From 18ae7652a99e2b0ebf1908037bf053c840df2944 Mon Sep 17 00:00:00 2001
From: Marian Buschsieweke <marian.buschsieweke@ovgu.de>
Date: Tue, 14 Aug 2018 10:40:09 +0200
Subject: [PATCH] cpu/lpc2387: Fixed doc and attribute of arm_reset
- arm_reset was completely undocumented, even though technical details buried
deeply in the data sheet of the LPC2387 are involved in the code
- The attribute "naked" is misplaced, it should only be used when no C code
is present. However, the function consists of C code only
- The attribute "noreturn" has to be used in the declaration [1] of a function,
not in the implementation. Otherwise the caller is not informed and code using
the function will not be optimized.
[1]: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html
---
cpu/lpc2387/cpu.c | 25 ++++++++++++++++++++-----
1 file changed, 20 insertions(+), 5 deletions(-)
diff --git a/cpu/lpc2387/cpu.c b/cpu/lpc2387/cpu.c
index 91e61e58b4..8190dcde74 100644
--- a/cpu/lpc2387/cpu.c
+++ b/cpu/lpc2387/cpu.c
@@ -85,13 +85,28 @@ bool install_irq(int IntNumber, void (*HandlerAddr)(void), int Priority)
}
}
-__attribute__((naked,noreturn)) void arm_reset(void)
+void arm_reset(void)
{
+ /*
+ * We abuse the watchdog timer for a reset.
+ */
irq_disable();
- WDTC = 0x0FFFF;
- WDMOD = 0x03;
- WDFEED= 0xAA;
- WDFEED= 0x55;
+ /* Set the watchdog timeout constant to 0xFFFF */
+ WDTC = 0xFFFF;
+ /*
+ * Enable watchdog interrupt and enable reset on watchdog timeout.
+ * (The reset on watchdog timeout flag is ignored, if interrupt on watchdog
+ * timeout is not set. Thus, we set both. The reset takes precedence over
+ * the interrupt, anyway.)
+ */
+ WDMOD = 0x03;
+ /*
+ * Feed the watchdog by writing 0xAA followed by 0x55:
+ * Reload the watchdog timer with the value in WDTC (0xFFFF)
+ */
+ WDFEED = 0xAA;
+ WDFEED = 0x55;
+ /* Wait for the watchdog timer to expire, thus performing a reset */
while(1) {}
}
--
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