diff options
Diffstat (limited to 'c/src/lib/libcpu/powerpc/ppc403/clock/clock.c')
| -rw-r--r-- | c/src/lib/libcpu/powerpc/ppc403/clock/clock.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/c/src/lib/libcpu/powerpc/ppc403/clock/clock.c b/c/src/lib/libcpu/powerpc/ppc403/clock/clock.c new file mode 100644 index 0000000000..fc17de4cc8 --- /dev/null +++ b/c/src/lib/libcpu/powerpc/ppc403/clock/clock.c @@ -0,0 +1,215 @@ +/* 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.demon.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: + * + * COPYRIGHT (c) 1989, 1990, 1991, 1992, 1993, 1994. + * On-Line Applications Research Corporation (OAR). + * All rights assigned to U.S. Government, 1994. + * + * This material may be reproduced by or for the U.S. Government pursuant + * to the copyright license under the clause at DFARS 252.227-7013. This + * notice must appear in all copies of this file and its derivatives. + * + * clock.c,v 1.2 1995/05/31 16:59:06 joel Exp + */ + +#include <bsp.h> +#include <clockdrv.h> + +#include <stdlib.h> /* for atexit() */ + +extern rtems_cpu_table Cpu_table; /* owned by BSP */ + +volatile rtems_unsigned32 Clock_driver_ticks; +static rtems_unsigned32 pit_value, tick_time; +static rtems_boolean auto_restart; + +rtems_device_driver Clock_initialize( + rtems_device_major_number major, + rtems_device_minor_number minor, + void *pargp, + rtems_id tid, + rtems_unsigned32 *rval +) +{ + Install_clock(Clock_isr); +} + + +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); +} + +static INLINE rtems_unsigned32 get_itimer(void) +{ + register rtems_unsigned32 rc; + + asm volatile ("mftblo %0" : "=r" ((rc))); + + return rc; +} + +void Install_clock(rtems_isr_entry clock_isr) +{ + rtems_isr_entry previous_isr; + rtems_unsigned32 pvr, iocr; + + Clock_driver_ticks = 0; + + asm volatile ("mfiocr %0" : "=r" (iocr)); + iocr &= ~4; + iocr |= 4; /* Select external timer clock */ + asm volatile ("mtiocr %0" : "=r" (iocr) : "0" (iocr)); + + asm volatile ("mfpvr %0" : "=r" ((pvr))); + + if (((pvr & 0xffff0000) >> 16) != 0x0020) + return; /* Not a ppc403 */ + + if ((pvr & 0xff00) == 0x0000) /* 403GA */ + auto_restart = (pvr & 0x00f0) > 0x0000 ? 1 : 0; + else if ((pvr & 0xff00) == 0x0100) /* 403GB */ + auto_restart = 1; + + pit_value = BSP_Configuration.microseconds_per_tick * + Cpu_table.clicks_per_usec; + + if (BSP_Configuration.ticks_per_timeslice) + { + register rtems_unsigned32 tcr; + /* + * 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 ("mtpit %0" : : "r" (pit_value)); + + asm volatile ("mftcr %0" : "=r" ((tcr))); + + tcr &= ~ 0x04400000; + + tcr |= (auto_restart ? 0x04400000 : 0x04000000); + + tick_time = get_itimer() + pit_value; + + asm volatile ("mttcr %0" : "=r" ((tcr)) : "0" ((tcr))); + } + atexit(Clock_exit); +} + + +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 ("mtpit %0" :: "r" (clicks_til_next_interrupt)); + } + + asm volatile ( "mttsr %0" :: "r" (0x08000000)); + + Clock_driver_ticks++; + + rtems_clock_tick(); +} + +/* + * Called via atexit() + * Remove the clock interrupt handler by setting handler to NULL + */ + +void +Clock_exit(void) +{ + if ( BSP_Configuration.ticks_per_timeslice ) + { + register rtems_unsigned32 tcr; + + asm volatile ("mftcr %0" : "=r" ((tcr))); + + tcr &= ~ 0x04400000; + + asm volatile ("mttcr %0" : "=r" ((tcr)) : "0" ((tcr))); + + (void) set_vector(0, PPC_IRQ_PIT, 1); + } +} + |