armcm_timer: Unify udelay() implementation

Move the udelay() code from various arm board directories into the
src/generic/armcm_timer.c code.

Signed-off-by: Kevin O'Connor <kevin@koconnor.net>

src/lpc176x/internal.h

@@ -18,6 +18,4 @@ int is_enabled_pclock(uint32_t pclk);
 void enable_pclock(uint32_t pclk);
 void gpio_peripheral(uint32_t gpio, int func, int pullup);
 
-void udelay(uint32_t usecs);
-
 #endif // internal.h

src/lpc176x/main.c

@@ -67,20 +67,6 @@ command_reset(uint32_t *args)
 }
 DECL_COMMAND_FLAGS(command_reset, HF_IN_SHUTDOWN, "reset");
 
-// Implement simple early-boot delay mechanism
-void
-udelay(uint32_t usecs)
-{
-    if (!(CoreDebug->DEMCR & CoreDebug_DEMCR_TRCENA_Msk)) {
-        CoreDebug->DEMCR |= CoreDebug_DEMCR_TRCENA_Msk;
-        DWT->CTRL |= DWT_CTRL_CYCCNTENA_Msk;
-    }
-
-    uint32_t end = timer_read_time() + timer_from_us(usecs);
-    while (timer_is_before(timer_read_time(), end))
-        ;
-}
-
 // Main entry point
 int
 main(void)

src/lpc176x/usbserial.c

@@ -7,6 +7,7 @@
 #include <string.h> // memcpy
 #include "LPC17xx.h" // LPC_SC
 #include "autoconf.h" // CONFIG_SMOOTHIEWARE_BOOTLOADER
+#include "board/armcm_timer.h" // udelay
 #include "board/irq.h" // irq_disable
 #include "board/misc.h" // timer_read_time
 #include "byteorder.h" // cpu_to_le32