gpiopps.c

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    1 /*-
    2  * Copyright (c) 2016 Ian Lepore <ian@FreeBSD.org>
    3  * All rights reserved.
    4  *
    5  * Redistribution and use in source and binary forms, with or without
    6  * modification, are permitted provided that the following conditions
    7  * are met:
    8  * 1.   Redistributions of source code must retain the above copyright
    9  *      notice, this list of conditions and the following disclaimer.
   10  * 2.   Redistributions in binary form must reproduce the above copyright
   11  *      notice, this list of conditions and the following disclaimer in the
   12  *      documentation and/or other materials provided with the distribution.
   13  *
   14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
   15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   17  * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
   18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   24  * SUCH DAMAGE.
   25  */
   26 
   27 #include <sys/cdefs.h>
   28 __FBSDID("$FreeBSD$");
   29 
   30 #include <sys/param.h>
   31 #include <sys/gpio.h>
   32 #include <sys/kernel.h>
   33 #include <sys/lock.h>
   34 #include <sys/module.h>
   35 #include <sys/bus.h>
   36 #include <sys/conf.h>
   37 #include <sys/timepps.h>
   38 
   39 #include <dev/gpio/gpiobusvar.h>
   40 
   41 #include "opt_platform.h"
   42 
   43 #ifdef FDT
   44 #include <dev/ofw/ofw_bus.h>
   45 
   46 static struct ofw_compat_data compat_data[] = {
   47         {"pps-gpio",    1},
   48         {NULL,          0}
   49 };
   50 SIMPLEBUS_PNP_INFO(compat_data);
   51 #endif /* FDT */
   52 
   53 static devclass_t pps_devclass;
   54 
   55 struct pps_softc {
   56         device_t         dev;
   57         gpio_pin_t       gpin;
   58         void            *ihandler;
   59         struct resource *ires;
   60         int              irid;
   61         struct cdev     *pps_cdev;
   62         struct pps_state pps_state;
   63         struct mtx       pps_mtx;
   64         bool             falling_edge;
   65 };
   66 
   67 #define PPS_CDEV_NAME   "gpiopps"
   68 
   69 static int
   70 gpiopps_open(struct cdev *dev, int flags, int fmt, struct thread *td)
   71 {
   72         struct pps_softc *sc = dev->si_drv1;
   73 
   74         /* We can't be unloaded while open, so mark ourselves BUSY. */
   75         mtx_lock(&sc->pps_mtx);
   76         if (device_get_state(sc->dev) < DS_BUSY) {
   77                 device_busy(sc->dev);
   78         }
   79         mtx_unlock(&sc->pps_mtx);
   80 
   81         return 0;
   82 }
   83 
   84 static  int
   85 gpiopps_close(struct cdev *dev, int flags, int fmt, struct thread *td)
   86 {
   87         struct pps_softc *sc = dev->si_drv1;
   88 
   89         /*
   90          * Un-busy on last close. We rely on the vfs counting stuff to only call
   91          * this routine on last-close, so we don't need any open-count logic.
   92          */
   93         mtx_lock(&sc->pps_mtx);
   94         device_unbusy(sc->dev);
   95         mtx_unlock(&sc->pps_mtx);
   96 
   97         return 0;
   98 }
   99 
  100 static int
  101 gpiopps_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, struct thread *td)
  102 {
  103         struct pps_softc *sc = dev->si_drv1;
  104         int err;
  105 
  106         /* Let the kernel do the heavy lifting for ioctl. */
  107         mtx_lock(&sc->pps_mtx);
  108         err = pps_ioctl(cmd, data, &sc->pps_state);
  109         mtx_unlock(&sc->pps_mtx);
  110 
  111         return err;
  112 }
  113 
  114 static struct cdevsw pps_cdevsw = {
  115         .d_version =    D_VERSION,
  116         .d_open =       gpiopps_open,
  117         .d_close =      gpiopps_close,
  118         .d_ioctl =      gpiopps_ioctl,
  119         .d_name =       PPS_CDEV_NAME,
  120 };
  121 
  122 static int
  123 gpiopps_ifltr(void *arg)
  124 {
  125         struct pps_softc *sc = arg;
  126 
  127         /*
  128          * There is no locking here by design... The kernel cleverly captures
  129          * the current time into an area of the pps_state structure which is
  130          * written only by the pps_capture() routine and read only by the
  131          * pps_event() routine.  We don't need lock-based management of access
  132          * to the capture area because we have time-based access management:  we
  133          * can't be reading and writing concurently because we can't be running
  134          * both the threaded and filter handlers concurrently (because a new
  135          * hardware interrupt can't happen until the threaded handler for the
  136          * current interrupt exits, after which the system does the EOI that
  137          * enables a new hardware interrupt).
  138          */
  139         pps_capture(&sc->pps_state);
  140         return (FILTER_SCHEDULE_THREAD);
  141 }
  142 
  143 static void
  144 gpiopps_ithrd(void *arg)
  145 {
  146         struct pps_softc *sc = arg;
  147 
  148         /*
  149          * Go create a pps event from the data captured in the filter handler.
  150          *
  151          * Note that we DO need locking here, unlike the case with the filter
  152          * handler.  The pps_event() routine updates the non-capture part of the
  153          * pps_state structure, and the ioctl() code could be accessing that
  154          * data right now in a non-interrupt context, so we need an interlock.
  155          */
  156         mtx_lock(&sc->pps_mtx);
  157         pps_event(&sc->pps_state, PPS_CAPTUREASSERT);
  158         mtx_unlock(&sc->pps_mtx);
  159 }
  160 
  161 static int
  162 gpiopps_detach(device_t dev)
  163 {
  164         struct pps_softc *sc = device_get_softc(dev);
  165 
  166         if (sc->pps_cdev != NULL)
  167                 destroy_dev(sc->pps_cdev);
  168         if (sc->ihandler != NULL)
  169                 bus_teardown_intr(dev, sc->ires, sc->ihandler);
  170         if (sc->ires != NULL)
  171                 bus_release_resource(dev, SYS_RES_IRQ, sc->irid, sc->ires);
  172         if (sc->gpin != NULL)
  173                 gpiobus_release_pin(GPIO_GET_BUS(sc->gpin->dev), sc->gpin->pin);
  174         return (0);
  175 }
  176 
  177 #ifdef FDT
  178 static int
  179 gpiopps_fdt_attach(device_t dev)
  180 {
  181         struct pps_softc *sc;
  182         struct make_dev_args devargs;
  183         phandle_t node;
  184         uint32_t edge, pincaps;
  185         int err;
  186 
  187         sc = device_get_softc(dev);
  188         sc->dev = dev;
  189 
  190         mtx_init(&sc->pps_mtx, device_get_nameunit(dev), NULL, MTX_DEF);
  191 
  192         /* Initialize the pps_state struct. */
  193         sc->pps_state.ppscap = PPS_CAPTUREASSERT | PPS_CAPTURECLEAR;
  194         sc->pps_state.driver_abi = PPS_ABI_VERSION;
  195         sc->pps_state.driver_mtx = &sc->pps_mtx;
  196         pps_init_abi(&sc->pps_state);
  197 
  198         /* Check which edge we're configured to capture (default is rising). */
  199         if (ofw_bus_has_prop(dev, "assert-falling-edge"))
  200                 edge = GPIO_INTR_EDGE_FALLING;
  201         else
  202                 edge = GPIO_INTR_EDGE_RISING;
  203 
  204         /*
  205          * Look up the configured gpio pin and ensure it can be configured for
  206          * the interrupt mode we need.
  207          */
  208         node = ofw_bus_get_node(dev);
  209         if ((err = gpio_pin_get_by_ofw_idx(dev, node, 0, &sc->gpin)) != 0) {
  210                 device_printf(dev, "Cannot obtain gpio pin\n");
  211                 return (err);
  212         }
  213         device_printf(dev, "PPS input on %s pin %u\n",
  214             device_get_nameunit(sc->gpin->dev), sc->gpin->pin);
  215 
  216         if ((err = gpio_pin_getcaps(sc->gpin, &pincaps)) != 0) {
  217                 device_printf(dev, "Cannot query capabilities of gpio pin\n");
  218                 gpiopps_detach(dev);
  219                 return (err);
  220         }
  221         if ((pincaps & edge) == 0) {
  222                 device_printf(dev, "Pin cannot be configured for the requested signal edge\n");
  223                 gpiopps_detach(dev);
  224                 return (ENOTSUP);
  225         }
  226 
  227         /*
  228          * Transform our 'gpios' property into an interrupt resource and set up
  229          * the interrupt.
  230          */
  231         if ((sc->ires = gpio_alloc_intr_resource(dev, &sc->irid, RF_ACTIVE,
  232             sc->gpin, edge)) == NULL) {
  233                 device_printf(dev, "Cannot allocate an IRQ for the GPIO\n");
  234                 gpiopps_detach(dev);
  235                 return (err);
  236         }
  237 
  238         err = bus_setup_intr(dev, sc->ires, INTR_TYPE_CLK | INTR_MPSAFE, 
  239             gpiopps_ifltr, gpiopps_ithrd, sc, &sc->ihandler);
  240         if (err != 0) {
  241                 device_printf(dev, "Unable to setup pps irq handler\n");
  242                 gpiopps_detach(dev);
  243                 return (err);
  244         }
  245 
  246         /* Create the RFC 2783 pps-api cdev. */
  247         make_dev_args_init(&devargs);
  248         devargs.mda_devsw = &pps_cdevsw;
  249         devargs.mda_uid = UID_ROOT;
  250         devargs.mda_gid = GID_WHEEL;
  251         devargs.mda_mode = 0660;
  252         devargs.mda_si_drv1 = sc;
  253         err = make_dev_s(&devargs, &sc->pps_cdev, PPS_CDEV_NAME "%d", 
  254             device_get_unit(dev));
  255         if (err != 0) {
  256                 device_printf(dev, "Unable to create pps cdev\n");
  257                 gpiopps_detach(dev);
  258                 return (err);
  259         }
  260 
  261         return (0);
  262 }
  263 
  264 static int
  265 gpiopps_fdt_probe(device_t dev)
  266 {
  267 
  268         if (!ofw_bus_status_okay(dev))
  269                 return (ENXIO);
  270 
  271         if (ofw_bus_search_compatible(dev, compat_data)->ocd_data != 0) {
  272                 device_set_desc(dev, "GPIO PPS");
  273                 return (BUS_PROBE_DEFAULT);
  274         }
  275 
  276         return (ENXIO);
  277 }
  278 
  279 static device_method_t pps_fdt_methods[] = {
  280         DEVMETHOD(device_probe,         gpiopps_fdt_probe),
  281         DEVMETHOD(device_attach,        gpiopps_fdt_attach),
  282         DEVMETHOD(device_detach,        gpiopps_detach),
  283 
  284         DEVMETHOD_END
  285 };
  286 
  287 static driver_t pps_fdt_driver = {
  288         "gpiopps",
  289         pps_fdt_methods,
  290         sizeof(struct pps_softc),
  291 };
  292 
  293 DRIVER_MODULE(gpiopps, simplebus, pps_fdt_driver, pps_devclass, 0, 0);
  294 
  295 #endif /* FDT */
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FreeBSD/Linux Kernel Cross Reference sys/dev/gpio/gpiopps.c

FreeBSD/Linux Kernel Cross Reference
sys/dev/gpio/gpiopps.c
