/* * Precise Delay Loops for S390 * * Copyright IBM Corp. 1999,2008 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>, * Heiko Carstens <heiko.carstens@de.ibm.com>, */ #include <linux/sched.h> #include <linux/delay.h> #include <linux/timex.h> #include <linux/module.h> #include <linux/irqflags.h> #include <linux/interrupt.h> void __delay(unsigned long loops) { /* * To end the bloody studid and useless discussion about the * BogoMips number I took the liberty to define the __delay * function in a way that that resulting BogoMips number will * yield the megahertz number of the cpu. The important function * is udelay and that is done using the tod clock. -- martin. */ asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1)); } static void __udelay_disabled(unsigned long usecs) { unsigned long mask, cr0, cr0_saved; u64 clock_saved; clock_saved = local_tick_disable(); set_clock_comparator(get_clock() + ((u64) usecs << 12)); __ctl_store(cr0_saved, 0, 0); cr0 = (cr0_saved & 0xffff00e0) | 0x00000800; __ctl_load(cr0 , 0, 0); mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT; trace_hardirqs_on(); __load_psw_mask(mask); local_irq_disable(); __ctl_load(cr0_saved, 0, 0); local_tick_enable(clock_saved); set_clock_comparator(S390_lowcore.clock_comparator); } static void __udelay_enabled(unsigned long usecs) { unsigned long mask; u64 end, time; mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT | PSW_MASK_IO; end = get_clock() + ((u64) usecs << 12); do { time = end < S390_lowcore.clock_comparator ? end : S390_lowcore.clock_comparator; set_clock_comparator(time); trace_hardirqs_on(); __load_psw_mask(mask); local_irq_disable(); } while (get_clock() < end); set_clock_comparator(S390_lowcore.clock_comparator); } /* * Waits for 'usecs' microseconds using the TOD clock comparator. */ void __udelay(unsigned long usecs) { unsigned long flags; preempt_disable(); local_irq_save(flags); if (in_irq()) { __udelay_disabled(usecs); goto out; } if (in_softirq()) { if (raw_irqs_disabled_flags(flags)) __udelay_disabled(usecs); else __udelay_enabled(usecs); goto out; } if (raw_irqs_disabled_flags(flags)) { local_bh_disable(); __udelay_disabled(usecs); _local_bh_enable(); goto out; } __udelay_enabled(usecs); out: local_irq_restore(flags); preempt_enable(); } EXPORT_SYMBOL(__udelay); /* * Simple udelay variant. To be used on startup and reboot * when the interrupt handler isn't working. */ void udelay_simple(unsigned long usecs) { u64 end; end = get_clock() + ((u64) usecs << 12); while (get_clock() < end) cpu_relax(); }