2 * Copyright (c) 2015 Ian lepore <ian@freebsd.org>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
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.
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
28 * AM335x PPS driver using DMTimer capture.
30 * Note that this PPS driver does not use an interrupt. Instead it uses the
31 * hardware's ability to latch the timer's count register in response to a
32 * signal on an IO pin. Each of timers 4-7 have an associated pin, and this
33 * code allows any one of those to be used.
35 * The timecounter routines in kern_tc.c call the pps poll routine periodically
36 * to see if a new counter value has been latched. When a new value has been
37 * latched, the only processing done in the poll routine is to capture the
38 * current set of timecounter timehands (done with pps_capture()) and the
39 * latched value from the timer. The remaining work (done by pps_event() while
40 * holding a mutex) is scheduled to be done later in a non-interrupt context.
43 #include <sys/cdefs.h>
44 __FBSDID("$FreeBSD$");
46 #include <sys/param.h>
47 #include <sys/systm.h>
50 #include <sys/kernel.h>
51 #include <sys/module.h>
52 #include <sys/malloc.h>
54 #include <sys/taskqueue.h>
55 #include <sys/timepps.h>
56 #include <sys/timetc.h>
57 #include <machine/bus.h>
59 #include <dev/ofw/openfirm.h>
60 #include <dev/ofw/ofw_bus.h>
61 #include <dev/ofw/ofw_bus_subr.h>
63 #include <arm/ti/ti_prcm.h>
64 #include <arm/ti/ti_hwmods.h>
65 #include <arm/ti/ti_pinmux.h>
66 #include <arm/ti/am335x/am335x_scm_padconf.h>
68 #include "am335x_dmtreg.h"
70 #define PPS_CDEV_NAME "dmtpps"
75 struct resource * mem_res;
76 int tmr_num; /* N from hwmod str "timerN" */
77 char tmr_name[12]; /* "DMTimerN" */
78 uint32_t tclr; /* Cached TCLR register. */
79 struct timecounter tc;
80 int pps_curmode; /* Edge mode now set in hw. */
81 struct task pps_task; /* For pps_event handling. */
82 struct cdev * pps_cdev;
83 struct pps_state pps_state;
87 static int dmtpps_tmr_num; /* Set by probe() */
89 /* List of compatible strings for FDT tree */
90 static struct ofw_compat_data compat_data[] = {
91 {"ti,am335x-timer", 1},
92 {"ti,am335x-timer-1ms", 1},
97 * A table relating pad names to the hardware timer number they can be mux'd to.
103 static struct padinfo dmtpps_padinfo[] = {
104 {"GPMC_ADVn_ALE", 4},
107 {"XDMA_EVENT_INTR0", 4},
108 {"GPMC_BEn0_CLE", 5},
119 {"XDMA_EVENT_INTR1", 7},
124 * This is either brilliantly user-friendly, or utterly lame...
126 * The am335x chip is used on the popular Beaglebone boards. Those boards have
127 * pins for all four capture-capable timers available on the P8 header. Allow
128 * users to configure the input pin by giving the name of the header pin.
134 static struct nicknames dmtpps_pin_nicks[] = {
135 {"P8-7", "GPMC_ADVn_ALE"},
136 {"P8-9", "GPMC_BEn0_CLE"},
137 {"P8-10", "GPMC_WEn"},
138 {"P8-8", "GPMC_OEn_REn",},
142 #define DMTIMER_READ4(sc, reg) bus_read_4((sc)->mem_res, (reg))
143 #define DMTIMER_WRITE4(sc, reg, val) bus_write_4((sc)->mem_res, (reg), (val))
146 * Translate a short friendly case-insensitive name to its canonical name.
149 dmtpps_translate_nickname(const char *nick)
151 struct nicknames *nn;
153 for (nn = dmtpps_pin_nicks; nn->nick != NULL; nn++)
154 if (strcasecmp(nick, nn->nick) == 0)
160 * See if our tunable is set to the name of the input pin. If not, that's NOT
161 * an error, return 0. If so, try to configure that pin as a timer capture
162 * input pin, and if that works, then we have our timer unit number and if it
163 * fails that IS an error, return -1.
166 dmtpps_find_tmr_num_by_tunable(void)
171 const char * ballname;
174 if (!TUNABLE_STR_FETCH("hw.am335x_dmtpps.input", iname, sizeof(iname)))
176 ballname = dmtpps_translate_nickname(iname);
177 for (pi = dmtpps_padinfo; pi->ballname != NULL; pi++) {
178 if (strcmp(ballname, pi->ballname) != 0)
180 snprintf(muxmode, sizeof(muxmode), "timer%d", pi->tmr_num);
181 err = ti_pinmux_padconf_set(pi->ballname, muxmode,
184 printf("am335x_dmtpps: unable to configure capture pin "
185 "for %s to input mode\n", muxmode);
187 } else if (bootverbose) {
188 printf("am335x_dmtpps: configured pin %s as input "
189 "for %s\n", iname, muxmode);
191 return (pi->tmr_num);
194 /* Invalid name in the tunable, that's an error. */
195 printf("am335x_dmtpps: unknown pin name '%s'\n", iname);
200 * Ask the pinmux driver whether any pin has been configured as a TIMER4..TIMER7
201 * input pin. If so, return the timer number, if not return 0.
204 dmtpps_find_tmr_num_by_padconf(void)
207 unsigned int padstate;
212 for (pi = dmtpps_padinfo; pi->ballname != NULL; pi++) {
213 err = ti_pinmux_padconf_get(pi->ballname, &padmux, &padstate);
214 snprintf(muxmode, sizeof(muxmode), "timer%d", pi->tmr_num);
215 if (err == 0 && (padstate & RXACTIVE) != 0 &&
216 strcmp(muxmode, padmux) == 0)
217 return (pi->tmr_num);
219 /* Nothing found, not an error. */
224 * Figure out which hardware timer number to use based on input pin
225 * configuration. This is done just once, the first time probe() runs.
228 dmtpps_find_tmr_num(void)
232 if ((tmr_num = dmtpps_find_tmr_num_by_tunable()) == 0)
233 tmr_num = dmtpps_find_tmr_num_by_padconf();
236 printf("am335x_dmtpps: PPS driver not enabled: unable to find "
237 "or configure a capture input pin\n");
238 tmr_num = -1; /* Must return non-zero to prevent re-probing. */
244 dmtpps_set_hw_capture(struct dmtpps_softc *sc, bool force_off)
251 newmode = sc->pps_state.ppsparam.mode & PPS_CAPTUREASSERT;
253 if (newmode == sc->pps_curmode)
255 sc->pps_curmode = newmode;
257 if (newmode == PPS_CAPTUREASSERT)
258 sc->tclr |= DMT_TCLR_CAPTRAN_LOHI;
260 sc->tclr &= ~DMT_TCLR_CAPTRAN_MASK;
261 DMTIMER_WRITE4(sc, DMT_TCLR, sc->tclr);
265 dmtpps_get_timecount(struct timecounter *tc)
267 struct dmtpps_softc *sc;
271 return (DMTIMER_READ4(sc, DMT_TCRR));
275 dmtpps_poll(struct timecounter *tc)
277 struct dmtpps_softc *sc;
282 * If a new value has been latched we've got a PPS event. Capture the
283 * timecounter data, then override the capcount field (pps_capture()
284 * populates it from the current DMT_TCRR register) with the latched
285 * value from the TCAR1 register.
287 * There is no locking here, by design. pps_capture() writes into an
288 * area of struct pps_state which is read only by pps_event(). The
289 * synchronization of access to that area is temporal rather than
290 * interlock based... we write in this routine and trigger the task that
291 * will read the data, so no simultaneous access can occur.
293 * Note that we don't have the TCAR interrupt enabled, but the hardware
294 * still provides the status bits in the "RAW" status register even when
295 * they're masked from generating an irq. However, when clearing the
296 * TCAR status to re-arm the capture for the next second, we have to
297 * write to the IRQ status register, not the RAW register. Quirky.
299 if (DMTIMER_READ4(sc, DMT_IRQSTATUS_RAW) & DMT_IRQ_TCAR) {
300 pps_capture(&sc->pps_state);
301 sc->pps_state.capcount = DMTIMER_READ4(sc, DMT_TCAR1);
302 DMTIMER_WRITE4(sc, DMT_IRQSTATUS, DMT_IRQ_TCAR);
303 taskqueue_enqueue(taskqueue_fast, &sc->pps_task);
308 dmtpps_event(void *arg, int pending)
310 struct dmtpps_softc *sc;
314 /* This is the task function that gets enqueued by poll_pps. Once the
315 * time has been captured by the timecounter polling code which runs in
316 * primary interrupt context, the remaining (more expensive) work to
317 * process the event is done later in a threaded context.
319 * Here there is an interlock that protects the event data in struct
320 * pps_state. That data can be accessed at any time from userland via
321 * ioctl() calls so we must ensure that there is no read access to
322 * partially updated data while pps_event() does its work.
324 mtx_lock(&sc->pps_mtx);
325 pps_event(&sc->pps_state, PPS_CAPTUREASSERT);
326 mtx_unlock(&sc->pps_mtx);
330 dmtpps_open(struct cdev *dev, int flags, int fmt,
333 struct dmtpps_softc *sc;
338 * Begin polling for pps and enable capture in the hardware whenever the
339 * device is open. Doing this stuff again is harmless if this isn't the
342 sc->tc.tc_poll_pps = dmtpps_poll;
343 dmtpps_set_hw_capture(sc, false);
349 dmtpps_close(struct cdev *dev, int flags, int fmt,
352 struct dmtpps_softc *sc;
357 * Stop polling and disable capture on last close. Use the force-off
358 * flag to override the configured mode and turn off the hardware.
360 sc->tc.tc_poll_pps = NULL;
361 dmtpps_set_hw_capture(sc, true);
367 dmtpps_ioctl(struct cdev *dev, u_long cmd, caddr_t data,
368 int flags, struct thread *td)
370 struct dmtpps_softc *sc;
375 /* Let the kernel do the heavy lifting for ioctl. */
376 mtx_lock(&sc->pps_mtx);
377 err = pps_ioctl(cmd, data, &sc->pps_state);
378 mtx_unlock(&sc->pps_mtx);
383 * The capture mode could have changed, set the hardware to whatever
384 * mode is now current. Effectively a no-op if nothing changed.
386 dmtpps_set_hw_capture(sc, false);
391 static struct cdevsw dmtpps_cdevsw = {
392 .d_version = D_VERSION,
393 .d_open = dmtpps_open,
394 .d_close = dmtpps_close,
395 .d_ioctl = dmtpps_ioctl,
396 .d_name = PPS_CDEV_NAME,
400 dmtpps_probe(device_t dev)
405 if (!ofw_bus_status_okay(dev))
408 if (ofw_bus_search_compatible(dev, compat_data)->ocd_data == 0)
412 * If we haven't chosen which hardware timer to use yet, go do that now.
413 * We need to know that to decide whether to return success for this
414 * hardware timer instance or not.
416 if (dmtpps_tmr_num == 0)
417 dmtpps_tmr_num = dmtpps_find_tmr_num();
420 * Figure out which hardware timer is being probed and see if it matches
421 * the configured timer number determined earlier.
423 tmr_num = ti_hwmods_get_unit(dev, "timer");
424 if (dmtpps_tmr_num != tmr_num)
427 snprintf(strbuf, sizeof(strbuf), "AM335x PPS-Capture DMTimer%d",
429 device_set_desc_copy(dev, strbuf);
431 return(BUS_PROBE_DEFAULT);
435 dmtpps_attach(device_t dev)
437 struct dmtpps_softc *sc;
438 clk_ident_t timer_id;
439 int err, sysclk_freq;
441 sc = device_get_softc(dev);
444 /* Get the base clock frequency. */
445 err = ti_prcm_clk_get_source_freq(SYS_CLK, &sysclk_freq);
447 /* Enable clocks and power on the device. */
448 if ((timer_id = ti_hwmods_get_clock(dev)) == INVALID_CLK_IDENT)
450 if ((err = ti_prcm_clk_set_source(timer_id, SYSCLK_CLK)) != 0)
452 if ((err = ti_prcm_clk_enable(timer_id)) != 0)
455 /* Request the memory resources. */
456 sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY,
457 &sc->mem_rid, RF_ACTIVE);
458 if (sc->mem_res == NULL) {
462 /* Figure out which hardware timer this is and set the name string. */
463 sc->tmr_num = ti_hwmods_get_unit(dev, "timer");
464 snprintf(sc->tmr_name, sizeof(sc->tmr_name), "DMTimer%d", sc->tmr_num);
467 * Configure the timer pulse/capture pin to input/capture mode. This is
468 * required in addition to configuring the pin as input with the pinmux
469 * controller (which was done via fdt data or tunable at probe time).
471 sc->tclr = DMT_TCLR_GPO_CFG;
472 DMTIMER_WRITE4(sc, DMT_TCLR, sc->tclr);
474 /* Set up timecounter hardware, start it. */
475 DMTIMER_WRITE4(sc, DMT_TSICR, DMT_TSICR_RESET);
476 while (DMTIMER_READ4(sc, DMT_TIOCP_CFG) & DMT_TIOCP_RESET)
479 sc->tclr |= DMT_TCLR_START | DMT_TCLR_AUTOLOAD;
480 DMTIMER_WRITE4(sc, DMT_TLDR, 0);
481 DMTIMER_WRITE4(sc, DMT_TCRR, 0);
482 DMTIMER_WRITE4(sc, DMT_TCLR, sc->tclr);
484 /* Register the timecounter. */
485 sc->tc.tc_name = sc->tmr_name;
486 sc->tc.tc_get_timecount = dmtpps_get_timecount;
487 sc->tc.tc_counter_mask = ~0u;
488 sc->tc.tc_frequency = sysclk_freq;
489 sc->tc.tc_quality = 1000;
495 * Indicate our PPS capabilities. Have the kernel init its part of the
496 * pps_state struct and add its capabilities.
498 * While the hardware has a mode to capture each edge, it's not clear we
499 * can use it that way, because there's only a single interrupt/status
500 * bit to say something was captured, but not which edge it was. For
501 * now, just say we can only capture assert events (the positive-going
502 * edge of the pulse).
504 mtx_init(&sc->pps_mtx, "dmtpps", NULL, MTX_DEF);
505 sc->pps_state.ppscap = PPS_CAPTUREASSERT;
506 sc->pps_state.driver_abi = PPS_ABI_VERSION;
507 sc->pps_state.driver_mtx = &sc->pps_mtx;
508 pps_init_abi(&sc->pps_state);
511 * Init the task that does deferred pps_event() processing after
512 * the polling routine has captured a pps pulse time.
514 TASK_INIT(&sc->pps_task, 0, dmtpps_event, sc);
516 /* Create the PPS cdev. */
517 sc->pps_cdev = make_dev(&dmtpps_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600,
519 sc->pps_cdev->si_drv1 = sc;
522 device_printf(sc->dev, "Using %s for PPS device /dev/%s\n",
523 sc->tmr_name, PPS_CDEV_NAME);
529 dmtpps_detach(device_t dev)
533 * There is no way to remove a timecounter once it has been registered,
534 * even if it's not in use, so we can never detach. If we were
535 * dynamically loaded as a module this will prevent unloading.
540 static device_method_t dmtpps_methods[] = {
541 DEVMETHOD(device_probe, dmtpps_probe),
542 DEVMETHOD(device_attach, dmtpps_attach),
543 DEVMETHOD(device_detach, dmtpps_detach),
547 static driver_t dmtpps_driver = {
550 sizeof(struct dmtpps_softc),
553 static devclass_t dmtpps_devclass;
555 DRIVER_MODULE(am335x_dmtpps, simplebus, dmtpps_driver, dmtpps_devclass, 0, 0);
556 MODULE_DEPEND(am335x_dmtpps, am335x_prcm, 1, 1, 1);