/*
 * lpbbfake.c -- test harness: virtual I2C bit-bang bridge for if_ic PoCs.
 *
 * Registers a driver named "lpbb" on the ISA bus (identify-driven, no real
 * hardware) and provides the iicbb_if bit-bang methods against virtual
 * lines: SDA always reads 0 (ACK), SCL always reads 1 (no clock stretch).
 *
 * This provides an iicbus instance on any system (incl. QEMU guests with
 * no I2C controller), so that if_ic (the I2C IP network driver) can attach
 * and its ioctl/output paths be exercised.
 *
 * DF-4939 / DF-4940 evidence harness. Not part of sys/.
 */
#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/systm.h>
#include <sys/module.h>
#include <sys/bus.h>

#include <bus/iicbus/iiconf.h>
#include <bus/iicbus/iicbus.h>

#include "iicbb_if.h"

static void	lpbbfake_identify(driver_t *, device_t);
static int	lpbbfake_probe(device_t);
static int	lpbbfake_attach(device_t);
static int	lpbbfake_detach(device_t);

static int	lpbbfake_callback(device_t, int, caddr_t);
static void	lpbbfake_setsda(device_t, int val);
static void	lpbbfake_setscl(device_t, int val);
static int	lpbbfake_getsda(device_t);
static int	lpbbfake_getscl(device_t);
static int	lpbbfake_reset(device_t, u_char speed, u_char addr,
		    u_char *oldaddr);

struct lpbbfake_softc {
	device_t	child;		/* our iicbb child */
};

static device_method_t lpbbfake_methods[] = {
	/* device interface */
	DEVMETHOD(device_identify,	lpbbfake_identify),
	DEVMETHOD(device_probe,		lpbbfake_probe),
	DEVMETHOD(device_attach,	lpbbfake_attach),
	DEVMETHOD(device_detach,	lpbbfake_detach),

	/* iicbb interface (we are the bit-bang backend) */
	DEVMETHOD(iicbb_callback,	lpbbfake_callback),
	DEVMETHOD(iicbb_setsda,		lpbbfake_setsda),
	DEVMETHOD(iicbb_setscl,		lpbbfake_setscl),
	DEVMETHOD(iicbb_getsda,		lpbbfake_getsda),
	DEVMETHOD(iicbb_getscl,		lpbbfake_getscl),
	DEVMETHOD(iicbb_reset,		lpbbfake_reset),

	DEVMETHOD_END
};

static driver_t lpbb_driver = {
	"lpbb",
	lpbbfake_methods,
	sizeof(struct lpbbfake_softc),
};

static devclass_t lpbb_devclass;

DRIVER_MODULE(lpbbfake, isa, lpbb_driver, lpbb_devclass, NULL, NULL);
MODULE_VERSION(lpbbfake, 1);

static void
lpbbfake_identify(driver_t *driver, device_t parent)
{

	/* one instance, no resources */
	if (device_find_child(parent, "lpbb", 0) == NULL)
		BUS_ADD_CHILD(parent, parent, 0, "lpbb", 0);
}

static int
lpbbfake_probe(device_t dev)
{
	device_set_desc(dev, "virtual I2C bit-bang bridge (lpbbfake)");
	return (BUS_PROBE_DEFAULT);
}

static int
lpbbfake_attach(device_t dev)
{
	struct lpbbfake_softc *sc = device_get_softc(dev);

	sc->child = device_add_child(dev, "iicbb", -1);
	if (sc->child == NULL)
		return (ENXIO);
	return (bus_generic_attach(dev));
}

static int
lpbbfake_detach(device_t dev)
{
	struct lpbbfake_softc *sc = device_get_softc(dev);
	device_t child = sc->child;

	bus_generic_detach(dev);
	if (child != NULL)
		device_delete_child(dev, child);
	sc->child = NULL;
	return (0);
}

static int
lpbbfake_callback(device_t dev, int index, caddr_t data)
{
	return (0);
}

static void
lpbbfake_setsda(device_t dev, int val)
{
}

static void
lpbbfake_setscl(device_t dev, int val)
{
}

static int
lpbbfake_getsda(device_t dev)
{
	return (0);		/* slave always ACKs */
}

static int
lpbbfake_getscl(device_t dev)
{
	return (1);		/* no clock stretching */
}

static int
lpbbfake_reset(device_t dev, u_char speed, u_char addr, u_char *oldaddr)
{
	if (oldaddr != NULL)
		*oldaddr = 0x55;
	return (0);
}