libpayload: Use Kconfig instead of weak symbol for arch_ndelay()

Weak symbols don't work as expected when you want to override them from
within the same static library. This patch changes the arch_ndelay()
function so that instead of having a weak generic implementation, the
choice between generic implementation and an arch-specific override is
explicitly made by Kconfig. Let's also drop the "arch_" prefix and just
call this ndelay().

Change-Id: Ie4fe2734e0683fa3537e2ebcabfe067e7499463a
Signed-off-by: Julius Werner <jwerner@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/87776
Reviewed-by: Yu-Ping Wu <yupingso@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subratabanik@google.com>
Reviewed-by: Jakub "Kuba" Czapiga <czapiga@google.com>

payloads/libpayload/Kconfig

@@ -512,6 +512,13 @@ config ARCH_HAS_MEM_FUNCTIONS
 	  Architectures must select this when they want to override memset,
 	  memcpy and memmove with optimized assembly implementations.
 
+config ARCH_HAS_NDELAY
+	default n
+	bool
+	help
+	  Architectures must select this when they want to override the ndelay()
+	  function with a custom implementation.
+
 source "arch/arm/Kconfig"
 source "arch/arm64/Kconfig"
 source "arch/x86/Kconfig"

payloads/libpayload/arch/x86/Kconfig

@@ -32,6 +32,7 @@ config ARCH_X86
 	select LITTLE_ENDIAN
 	select IO_ADDRESS_SPACE
 	select ARCH_HAS_MEM_FUNCTIONS if GPL
+	select ARCH_HAS_NDELAY
 
 if ARCH_X86
 

payloads/libpayload/arch/x86/apic.c

@@ -249,7 +249,7 @@ static void apic_init_timer(void)
 		apic_write32(APIC_TIMER_INIT_COUNT, UINT32_MAX);
 
 		/* This is safe because apic_initialized() returns false so
-		 * arch_ndelay() falls back to a busy loop. */
+		 * ndelay() falls back to a busy loop. */
 		mdelay(1);
 
 		ticks_per_ms =

payloads/libpayload/arch/x86/delay.c

@@ -38,7 +38,7 @@
 /* Let's assume APIC interrupts take at least 100us */
 #define APIC_INTERRUPT_LATENCY_NS	(100 * NSECS_PER_USEC)
 
-void arch_ndelay(uint64_t ns)
+void ndelay(uint64_t ns)
 {
 	uint64_t delta = ns * timer_hz() / NSECS_PER_SEC;
 	uint64_t pause_delta = 0;

payloads/libpayload/include/delay.h

@@ -14,17 +14,12 @@
 
 unsigned int get_cpu_speed(void);
 
-void arch_ndelay(uint64_t n);
-
 /**
  * Delay for a specified number of nanoseconds.
  *
  * @param ns Number of nanoseconds to delay for.
  */
-static inline void ndelay(unsigned int ns)
-{
-	arch_ndelay((uint64_t)ns);
-}
+void ndelay(uint64_t n);
 
 /**
  * Delay for a specified number of microseconds.
@@ -33,7 +28,7 @@ static inline void ndelay(unsigned int ns)
  */
 static inline void udelay(unsigned int us)
 {
-	arch_ndelay((uint64_t)us * NSECS_PER_USEC);
+	ndelay((uint64_t)us * NSECS_PER_USEC);
 }
 
 /**
@@ -43,7 +38,7 @@ static inline void udelay(unsigned int us)
  */
 static inline void mdelay(unsigned int ms)
 {
-	arch_ndelay((uint64_t)ms * NSECS_PER_MSEC);
+	ndelay((uint64_t)ms * NSECS_PER_MSEC);
 }
 
 /**
@@ -53,7 +48,7 @@ static inline void mdelay(unsigned int ms)
  */
 static inline void delay(unsigned int s)
 {
-	arch_ndelay((uint64_t)s * NSECS_PER_SEC);
+	ndelay((uint64_t)s * NSECS_PER_SEC);
 }
 
 #endif /* LIBPAYLOAD_DELAY_H */

payloads/libpayload/libc/time.c

@@ -161,13 +161,14 @@ int gettimeofday(struct timeval *tv, void *tz)
 	return 0;
 }
 
-__attribute__((weak))
-void arch_ndelay(uint64_t ns)
+#if !CONFIG(LP_ARCH_HAS_NDELAY)
+void ndelay(uint64_t ns)
 {
 	uint64_t delta = ns * timer_hz() / NSECS_PER_SEC;
 	uint64_t start = timer_raw_value();
 	while (timer_raw_value() - start < delta) ;
 }
+#endif
 
 u64 timer_us(u64 base)
 {

payloads/libpayload/tests/drivers/Makefile.mk

@@ -8,4 +8,4 @@ graphics-test-srcs += libc/fpmath.c
 speaker-test-srcs += tests/drivers/speaker-test.c
 speaker-test-mocks += inb
 speaker-test-mocks += outb
-speaker-test-mocks += arch_ndelay
+speaker-test-mocks += ndelay

payloads/libpayload/tests/drivers/speaker-test.c

@@ -104,7 +104,7 @@ static void test_speaker_disable(void **state)
 	speaker_disable();
 }
 
-void arch_ndelay(uint64_t ns)
+void ndelay(uint64_t ns)
 {
 	check_expected(ns);
 }
@@ -112,9 +112,9 @@ void arch_ndelay(uint64_t ns)
 static void setup_speaker_tone_calls(u16 freq, unsigned int duration)
 {
 	setup_speaker_enable_calls(freq, ~freq & 0xff);
-	expect_value(arch_ndelay, ns, (uint64_t)duration * NSECS_PER_MSEC);
+	expect_value(ndelay, ns, (uint64_t)duration * NSECS_PER_MSEC);
 	setup_speaker_disable_calls(0xff);
-	expect_any(arch_ndelay, ns);
+	expect_any(ndelay, ns);
 }
 
 static void test_speaker_tone(void **state)