diff --git a/litex/soc/cores/cpu/blackparrot/system.h b/litex/soc/cores/cpu/blackparrot/system.h
index 079c7cfd7..9165ec802 100644
--- a/litex/soc/cores/cpu/blackparrot/system.h
+++ b/litex/soc/cores/cpu/blackparrot/system.h
@@ -9,6 +9,7 @@ __attribute__((unused)) static void flush_cpu_icache(void){};  /* FIXME: do some
 __attribute__((unused)) static void flush_cpu_dcache(void){};  /* FIXME: do something useful here! */
 void flush_l2_cache(void);
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #include <csr-defs.h>
 
diff --git a/litex/soc/cores/cpu/cv32e40p/system.h b/litex/soc/cores/cpu/cv32e40p/system.h
index b787320a2..fa134fc38 100644
--- a/litex/soc/cores/cpu/cv32e40p/system.h
+++ b/litex/soc/cores/cpu/cv32e40p/system.h
@@ -22,6 +22,7 @@ __attribute__((unused)) static void flush_cpu_dcache(void)
 void flush_l2_cache(void);
 
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #define csrr(reg) ({ unsigned long __tmp; \
   asm volatile ("csrr %0, " #reg : "=r"(__tmp)); \
diff --git a/litex/soc/cores/cpu/lm32/system.h b/litex/soc/cores/cpu/lm32/system.h
index 1272cf1ae..6fe734551 100644
--- a/litex/soc/cores/cpu/lm32/system.h
+++ b/litex/soc/cores/cpu/lm32/system.h
@@ -27,6 +27,7 @@ __attribute__((unused)) static void flush_cpu_dcache(void)
 void flush_l2_cache(void);
 
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #ifdef __cplusplus
 }
diff --git a/litex/soc/cores/cpu/microwatt/system.h b/litex/soc/cores/cpu/microwatt/system.h
index c8c4e41c2..4a53f0760 100644
--- a/litex/soc/cores/cpu/microwatt/system.h
+++ b/litex/soc/cores/cpu/microwatt/system.h
@@ -13,6 +13,7 @@ static inline void flush_cpu_dcache(void){}; /* FIXME: do something useful here!
 void flush_l2_cache(void);
 
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #ifdef __cplusplus
 }
diff --git a/litex/soc/cores/cpu/minerva/system.h b/litex/soc/cores/cpu/minerva/system.h
index 408ab3659..220d1fed1 100644
--- a/litex/soc/cores/cpu/minerva/system.h
+++ b/litex/soc/cores/cpu/minerva/system.h
@@ -9,6 +9,7 @@ __attribute__((unused)) static void flush_cpu_icache(void){}; /* FIXME: do somet
 __attribute__((unused)) static void flush_cpu_dcache(void){}; /* FIXME: do something useful here! */
 void flush_l2_cache(void);
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #include <csr-defs.h>
 
diff --git a/litex/soc/cores/cpu/mor1kx/system.h b/litex/soc/cores/cpu/mor1kx/system.h
index 77366810a..554162278 100644
--- a/litex/soc/cores/cpu/mor1kx/system.h
+++ b/litex/soc/cores/cpu/mor1kx/system.h
@@ -62,6 +62,7 @@ __attribute__((unused)) static void flush_cpu_dcache(void)
 void flush_l2_cache(void);
 
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #ifdef __cplusplus
 }
diff --git a/litex/soc/cores/cpu/picorv32/system.h b/litex/soc/cores/cpu/picorv32/system.h
index afa56d677..262446a62 100644
--- a/litex/soc/cores/cpu/picorv32/system.h
+++ b/litex/soc/cores/cpu/picorv32/system.h
@@ -10,6 +10,7 @@ __attribute__((unused)) static void flush_cpu_dcache(void){}; /* No instruction
 void flush_l2_cache(void);
 
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #ifdef __cplusplus
 }
diff --git a/litex/soc/cores/cpu/rocket/system.h b/litex/soc/cores/cpu/rocket/system.h
index d3e98e1db..5ed09d2a5 100644
--- a/litex/soc/cores/cpu/rocket/system.h
+++ b/litex/soc/cores/cpu/rocket/system.h
@@ -10,6 +10,7 @@ __attribute__((unused)) static void flush_cpu_dcache(void){}; /* FIXME: do somet
 void flush_l2_cache(void);
 
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #include <csr-defs.h>
 
diff --git a/litex/soc/cores/cpu/serv/system.h b/litex/soc/cores/cpu/serv/system.h
index afa56d677..262446a62 100644
--- a/litex/soc/cores/cpu/serv/system.h
+++ b/litex/soc/cores/cpu/serv/system.h
@@ -10,6 +10,7 @@ __attribute__((unused)) static void flush_cpu_dcache(void){}; /* No instruction
 void flush_l2_cache(void);
 
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #ifdef __cplusplus
 }
diff --git a/litex/soc/cores/cpu/vexriscv/system.h b/litex/soc/cores/cpu/vexriscv/system.h
index f441a197e..c1239889b 100644
--- a/litex/soc/cores/cpu/vexriscv/system.h
+++ b/litex/soc/cores/cpu/vexriscv/system.h
@@ -37,6 +37,7 @@ __attribute__((unused)) static void flush_cpu_dcache(void)
 void flush_l2_cache(void);
 
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #define csrr(reg) ({ unsigned long __tmp; \
   asm volatile ("csrr %0, " #reg : "=r"(__tmp)); \
diff --git a/litex/soc/cores/cpu/vexriscv_smp/system.h b/litex/soc/cores/cpu/vexriscv_smp/system.h
index a3759aec6..15649f602 100644
--- a/litex/soc/cores/cpu/vexriscv_smp/system.h
+++ b/litex/soc/cores/cpu/vexriscv_smp/system.h
@@ -27,6 +27,7 @@ __attribute__((unused)) static void flush_cpu_dcache(void)
 void flush_l2_cache(void);
 
 void busy_wait(unsigned int ms);
+void busy_wait_us(unsigned int us);
 
 #include <csr-defs.h>
 
diff --git a/litex/soc/software/libbase/system.c b/litex/soc/software/libbase/system.c
index ed4110dde..4e5318323 100644
--- a/litex/soc/software/libbase/system.c
+++ b/litex/soc/software/libbase/system.c
@@ -24,3 +24,13 @@ void busy_wait(unsigned int ms)
 	timer0_update_value_write(1);
 	while(timer0_value_read()) timer0_update_value_write(1);
 }
+
+void busy_wait_us(unsigned int us)
+{
+	timer0_en_write(0);
+	timer0_reload_write(0);
+	timer0_load_write(CONFIG_CLOCK_FREQUENCY/1000000*us);
+	timer0_en_write(1);
+	timer0_update_value_write(1);
+	while(timer0_value_read()) timer0_update_value_write(1);
+}
diff --git a/litex/soc/software/liblitesdcard/sdcard.c b/litex/soc/software/liblitesdcard/sdcard.c
index fc9e3ff0a..52e87af6d 100644
--- a/litex/soc/software/liblitesdcard/sdcard.c
+++ b/litex/soc/software/liblitesdcard/sdcard.c
@@ -42,16 +42,6 @@ unsigned int sdcard_response[SD_CMD_RESPONSE_SIZE/4];
 /* SDCard command helpers                                                */
 /*-----------------------------------------------------------------------*/
 
-static void busy_wait_us(unsigned int us)
-{
-    timer0_en_write(0);
-    timer0_reload_write(0);
-    timer0_load_write(CONFIG_CLOCK_FREQUENCY/1000000*us);
-    timer0_en_write(1);
-    timer0_update_value_write(1);
-    while(timer0_value_read()) timer0_update_value_write(1);
-}
-
 int sdcard_wait_cmd_done(void) {
 	unsigned int cmdevt;
 	while (1) {
diff --git a/litex/soc/software/liblitesdcard/spisdcard.c b/litex/soc/software/liblitesdcard/spisdcard.c
index 01c62d4cf..eeb8dee5d 100644
--- a/litex/soc/software/liblitesdcard/spisdcard.c
+++ b/litex/soc/software/liblitesdcard/spisdcard.c
@@ -123,16 +123,6 @@ static void spisdcardread_bytes(uint8_t* buf, uint16_t n) {
 /* SPI SDCard blocks Xfer functions                                      */
 /*-----------------------------------------------------------------------*/
 
-static void busy_wait_us(unsigned int us)
-{
-    timer0_en_write(0);
-    timer0_reload_write(0);
-    timer0_load_write(CONFIG_CLOCK_FREQUENCY/1000000*us);
-    timer0_en_write(1);
-    timer0_update_value_write(1);
-    while(timer0_value_read()) timer0_update_value_write(1);
-}
-
 static uint8_t spisdcardreceive_block(uint8_t *buf) {
     uint16_t i;
     uint32_t timeout;