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 struct pps_softc {
   54         device_t         dev;
   55         gpio_pin_t       gpin;
   56         void            *ihandler;
   57         struct resource *ires;
   58         int              irid;
   59         struct cdev     *pps_cdev;
   60         struct pps_state pps_state;
   61         struct mtx       pps_mtx;
   62         bool             falling_edge;
   63 };
   64 
   65 #define PPS_CDEV_NAME   "gpiopps"
   66 
   67 static int
   68 gpiopps_open(struct cdev *dev, int flags, int fmt, struct thread *td)
   69 {
   70         struct pps_softc *sc = dev->si_drv1;
   71 
   72         /* We can't be unloaded while open, so mark ourselves BUSY. */
   73         mtx_lock(&sc->pps_mtx);
   74         device_busy(sc->dev);
   75         mtx_unlock(&sc->pps_mtx);
   76 
   77         return 0;
   78 }
   79 
   80 static  int
   81 gpiopps_close(struct cdev *dev, int flags, int fmt, struct thread *td)
   82 {
   83         struct pps_softc *sc = dev->si_drv1;
   84 
   85         mtx_lock(&sc->pps_mtx);
   86         device_unbusy(sc->dev);
   87         mtx_unlock(&sc->pps_mtx);
   88 
   89         return 0;
   90 }
   91 
   92 static int
   93 gpiopps_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, struct thread *td)
   94 {
   95         struct pps_softc *sc = dev->si_drv1;
   96         int err;
   97 
   98         /* Let the kernel do the heavy lifting for ioctl. */
   99         mtx_lock(&sc->pps_mtx);
  100         err = pps_ioctl(cmd, data, &sc->pps_state);
  101         mtx_unlock(&sc->pps_mtx);
  102 
  103         return err;
  104 }
  105 
  106 static struct cdevsw pps_cdevsw = {
  107         .d_version =    D_VERSION,
  108         .d_flags =      D_TRACKCLOSE,
  109         .d_open =       gpiopps_open,
  110         .d_close =      gpiopps_close,
  111         .d_ioctl =      gpiopps_ioctl,
  112         .d_name =       PPS_CDEV_NAME,
  113 };
  114 
  115 static int
  116 gpiopps_ifltr(void *arg)
  117 {
  118         struct pps_softc *sc = arg;
  119 
  120         /*
  121          * There is no locking here by design... The kernel cleverly captures
  122          * the current time into an area of the pps_state structure which is
  123          * written only by the pps_capture() routine and read only by the
  124          * pps_event() routine.  We don't need lock-based management of access
  125          * to the capture area because we have time-based access management:  we
  126          * can't be reading and writing concurrently because we can't be running
  127          * both the threaded and filter handlers concurrently (because a new
  128          * hardware interrupt can't happen until the threaded handler for the
  129          * current interrupt exits, after which the system does the EOI that
  130          * enables a new hardware interrupt).
  131          */
  132         pps_capture(&sc->pps_state);
  133         return (FILTER_SCHEDULE_THREAD);
  134 }
  135 
  136 static void
  137 gpiopps_ithrd(void *arg)
  138 {
  139         struct pps_softc *sc = arg;
  140 
  141         /*
  142          * Go create a pps event from the data captured in the filter handler.
  143          *
  144          * Note that we DO need locking here, unlike the case with the filter
  145          * handler.  The pps_event() routine updates the non-capture part of the
  146          * pps_state structure, and the ioctl() code could be accessing that
  147          * data right now in a non-interrupt context, so we need an interlock.
  148          */
  149         mtx_lock(&sc->pps_mtx);
  150         pps_event(&sc->pps_state, PPS_CAPTUREASSERT);
  151         mtx_unlock(&sc->pps_mtx);
  152 }
  153 
  154 static int
  155 gpiopps_detach(device_t dev)
  156 {
  157         struct pps_softc *sc = device_get_softc(dev);
  158 
  159         if (sc->pps_cdev != NULL)
  160                 destroy_dev(sc->pps_cdev);
  161         if (sc->ihandler != NULL)
  162                 bus_teardown_intr(dev, sc->ires, sc->ihandler);
  163         if (sc->ires != NULL)
  164                 bus_release_resource(dev, SYS_RES_IRQ, sc->irid, sc->ires);
  165         if (sc->gpin != NULL)
  166                 gpiobus_release_pin(GPIO_GET_BUS(sc->gpin->dev), sc->gpin->pin);
  167         return (0);
  168 }
  169 
  170 #ifdef FDT
  171 static int
  172 gpiopps_fdt_attach(device_t dev)
  173 {
  174         struct pps_softc *sc;
  175         struct make_dev_args devargs;
  176         phandle_t node;
  177         uint32_t edge, pincaps;
  178         int err;
  179 
  180         sc = device_get_softc(dev);
  181         sc->dev = dev;
  182 
  183         mtx_init(&sc->pps_mtx, device_get_nameunit(dev), NULL, MTX_DEF);
  184 
  185         /* Initialize the pps_state struct. */
  186         sc->pps_state.ppscap = PPS_CAPTUREASSERT | PPS_CAPTURECLEAR;
  187         sc->pps_state.driver_abi = PPS_ABI_VERSION;
  188         sc->pps_state.driver_mtx = &sc->pps_mtx;
  189         pps_init_abi(&sc->pps_state);
  190 
  191         /* Check which edge we're configured to capture (default is rising). */
  192         if (ofw_bus_has_prop(dev, "assert-falling-edge"))
  193                 edge = GPIO_INTR_EDGE_FALLING;
  194         else
  195                 edge = GPIO_INTR_EDGE_RISING;
  196 
  197         /*
  198          * Look up the configured gpio pin and ensure it can be configured for
  199          * the interrupt mode we need.
  200          */
  201         node = ofw_bus_get_node(dev);
  202         if ((err = gpio_pin_get_by_ofw_idx(dev, node, 0, &sc->gpin)) != 0) {
  203                 device_printf(dev, "Cannot obtain gpio pin\n");
  204                 return (err);
  205         }
  206         device_printf(dev, "PPS input on %s pin %u\n",
  207             device_get_nameunit(sc->gpin->dev), sc->gpin->pin);
  208 
  209         if ((err = gpio_pin_getcaps(sc->gpin, &pincaps)) != 0) {
  210                 device_printf(dev, "Cannot query capabilities of gpio pin\n");
  211                 gpiopps_detach(dev);
  212                 return (err);
  213         }
  214         if ((pincaps & edge) == 0) {
  215                 device_printf(dev, "Pin cannot be configured for the requested signal edge\n");
  216                 gpiopps_detach(dev);
  217                 return (ENOTSUP);
  218         }
  219 
  220         /*
  221          * Transform our 'gpios' property into an interrupt resource and set up
  222          * the interrupt.
  223          */
  224         if ((sc->ires = gpio_alloc_intr_resource(dev, &sc->irid, RF_ACTIVE,
  225             sc->gpin, edge)) == NULL) {
  226                 device_printf(dev, "Cannot allocate an IRQ for the GPIO\n");
  227                 gpiopps_detach(dev);
  228                 return (err);
  229         }
  230 
  231         err = bus_setup_intr(dev, sc->ires, INTR_TYPE_CLK | INTR_MPSAFE, 
  232             gpiopps_ifltr, gpiopps_ithrd, sc, &sc->ihandler);
  233         if (err != 0) {
  234                 device_printf(dev, "Unable to setup pps irq handler\n");
  235                 gpiopps_detach(dev);
  236                 return (err);
  237         }
  238 
  239         /* Create the RFC 2783 pps-api cdev. */
  240         make_dev_args_init(&devargs);
  241         devargs.mda_devsw = &pps_cdevsw;
  242         devargs.mda_uid = UID_ROOT;
  243         devargs.mda_gid = GID_WHEEL;
  244         devargs.mda_mode = 0660;
  245         devargs.mda_si_drv1 = sc;
  246         err = make_dev_s(&devargs, &sc->pps_cdev, PPS_CDEV_NAME "%d", 
  247             device_get_unit(dev));
  248         if (err != 0) {
  249                 device_printf(dev, "Unable to create pps cdev\n");
  250                 gpiopps_detach(dev);
  251                 return (err);
  252         }
  253 
  254         return (0);
  255 }
  256 
  257 static int
  258 gpiopps_fdt_probe(device_t dev)
  259 {
  260 
  261         if (!ofw_bus_status_okay(dev))
  262                 return (ENXIO);
  263 
  264         if (ofw_bus_search_compatible(dev, compat_data)->ocd_data != 0) {
  265                 device_set_desc(dev, "GPIO PPS");
  266                 return (BUS_PROBE_DEFAULT);
  267         }
  268 
  269         return (ENXIO);
  270 }
  271 
  272 static device_method_t pps_fdt_methods[] = {
  273         DEVMETHOD(device_probe,         gpiopps_fdt_probe),
  274         DEVMETHOD(device_attach,        gpiopps_fdt_attach),
  275         DEVMETHOD(device_detach,        gpiopps_detach),
  276 
  277         DEVMETHOD_END
  278 };
  279 
  280 static driver_t pps_fdt_driver = {
  281         "gpiopps",
  282         pps_fdt_methods,
  283         sizeof(struct pps_softc),
  284 };
  285 
  286 DRIVER_MODULE(gpiopps, simplebus, pps_fdt_driver, 0, 0);
  287 
  288 #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
