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