/**
 * @file
 * This driver implements a bitbang jtag interface using gpio lines via
 * router ob BCM63XX SoC.
 * The aim of this driver implementation is use system GPIOs but avoid the
 * need for a additional kernel driver.
 * (Note memory mapped IO is another option, however it doesn't mix well with
 * the kernel gpiolib driver - which makes sense I guess.)
 *
 * A gpio is required for tck, tms, tdi and tdo. One or both of srst and trst
 * must be also be specified. The required jtag gpios are specified via the
 * bcm63xx_gpio_jtag_nums command or the relevant bcm63xx_gpio_XXX_num commang.
 * The srst and trst gpios are set via the bcm63xx_gpio_srst_num and
 * bcm63xx_gpio_trst_num respectively. GPIO numbering follows the kernel
 * convention of starting from 0.
 *
 * The gpios should not be in use by another entity, and must not be requested
 * by a kernel driver without also being exported by it (otherwise they can't
 * be exported by bcm63xx_).
 *
 * The bcm63xx gpio interface can only manipulate one gpio at a time, so the
 * bitbang write handler remembers the last state for tck, tms, tdi to avoid
 * superfluous writes.
 * For speed the bcm63xx "value" entry is opened at init and held open.
 * This results in considerable gains over open-write-close (45s vs 900s)
 *
 * Further work could address:
 *  -srst and trst open drain/ push pull
 *  -configurable active high/low for srst & trst
 */
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <jtag/interface.h>
#include "bitbang.h"

#include <sys/mman.h>

/*
 * Helper func to determine if gpio number valid
 *
 * Assume here that there will be less than 1000 gpios on a system
 */
static int is_gpio_valid(int gpio)
{
	return gpio >= 0 && gpio < 32;
}

off_t address_dir = NULL;
off_t address_val = NULL;

static int dev_mem_fd = -1;
static volatile uint32_t *pio_base = NULL;
static volatile uint32_t *pval_base = NULL;
static volatile uint32_t *pads_base = NULL;
static unsigned int jtag_delay = 0;


static void set_dir_gpio(const int gpio, const int direction)
{
	if(direction)
		*pio_base |= 1 << gpio;
	else
		*pio_base &= ~(1 << gpio);
}


static void set_value_gpio(const int gpio, const int value)
{
	if(value)
		*pval_base |= 1 << gpio;
	else
		*pval_base &= ~(1 << gpio);

	for (unsigned int i = 0; i < jtag_delay; i++)
		asm volatile ("");
}

static int read_gpio(const int gpio)
{
	uint32_t val = *pval_base & (1 << gpio);
	val = val ? 1 : 0;
	return val;
}

static int setup_bcm63xx_gpio(int gpio, int is_output, int init_high)
{
	char buf[40];
	char gpiostr[4];
	int ret;

	if (!is_gpio_valid(gpio))
		return ERROR_OK;

	if((address_dir == NULL) || (address_val == NULL)){
		perror("address of gpio register don't set");
		return ERROR_FAIL; 
	}


	if( dev_mem_fd < 0 )
	{

		dev_mem_fd = open("/dev/mem", O_RDWR | O_SYNC);
		if (dev_mem_fd < 0) {
			perror("open");
			return ERROR_FAIL;
		}

		const uint32_t mapped_size = getpagesize();

		const off_t target_mmap = address_dir & ~(off_t)(mapped_size - 1);

		pads_base = mmap(NULL, mapped_size, PROT_READ | PROT_WRITE,
					MAP_SHARED, dev_mem_fd, target_mmap);

		if (pads_base == MAP_FAILED) {
			perror("mmap. Check correct register address.");
			close(dev_mem_fd);
			return ERROR_FAIL;
		}

		pio_base 	= (char*)pads_base + (unsigned)(address_dir -  target_mmap);
		pval_base 	= (char*)pads_base + (unsigned)(address_val - target_mmap);
	}

	set_dir_gpio(gpio, is_output);
	set_value_gpio(gpio, init_high);

	return 0;
}

/* gpio numbers for each gpio. Negative values are invalid */
static int tck_gpio = -1;
static int tms_gpio = -1;
static int tdi_gpio = -1;
static int tdo_gpio = -1;
static int trst_gpio = -1;
static int srst_gpio = -1;
static int swclk_gpio = -1;
static int swdio_gpio = -1;

/*
 * file descriptors for /sys/class/gpio/gpioXX/value
 * Set up during init.
 */
static int tck_fd = -1;
static int tms_fd = -1;
static int tdi_fd = -1;
static int tdo_fd = -1;
static int trst_fd = -1;
static int srst_fd = -1;
static int swclk_fd = -1;
static int swdio_fd = -1;

static int last_swclk;
static int last_swdio;
static bool last_stored;
static bool swdio_input;

static void bcm63xx_gpio_swdio_drive(bool is_output)
{
	set_dir_gpio(swdio_gpio, is_output ? 1 : 0);

	last_stored = false;
	swdio_input = !is_output;
}

static int bcm63xx_gpio_swdio_read(void)
{
	return read_gpio(swdio_gpio);
}

static void bcm63xx_gpio_swdio_write(int swclk, int swdio)
{

	const char one[] = "1";
	const char zero[] = "0";

	size_t bytes_written;

	if (!swdio_input) {
		if (!last_stored || (swdio != last_swdio)) {
			set_value_gpio(swdio_gpio, swdio ? 1 : 0);
		}

	}

	/* write swclk last */
	if (!last_stored || (swclk != last_swclk)) {
			set_value_gpio(swclk_gpio, swclk ? 1 : 0);
	}

	last_swdio = swdio;
	last_swclk = swclk;
	last_stored = true;
}

/*
 * Bitbang interface read of TDO
 *
 * The bcm63xx value will read back either '0' or '1'. The trick here is to call
 * lseek to bypass buffering in the bcm63xx kernel driver.
 */
static int bcm63xx_gpio_read(void)
{
	return read_gpio(tdo_gpio);
}

/*
 * Bitbang interface write of TCK, TMS, TDI
 *
 * Seeing as this is the only function where the outputs are changed,
 * we can cache the old value to avoid needlessly writing it.
 */
static void bcm63xx_gpio_write(int tck, int tms, int tdi)
{
	if (swd_mode) {
		bcm63xx_gpio_swdio_write(tck, tdi);
		return;
	}

	const char one[] = "1";
	const char zero[] = "0";

	static int last_tck;
	static int last_tms;
	static int last_tdi;

	static int first_time;
	size_t bytes_written;

	if (!first_time) {
		last_tck = !tck;
		last_tms = !tms;
		last_tdi = !tdi;
		first_time = 1;
	}

	if (tdi != last_tdi) {
		set_value_gpio(tdi_gpio,tdi);
	}

	if (tms != last_tms) {
		set_value_gpio(tms_gpio,tms);
	}

	/* write clk last */
	if (tck != last_tck) {
		set_value_gpio(tck_gpio,tck);

	}

	last_tdi = tdi;
	last_tms = tms;
	last_tck = tck;
}

/*
 * Bitbang interface to manipulate reset lines SRST and TRST
 *
 * (1) assert or (0) deassert reset lines
 */
static void bcm63xx_gpio_reset(int trst, int srst)
{
	LOG_DEBUG("bcm63xx_gpio_reset");
	const char one[] = "1";
	const char zero[] = "0";
	size_t bytes_written;

	/* assume active low */
	if (srst_fd >= 0) {
		set_value_gpio(srst_gpio,srst);
	}

	/* assume active low */
	if (trst_fd >= 0) {
		set_value_gpio(trst_gpio,trst);
	}
}

COMMAND_HANDLER(bcm63xx_gpio_handle_jtag_gpionums)
{
	if (CMD_ARGC == 4) {
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], tms_gpio);
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[2], tdi_gpio);
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[3], tdo_gpio);
	} else if (CMD_ARGC != 0) {
		return ERROR_COMMAND_SYNTAX_ERROR;
	}

	command_print(CMD_CTX,
			"bcm63xx_GPIO nums: tck = %d, tms = %d, tdi = %d, tdo = %d",
			tck_gpio, tms_gpio, tdi_gpio, tdo_gpio);

	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_handle_jtag_gpionum_tck)
{
	if (CMD_ARGC == 1)
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tck_gpio);

	command_print(CMD_CTX, "bcm63xx_GPIO num: tck = %d", tck_gpio);
	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_handle_jtag_gpionum_tms)
{
	if (CMD_ARGC == 1)
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tms_gpio);

	command_print(CMD_CTX, "bcm63xx_GPIO num: tms = %d", tms_gpio);
	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_handle_jtag_gpionum_tdo)
{
	if (CMD_ARGC == 1)
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdo_gpio);

	command_print(CMD_CTX, "bcm63xx_GPIO num: tdo = %d", tdo_gpio);
	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_handle_jtag_gpionum_tdi)
{
	if (CMD_ARGC == 1)
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], tdi_gpio);

	command_print(CMD_CTX, "bcm63xx_GPIO num: tdi = %d", tdi_gpio);
	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_handle_jtag_gpionum_srst)
{
	if (CMD_ARGC == 1)
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], srst_gpio);

	command_print(CMD_CTX, "bcm63xx_GPIO num: srst = %d", srst_gpio);
	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_handle_jtag_gpionum_trst)
{
	if (CMD_ARGC == 1)
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], trst_gpio);

	command_print(CMD_CTX, "bcm63xx_GPIO num: trst = %d", trst_gpio);
	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_handle_swd_gpionums)
{
	if (CMD_ARGC == 2) {
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[1], swdio_gpio);
	} else if (CMD_ARGC != 0) {
		return ERROR_COMMAND_SYNTAX_ERROR;
	}

	command_print(CMD_CTX,
			"bcm63xx_GPIO nums: swclk = %d, swdio = %d",
			swclk_gpio, swdio_gpio);

	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_handle_swd_gpionum_swclk)
{
	if (CMD_ARGC == 1)
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swclk_gpio);

	command_print(CMD_CTX, "bcm63xx_GPIO num: swclk = %d", swclk_gpio);
	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_handle_swd_gpionum_swdio)
{
	if (CMD_ARGC == 1)
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], swdio_gpio);

	command_print(CMD_CTX, "bcm63xx_GPIO num: swdio = %d", swdio_gpio);
	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_jtag_delay)
{
	if (CMD_ARGC == 1)
		COMMAND_PARSE_NUMBER(int, CMD_ARGV[0], jtag_delay);

	command_print(CMD_CTX, "bcm63xx_GPIO jtag_delay:= %d tics", jtag_delay);
	return ERROR_OK;
}

COMMAND_HANDLER(bcm63xx_gpio_adresses)
{
	if (CMD_ARGC == 2) {
		COMMAND_PARSE_NUMBER(u32, CMD_ARGV[0], address_dir);
		COMMAND_PARSE_NUMBER(u32, CMD_ARGV[1], address_val);
	} else if (CMD_ARGC != 0) {
		return ERROR_COMMAND_SYNTAX_ERROR;
	}

	command_print(CMD_CTX,
			"bcm63xx_GPIO address: direction = %x, value = %x",
			address_dir, address_val);

	return ERROR_OK;
}


static const struct command_registration bcm63xx_gpio_command_handlers[] = {
	{
		.name = "bcm63xx_gpio_jtag_nums",
		.handler = &bcm63xx_gpio_handle_jtag_gpionums,
		.mode = COMMAND_CONFIG,
		.help = "gpio numbers for tck, tms, tdi, tdo. (in that order)",
		.usage = "(tck tms tdi tdo)* ",
	},
	{
		.name = "bcm63xx_gpio_tck_num",
		.handler = &bcm63xx_gpio_handle_jtag_gpionum_tck,
		.mode = COMMAND_CONFIG,
		.help = "gpio number for tck.",
	},
	{
		.name = "bcm63xx_gpio_tms_num",
		.handler = &bcm63xx_gpio_handle_jtag_gpionum_tms,
		.mode = COMMAND_CONFIG,
		.help = "gpio number for tms.",
	},
	{
		.name = "bcm63xx_gpio_tdo_num",
		.handler = &bcm63xx_gpio_handle_jtag_gpionum_tdo,
		.mode = COMMAND_CONFIG,
		.help = "gpio number for tdo.",
	},
	{
		.name = "bcm63xx_gpio_tdi_num",
		.handler = &bcm63xx_gpio_handle_jtag_gpionum_tdi,
		.mode = COMMAND_CONFIG,
		.help = "gpio number for tdi.",
	},
	{
		.name = "bcm63xx_gpio_srst_num",
		.handler = &bcm63xx_gpio_handle_jtag_gpionum_srst,
		.mode = COMMAND_CONFIG,
		.help = "gpio number for srst.",
	},
	{
		.name = "bcm63xx_gpio_trst_num",
		.handler = &bcm63xx_gpio_handle_jtag_gpionum_trst,
		.mode = COMMAND_CONFIG,
		.help = "gpio number for trst.",
	},
	{
		.name = "bcm63xx_gpio_swd_nums",
		.handler = &bcm63xx_gpio_handle_swd_gpionums,
		.mode = COMMAND_CONFIG,
		.help = "gpio numbers for swclk, swdio. (in that order)",
		.usage = "(swclk swdio)* ",
	},
	{
		.name = "bcm63xx_gpio_swclk_num",
		.handler = &bcm63xx_gpio_handle_swd_gpionum_swclk,
		.mode = COMMAND_CONFIG,
		.help = "gpio number for swclk.",
	},
	{
		.name = "bcm63xx_gpio_swdio_num",
		.handler = &bcm63xx_gpio_handle_swd_gpionum_swdio,
		.mode = COMMAND_CONFIG,
		.help = "gpio number for swdio.",
	},
	{
		.name = "bcm63xx_gpio_jtag_delay",
		.handler = &bcm63xx_gpio_jtag_delay,
		.mode = COMMAND_CONFIG,
		.help = "qty tics gpio delay.",
	},
	{
		.name = "bcm63xx_gpio_adresses",
		.handler = &bcm63xx_gpio_adresses,
		.mode = COMMAND_CONFIG,
		.help = "addresses for direction and value setup. (in that order)",
		.usage = "(address_dir address_val)* ",
	},
	COMMAND_REGISTRATION_DONE
};

static int bcm63xx_gpio_init(void);
static int bcm63xx_gpio_quit(void);

static const char * const bcm63xx_gpio_transports[] = { "jtag", "swd", NULL };

struct jtag_interface bcm63xxgpio_interface = {
	.name = "bcm63xxgpio",
	.supported = DEBUG_CAP_TMS_SEQ,
	.execute_queue = bitbang_execute_queue,
	.transports = bcm63xx_gpio_transports,
	.swd = &bitbang_swd,
	.commands = bcm63xx_gpio_command_handlers,
	.init = bcm63xx_gpio_init,
	.quit = bcm63xx_gpio_quit,
};

static struct bitbang_interface bcm63xx_gpio_bitbang = {
	.read = bcm63xx_gpio_read,
	.write = bcm63xx_gpio_write,
	.reset = bcm63xx_gpio_reset,
	.swdio_read = bcm63xx_gpio_swdio_read,
	.swdio_drive = bcm63xx_gpio_swdio_drive,
	.blink = 0
};

static void unusing_all_gpio(void)
{
	munmap(pads_base, sysconf(_SC_PAGE_SIZE));
	close(dev_mem_fd);
	LOG_INFO("unusing_all_gpio\n");
}

static bool bcm63xx_gpio_jtag_mode_possible(void)
{
	if (!is_gpio_valid(tck_gpio))
		return 0;
	if (!is_gpio_valid(tms_gpio))
		return 0;
	if (!is_gpio_valid(tdi_gpio))
		return 0;
	if (!is_gpio_valid(tdo_gpio))
		return 0;
	return 1;
}

static bool bcm63xx_gpio_swd_mode_possible(void)
{
	if (!is_gpio_valid(swclk_gpio))
		return 0;
	if (!is_gpio_valid(swdio_gpio))
		return 0;
	return 1;
}

static int bcm63xx_gpio_init(void)
{
	bitbang_interface = &bcm63xx_gpio_bitbang;

	LOG_INFO("bcm63xx_gpio JTAG/SWD bitbang driver");

	if (bcm63xx_gpio_jtag_mode_possible()) {
		if (bcm63xx_gpio_swd_mode_possible())
			LOG_INFO("JTAG and SWD modes enabled");
		else
			LOG_INFO("JTAG only mode enabled (specify swclk and swdio gpio to add SWD mode)");
		if (!is_gpio_valid(trst_gpio) && !is_gpio_valid(srst_gpio)) {
			LOG_ERROR("Require at least one of trst or srst gpios to be specified");
			return ERROR_JTAG_INIT_FAILED;
		}
	} else if (bcm63xx_gpio_swd_mode_possible()) {
		LOG_INFO("SWD only mode enabled (specify tck, tms, tdi and tdo gpios to add JTAG mode)");
	} else {
		LOG_ERROR("Require tck, tms, tdi and tdo gpios for JTAG mode and/or swclk and swdio gpio for SWD mode");
		return ERROR_JTAG_INIT_FAILED;
	}


	/*
	 * Configure TDO as an input, and TDI, TCK, TMS, TRST, SRST
	 * as outputs.  Drive TDI and TCK low, and TMS/TRST/SRST high.
	 * For SWD, SWCLK and SWDIO are configures as output high.
	 */
	if (tck_gpio >= 0) {
		tck_fd = setup_bcm63xx_gpio(tck_gpio, 1, 0);
		if (tck_fd < 0)
			goto out_error;
	}

	if (tms_gpio >= 0) {
		tms_fd = setup_bcm63xx_gpio(tms_gpio, 1, 1);
		if (tms_fd < 0)
			goto out_error;
	}

	if (tdi_gpio >= 0) {
		tdi_fd = setup_bcm63xx_gpio(tdi_gpio, 1, 0);
		if (tdi_fd < 0)
			goto out_error;
	}

	if (tdo_gpio >= 0) {
		tdo_fd = setup_bcm63xx_gpio(tdo_gpio, 0, 0);
		if (tdo_fd < 0)
			goto out_error;
	}

	/* assume active low*/
	if (trst_gpio >= 0) {
		trst_fd = setup_bcm63xx_gpio(trst_gpio, 1, 1);
		if (trst_fd < 0)
			goto out_error;
	}

	/* assume active low*/
	if (srst_gpio >= 0) {
		srst_fd = setup_bcm63xx_gpio(srst_gpio, 1, 1);
		if (srst_fd < 0)
			goto out_error;
	}

	if (swclk_gpio >= 0) {
		swclk_fd = setup_bcm63xx_gpio(swclk_gpio, 1, 0);
		if (swclk_fd < 0)
			goto out_error;
	}

	if (swdio_gpio >= 0) {
		swdio_fd = setup_bcm63xx_gpio(swdio_gpio, 1, 0);
		if (swdio_fd < 0)
			goto out_error;
	}

	if (bcm63xx_gpio_swd_mode_possible()) {
		if (swd_mode)
			bitbang_swd_switch_seq(JTAG_TO_SWD);
		else
			bitbang_swd_switch_seq(SWD_TO_JTAG);
	}

	return ERROR_OK;

out_error:
	unusing_all_gpio();
	return ERROR_JTAG_INIT_FAILED;
}

static int bcm63xx_gpio_quit(void)
{
	unusing_all_gpio();
	return ERROR_OK;
}