/*- * Copyright (c) 2015 Ian lepore <ian@freebsd.org> * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ /* * AM335x PPS driver using DMTimer capture. * * Note that this PPS driver does not use an interrupt. Instead it uses the * hardware's ability to latch the timer's count register in response to a * signal on an IO pin. Each of timers 4-7 have an associated pin, and this * code allows any one of those to be used. * * The timecounter routines in kern_tc.c call the pps poll routine periodically * to see if a new counter value has been latched. When a new value has been * latched, the only processing done in the poll routine is to capture the * current set of timecounter timehands (done with pps_capture()) and the * latched value from the timer. The remaining work (done by pps_event() while * holding a mutex) is scheduled to be done later in a non-interrupt context. */ #include <sys/cdefs.h> __FBSDID("$FreeBSD$"); #include <sys/param.h> #include <sys/systm.h> #include <sys/bus.h> #include <sys/conf.h> #include <sys/kernel.h> #include <sys/module.h> #include <sys/malloc.h> #include <sys/rman.h> #include <sys/taskqueue.h> #include <sys/timepps.h> #include <sys/timetc.h> #include <machine/bus.h> #include <dev/ofw/openfirm.h> #include <dev/ofw/ofw_bus.h> #include <dev/ofw/ofw_bus_subr.h> #include <arm/ti/ti_prcm.h> #include <arm/ti/ti_hwmods.h> #include <arm/ti/ti_pinmux.h> #include <arm/ti/am335x/am335x_scm_padconf.h> #include "am335x_dmtreg.h" #define PPS_CDEV_NAME "dmtpps" struct dmtpps_softc { device_t dev; int mem_rid; struct resource * mem_res; int tmr_num; /* N from hwmod str "timerN" */ char tmr_name[12]; /* "DMTimerN" */ uint32_t tclr; /* Cached TCLR register. */ struct timecounter tc; int pps_curmode; /* Edge mode now set in hw. */ struct task pps_task; /* For pps_event handling. */ struct cdev * pps_cdev; struct pps_state pps_state; struct mtx pps_mtx; }; static int dmtpps_tmr_num; /* Set by probe() */ /* List of compatible strings for FDT tree */ static struct ofw_compat_data compat_data[] = { {"ti,am335x-timer", 1}, {"ti,am335x-timer-1ms", 1}, {NULL, 0}, }; /* * A table relating pad names to the hardware timer number they can be mux'd to. */ struct padinfo { char * ballname; int tmr_num; }; static struct padinfo dmtpps_padinfo[] = { {"GPMC_ADVn_ALE", 4}, {"I2C0_SDA", 4}, {"MII1_TX_EN", 4}, {"XDMA_EVENT_INTR0", 4}, {"GPMC_BEn0_CLE", 5}, {"MDC", 5}, {"MMC0_DAT3", 5}, {"UART1_RTSn", 5}, {"GPMC_WEn", 6}, {"MDIO", 6}, {"MMC0_DAT2", 6}, {"UART1_CTSn", 6}, {"GPMC_OEn_REn", 7}, {"I2C0_SCL", 7}, {"UART0_CTSn", 7}, {"XDMA_EVENT_INTR1", 7}, {NULL, 0} }; /* * This is either brilliantly user-friendly, or utterly lame... * * The am335x chip is used on the popular Beaglebone boards. Those boards have * pins for all four capture-capable timers available on the P8 header. Allow * users to configure the input pin by giving the name of the header pin. */ struct nicknames { const char * nick; const char * name; }; static struct nicknames dmtpps_pin_nicks[] = { {"P8-7", "GPMC_ADVn_ALE"}, {"P8-9", "GPMC_BEn0_CLE"}, {"P8-10", "GPMC_WEn"}, {"P8-8", "GPMC_OEn_REn",}, {NULL, NULL} }; #define DMTIMER_READ4(sc, reg) bus_read_4((sc)->mem_res, (reg)) #define DMTIMER_WRITE4(sc, reg, val) bus_write_4((sc)->mem_res, (reg), (val)) /* * Translate a short friendly case-insensitive name to its canonical name. */ static const char * dmtpps_translate_nickname(const char *nick) { struct nicknames *nn; for (nn = dmtpps_pin_nicks; nn->nick != NULL; nn++) if (strcasecmp(nick, nn->nick) == 0) return nn->name; return (nick); } /* * See if our tunable is set to the name of the input pin. If not, that's NOT * an error, return 0. If so, try to configure that pin as a timer capture * input pin, and if that works, then we have our timer unit number and if it * fails that IS an error, return -1. */ static int dmtpps_find_tmr_num_by_tunable() { struct padinfo *pi; char iname[20]; char muxmode[12]; const char * ballname; int err; if (!TUNABLE_STR_FETCH("hw.am335x_dmtpps.input", iname, sizeof(iname))) return (0); ballname = dmtpps_translate_nickname(iname); for (pi = dmtpps_padinfo; pi->ballname != NULL; pi++) { if (strcmp(ballname, pi->ballname) != 0) continue; snprintf(muxmode, sizeof(muxmode), "timer%d", pi->tmr_num); err = ti_pinmux_padconf_set(pi->ballname, muxmode, PADCONF_INPUT); if (err != 0) { printf("am335x_dmtpps: unable to configure capture pin " "for %s to input mode\n", muxmode); return (-1); } else if (bootverbose) { printf("am335x_dmtpps: configured pin %s as input " "for %s\n", iname, muxmode); } return (pi->tmr_num); } /* Invalid name in the tunable, that's an error. */ printf("am335x_dmtpps: unknown pin name '%s'\n", iname); return (-1); } /* * Ask the pinmux driver whether any pin has been configured as a TIMER4..TIMER7 * input pin. If so, return the timer number, if not return 0. */ static int dmtpps_find_tmr_num_by_padconf() { int err; unsigned int padstate; const char * padmux; struct padinfo *pi; char muxmode[12]; for (pi = dmtpps_padinfo; pi->ballname != NULL; pi++) { err = ti_pinmux_padconf_get(pi->ballname, &padmux, &padstate); snprintf(muxmode, sizeof(muxmode), "timer%d", pi->tmr_num); if (err == 0 && (padstate & RXACTIVE) != 0 && strcmp(muxmode, padmux) == 0) return (pi->tmr_num); } /* Nothing found, not an error. */ return (0); } /* * Figure out which hardware timer number to use based on input pin * configuration. This is done just once, the first time probe() runs. */ static int dmtpps_find_tmr_num() { int tmr_num; if ((tmr_num = dmtpps_find_tmr_num_by_tunable()) == 0) tmr_num = dmtpps_find_tmr_num_by_padconf(); if (tmr_num <= 0) { printf("am335x_dmtpps: PPS driver not enabled: unable to find " "or configure a capture input pin\n"); tmr_num = -1; /* Must return non-zero to prevent re-probing. */ } return (tmr_num); } static void dmtpps_set_hw_capture(struct dmtpps_softc *sc, bool force_off) { int newmode; if (force_off) newmode = 0; else newmode = sc->pps_state.ppsparam.mode & PPS_CAPTUREASSERT; if (newmode == sc->pps_curmode) return; sc->pps_curmode = newmode; if (newmode == PPS_CAPTUREASSERT) sc->tclr |= DMT_TCLR_CAPTRAN_LOHI; else sc->tclr &= ~DMT_TCLR_CAPTRAN_MASK; DMTIMER_WRITE4(sc, DMT_TCLR, sc->tclr); } static unsigned dmtpps_get_timecount(struct timecounter *tc) { struct dmtpps_softc *sc; sc = tc->tc_priv; return (DMTIMER_READ4(sc, DMT_TCRR)); } static void dmtpps_poll(struct timecounter *tc) { struct dmtpps_softc *sc; sc = tc->tc_priv; /* * If a new value has been latched we've got a PPS event. Capture the * timecounter data, then override the capcount field (pps_capture() * populates it from the current DMT_TCRR register) with the latched * value from the TCAR1 register. * * There is no locking here, by design. pps_capture() writes into an * area of struct pps_state which is read only by pps_event(). The * synchronization of access to that area is temporal rather than * interlock based... we write in this routine and trigger the task that * will read the data, so no simultaneous access can occur. * * Note that we don't have the TCAR interrupt enabled, but the hardware * still provides the status bits in the "RAW" status register even when * they're masked from generating an irq. However, when clearing the * TCAR status to re-arm the capture for the next second, we have to * write to the IRQ status register, not the RAW register. Quirky. */ if (DMTIMER_READ4(sc, DMT_IRQSTATUS_RAW) & DMT_IRQ_TCAR) { pps_capture(&sc->pps_state); sc->pps_state.capcount = DMTIMER_READ4(sc, DMT_TCAR1); DMTIMER_WRITE4(sc, DMT_IRQSTATUS, DMT_IRQ_TCAR); taskqueue_enqueue(taskqueue_fast, &sc->pps_task); } } static void dmtpps_event(void *arg, int pending) { struct dmtpps_softc *sc; sc = arg; /* This is the task function that gets enqueued by poll_pps. Once the * time has been captured by the timecounter polling code which runs in * primary interrupt context, the remaining (more expensive) work to * process the event is done later in a threaded context. * * Here there is an interlock that protects the event data in struct * pps_state. That data can be accessed at any time from userland via * ioctl() calls so we must ensure that there is no read access to * partially updated data while pps_event() does its work. */ mtx_lock(&sc->pps_mtx); pps_event(&sc->pps_state, PPS_CAPTUREASSERT); mtx_unlock(&sc->pps_mtx); } static int dmtpps_open(struct cdev *dev, int flags, int fmt, struct thread *td) { struct dmtpps_softc *sc; sc = dev->si_drv1; /* * Begin polling for pps and enable capture in the hardware whenever the * device is open. Doing this stuff again is harmless if this isn't the * first open. */ sc->tc.tc_poll_pps = dmtpps_poll; dmtpps_set_hw_capture(sc, false); return 0; } static int dmtpps_close(struct cdev *dev, int flags, int fmt, struct thread *td) { struct dmtpps_softc *sc; sc = dev->si_drv1; /* * Stop polling and disable capture on last close. Use the force-off * flag to override the configured mode and turn off the hardware. */ sc->tc.tc_poll_pps = NULL; dmtpps_set_hw_capture(sc, true); return 0; } static int dmtpps_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flags, struct thread *td) { struct dmtpps_softc *sc; int err; sc = dev->si_drv1; /* Let the kernel do the heavy lifting for ioctl. */ mtx_lock(&sc->pps_mtx); err = pps_ioctl(cmd, data, &sc->pps_state); mtx_unlock(&sc->pps_mtx); if (err != 0) return (err); /* * The capture mode could have changed, set the hardware to whatever * mode is now current. Effectively a no-op if nothing changed. */ dmtpps_set_hw_capture(sc, false); return (err); } static struct cdevsw dmtpps_cdevsw = { .d_version = D_VERSION, .d_open = dmtpps_open, .d_close = dmtpps_close, .d_ioctl = dmtpps_ioctl, .d_name = PPS_CDEV_NAME, }; static int dmtpps_probe(device_t dev) { char strbuf[64]; int tmr_num; if (!ofw_bus_status_okay(dev)) return (ENXIO); if (ofw_bus_search_compatible(dev, compat_data)->ocd_data == 0) return (ENXIO); /* * If we haven't chosen which hardware timer to use yet, go do that now. * We need to know that to decide whether to return success for this * hardware timer instance or not. */ if (dmtpps_tmr_num == 0) dmtpps_tmr_num = dmtpps_find_tmr_num(); /* * Figure out which hardware timer is being probed and see if it matches * the configured timer number determined earlier. */ tmr_num = ti_hwmods_get_unit(dev, "timer"); if (dmtpps_tmr_num != tmr_num) return (ENXIO); snprintf(strbuf, sizeof(strbuf), "AM335x PPS-Capture DMTimer%d", tmr_num); device_set_desc_copy(dev, strbuf); return(BUS_PROBE_DEFAULT); } static int dmtpps_attach(device_t dev) { struct dmtpps_softc *sc; clk_ident_t timer_id; int err, sysclk_freq; sc = device_get_softc(dev); sc->dev = dev; /* Get the base clock frequency. */ err = ti_prcm_clk_get_source_freq(SYS_CLK, &sysclk_freq); /* Enable clocks and power on the device. */ if ((timer_id = ti_hwmods_get_clock(dev)) == INVALID_CLK_IDENT) return (ENXIO); if ((err = ti_prcm_clk_set_source(timer_id, SYSCLK_CLK)) != 0) return (err); if ((err = ti_prcm_clk_enable(timer_id)) != 0) return (err); /* Request the memory resources. */ sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &sc->mem_rid, RF_ACTIVE); if (sc->mem_res == NULL) { return (ENXIO); } /* Figure out which hardware timer this is and set the name string. */ sc->tmr_num = ti_hwmods_get_unit(dev, "timer"); snprintf(sc->tmr_name, sizeof(sc->tmr_name), "DMTimer%d", sc->tmr_num); /* Set up timecounter hardware, start it. */ DMTIMER_WRITE4(sc, DMT_TSICR, DMT_TSICR_RESET); while (DMTIMER_READ4(sc, DMT_TIOCP_CFG) & DMT_TIOCP_RESET) continue; sc->tclr |= DMT_TCLR_START | DMT_TCLR_AUTOLOAD; DMTIMER_WRITE4(sc, DMT_TLDR, 0); DMTIMER_WRITE4(sc, DMT_TCRR, 0); DMTIMER_WRITE4(sc, DMT_TCLR, sc->tclr); /* Register the timecounter. */ sc->tc.tc_name = sc->tmr_name; sc->tc.tc_get_timecount = dmtpps_get_timecount; sc->tc.tc_counter_mask = ~0u; sc->tc.tc_frequency = sysclk_freq; sc->tc.tc_quality = 1000; sc->tc.tc_priv = sc; tc_init(&sc->tc); /* * Indicate our PPS capabilities. Have the kernel init its part of the * pps_state struct and add its capabilities. * * While the hardware has a mode to capture each edge, it's not clear we * can use it that way, because there's only a single interrupt/status * bit to say something was captured, but not which edge it was. For * now, just say we can only capture assert events (the positive-going * edge of the pulse). */ mtx_init(&sc->pps_mtx, "dmtpps", NULL, MTX_DEF); sc->pps_state.ppscap = PPS_CAPTUREASSERT; sc->pps_state.driver_abi = PPS_ABI_VERSION; sc->pps_state.driver_mtx = &sc->pps_mtx; pps_init_abi(&sc->pps_state); /* * Init the task that does deferred pps_event() processing after * the polling routine has captured a pps pulse time. */ TASK_INIT(&sc->pps_task, 0, dmtpps_event, sc); /* Create the PPS cdev. */ sc->pps_cdev = make_dev(&dmtpps_cdevsw, 0, UID_ROOT, GID_WHEEL, 0600, PPS_CDEV_NAME); sc->pps_cdev->si_drv1 = sc; if (bootverbose) device_printf(sc->dev, "Using %s for PPS device /dev/%s\n", sc->tmr_name, PPS_CDEV_NAME); return (0); } static int dmtpps_detach(device_t dev) { /* * There is no way to remove a timecounter once it has been registered, * even if it's not in use, so we can never detach. If we were * dynamically loaded as a module this will prevent unloading. */ return (EBUSY); } static device_method_t dmtpps_methods[] = { DEVMETHOD(device_probe, dmtpps_probe), DEVMETHOD(device_attach, dmtpps_attach), DEVMETHOD(device_detach, dmtpps_detach), { 0, 0 } }; static driver_t dmtpps_driver = { "am335x_dmtpps", dmtpps_methods, sizeof(struct dmtpps_softc), }; static devclass_t dmtpps_devclass; DRIVER_MODULE(am335x_dmtpps, simplebus, dmtpps_driver, dmtpps_devclass, 0, 0); MODULE_DEPEND(am335x_dmtpps, am335x_prcm, 1, 1, 1);