/* $NetBSD: spi.c,v 1.26 2022/05/17 05:05:20 andvar Exp $ */

/*-
* Copyright (c) 2006 Urbana-Champaign Independent Media Center.
* Copyright (c) 2006 Garrett D'Amore.
* All rights reserved.
*
* Portions of this code were written by Garrett D'Amore for the
* Champaign-Urbana Community Wireless Network Project.
*
* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. 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.
* 3. All advertising materials mentioning features or use of this
*    software must display the following acknowledgements:
*      This product includes software developed by the Urbana-Champaign
*      Independent Media Center.
*      This product includes software developed by Garrett D'Amore.
* 4. Urbana-Champaign Independent Media Center's name and Garrett
*    D'Amore's name may not be used to endorse or promote products
*    derived from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE URBANA-CHAMPAIGN INDEPENDENT
* MEDIA CENTER AND GARRETT D'AMORE ``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 URBANA-CHAMPAIGN INDEPENDENT
* MEDIA CENTER OR GARRETT D'AMORE 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 <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: spi.c,v 1.26 2022/05/17 05:05:20 andvar Exp $");

#include "locators.h"

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/device.h>
#include <sys/conf.h>
#include <sys/malloc.h>
#include <sys/mutex.h>
#include <sys/condvar.h>
#include <sys/errno.h>

#include <dev/spi/spivar.h>
#include <dev/spi/spi_io.h>

#include "ioconf.h"
#include "locators.h"

struct spi_softc {
       device_t                sc_dev;
       struct spi_controller   sc_controller;
       int                     sc_mode;
       int                     sc_speed;
       int                     sc_slave;
       int                     sc_nslaves;
       struct spi_handle       *sc_slaves;
       kmutex_t                sc_lock;
       kcondvar_t              sc_cv;
       kmutex_t                sc_dev_lock;
       int                     sc_flags;
#define SPIC_BUSY               1
};

static dev_type_open(spi_open);
static dev_type_close(spi_close);
static dev_type_ioctl(spi_ioctl);

const struct cdevsw spi_cdevsw = {
       .d_open = spi_open,
       .d_close = spi_close,
       .d_read = noread,
       .d_write = nowrite,
       .d_ioctl = spi_ioctl,
       .d_stop = nostop,
       .d_tty = notty,
       .d_poll = nopoll,
       .d_mmap = nommap,
       .d_kqfilter = nokqfilter,
       .d_discard = nodiscard,
       .d_flag = D_OTHER | D_MPSAFE
};

/*
* SPI slave device.  We have one of these per slave.
*/
struct spi_handle {
       struct spi_softc        *sh_sc;
       struct spi_controller   *sh_controller;
       int                     sh_slave;
       int                     sh_mode;
       int                     sh_speed;
       int                     sh_flags;
#define SPIH_ATTACHED           1
};

#define SPI_MAXDATA 4096

/*
* API for bus drivers.
*/

int
spibus_print(void *aux, const char *pnp)
{

       if (pnp != NULL)
               aprint_normal("spi at %s", pnp);

       return (UNCONF);
}


static int
spi_match(device_t parent, cfdata_t cf, void *aux)
{

       return 1;
}

static int
spi_print(void *aux, const char *pnp)
{
       struct spi_attach_args *sa = aux;

       if (sa->sa_handle->sh_slave != -1)
               aprint_normal(" slave %d", sa->sa_handle->sh_slave);

       return (UNCONF);
}

static int
spi_search(device_t parent, cfdata_t cf, const int *ldesc, void *aux)
{
       struct spi_softc *sc = device_private(parent);
       struct spi_attach_args sa;
       int addr;

       addr = cf->cf_loc[SPICF_SLAVE];
       if ((addr < 0) || (addr >= sc->sc_controller.sct_nslaves)) {
               return -1;
       }

       memset(&sa, 0, sizeof sa);
       sa.sa_handle = &sc->sc_slaves[addr];
       if (ISSET(sa.sa_handle->sh_flags, SPIH_ATTACHED))
               return -1;

       if (config_probe(parent, cf, &sa)) {
               SET(sa.sa_handle->sh_flags, SPIH_ATTACHED);
               config_attach(parent, cf, &sa, spi_print, CFARGS_NONE);
       }

       return 0;
}

/*
* XXX this is the same as i2c_fill_compat. It could be refactored into a
* common fill_compat function with pointers to compat & ncompat instead
* of attach_args as the first parameter.
*/
static void
spi_fill_compat(struct spi_attach_args *sa, const char *compat, size_t len,
       char **buffer)
{
       int count, i;
       const char *c, *start, **ptr;

       *buffer = NULL;
       for (i = count = 0, c = compat; i < len; i++, c++)
               if (*c == 0)
                       count++;
       count += 2;
       ptr = malloc(sizeof(char*)*count, M_TEMP, M_WAITOK);
       if (!ptr)
               return;

       for (i = count = 0, start = c = compat; i < len; i++, c++) {
               if (*c == 0) {
                       ptr[count++] = start;
                       start = c + 1;
               }
       }
       if (start < compat + len) {
               /* last string not 0 terminated */
               size_t l = c - start;
               *buffer = malloc(l + 1, M_TEMP, M_WAITOK);
               memcpy(*buffer, start, l);
               (*buffer)[l] = 0;
               ptr[count++] = *buffer;
       }
       ptr[count] = NULL;

       sa->sa_compat = ptr;
       sa->sa_ncompat = count;
}

static void
spi_direct_attach_child_devices(device_t parent, struct spi_softc *sc,
   prop_array_t child_devices)
{
       unsigned int count;
       prop_dictionary_t child;
       prop_data_t cdata;
       uint32_t slave;
       uint64_t cookie;
       struct spi_attach_args sa;
       int loc[SPICF_NLOCS];
       char *buf;
       int i;

       memset(loc, 0, sizeof loc);
       count = prop_array_count(child_devices);
       for (i = 0; i < count; i++) {
               child = prop_array_get(child_devices, i);
               if (!child)
                       continue;
               if (!prop_dictionary_get_uint32(child, "slave", &slave))
                       continue;
               if(slave >= sc->sc_controller.sct_nslaves)
                       continue;
               if (!prop_dictionary_get_uint64(child, "cookie", &cookie))
                       continue;
               if (!(cdata = prop_dictionary_get(child, "compatible")))
                       continue;
               loc[SPICF_SLAVE] = slave;

               memset(&sa, 0, sizeof sa);
               sa.sa_handle = &sc->sc_slaves[i];
               sa.sa_prop = child;
               sa.sa_cookie = cookie;
               if (ISSET(sa.sa_handle->sh_flags, SPIH_ATTACHED))
                       continue;
               SET(sa.sa_handle->sh_flags, SPIH_ATTACHED);

               buf = NULL;
               spi_fill_compat(&sa,
                               prop_data_value(cdata),
                               prop_data_size(cdata), &buf);
               config_found(parent, &sa, spi_print,
                   CFARGS(.locators = loc));

               if (sa.sa_compat)
                       free(sa.sa_compat, M_TEMP);
               if (buf)
                       free(buf, M_TEMP);
       }
}

int
spi_compatible_match(const struct spi_attach_args *sa, const cfdata_t cf,
                    const struct device_compatible_entry *compats)
{
       if (sa->sa_ncompat > 0)
               return device_compatible_match(sa->sa_compat, sa->sa_ncompat,
                                              compats);

       return 1;
}

const struct device_compatible_entry *
spi_compatible_lookup(const struct spi_attach_args *sa,
   const struct device_compatible_entry *compats)
{
       return device_compatible_lookup(sa->sa_compat, sa->sa_ncompat,
                                       compats);
}

/*
* API for device drivers.
*
* We provide wrapper routines to decouple the ABI for the SPI
* device drivers from the ABI for the SPI bus drivers.
*/
static void
spi_attach(device_t parent, device_t self, void *aux)
{
       struct spi_softc *sc = device_private(self);
       struct spibus_attach_args *sba = aux;
       int i;

       aprint_naive(": SPI bus\n");
       aprint_normal(": SPI bus\n");

       mutex_init(&sc->sc_dev_lock, MUTEX_DEFAULT, IPL_NONE);
       mutex_init(&sc->sc_lock, MUTEX_DEFAULT, IPL_VM);
       cv_init(&sc->sc_cv, "spictl");

       sc->sc_dev = self;
       sc->sc_controller = *sba->sba_controller;
       sc->sc_nslaves = sba->sba_controller->sct_nslaves;
       /* allocate slave structures */
       sc->sc_slaves = malloc(sizeof (struct spi_handle) * sc->sc_nslaves,
           M_DEVBUF, M_WAITOK | M_ZERO);

       sc->sc_speed = 0;
       sc->sc_mode = -1;
       sc->sc_slave = -1;

       /*
        * Initialize slave handles
        */
       for (i = 0; i < sc->sc_nslaves; i++) {
               sc->sc_slaves[i].sh_slave = i;
               sc->sc_slaves[i].sh_sc = sc;
               sc->sc_slaves[i].sh_controller = &sc->sc_controller;
       }

       /* First attach devices known to be present via fdt */
       if (sba->sba_child_devices) {
               spi_direct_attach_child_devices(self, sc, sba->sba_child_devices);
       }
       /* Then do any other devices the user may have manually wired */
       config_search(self, NULL,
           CFARGS(.search = spi_search));
}

static int
spi_open(dev_t dev, int flag, int fmt, lwp_t *l)
{
       struct spi_softc *sc = device_lookup_private(&spi_cd, minor(dev));

       if (sc == NULL)
               return ENXIO;

       return 0;
}

static int
spi_close(dev_t dev, int flag, int fmt, lwp_t *l)
{

       return 0;
}

static int
spi_ioctl(dev_t dev, u_long cmd, void *data, int flag, lwp_t *l)
{
       struct spi_softc *sc = device_lookup_private(&spi_cd, minor(dev));
       struct spi_handle *sh;
       spi_ioctl_configure_t *sic;
       spi_ioctl_transfer_t *sit;
       uint8_t *sbuf, *rbuf;
       int error;

       if (sc == NULL)
               return ENXIO;

       mutex_enter(&sc->sc_dev_lock);

       switch (cmd) {
       case SPI_IOCTL_CONFIGURE:
               sic = (spi_ioctl_configure_t *)data;
               if (sic->sic_addr < 0 || sic->sic_addr >= sc->sc_nslaves) {
                       error = EINVAL;
                       break;
               }
               sh = &sc->sc_slaves[sic->sic_addr];
               error = spi_configure(sc->sc_dev, sh, sic->sic_mode,
                   sic->sic_speed);
               break;
       case SPI_IOCTL_TRANSFER:
               sit = (spi_ioctl_transfer_t *)data;
               if (sit->sit_addr < 0 || sit->sit_addr >= sc->sc_nslaves) {
                       error = EINVAL;
                       break;
               }
               if ((sit->sit_send && sit->sit_sendlen == 0)
                   || (sit->sit_recv && sit->sit_recvlen == 0)) {
                       error = EINVAL;
                       break;
               }
               sh = &sc->sc_slaves[sit->sit_addr];
               sbuf = rbuf = NULL;
               error = 0;
               if (sit->sit_send && sit->sit_sendlen <= SPI_MAXDATA) {
                       sbuf = malloc(sit->sit_sendlen, M_DEVBUF, M_WAITOK);
                       error = copyin(sit->sit_send, sbuf, sit->sit_sendlen);
               }
               if (sit->sit_recv && sit->sit_recvlen <= SPI_MAXDATA) {
                       rbuf = malloc(sit->sit_recvlen, M_DEVBUF, M_WAITOK);
               }
               if (error == 0) {
                       if (sbuf && rbuf)
                               error = spi_send_recv(sh,
                                       sit->sit_sendlen, sbuf,
                                       sit->sit_recvlen, rbuf);
                       else if (sbuf)
                               error = spi_send(sh,
                                       sit->sit_sendlen, sbuf);
                       else if (rbuf)
                               error = spi_recv(sh,
                                       sit->sit_recvlen, rbuf);
               }
               if (rbuf) {
                       if (error == 0)
                               error = copyout(rbuf, sit->sit_recv,
                                               sit->sit_recvlen);
                       free(rbuf, M_DEVBUF);
               }
               if (sbuf) {
                       free(sbuf, M_DEVBUF);
               }
               break;
       default:
               error = ENODEV;
               break;
       }

       mutex_exit(&sc->sc_dev_lock);

       return error;
}

CFATTACH_DECL_NEW(spi, sizeof(struct spi_softc),
   spi_match, spi_attach, NULL, NULL);

/*
* Configure.  This should be the first thing that the SPI driver
* should do, to configure which mode (e.g. SPI_MODE_0, which is the
* same as Philips Microwire mode), and speed.  If the bus driver
* cannot run fast enough, then it should just configure the fastest
* mode that it can support.  If the bus driver cannot run slow
* enough, then the device is incompatible and an error should be
* returned.
*/
int
spi_configure(device_t dev __unused, struct spi_handle *sh, int mode, int speed)
{

       sh->sh_mode = mode;
       sh->sh_speed = speed;

       /* No need to report errors; no failures. */

       return 0;
}

/*
* Acquire controller
*/
static void
spi_acquire(struct spi_handle *sh)
{
       struct spi_softc *sc = sh->sh_sc;

       mutex_enter(&sc->sc_lock);
       while ((sc->sc_flags & SPIC_BUSY) != 0)
               cv_wait(&sc->sc_cv, &sc->sc_lock);
       sc->sc_flags |= SPIC_BUSY;
       mutex_exit(&sc->sc_lock);
}

/*
* Release controller
*/
static void
spi_release(struct spi_handle *sh)
{
       struct spi_softc *sc = sh->sh_sc;

       mutex_enter(&sc->sc_lock);
       sc->sc_flags &= ~SPIC_BUSY;
       cv_broadcast(&sc->sc_cv);
       mutex_exit(&sc->sc_lock);
}

void
spi_transfer_init(struct spi_transfer *st)
{

       mutex_init(&st->st_lock, MUTEX_DEFAULT, IPL_VM);
       cv_init(&st->st_cv, "spixfr");

       st->st_flags = 0;
       st->st_errno = 0;
       st->st_done = NULL;
       st->st_chunks = NULL;
       st->st_private = NULL;
       st->st_slave = -1;
}

void
spi_chunk_init(struct spi_chunk *chunk, int cnt, const uint8_t *wptr,
   uint8_t *rptr)
{

       chunk->chunk_write = chunk->chunk_wptr = wptr;
       chunk->chunk_read = chunk->chunk_rptr = rptr;
       chunk->chunk_rresid = chunk->chunk_wresid = chunk->chunk_count = cnt;
       chunk->chunk_next = NULL;
}

void
spi_transfer_add(struct spi_transfer *st, struct spi_chunk *chunk)
{
       struct spi_chunk **cpp;

       /* this is an O(n) insert -- perhaps we should use a simpleq? */
       for (cpp = &st->st_chunks; *cpp; cpp = &(*cpp)->chunk_next);
       *cpp = chunk;
}

int
spi_transfer(struct spi_handle *sh, struct spi_transfer *st)
{
       struct spi_softc        *sc = sh->sh_sc;
       struct spi_controller   *tag = sh->sh_controller;
       struct spi_chunk        *chunk;
       int error;

       /*
        * Initialize "resid" counters and pointers, so that callers
        * and bus drivers don't have to.
        */
       for (chunk = st->st_chunks; chunk; chunk = chunk->chunk_next) {
               chunk->chunk_wresid = chunk->chunk_rresid = chunk->chunk_count;
               chunk->chunk_wptr = chunk->chunk_write;
               chunk->chunk_rptr = chunk->chunk_read;
       }

       /*
        * Match slave and parameters to handle
        */
       st->st_slave = sh->sh_slave;

       /*
        * Reserve controller during transaction
        */
       spi_acquire(sh);

       st->st_spiprivate = (void *)sh;

       /*
        * Reconfigure controller
        *
        * XXX backends don't configure per-slave parameters
        * Whenever we switch slaves or change mode or speed, we
        * need to tell the backend.
        */
       if (sc->sc_slave != sh->sh_slave
           || sc->sc_mode != sh->sh_mode
           || sc->sc_speed != sh->sh_speed) {
               error = (*tag->sct_configure)(tag->sct_cookie,
                               sh->sh_slave, sh->sh_mode, sh->sh_speed);
               if (error)
                       return error;
       }
       sc->sc_mode = sh->sh_mode;
       sc->sc_speed = sh->sh_speed;
       sc->sc_slave = sh->sh_slave;

       error = (*tag->sct_transfer)(tag->sct_cookie, st);

       return error;
}

void
spi_wait(struct spi_transfer *st)
{
       struct spi_handle *sh = st->st_spiprivate;

       mutex_enter(&st->st_lock);
       while (!(st->st_flags & SPI_F_DONE)) {
               cv_wait(&st->st_cv, &st->st_lock);
       }
       mutex_exit(&st->st_lock);
       cv_destroy(&st->st_cv);
       mutex_destroy(&st->st_lock);

       /*
        * End transaction
        */
       spi_release(sh);
}

void
spi_done(struct spi_transfer *st, int err)
{

       mutex_enter(&st->st_lock);
       if ((st->st_errno = err) != 0) {
               st->st_flags |= SPI_F_ERROR;
       }
       st->st_flags |= SPI_F_DONE;
       if (st->st_done != NULL) {
               (*st->st_done)(st);
       } else {
               cv_broadcast(&st->st_cv);
       }
       mutex_exit(&st->st_lock);
}

/*
* Some convenience routines.  These routines block until the work
* is done.
*
* spi_recv - receives data from the bus
*
* spi_send - sends data to the bus
*
* spi_send_recv - sends data to the bus, and then receives.  Note that this is
* done synchronously, i.e. send a command and get the response.  This is
* not full duplex.  If you want full duplex, you can't use these convenience
* wrappers.
*/
int
spi_recv(struct spi_handle *sh, int cnt, uint8_t *data)
{
       struct spi_transfer     trans;
       struct spi_chunk        chunk;

       spi_transfer_init(&trans);
       spi_chunk_init(&chunk, cnt, NULL, data);
       spi_transfer_add(&trans, &chunk);

       /* enqueue it and wait for it to complete */
       spi_transfer(sh, &trans);
       spi_wait(&trans);

       if (trans.st_flags & SPI_F_ERROR)
               return trans.st_errno;

       return 0;
}

int
spi_send(struct spi_handle *sh, int cnt, const uint8_t *data)
{
       struct spi_transfer     trans;
       struct spi_chunk        chunk;

       spi_transfer_init(&trans);
       spi_chunk_init(&chunk, cnt, data, NULL);
       spi_transfer_add(&trans, &chunk);

       /* enqueue it and wait for it to complete */
       spi_transfer(sh, &trans);
       spi_wait(&trans);

       if (trans.st_flags & SPI_F_ERROR)
               return trans.st_errno;

       return 0;
}

int
spi_send_recv(struct spi_handle *sh, int scnt, const uint8_t *snd,
   int rcnt, uint8_t *rcv)
{
       struct spi_transfer     trans;
       struct spi_chunk        chunk1, chunk2;

       spi_transfer_init(&trans);
       spi_chunk_init(&chunk1, scnt, snd, NULL);
       spi_chunk_init(&chunk2, rcnt, NULL, rcv);
       spi_transfer_add(&trans, &chunk1);
       spi_transfer_add(&trans, &chunk2);

       /* enqueue it and wait for it to complete */
       spi_transfer(sh, &trans);
       spi_wait(&trans);

       if (trans.st_flags & SPI_F_ERROR)
               return trans.st_errno;

       return 0;
}

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