FreeBSD/Linux Kernel Cross Reference
sys/arm/arm/mpcore_timer.c

     /*-
      * SPDX-License-Identifier: BSD-3-Clause
      *
      * Copyright (c) 2011 The FreeBSD Foundation
      * All rights reserved.
      *
      * Developed by Ben Gray <ben.r.gray@gmail.com>
      *
      * 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.
     * 3. The name of the company nor the name of the author may be used to
     *    endorse or promote products derived from this software without specific
     *    prior written permission.
     *
     * 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.
     */
    
    /**
     * The ARM Cortex-A9 core can support a global timer plus a private and
     * watchdog timer per core.  This driver reserves memory and interrupt
     * resources for accessing both timer register sets, these resources are
     * stored globally and used to setup the timecount and eventtimer.
     *
     * The timecount timer uses the global 64-bit counter, whereas the
     * per-CPU eventtimer uses the private 32-bit counters.
     *
     *
     * REF: ARM Cortex-A9 MPCore, Technical Reference Manual (rev. r2p2)
     */
    
    #include <sys/cdefs.h>
    __FBSDID("$FreeBSD$");
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/bus.h>
    #include <sys/kernel.h>
    #include <sys/module.h>
    #include <sys/malloc.h>
    #include <sys/rman.h>
    #include <sys/timeet.h>
    #include <sys/timetc.h>
    #include <sys/watchdog.h>
    #include <machine/bus.h>
    #include <machine/cpu.h>
    #include <machine/intr.h>
    
    #include <machine/machdep.h> /* For arm_set_delay */
    
    #include <dev/ofw/openfirm.h>
    #include <dev/ofw/ofw_bus.h>
    #include <dev/ofw/ofw_bus_subr.h>
    
    #include <machine/bus.h>
    
    #include <arm/arm/mpcore_timervar.h>
    
    /* Private (per-CPU) timer register map */
    #define PRV_TIMER_LOAD                 0x0000
    #define PRV_TIMER_COUNT                0x0004
    #define PRV_TIMER_CTRL                 0x0008
    #define PRV_TIMER_INTR                 0x000C
    
    #define PRV_TIMER_CTR_PRESCALER_SHIFT  8
    #define PRV_TIMER_CTRL_IRQ_ENABLE      (1UL << 2)
    #define PRV_TIMER_CTRL_AUTO_RELOAD     (1UL << 1)
    #define PRV_TIMER_CTRL_TIMER_ENABLE    (1UL << 0)
    
    #define PRV_TIMER_INTR_EVENT           (1UL << 0)
    
    /* Global timer register map */
    #define GBL_TIMER_COUNT_LOW            0x0000
    #define GBL_TIMER_COUNT_HIGH           0x0004
    #define GBL_TIMER_CTRL                 0x0008
    #define GBL_TIMER_INTR                 0x000C
    
    #define GBL_TIMER_CTR_PRESCALER_SHIFT  8
    #define GBL_TIMER_CTRL_AUTO_INC        (1UL << 3)
    #define GBL_TIMER_CTRL_IRQ_ENABLE      (1UL << 2)
    #define GBL_TIMER_CTRL_COMP_ENABLE     (1UL << 1)
    #define GBL_TIMER_CTRL_TIMER_ENABLE    (1UL << 0)
    
    #define GBL_TIMER_INTR_EVENT           (1UL << 0)
   
   struct arm_tmr_softc {
           device_t                dev;
           int                     irqrid;
           int                     memrid;
           struct resource *       gbl_mem;
           struct resource *       prv_mem;
           struct resource *       prv_irq;
           uint64_t                clkfreq;
           struct eventtimer       et;
   };
   
   static struct eventtimer *arm_tmr_et;
   static struct timecounter *arm_tmr_tc;
   static uint64_t arm_tmr_freq;
   static boolean_t arm_tmr_freq_varies;
   
   #define tmr_prv_read_4(sc, reg)         bus_read_4((sc)->prv_mem, reg)
   #define tmr_prv_write_4(sc, reg, val)   bus_write_4((sc)->prv_mem, reg, val)
   #define tmr_gbl_read_4(sc, reg)         bus_read_4((sc)->gbl_mem, reg)
   #define tmr_gbl_write_4(sc, reg, val)   bus_write_4((sc)->gbl_mem, reg, val)
   
   static void arm_tmr_delay(int, void *);
   
   static timecounter_get_t arm_tmr_get_timecount;
   
   static struct timecounter arm_tmr_timecount = {
           .tc_name           = "MPCore",
           .tc_get_timecount  = arm_tmr_get_timecount,
           .tc_poll_pps       = NULL,
           .tc_counter_mask   = ~0u,
           .tc_frequency      = 0,
           .tc_quality        = 800,
   };
   
   #define TMR_GBL         0x01
   #define TMR_PRV         0x02
   #define TMR_BOTH        (TMR_GBL | TMR_PRV)
   #define TMR_NONE        0
   
   static struct ofw_compat_data compat_data[] = {
           {"arm,mpcore-timers",           TMR_BOTH}, /* Non-standard, FreeBSD. */
           {"arm,cortex-a9-global-timer",  TMR_GBL},
           {"arm,cortex-a5-global-timer",  TMR_GBL},
           {"arm,cortex-a9-twd-timer",     TMR_PRV},
           {"arm,cortex-a5-twd-timer",     TMR_PRV},
           {"arm,arm11mp-twd-timer",       TMR_PRV},
           {NULL,                          TMR_NONE}
   };
   
   /**
    *      arm_tmr_get_timecount - reads the timecount (global) timer
    *      @tc: pointer to arm_tmr_timecount struct
    *
    *      We only read the lower 32-bits, the timecount stuff only uses 32-bits
    *      so (for now?) ignore the upper 32-bits.
    *
    *      RETURNS
    *      The lower 32-bits of the counter.
    */
   static unsigned
   arm_tmr_get_timecount(struct timecounter *tc)
   {
           struct arm_tmr_softc *sc;
   
           sc = tc->tc_priv;
           return (tmr_gbl_read_4(sc, GBL_TIMER_COUNT_LOW));
   }
   
   /**
    *      arm_tmr_start - starts the eventtimer (private) timer
    *      @et: pointer to eventtimer struct
    *      @first: the number of seconds and fractional sections to trigger in
    *      @period: the period (in seconds and fractional sections) to set
    *
    *      If the eventtimer is required to be in oneshot mode, period will be
    *      NULL and first will point to the time to trigger.  If in periodic mode
    *      period will contain the time period and first may optionally contain
    *      the time for the first period.
    *
    *      RETURNS
    *      Always returns 0
    */
   static int
   arm_tmr_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
   {
           struct arm_tmr_softc *sc;
           uint32_t load, count;
           uint32_t ctrl;
   
           sc = et->et_priv;
           tmr_prv_write_4(sc, PRV_TIMER_CTRL, 0);
           tmr_prv_write_4(sc, PRV_TIMER_INTR, PRV_TIMER_INTR_EVENT);
   
           ctrl = PRV_TIMER_CTRL_IRQ_ENABLE | PRV_TIMER_CTRL_TIMER_ENABLE;
   
           if (period != 0) {
                   load = ((uint32_t)et->et_frequency * period) >> 32;
                   ctrl |= PRV_TIMER_CTRL_AUTO_RELOAD;
           } else
                   load = 0;
   
           if (first != 0)
                   count = (uint32_t)((et->et_frequency * first) >> 32);
           else
                   count = load;
   
           tmr_prv_write_4(sc, PRV_TIMER_LOAD, load);
           tmr_prv_write_4(sc, PRV_TIMER_COUNT, count);
           tmr_prv_write_4(sc, PRV_TIMER_CTRL, ctrl);
   
           return (0);
   }
   
   /**
    *      arm_tmr_stop - stops the eventtimer (private) timer
    *      @et: pointer to eventtimer struct
    *
    *      Simply stops the private timer by clearing all bits in the ctrl register.
    *
    *      RETURNS
    *      Always returns 0
    */
   static int
   arm_tmr_stop(struct eventtimer *et)
   {
           struct arm_tmr_softc *sc;
   
           sc = et->et_priv;
           tmr_prv_write_4(sc, PRV_TIMER_CTRL, 0);
           tmr_prv_write_4(sc, PRV_TIMER_INTR, PRV_TIMER_INTR_EVENT);
           return (0);
   }
   
   /**
    *      arm_tmr_intr - ISR for the eventtimer (private) timer
    *      @arg: pointer to arm_tmr_softc struct
    *
    *      Clears the event register and then calls the eventtimer callback.
    *
    *      RETURNS
    *      Always returns FILTER_HANDLED
    */
   static int
   arm_tmr_intr(void *arg)
   {
           struct arm_tmr_softc *sc;
   
           sc = arg;
           tmr_prv_write_4(sc, PRV_TIMER_INTR, PRV_TIMER_INTR_EVENT);
           if (sc->et.et_active)
                   sc->et.et_event_cb(&sc->et, sc->et.et_arg);
           return (FILTER_HANDLED);
   }
   
   /**
    *      arm_tmr_probe - timer probe routine
    *      @dev: new device
    *
    *      The probe function returns success when probed with the fdt compatible
    *      string set to "arm,mpcore-timers".
    *
    *      RETURNS
    *      BUS_PROBE_DEFAULT if the fdt device is compatible, otherwise ENXIO.
    */
   static int
   arm_tmr_probe(device_t dev)
   {
   
           if (!ofw_bus_status_okay(dev))
                   return (ENXIO);
   
           if (ofw_bus_search_compatible(dev, compat_data)->ocd_data == TMR_NONE)
                   return (ENXIO);
   
           device_set_desc(dev, "ARM MPCore Timers");
           return (BUS_PROBE_DEFAULT);
   }
   
   static int
   attach_tc(struct arm_tmr_softc *sc)
   {
           int rid;
   
           if (arm_tmr_tc != NULL)
                   return (EBUSY);
   
           rid = sc->memrid;
           sc->gbl_mem = bus_alloc_resource_any(sc->dev, SYS_RES_MEMORY, &rid,
               RF_ACTIVE);
           if (sc->gbl_mem == NULL) {
                   device_printf(sc->dev, "could not allocate gbl mem resources\n");
                   return (ENXIO);
           }
           tmr_gbl_write_4(sc, GBL_TIMER_CTRL, 0x00000000);
   
           arm_tmr_timecount.tc_frequency = sc->clkfreq;
           arm_tmr_timecount.tc_priv = sc;
           tc_init(&arm_tmr_timecount);
           arm_tmr_tc = &arm_tmr_timecount;
   
           tmr_gbl_write_4(sc, GBL_TIMER_CTRL, GBL_TIMER_CTRL_TIMER_ENABLE);
   
           return (0);
   }
   
   static int
   attach_et(struct arm_tmr_softc *sc)
   {
           void *ihl;
           int irid, mrid;
   
           if (arm_tmr_et != NULL)
                   return (EBUSY);
   
           mrid = sc->memrid;
           sc->prv_mem = bus_alloc_resource_any(sc->dev, SYS_RES_MEMORY, &mrid,
               RF_ACTIVE);
           if (sc->prv_mem == NULL) {
                   device_printf(sc->dev, "could not allocate prv mem resources\n");
                   return (ENXIO);
           }
           tmr_prv_write_4(sc, PRV_TIMER_CTRL, 0x00000000);
   
           irid = sc->irqrid;
           sc->prv_irq = bus_alloc_resource_any(sc->dev, SYS_RES_IRQ, &irid, RF_ACTIVE);
           if (sc->prv_irq == NULL) {
                   bus_release_resource(sc->dev, SYS_RES_MEMORY, mrid, sc->prv_mem);
                   device_printf(sc->dev, "could not allocate prv irq resources\n");
                   return (ENXIO);
           }
   
           if (bus_setup_intr(sc->dev, sc->prv_irq, INTR_TYPE_CLK, arm_tmr_intr,
                           NULL, sc, &ihl) != 0) {
                   bus_release_resource(sc->dev, SYS_RES_MEMORY, mrid, sc->prv_mem);
                   bus_release_resource(sc->dev, SYS_RES_IRQ, irid, sc->prv_irq);
                   device_printf(sc->dev, "unable to setup the et irq handler.\n");
                   return (ENXIO);
           }
   
           /*
            * Setup and register the eventtimer.  Most event timers set their min
            * and max period values to some value calculated from the clock
            * frequency.  We might not know yet what our runtime clock frequency
            * will be, so we just use some safe values.  A max of 2 seconds ensures
            * that even if our base clock frequency is 2GHz (meaning a 4GHz CPU),
            * we won't overflow our 32-bit timer count register.  A min of 20
            * nanoseconds is pretty much completely arbitrary.
            */
           sc->et.et_name = "MPCore";
           sc->et.et_flags = ET_FLAGS_PERIODIC | ET_FLAGS_ONESHOT | ET_FLAGS_PERCPU;
           sc->et.et_quality = 1000;
           sc->et.et_frequency = sc->clkfreq;
           sc->et.et_min_period = nstosbt(20);
           sc->et.et_max_period =  2 * SBT_1S;
           sc->et.et_start = arm_tmr_start;
           sc->et.et_stop = arm_tmr_stop;
           sc->et.et_priv = sc;
           et_register(&sc->et);
           arm_tmr_et = &sc->et;
   
           return (0);
   }
   
   /**
    *      arm_tmr_attach - attaches the timer to the simplebus
    *      @dev: new device
    *
    *      Reserves memory and interrupt resources, stores the softc structure
    *      globally and registers both the timecount and eventtimer objects.
    *
    *      RETURNS
    *      Zero on success or ENXIO if an error occuried.
    */
   static int
   arm_tmr_attach(device_t dev)
   {
           struct arm_tmr_softc *sc;
           phandle_t node;
           pcell_t clock;
           int et_err, tc_err, tmrtype;
   
           sc = device_get_softc(dev);
           sc->dev = dev;
   
           if (arm_tmr_freq_varies) {
                   sc->clkfreq = arm_tmr_freq;
           } else {
                   if (arm_tmr_freq != 0) {
                           sc->clkfreq = arm_tmr_freq;
                   } else {
                           /* Get the base clock frequency */
                           node = ofw_bus_get_node(dev);
                           if ((OF_getencprop(node, "clock-frequency", &clock,
                               sizeof(clock))) <= 0) {
                                   device_printf(dev, "missing clock-frequency "
                                       "attribute in FDT\n");
                                   return (ENXIO);
                           }
                           sc->clkfreq = clock;
                   }
           }
   
           tmrtype = ofw_bus_search_compatible(dev, compat_data)->ocd_data;
           tc_err = ENXIO;
           et_err = ENXIO;
   
           /*
            * If we're handling the global timer and it is fixed-frequency, set it
            * up to use as a timecounter.  If it's variable frequency it won't work
            * as a timecounter.  We also can't use it for DELAY(), so hopefully the
            * platform provides its own implementation. If it doesn't, ours will
            * get used, but since the frequency isn't set, it will only use the
            * bogus loop counter.
            */
           if (tmrtype & TMR_GBL) {
                   if (!arm_tmr_freq_varies)
                           tc_err = attach_tc(sc);
                   else if (bootverbose)
                           device_printf(sc->dev,
                               "not using variable-frequency device as timecounter\n");
                   sc->memrid++;
                   sc->irqrid++;
           }
   
           /* If we are handling the private timer, set it up as an eventtimer. */
           if (tmrtype & TMR_PRV) {
                   et_err = attach_et(sc);
           }
   
           /*
            * If we didn't successfully set up a timecounter or eventtimer then we
            * didn't actually attach at all, return error.
            */
           if (tc_err != 0 && et_err != 0) {
                   return (ENXIO);
           }
   
   #ifdef PLATFORM
           /*
            * We can register as the DELAY() implementation only if we successfully
            * set up the global timer.
            */
           if (tc_err == 0)
                   arm_set_delay(arm_tmr_delay, sc);
   #endif
   
           return (0);
   }
   
   static device_method_t arm_tmr_methods[] = {
           DEVMETHOD(device_probe,         arm_tmr_probe),
           DEVMETHOD(device_attach,        arm_tmr_attach),
           { 0, 0 }
   };
   
   static driver_t arm_tmr_driver = {
           "mp_tmr",
           arm_tmr_methods,
           sizeof(struct arm_tmr_softc),
   };
   
   static devclass_t arm_tmr_devclass;
   
   EARLY_DRIVER_MODULE(mp_tmr, simplebus, arm_tmr_driver, arm_tmr_devclass, 0, 0,
       BUS_PASS_TIMER + BUS_PASS_ORDER_MIDDLE);
   EARLY_DRIVER_MODULE(mp_tmr, ofwbus, arm_tmr_driver, arm_tmr_devclass, 0, 0,
       BUS_PASS_TIMER + BUS_PASS_ORDER_MIDDLE);
   
   /*
    * Handle a change in clock frequency.  The mpcore timer runs at half the CPU
    * frequency.  When the CPU frequency changes due to power-saving or thermal
    * management, the platform-specific code that causes the frequency change calls
    * this routine to inform the clock driver, and we in turn inform the event
    * timer system, which actually updates the value in et->frequency for us and
    * reschedules the current event(s) in a way that's atomic with respect to
    * start/stop/intr code that may be running on various CPUs at the time of the
    * call.
    *
    * This routine can also be called by a platform's early init code.  If the
    * value passed is ARM_TMR_FREQUENCY_VARIES, that will cause the attach() code
    * to register as an eventtimer, but not a timecounter.  If the value passed in
    * is any other non-zero value it is used as the fixed frequency for the timer.
    */
   void
   arm_tmr_change_frequency(uint64_t newfreq)
   {
   
           if (newfreq == ARM_TMR_FREQUENCY_VARIES) {
                   arm_tmr_freq_varies = true;
                   return;
           }
   
           arm_tmr_freq = newfreq;
           if (arm_tmr_et != NULL)
                   et_change_frequency(arm_tmr_et, newfreq);
   }
   
   static void
   arm_tmr_delay(int usec, void *arg)
   {
           struct arm_tmr_softc *sc = arg;
           int32_t counts_per_usec;
           int32_t counts;
           uint32_t first, last;
   
           /* Get the number of times to count */
           counts_per_usec = ((arm_tmr_timecount.tc_frequency / 1000000) + 1);
   
           /*
            * Clamp the timeout at a maximum value (about 32 seconds with
            * a 66MHz clock). *Nobody* should be delay()ing for anywhere
            * near that length of time and if they are, they should be hung
            * out to dry.
            */
           if (usec >= (0x80000000U / counts_per_usec))
                   counts = (0x80000000U / counts_per_usec) - 1;
           else
                   counts = usec * counts_per_usec;
   
           first = tmr_gbl_read_4(sc, GBL_TIMER_COUNT_LOW);
   
           while (counts > 0) {
                   last = tmr_gbl_read_4(sc, GBL_TIMER_COUNT_LOW);
                   counts -= (int32_t)(last - first);
                   first = last;
           }
   }
   
   #ifndef PLATFORM
   /**
    *      DELAY - Delay for at least usec microseconds.
    *      @usec: number of microseconds to delay by
    *
    *      This function is called all over the kernel and is suppose to provide a
    *      consistent delay.  This function may also be called before the console
    *      is setup so no printf's can be called here.
    *
    *      RETURNS:
    *      nothing
    */
   void
   DELAY(int usec)
   {
           struct arm_tmr_softc *sc;
           int32_t counts;
   
           TSENTER();
           /* Check the timers are setup, if not just use a for loop for the meantime */
           if (arm_tmr_tc == NULL || arm_tmr_timecount.tc_frequency == 0) {
                   for (; usec > 0; usec--)
                           for (counts = 200; counts > 0; counts--)
                                   cpufunc_nullop();       /* Prevent gcc from optimizing
                                                            * out the loop
                                                            */
           } else {
                   sc = arm_tmr_tc->tc_priv;
                   arm_tmr_delay(usec, sc);
           }
           TSEXIT();
   }
   #endif

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