include/wait_bit.h

   1 /*
   2  * Wait for bit with timeout and ctrlc
   3  *
   4  * (C) Copyright 2015 Mateusz Kulikowski <mateusz.kulikowski@gmail.com>
   5  *
   6  * SPDX-License-Identifier:     GPL-2.0+
   7  */
   8
   9 #ifndef __WAIT_BIT_H
  10 #define __WAIT_BIT_H
  11
  12 #include <common.h>
  13 #include <console.h>
  14 #include <asm/errno.h>
  15 #include <asm/io.h>
  16
  17 /**
  18  * wait_for_bit()       waits for bit set/cleared in register
  19  *
  20  * Function polls register waiting for specific bit(s) change
  21  * (either 0->1 or 1->0). It can fail under two conditions:
  22  * - Timeout
  23  * - User interaction (CTRL-C)
  24  * Function succeeds only if all bits of masked register are set/cleared
  25  * (depending on set option).
  26  *
  27  * @param prefix        Prefix added to timeout messagge (message visible only
  28  *                      with debug enabled)
  29  * @param reg           Register that will be read (using readl())
  30  * @param mask          Bit(s) of register that must be active
  31  * @param set           Selects wait condition (bit set or clear)
  32  * @param timeout_ms    Timeout (in miliseconds)
  33  * @param breakable     Enables CTRL-C interruption
  34  * @return              0 on success, -ETIMEDOUT or -EINTR on failure
  35  */
  36 static inline int wait_for_bit(const char *prefix, const u32 *reg,
  37                                const u32 mask, const bool set,
  38                                const unsigned int timeout_ms,
  39                                const bool breakable)
  40 {
  41         u32 val;
  42         unsigned long start = get_timer(0);
  43
  44         while (1) {
  45                 val = readl(reg);
  46
  47                 if (!set)
  48                         val = ~val;
  49
  50                 if ((val & mask) == mask)
  51                         return 0;
  52
  53                 if (get_timer(start) > timeout_ms)
  54                         break;
  55
  56                 if (breakable && ctrlc()) {
  57                         puts("Abort\n");
  58                         return -EINTR;
  59                 }
  60
  61                 udelay(1);
  62         }
  63
  64         debug("%s: Timeout (reg=%p mask=%08x wait_set=%i)\n", prefix, reg, mask,
  65               set);
  66
  67         return -ETIMEDOUT;
  68 }
  69
  70
  71 #endif