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[/] [openrisc/] [trunk/] [rtos/] [rtems/] [c/] [src/] [lib/] [libcpu/] [powerpc/] [ppc403/] [clock/] [clock.c] - Rev 173
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/* clock.c * * This routine initializes the interval timer on the * PowerPC 403 CPU. The tick frequency is specified by the bsp. * * Author: Andrew Bray <andy@i-cubed.co.uk> * * COPYRIGHT (c) 1995 by i-cubed ltd. * * To anyone who acknowledges that this file is provided "AS IS" * without any express or implied warranty: * permission to use, copy, modify, and distribute this file * for any purpose is hereby granted without fee, provided that * the above copyright notice and this notice appears in all * copies, and that the name of i-cubed limited not be used in * advertising or publicity pertaining to distribution of the * software without specific, written prior permission. * i-cubed limited makes no representations about the suitability * of this software for any purpose. * * Derived from c/src/lib/libcpu/hppa1.1/clock/clock.c: * * Modifications for deriving timer clock from cpu system clock by * Thomas Doerfler <td@imd.m.isar.de> * for these modifications: * COPYRIGHT (c) 1997 by IMD, Puchheim, Germany. * * * COPYRIGHT (c) 1989-1999. * On-Line Applications Research Corporation (OAR). * * The license and distribution terms for this file may be * found in the file LICENSE in this distribution or at * http://www.OARcorp.com/rtems/license.html. * * $Id: clock.c,v 1.2 2001-09-27 12:01:29 chris Exp $ */ #include <rtems.h> #include <clockdrv.h> #include <rtems/libio.h> #include <stdlib.h> /* for atexit() */ volatile rtems_unsigned32 Clock_driver_ticks; static rtems_unsigned32 pit_value, tick_time; static rtems_boolean auto_restart; void Clock_exit( void ); /* * These are set by clock driver during its init */ rtems_device_major_number rtems_clock_major = ~0; rtems_device_minor_number rtems_clock_minor; static inline rtems_unsigned32 get_itimer(void) { register rtems_unsigned32 rc; asm volatile ("mfspr %0, 0x3dd" : "=r" ((rc))); /* TBLO */ return rc; } /* * ISR Handler */ rtems_isr Clock_isr(rtems_vector_number vector) { if (!auto_restart) { rtems_unsigned32 clicks_til_next_interrupt; rtems_unsigned32 itimer_value; /* * setup for next interrupt; making sure the new value is reasonably * in the future.... in case we lost out on an interrupt somehow */ itimer_value = get_itimer(); tick_time += pit_value; /* * how far away is next interrupt *really* * It may be a long time; this subtraction works even if * Clock_clicks_interrupt < Clock_clicks_low_order via * the miracle of unsigned math. */ clicks_til_next_interrupt = tick_time - itimer_value; /* * If it is too soon then bump it up. * This should only happen if CPU_HPPA_CLICKS_PER_TICK is too small. * But setting it low is useful for debug, so... */ if (clicks_til_next_interrupt < 400) { tick_time = itimer_value + 1000; clicks_til_next_interrupt = 1000; /* XXX: count these! this should be rare */ } /* * If it is too late, that means we missed the interrupt somehow. * Rather than wait 35-50s for a wrap, we just fudge it here. */ if (clicks_til_next_interrupt > pit_value) { tick_time = itimer_value + 1000; clicks_til_next_interrupt = 1000; /* XXX: count these! this should never happen :-) */ } asm volatile ("mtspr 0x3db, %0" :: "r" (clicks_til_next_interrupt)); /* PIT */ } asm volatile ( "mtspr 0x3d8, %0" :: "r" (0x08000000)); /* TSR */ Clock_driver_ticks++; rtems_clock_tick(); } void Install_clock(rtems_isr_entry clock_isr) { rtems_isr_entry previous_isr; rtems_unsigned32 pvr, iocr; register rtems_unsigned32 tcr; Clock_driver_ticks = 0; asm volatile ("mfdcr %0, 0xa0" : "=r" (iocr)); /* IOCR */ if (rtems_cpu_configuration_get_timer_internal_clock()) { iocr &= ~4; /* timer clocked from system clock */ } else { iocr |= 4; /* select external timer clock */ } asm volatile ("mtdcr 0xa0, %0" : "=r" (iocr) : "0" (iocr)); /* IOCR */ asm volatile ("mfspr %0, 0x11f" : "=r" ((pvr))); /* PVR */ if (((pvr & 0xffff0000) >> 16) != 0x0020) return; /* Not a ppc403 */ if ((pvr & 0xff00) == 0x0000) /* 403GA */ #if 0 /* FIXME: in which processor versions will "autoload" work properly? */ auto_restart = (pvr & 0x00f0) > 0x0000 ? 1 : 0; #else /* no known chip version supports auto restart of timer... */ auto_restart = 0; #endif else if ((pvr & 0xff00) == 0x0100) /* 403GB */ auto_restart = 1; pit_value = rtems_configuration_get_microseconds_per_tick() * rtems_cpu_configuration_get_clicks_per_usec(); /* * initialize the interval here * First tick is set to right amount of time in the future * Future ticks will be incremented over last value set * in order to provide consistent clicks in the face of * interrupt overhead */ rtems_interrupt_catch(clock_isr, PPC_IRQ_PIT, &previous_isr); asm volatile ("mtspr 0x3db, %0" : : "r" (pit_value)); /* PIT */ asm volatile ("mfspr %0, 0x3da" : "=r" ((tcr))); /* TCR */ tcr &= ~ 0x04400000; tcr |= (auto_restart ? 0x04400000 : 0x04000000); tick_time = get_itimer() + pit_value; asm volatile ("mtspr 0x3da, %0" : "=r" ((tcr)) : "0" ((tcr))); /* TCR */ atexit(Clock_exit); } void ReInstall_clock(rtems_isr_entry new_clock_isr) { rtems_isr_entry previous_isr; rtems_unsigned32 isrlevel = 0; rtems_interrupt_disable(isrlevel); rtems_interrupt_catch(new_clock_isr, PPC_IRQ_PIT, &previous_isr); rtems_interrupt_enable(isrlevel); } /* * Called via atexit() * Remove the clock interrupt handler by setting handler to NULL */ void Clock_exit(void) { register rtems_unsigned32 tcr; asm volatile ("mfspr %0, 0x3da" : "=r" ((tcr))); /* TCR */ tcr &= ~ 0x04400000; asm volatile ("mtspr 0x3da, %0" : "=r" ((tcr)) : "0" ((tcr))); /* TCR */ (void) set_vector(0, PPC_IRQ_PIT, 1); } rtems_device_driver Clock_initialize( rtems_device_major_number major, rtems_device_minor_number minor, void *pargp ) { Install_clock( Clock_isr ); /* * make major/minor avail to others such as shared memory driver */ rtems_clock_major = major; rtems_clock_minor = minor; return RTEMS_SUCCESSFUL; } rtems_device_driver Clock_control( rtems_device_major_number major, rtems_device_minor_number minor, void *pargp ) { rtems_libio_ioctl_args_t *args = pargp; if (args == 0) goto done; /* * This is hokey, but until we get a defined interface * to do this, it will just be this simple... */ if (args->command == rtems_build_name('I', 'S', 'R', ' ')) { Clock_isr(PPC_IRQ_PIT); } else if (args->command == rtems_build_name('N', 'E', 'W', ' ')) { ReInstall_clock(args->buffer); } done: return RTEMS_SUCCESSFUL; }