[mynewt-core] branch master updated: [NRF52] Remove uint64_t div in watchdog init

[ut...@apache.org]

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utzig pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/mynewt-core.git


The following commit(s) were added to refs/heads/master by this push:
     new 0003fd9  [NRF52] Remove uint64_t div in watchdog init
0003fd9 is described below

commit 0003fd9f4d999bd2f28cec3219fa6f371629d3aa
Author: Fabio Utzig <ut...@apache.org>
AuthorDate: Fri Jul 27 10:08:00 2018 -0300

    [NRF52] Remove uint64_t div in watchdog init
    
    Because of precision requirements the watchdog was using a uint64_t
    division cause it allowed any possible timeout to be used. This updates the
    code to rely only on uint32_t division with the limitation of a maximum
    timeout of slightly more than 12 hours. It shrinks the code due to not
    linking in the div emulation code.
---
 hw/mcu/nordic/nrf52xxx/src/hal_watchdog.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/hw/mcu/nordic/nrf52xxx/src/hal_watchdog.c b/hw/mcu/nordic/nrf52xxx/src/hal_watchdog.c
index 6248dbe..cfbaff6 100644
--- a/hw/mcu/nordic/nrf52xxx/src/hal_watchdog.c
+++ b/hw/mcu/nordic/nrf52xxx/src/hal_watchdog.c
@@ -44,13 +44,14 @@ nrf52_wdt_irq_handler(void)
 int
 hal_watchdog_init(uint32_t expire_msecs)
 {
-    uint64_t expiration;
-
     NRF_WDT->CONFIG = WDT_CONFIG_SLEEP_Msk;
 
-    /* Convert msec timeout to counts of a 32768 crystal */
-    expiration = ((uint64_t)expire_msecs * 32768) / 1000;
-    NRF_WDT->CRV = (uint32_t)expiration;
+    if (expire_msecs >= 44739243) {
+        /* maximum allowed time is near 12.5 hours! */
+        assert(0);
+    } else {
+        NRF_WDT->CRV = (expire_msecs * 32) + ((expire_msecs * 96) / 125);
+    }
 
     NVIC_SetVector(WDT_IRQn, (uint32_t) nrf52_wdt_irq_handler);
     NVIC_SetPriority(WDT_IRQn, (1 << __NVIC_PRIO_BITS) - 1);