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
46static struct ofw_compat_data compat_data[] = {
47	{"pps-gpio", 	1},
48	{NULL,          0}
49};
50SIMPLEBUS_PNP_INFO(compat_data);
51#endif /* FDT */
52
53static devclass_t pps_devclass;
54
55struct 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
69static int
70gpiopps_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
84static	int
85gpiopps_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
100static int
101gpiopps_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
114static 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
122static int
123gpiopps_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
143static void
144gpiopps_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
161static int
162gpiopps_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
178static int
179gpiopps_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
264static int
265gpiopps_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
279static 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
287static driver_t pps_fdt_driver = {
288	"gpiopps",
289	pps_fdt_methods,
290	sizeof(struct pps_softc),
291};
292
293DRIVER_MODULE(gpiopps, simplebus, pps_fdt_driver, pps_devclass, 0, 0);
294
295#endif /* FDT */
296