lib: Add wait_for_bit

Add function to poll register waiting for specific bit(s).
Similar functions are implemented in few drivers - they are almost
identical and can be generalized.
Signed-off-by: Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
Reviewed-by: Tom Rini <trini@konsulko.com>

include/wait_bit.h

@@ -0,0 +1,71 @@
+/*
+ * Wait for bit with timeout and ctrlc
+ *
+ * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#ifndef __WAIT_BIT_H
+#define __WAIT_BIT_H
+
+#include <common.h>
+#include <console.h>
+#include <asm/errno.h>
+#include <asm/io.h>
+
+/**
+ * wait_for_bit()	waits for bit set/cleared in register
+ *
+ * Function polls register waiting for specific bit(s) change
+ * (either 0->1 or 1->0). It can fail under two conditions:
+ * - Timeout
+ * - User interaction (CTRL-C)
+ * Function succeeds only if all bits of masked register are set/cleared
+ * (depending on set option).
+ *
+ * @param prefix	Prefix added to timeout messagge (message visible only
+ *			with debug enabled)
+ * @param reg		Register that will be read (using readl())
+ * @param mask		Bit(s) of register that must be active
+ * @param set		Selects wait condition (bit set or clear)
+ * @param timeout_ms	Timeout (in miliseconds)
+ * @param breakable	Enables CTRL-C interruption
+ * @return		0 on success, -ETIMEDOUT or -EINTR on failure
+ */
+static inline int wait_for_bit(const char *prefix, const u32 *reg,
+			       const u32 mask, const bool set,
+			       const unsigned int timeout_ms,
+			       const bool breakable)
+{
+	u32 val;
+	unsigned long start = get_timer(0);
+
+	while (1) {
+		val = readl(reg);
+
+		if (!set)
+			val = ~val;
+
+		if ((val & mask) == mask)
+			return 0;
+
+		if (get_timer(start) > timeout_ms)
+			break;
+
+		if (breakable && ctrlc()) {
+			puts("Abort\n");
+			return -EINTR;
+		}
+
+		udelay(1);
+	}
+
+	debug("%s: Timeout (reg=%p mask=%08x wait_set=%i)\n", prefix, reg, mask,
+	      set);
+
+	return -ETIMEDOUT;
+}
+
+
+#endif