| Message ID | 1404147116-4598-4-git-send-email-ohaugan@codeaurora.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Jun 30, 2014 at 09:51:52AM -0700, Olav Haugan wrote: [...] > diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h [...] > +/** > + * readl_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs > + * @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) s/uS/us/ here and elsewhere. S is the symbol for Siemens. > + * @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. > + */ > +#define readl_poll_timeout(addr, val, cond, sleep_us, timeout_us) \ > +({ \ > + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ > + might_sleep_if(timeout_us); \ > + for (;;) { \ > + (val) = readl(addr); \ > + if (cond) \ > + break; \ > + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ > + (val) = readl(addr); \ > + break; \ > + } \ > + if (sleep_us) \ > + usleep_range(DIV_ROUND_UP(sleep_us, 4), sleep_us); \ > + } \ > + (cond) ? 0 : -ETIMEDOUT; \ > +}) Why can't these be functions? Thierry
Hi Matt, On Mon, Jun 30, 2014 at 05:51:52PM +0100, Olav Haugan wrote: > From: Matt Wagantall <mattw@codeaurora.org> > > 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-loop and sleeping versions are provided with and > without timeouts. We could certainly use something like this in the SMMU and GICv3 drivers, so I agree that it makes sense for this to be in generic code. > +/** > + * readl_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs > + * @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 I think 0 should actually mean `use the default timeout', which could be something daft like 1s. Removing the timeout is asking for kernel lock-ups. We could also have a version without the timeout parameter at all, which acts like a timeout of 0. > + * > + * 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. > + */ > +#define readl_poll_timeout(addr, val, cond, sleep_us, timeout_us) \ > +({ \ > + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ > + might_sleep_if(timeout_us); \ > + for (;;) { \ > + (val) = readl(addr); \ > + if (cond) \ > + break; \ > + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ > + (val) = readl(addr); \ > + break; \ > + } \ > + if (sleep_us) \ > + usleep_range(DIV_ROUND_UP(sleep_us, 4), sleep_us); \ > + } \ > + (cond) ? 0 : -ETIMEDOUT; \ > +}) > + > +/** > + * readl_poll_timeout_noirq - Periodically poll an address until a condition is met or a timeout occurs > + * @addr: Address to poll > + * @val: Variable to read the value into > + * @cond: Break condition (usually involving @val) > + * @max_reads: Maximum number of reads before giving up I don't think max_reads is a useful tunable. > + * @time_between_us: Time to udelay() between successive reads > + * > + * Returns 0 on success and -ETIMEDOUT upon a timeout. > + */ > +#define readl_poll_timeout_noirq(addr, val, cond, max_reads, time_between_us) \ Maybe readl_poll_[timeout_]atomic is a better name? > +({ \ > + int count; \ > + for (count = (max_reads); count > 0; count--) { \ > + (val) = readl(addr); \ > + if (cond) \ > + break; \ > + udelay(time_between_us); \ > + } \ > + (cond) ? 0 : -ETIMEDOUT; \ > +}) > + > +/** > + * readl_poll - Periodically poll an address until a condition is met > + * @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) > + * > + * Must not be called from atomic context if sleep_us is used. > + */ > +#define readl_poll(addr, val, cond, sleep_us) \ > + readl_poll_timeout(addr, val, cond, sleep_us, 0) Good idea ;) > +/** > + * readl_tight_poll_timeout - Tight-loop on an address until a condition is met or a timeout occurs > + * @addr: Address to poll > + * @val: Variable to read the value into > + * @cond: Break condition (usually involving @val) > + * @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 timeout_us is used. > + */ > +#define readl_tight_poll_timeout(addr, val, cond, timeout_us) \ > + readl_poll_timeout(addr, val, cond, 0, timeout_us) > + > +/** > + * readl_tight_poll - Tight-loop on an address until a condition is met > + * @addr: Address to poll > + * @val: Variable to read the value into > + * @cond: Break condition (usually involving @val) > + * > + * May be called from atomic context. > + */ > +#define readl_tight_poll(addr, val, cond) \ > + readl_poll_timeout(addr, val, cond, 0, 0) This would be readl_poll_timeout_atomic if you went with my suggestion (i.e. readl_poll_timeout would have an unconditional might_sleep). What do you reckon? Will -- To unsubscribe from this list: send the line "unsubscribe linux-arm-msm" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h new file mode 100644 index 0000000..d085e03 --- /dev/null +++ b/include/linux/iopoll.h @@ -0,0 +1,114 @@ +/* + * 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 <asm-generic/errno.h> +#include <asm/io.h> + +/** + * readl_poll_timeout - Periodically poll an address until a condition is met or a timeout occurs + * @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. + */ +#define readl_poll_timeout(addr, val, cond, sleep_us, timeout_us) \ +({ \ + ktime_t timeout = ktime_add_us(ktime_get(), timeout_us); \ + might_sleep_if(timeout_us); \ + for (;;) { \ + (val) = readl(addr); \ + if (cond) \ + break; \ + if (timeout_us && ktime_compare(ktime_get(), timeout) > 0) { \ + (val) = readl(addr); \ + break; \ + } \ + if (sleep_us) \ + usleep_range(DIV_ROUND_UP(sleep_us, 4), sleep_us); \ + } \ + (cond) ? 0 : -ETIMEDOUT; \ +}) + +/** + * readl_poll_timeout_noirq - Periodically poll an address until a condition is met or a timeout occurs + * @addr: Address to poll + * @val: Variable to read the value into + * @cond: Break condition (usually involving @val) + * @max_reads: Maximum number of reads before giving up + * @time_between_us: Time to udelay() between successive reads + * + * Returns 0 on success and -ETIMEDOUT upon a timeout. + */ +#define readl_poll_timeout_noirq(addr, val, cond, max_reads, time_between_us) \ +({ \ + int count; \ + for (count = (max_reads); count > 0; count--) { \ + (val) = readl(addr); \ + if (cond) \ + break; \ + udelay(time_between_us); \ + } \ + (cond) ? 0 : -ETIMEDOUT; \ +}) + +/** + * readl_poll - Periodically poll an address until a condition is met + * @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) + * + * Must not be called from atomic context if sleep_us is used. + */ +#define readl_poll(addr, val, cond, sleep_us) \ + readl_poll_timeout(addr, val, cond, sleep_us, 0) + +/** + * readl_tight_poll_timeout - Tight-loop on an address until a condition is met or a timeout occurs + * @addr: Address to poll + * @val: Variable to read the value into + * @cond: Break condition (usually involving @val) + * @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 timeout_us is used. + */ +#define readl_tight_poll_timeout(addr, val, cond, timeout_us) \ + readl_poll_timeout(addr, val, cond, 0, timeout_us) + +/** + * readl_tight_poll - Tight-loop on an address until a condition is met + * @addr: Address to poll + * @val: Variable to read the value into + * @cond: Break condition (usually involving @val) + * + * May be called from atomic context. + */ +#define readl_tight_poll(addr, val, cond) \ + readl_poll_timeout(addr, val, cond, 0, 0) + +#endif /* _LINUX_IOPOLL_H */