On Mon, Nov 24, 2014 at 08:14:52PM +, Mitchel Humpherys wrote:
From: Matt Wagantall ma...@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-looping, sleeping, and timing out can all be accomplished using
these macros.
Cc: Thierry Reding thierry.red...@gmail.com
Cc: Will Deacon will.dea...@arm.com
Cc: Arnd Bergmann a...@arndb.de
Cc: Andrew Morton a...@linux-foundation.org
Signed-off-by: Matt Wagantall ma...@codeaurora.org
Signed-off-by: Mitchel Humpherys mitch...@codeaurora.org
---
This patch was originally part of a series [1] for adding support for IOMMU
address translations through an ARM SMMU hardware register. The other
patch in the series (the one that actually uses these macros and implements
said hardware address translations) was Ack'd by the driver maintainer
there (Will Deacon) so I've pulled this patch out to avoid resending an
already Ack'd patch over and over again.
In short, please see [1] for previous discussion and the first user of
these macros.
This patch has been resent previously here [2], here [3], and here [4] on
2014-10-30, 2014-11-06, and 2014-11-17, respectively. It has not changed
since [2] and has not received any comments since [1] on 2014-10-19.
Thanks to everyone who has taken a look at this.
[1] http://thread.gmane.org/gmane.linux.kernel.iommu/7140
[2] http://thread.gmane.org/gmane.linux.kernel/1818213
[3] http://thread.gmane.org/gmane.linux.kernel/1823422
[4] http://thread.gmane.org/gmane.linux.kernel.iommu/7394
Did this ever get queued? It would be pretty useful for a bunch of drivers
that seem to copy-paste this sort of code.
If it helps:
Acked-by: Will Deacon will.dea...@arm.com
Will
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
diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h
new file mode 100644
index 00..bd161dae2d
--- /dev/null
+++ b/include/linux/iopoll.h
@@ -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,