[RESEND PATCH v2 08/18] linux/compat.h: Add wait_event_timeout macro

Anastasiia Lukianenko
2020-08-06T09:42:51Z

From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Add wait_event_timeout - sleep until a condition gets true or a
timeout elapses.

This is a stripped version of the same from Linux kernel with the
following u-boot specific modifications:
- no wait queues supported
- use u-boot timer to detect timeouts
- check for Ctrl-C pressed during wait

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>
---

Changes since v1:
- add comment
- correct code style

include/linux/compat.h | 54 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 54 insertions(+)

diff --git a/include/linux/compat.h b/include/linux/compat.h
index 712eeaef4e..363b2b9425 100644
--- a/include/linux/compat.h
+++ b/include/linux/compat.h
@@ -1,12 +1,20 @@
#ifndef _LINUX_COMPAT_H_
#define _LINUX_COMPAT_H_

+#include <console.h>
#include <log.h>
#include <malloc.h>
+
+#include <asm/processor.h>
+
#include <linux/types.h>
#include <linux/err.h>
#include <linux/kernel.h>

+#ifdef CONFIG_XEN
+#include <xen/events.h>
+#endif
+
struct unused {};
typedef struct unused unused_t;

@@ -122,6 +130,52 @@ static inline void kmem_cache_destroy(struct kmem_cache *cachep)
#define add_wait_queue(...) do { } while (0)
#define remove_wait_queue(...) do { } while (0)

+#ifndef CONFIG_XEN
+#define eventchn_poll()
+#endif
+
+#define __wait_event_timeout(condition, timeout, ret) \
+({ \
+ ulong __ret = ret; /* explicit shadow */ \
+ ulong start = get_timer(0); \
+ for (;;) { \
+ eventchn_poll(); \
+ if (condition) { \
+ __ret = 1; \
+ break; \
+ } \
+ if ((get_timer(start) > timeout) || ctrlc()) { \
+ __ret = 0; \
+ break; \
+ } \
+ cpu_relax(); \
+ } \
+ __ret; \
+})
+
+/**
+ * wait_event_timeout() - Wait until the event occurs before the timeout.
+ * @wr_head: The wait queue to wait on.
+ * @condition: Expression for the event to wait for.
+ * @timeout: Maximum waiting time.
+ *
+ * We wait until the @condition evaluates to %true (succeed) or
+ * %false (@timeout elapsed).
+ *
+ * Return:
+ * 0 - if the @condition evaluated to %false after the @timeout elapsed
+ * 1 - if the @condition evaluated to %true
+ */
+#define wait_event_timeout(wq_head, condition, timeout) \
+({ \
+ ulong __ret; \
+ if (condition) \
+ __ret = 1; \
+ else \
+ __ret = __wait_event_timeout(condition, timeout, __ret);\
+ __ret; \
+})
+
#define KERNEL_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))

/* This is also defined in ARMv8's mmu.h */
--
2.17.1