/*      $NetBSD: scmdi2c.c,v 1.2 2022/03/30 00:06:50 pgoyette Exp $     */

/*
* Copyright (c) 2021 Brad Spencer <[email protected]>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: scmdi2c.c,v 1.2 2022/03/30 00:06:50 pgoyette Exp $");

/*
* I2C driver for the Sparkfun Serial motor controller.
* Uses the common code to do the actual work.
*/

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/device.h>
#include <sys/module.h>
#include <sys/conf.h>
#include <sys/sysctl.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/pool.h>
#include <sys/kmem.h>

#include <dev/i2c/i2cvar.h>
#include <dev/spi/spivar.h>
#include <dev/ic/scmdreg.h>
#include <dev/ic/scmdvar.h>

extern struct cdevsw scmd_cdevsw;

extern void     scmd_attach(struct scmd_sc *);

static int      scmdi2c_poke(i2c_tag_t, i2c_addr_t, bool);
static int      scmdi2c_match(device_t, cfdata_t, void *);
static void     scmdi2c_attach(device_t, device_t, void *);
static int      scmdi2c_detach(device_t, int);
static int      scmdi2c_activate(device_t, enum devact);

#define SCMD_DEBUG
#ifdef SCMD_DEBUG
#define DPRINTF(s, l, x) \
   do { \
       if (l <= s->sc_scmddebug) \
           printf x; \
   } while (/*CONSTCOND*/0)
#else
#define DPRINTF(s, l, x)
#endif

CFATTACH_DECL_NEW(scmdi2c, sizeof(struct scmd_sc),
   scmdi2c_match, scmdi2c_attach, scmdi2c_detach, scmdi2c_activate);

static int
scmdi2c_read_reg_direct(i2c_tag_t tag, i2c_addr_t addr, uint8_t reg,
   uint8_t *buf)
{
       return iic_exec(tag, I2C_OP_READ_WITH_STOP, addr, &reg, 1, buf,
           1, 0);
}

static int
scmdi2c_read_reg(struct scmd_sc *sc, uint8_t reg, uint8_t *buf)
{
       return scmdi2c_read_reg_direct(sc->sc_tag, sc->sc_addr, reg, buf);
}

static int
scmdi2c_write_reg_direct(i2c_tag_t tag, i2c_addr_t addr, uint8_t reg,
   uint8_t buf)
{
       return iic_exec(tag, I2C_OP_WRITE_WITH_STOP, addr, &reg, 1, &buf,
           1, 0);
}

static int
scmdi2c_write_reg(struct scmd_sc *sc, uint8_t reg, uint8_t buf)
{
       return scmdi2c_write_reg_direct(sc->sc_tag, sc->sc_addr, reg, buf);
}

static int
scmdi2c_acquire_bus(struct scmd_sc *sc)
{
       return(iic_acquire_bus(sc->sc_tag, 0));
}

static void
scmdi2c_release_bus(struct scmd_sc *sc)
{
       iic_release_bus(sc->sc_tag, 0);
}

static int
scmdi2c_poke(i2c_tag_t tag, i2c_addr_t addr, bool matchdebug)
{
       uint8_t reg = SCMD_REG_ID;
       uint8_t buf;
       int error;

       error = scmdi2c_read_reg_direct(tag, addr, reg, &buf);
       if (matchdebug) {
               printf("poke X 1: %d %02x %d\n", addr, buf, error);
       }
       return error;
}

static int
scmdi2c_match(device_t parent, cfdata_t match, void *aux)
{
       struct i2c_attach_args *ia = aux;
       int error, match_result;
       const bool matchdebug = false;

       if (iic_use_direct_match(ia, match, NULL, &match_result))
               return match_result;

       if (matchdebug) {
               printf("Looking at ia_addr: %x\n",ia->ia_addr);
       }

       /* indirect config - check for configured address */
       if (!(ia->ia_addr >= SCMD_LOW_I2C_ADDR &&
           ia->ia_addr <= SCMD_HIGH_I2C_ADDR))
               return 0;

       /*
        * Check to see if something is really at this i2c address.
        * This will keep phantom devices from appearing
        */
       if (iic_acquire_bus(ia->ia_tag, 0) != 0) {
               if (matchdebug)
                       printf("in match acquire bus failed\n");
               return 0;
       }

       error = scmdi2c_poke(ia->ia_tag, ia->ia_addr, matchdebug);
       iic_release_bus(ia->ia_tag, 0);

       return error == 0 ? I2C_MATCH_ADDRESS_AND_PROBE : 0;
}

static void
scmdi2c_attach(device_t parent, device_t self, void *aux)
{
       struct scmd_sc *sc;
       struct i2c_attach_args *ia;

       ia = aux;
       sc = device_private(self);

       sc->sc_dev = self;
       sc->sc_tag = ia->ia_tag;
       sc->sc_addr = ia->ia_addr;
       sc->sc_scmddebug = 0;
       sc->sc_topaddr = 0xff;
       sc->sc_opened = false;
       sc->sc_dying = false;
       sc->sc_func_acquire_bus = &scmdi2c_acquire_bus;
       sc->sc_func_release_bus = &scmdi2c_release_bus;
       sc->sc_func_read_register = &scmdi2c_read_reg;
       sc->sc_func_write_register = &scmdi2c_write_reg;

       mutex_init(&sc->sc_mutex, MUTEX_DEFAULT, IPL_NONE);
       mutex_init(&sc->sc_condmutex, MUTEX_DEFAULT, IPL_NONE);
       mutex_init(&sc->sc_dying_mutex, MUTEX_DEFAULT, IPL_NONE);
       cv_init(&sc->sc_condvar, "scmdi2ccv");
       cv_init(&sc->sc_cond_dying, "scmdi2cdc");

       scmd_attach(sc);

       return;
}

static int
scmdi2c_detach(device_t self, int flags)
{
       struct scmd_sc *sc;

       sc = device_private(self);

       mutex_enter(&sc->sc_mutex);
       sc->sc_dying = true;
       /* If this is true we are still open, destroy the condvar */
       if (sc->sc_opened) {
               mutex_enter(&sc->sc_dying_mutex);
               DPRINTF(sc, 2, ("%s: Will wait for anything to exit\n",
                   device_xname(sc->sc_dev)));
               /* In the worst case this will time out after 5 seconds.
                * It really should not take that long for the drain / whatever
                * to happen
                */
               cv_timedwait_sig(&sc->sc_cond_dying,
                   &sc->sc_dying_mutex, mstohz(5000));
               mutex_exit(&sc->sc_dying_mutex);
               cv_destroy(&sc->sc_cond_dying);
       }
       cv_destroy(&sc->sc_condvar);
       mutex_exit(&sc->sc_mutex);

       mutex_destroy(&sc->sc_mutex);
       mutex_destroy(&sc->sc_condmutex);

       return 0;
}

int
scmdi2c_activate(device_t self, enum devact act)
{
       struct scmd_sc *sc = device_private(self);

       switch (act) {
       case DVACT_DEACTIVATE:
               sc->sc_dying = true;
               return 0;
       default:
               return EOPNOTSUPP;
       }
}

MODULE(MODULE_CLASS_DRIVER, scmdi2c, "iic,scmd");

#ifdef _MODULE
/* Like other drivers, we do this because the scmd common
* driver has the definitions already.
*/
#undef  CFDRIVER_DECL
#define CFDRIVER_DECL(name, class, attr)
#include "ioconf.c"
#endif

static int
scmdi2c_modcmd(modcmd_t cmd, void *opaque)
{
#ifdef _MODULE
       int error = 0;
       static struct cfdriver * const no_cfdriver_vec[] = { NULL };
#endif

       switch (cmd) {
       case MODULE_CMD_INIT:
#ifdef _MODULE
               /* I really do not understand why I had to do this this way.
                * If I did not then the module would either not install when
                * the SPI driver and hence the scmd dependent driver was compiled
                * into the kernel, or it would not install if it was not.
                * I suspect something is still not set up correctly somewhere, but
                * I am at a lose to see what.
                *
                * The first config_init_component will fail if the SPI driver and the
                * scmd dependent is in the kernel already, but the second one will work.
                * Otherwise the other way around.
                *
                * This all manages to get this module set up in any situation.
                */
               error = config_init_component(cfdriver_ioconf_scmdi2c,
                   cfattach_ioconf_scmdi2c, cfdata_ioconf_scmdi2c);
               if (error) {
                       aprint_error("%s: Trying no_cfdriver_vec method: %d\n",
                           scmd_cd.cd_name, error);
                       error = config_init_component(no_cfdriver_vec,
                           cfattach_ioconf_scmdi2c, cfdata_ioconf_scmdi2c);
               }

               return error;
#else
               return 0;
#endif
       case MODULE_CMD_FINI:
#ifdef _MODULE
               /* See above.. same thing */
               error = config_fini_component(cfdriver_ioconf_scmdi2c,
                   cfattach_ioconf_scmdi2c, cfdata_ioconf_scmdi2c);
               if (error) {
                       aprint_error("%s: Trying no_cfdriver_vec method: %d\n",
                           scmd_cd.cd_name, error);
                       error = config_fini_component(no_cfdriver_vec,
                           cfattach_ioconf_scmdi2c, cfdata_ioconf_scmdi2c);
               }

               return error;
#else
               return 0;
#endif
       default:
               return ENOTTY;
       }
}

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