iopoll: Introduce memory-mapped IO polling macros
PATCH v8 1/1 iopoll: Introduce memory-mapped IO polling macros
From: Matt Wagantall <[email protected]>
It is sometimes necessary to poll a memory-mapped register until its value satisfies some condition. Introduce a family of convenience macros that do this. Tight-looping, sleeping, and timing out can all be accomplished using these macros.
Cc Thierry Reding <[email protected]>
Cc Will Deacon <[email protected]>
Cc Arnd Bergmann <[email protected]>
Signed-off-by Matt Wagantall <[email protected]>
Signed-off-by Mitchel Humpherys <[email protected]>
---
Changes since v7:
- sorted helper macros by size (b, w, l, q)
- removed some of the more esoteric (or flat-out bogus) helper macros
--- include/linux/iopoll.h | 140 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 140 insertions(+) create mode 100644 include/linux/iopoll.h
include/linux/iopoll.h new file +140 -0
@@ -0,0 +1,140 @@ +/* +* Copyright (c) 2012-2014 The Linux Foundation. All rights reserved. +* +* This program is free software; you can redistribute it and/or modify +* it under the terms of the GNU General Public License version 2 and +* only version 2 as published by the Free Software Foundation. +* +* This program is distributed in the hope that it will be useful, +* but WITHOUT ANY WARRANTY; without even the implied warranty of +* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +* GNU General Public License for more details. +* +*/ + +#ifndef _LINUX_IOPOLL_H +#define _LINUX_IOPOLL_H + +#include <linux/kernel.h> +#include <linux/types.h> +#include <linux/hrtimer.h> +#include <linux/delay.h> +#include <linux/errno.h> +#include <linux/io.h> + +/** +* readx_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs +* @op: accessor function (takes @addr as its only argument) +* @addr: Address to poll +* @val: Variable to read the value into +* @cond: Break condition (usually involving @val) +* @sleep_us: Maximum time to sleep between reads in us (0 tight-loops) +* @timeout_us: Timeout in us, 0 means never timeout +* +* Returns 0 on success and -ETIMEDOUT upon a timeout. In either +* case, the last read value at @addr is stored in @val. Must not +* be called from atomic context if sleep_us or timeout_us are used. +* +* When available, you'll probably want to use one of the specialized +* macros defined below rather than this macro directly. +*/ +#define readx_poll_timeout (op, addr, val, cond, sleep_us, timeout_us) \ +({ \ + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ + might_sleep_if(sleep_us); \ + for (;;) { \ + (val) = op(addr); \ + if (cond) \ + break; \ + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ + (val) = op(addr); \ + break; \ + } \ + if (sleep_us) \ + usleep_range((sleep_us >> 2) + 1, sleep_us); \ + } \ + (cond) ? 0 : -ETIMEDOUT; \ +}) + +/** +* readx_poll_timeout_atomic - Periodically poll an address until a condition is met or a timeout occurs +* @op: accessor function (takes @addr as its only argument) +* @addr: Address to poll +* @val: Variable to read the value into +* @cond: Break condition (usually involving @val) +* @delay_us: Time to udelay between reads in us (0 tight-loops) +* @timeout_us: Timeout in us, 0 means never timeout +* +* Returns 0 on success and -ETIMEDOUT upon a timeout. In either +* case, the last read value at @addr is stored in @val. +* +* When available, you'll probably want to use one of the specialized +* macros defined below rather than this macro directly. +*/ +#define readx_poll_timeout_atomic (op, addr, val, cond, delay_us, timeout_us) \ +({ \ + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ + for (;;) { \ + (val) = op(addr); \ + if (cond) \ + break; \ + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ + (val) = op(addr); \ + break; \ + } \ + if (delay_us) \ + udelay(delay_us); \ + } \ + (cond) ? 0 : -ETIMEDOUT; \ +}) + + +#define readb_poll_timeout (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readb, addr, val, cond, delay_us, timeout_us) + +#define readb_poll_timeout_atomic (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readb, addr, val, cond, delay_us, timeout_us) + +#define readw_poll_timeout (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readw, addr, val, cond, delay_us, timeout_us) + +#define readw_poll_timeout_atomic (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readw, addr, val, cond, delay_us, timeout_us) + +#define readl_poll_timeout (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readl, addr, val, cond, delay_us, timeout_us) + +#define readl_poll_timeout_atomic (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readl, addr, val, cond, delay_us, timeout_us) + +#define readq_poll_timeout (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readq, addr, val, cond, delay_us, timeout_us) + +#define readq_poll_timeout_atomic (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readq, addr, val, cond, delay_us, timeout_us) + +#define readb_relaxed_poll_timeout (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readb_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readb_relaxed_poll_timeout_atomic (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readb_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readw_relaxed_poll_timeout (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readw_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readw_relaxed_poll_timeout_atomic (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readw_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readl_relaxed_poll_timeout (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readl_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readl_relaxed_poll_timeout_atomic (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readl_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readq_relaxed_poll_timeout (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout(readq_relaxed, addr, val, cond, delay_us, timeout_us) + +#define readq_relaxed_poll_timeout_atomic (addr, val, cond, delay_us, timeout_us) \ + readx_poll_timeout_atomic(readq_relaxed, addr, val, cond, delay_us, timeout_us) + +#endif /* _LINUX_IOPOLL_H */
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