iopoll: Introduce the readl_iopoll_timeout_noirq macro
It is sometimes necessary to poll a register - until a
certain value is read - in atomic context. Introduce
a macro that allows one to specify the maximum number
of reads attempts and the number of microseconds to
delay between each read attempt.
Change-Id: Ice27e78cf4e156da9de00d58783c220bdbc758d3
Signed-off-by: Vikram Mulukutla <markivx@codeaurora.org>
(cherry picked from commit 7a35f5abde0192e72d4e7982411e376d8b898944)
diff --git a/include/linux/iopoll.h b/include/linux/iopoll.h
index 7169870..f28053c 100644
--- a/include/linux/iopoll.h
+++ b/include/linux/iopoll.h
@@ -49,6 +49,28 @@
})
/**
+ * 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