1 /* SPDX-License-Identifier: GPL-2.0-or-later */ 2 #ifndef _ASM_POWERPC_DELAY_H 3 #define _ASM_POWERPC_DELAY_H 4 #ifdef __KERNEL__ 5 6 #include <linux/processor.h> 7 #include <asm/time.h> 8 9 /* 10 * Copyright 1996, Paul Mackerras. 11 * Copyright (C) 2009 Freescale Semiconductor, Inc. All rights reserved. 12 * 13 * PPC64 Support added by Dave Engebretsen, Todd Inglett, Mike Corrigan, 14 * Anton Blanchard. 15 */ 16 17 extern void __delay(unsigned long loops); 18 extern void udelay(unsigned long usecs); 19 20 /* 21 * On shared processor machines the generic implementation of mdelay can 22 * result in large errors. While each iteration of the loop inside mdelay 23 * is supposed to take 1ms, the hypervisor could sleep our partition for 24 * longer (eg 10ms). With the right timing these errors can add up. 25 * 26 * Since there is no 32bit overflow issue on 64bit kernels, just call 27 * udelay directly. 28 */ 29 #ifdef CONFIG_PPC64 30 #define mdelay(n) udelay((n) * 1000) 31 #endif 32 33 /** 34 * spin_event_timeout - spin until a condition gets true or a timeout elapses 35 * @condition: a C expression to evalate 36 * @timeout: timeout, in microseconds 37 * @delay: the number of microseconds to delay between each evaluation of 38 * @condition 39 * 40 * The process spins until the condition evaluates to true (non-zero) or the 41 * timeout elapses. The return value of this macro is the value of 42 * @condition when the loop terminates. This allows you to determine the cause 43 * of the loop terminates. If the return value is zero, then you know a 44 * timeout has occurred. 45 * 46 * This primary purpose of this macro is to poll on a hardware register 47 * until a status bit changes. The timeout ensures that the loop still 48 * terminates even if the bit never changes. The delay is for devices that 49 * need a delay in between successive reads. 50 * 51 * gcc will optimize out the if-statement if @delay is a constant. 52 */ 53 #define spin_event_timeout(condition, timeout, delay) \ 54 ({ \ 55 typeof(condition) __ret; \ 56 unsigned long __loops = tb_ticks_per_usec * timeout; \ 57 unsigned long __start = mftb(); \ 58 \ 59 if (delay) { \ 60 while (!(__ret = (condition)) && \ 61 (tb_ticks_since(__start) <= __loops)) \ 62 udelay(delay); \ 63 } else { \ 64 spin_begin(); \ 65 while (!(__ret = (condition)) && \ 66 (tb_ticks_since(__start) <= __loops)) \ 67 spin_cpu_relax(); \ 68 spin_end(); \ 69 } \ 70 if (!__ret) \ 71 __ret = (condition); \ 72 __ret; \ 73 }) 74 75 #endif /* __KERNEL__ */ 76 #endif /* _ASM_POWERPC_DELAY_H */ 77