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 <watchdog.h>
  15 #include <linux/errno.h>
  16 #include <asm/io.h>
  17
  18 /**
  19  * wait_for_bit()       waits for bit set/cleared in register
  20  *
  21  * Function polls register waiting for specific bit(s) change
  22  * (either 0->1 or 1->0). It can fail under two conditions:
  23  * - Timeout
  24  * - User interaction (CTRL-C)
  25  * Function succeeds only if all bits of masked register are set/cleared
  26  * (depending on set option).
  27  *
  28  * @param prefix        Prefix added to timeout messagge (message visible only
  29  *                      with debug enabled)
  30  * @param reg           Register that will be read (using readl())
  31  * @param mask          Bit(s) of register that must be active
  32  * @param set           Selects wait condition (bit set or clear)
  33  * @param timeout_ms    Timeout (in miliseconds)
  34  * @param breakable     Enables CTRL-C interruption
  35  * @return              0 on success, -ETIMEDOUT or -EINTR on failure
  36  */
  37 static inline int wait_for_bit(const char *prefix, const u32 *reg,
  38                                const u32 mask, const bool set,
  39                                const unsigned int timeout_ms,
  40                                const bool breakable)
  41 {
  42         u32 val;
  43         unsigned long start = get_timer(0);
  44
  45         while (1) {
  46                 val = readl(reg);
  47
  48                 if (!set)
  49                         val = ~val;
  50
  51                 if ((val & mask) == mask)
  52                         return 0;
  53
  54                 if (get_timer(start) > timeout_ms)
  55                         break;
  56
  57                 if (breakable && ctrlc()) {
  58                         puts("Abort\n");
  59                         return -EINTR;
  60                 }
  61
  62                 udelay(1);
  63                 WATCHDOG_RESET();
  64         }
  65
  66         debug("%s: Timeout (reg=%p mask=%08x wait_set=%i)\n", prefix, reg, mask,
  67               set);
  68
  69         return -ETIMEDOUT;
  70 }
  71
  72
  73 #endif