	assert(count);

	size_t done = 0;
	while (!done) {
		if (!self->read_open)
			return -1;
		uint8_t state = w5500ll_read_sock_reg(chip->spidev, socknum, state);
		switch (state) {
		case STATE_TCP_CLOSE_WAIT:
			return 0; /* EOF */
		case STATE_TCP_ESTABLISHED: case STATE_TCP_FIN_WAIT:
			break; /* OK */
		default:
			return -1;
		}

		uint16_t avail = decode_u16be(w5500ll_read_sock_reg(chip->spidev, socknum, rx_size));
		if (!avail) {
			cr_sema_wait(&listener->read_sema);
			continue;
		}
		if ((size_t)avail > count)
			avail = count;
		uint16_t ptr = decode_u16be(w5500ll_read_sock_reg(chip->spidev, socknum, rx_read_pointer));
		w5500ll_read(chip->spidev, ptr, CTL_BLOCK_SOCK(socknum, RX), &((char *)buf)[done], avail);
		w5500ll_write_sock_reg(chip->spidev, socknum, rx_read_pointer, encode_u16be(ptr+avail));

		w5500_sock_cmd(listener, CMD_RECV);
		done += avail;
	}
	return done;
}

static int w5500_close(implements_net_conn *_self, bool rd, bool wr) {
	ASSERT_CONN();

	if (rd)
		self->read_open = false;

	if (wr && self->write_open) {
		w5500_sock_cmd(listener, CMD_DISCON);
		while (self->write_open) {
			uint8_t state = w5500ll_read_sock_reg(chip->spidev, socknum, state);
			switch (state) {
			case STATE_TCP_FIN_WAIT:
				self->write_open = false;
				/* Can still read */
				if (!self->read_open)
					w5500_sock_cmd_close(listener);
				break;
			case STATE_CLOSED:
				self->write_open = false;
				break;
			}
		}
	}

	return 0;
}