[U-Boot] [PATCH v3 1/5] lib: Add wait_for_bit

Mateusz Kulikowski
2015-12-27T17:28:08Z

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>
---

include/wait_bit.h | 71 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 71 insertions(+)
create mode 100644 include/wait_bit.h

diff --git a/include/wait_bit.h b/include/wait_bit.h
new file mode 100644
index 0000000..4867ced
--- /dev/null
+++ b/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 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,
+ 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)
+ 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
--
2.5.0