random: Remove duplicated code

All implementations of random number generator where duplicating logic
for sys_rand32_get. Since this subsystem already has a logic to
generate random values of arbitrary size, we can generically implement
sys_rand32_get on top of that.

Signed-off-by: Flavio Ceolin <flavio.ceolin@intel.com>

include/zephyr/random/random.h

@@ -38,16 +38,6 @@
 extern "C" {
 #endif
 
-/**
- * @brief Return a 32-bit random value that should pass general
- * randomness tests.
- *
- * @note The random value returned is not a cryptographically secure
- * random number value.
- *
- * @return 32-bit random value.
- */
-__syscall uint32_t sys_rand32_get(void);
 
 /**
  * @brief Fill the destination buffer with random data values that should
@@ -77,6 +67,25 @@ __syscall void sys_rand_get(void *dst, size_t len);
  */
 __syscall int sys_csrand_get(void *dst, size_t len);
 
+/**
+ * @brief Return a 32-bit random value that should pass general
+ * randomness tests.
+ *
+ * @note The random value returned is not a cryptographically secure
+ * random number value.
+ *
+ * @return 32-bit random value.
+ */
+static inline uint32_t sys_rand32_get(void)
+{
+	uint32_t ret;
+
+	sys_rand_get(&ret, sizeof(ret));
+
+	return ret;
+}
+
+
 #ifdef __cplusplus
 }
 #endif

subsys/random/rand32_entropy_device.c

@@ -12,31 +12,6 @@
 static const struct device *const entropy_dev =
 	DEVICE_DT_GET(DT_CHOSEN(zephyr_entropy));
 
-#if defined(CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR)
-uint32_t z_impl_sys_rand32_get(void)
-{
-	uint32_t random_num;
-	int ret;
-
-	__ASSERT(device_is_ready(entropy_dev), "Entropy device %s not ready",
-		 entropy_dev->name);
-
-	ret = entropy_get_entropy(entropy_dev, (uint8_t *)&random_num,
-				  sizeof(random_num));
-	if (unlikely(ret < 0)) {
-		/* Use system timer in case the entropy device couldn't deliver
-		 * 32-bit of data.  There's not much that can be done in this
-		 * situation.  An __ASSERT() isn't used here as the HWRNG might
-		 * still be gathering entropy during early boot situations.
-		 */
-
-		random_num = k_cycle_get_32();
-	}
-
-	return random_num;
-}
-#endif /* CONFIG_ENTROPY_DEVICE_RANDOM_GENERATOR */
-
 static int rand_get(uint8_t *dst, size_t outlen, bool csrand)
 {
 	uint32_t random_num;

subsys/random/rand32_handlers.c

@@ -7,12 +7,6 @@
 #include <zephyr/random/random.h>
 #include <zephyr/internal/syscall_handler.h>
 
-static inline uint32_t z_vrfy_sys_rand32_get(void)
-{
-	return z_impl_sys_rand32_get();
-}
-#include <syscalls/sys_rand32_get_mrsh.c>
-
 static inline void z_vrfy_sys_rand_get(void *dst, size_t len)
 {
 	K_OOPS(K_SYSCALL_MEMORY_WRITE(dst, len));

subsys/random/rand32_timer.c

@@ -33,7 +33,7 @@ static struct k_spinlock rand32_lock;
  *
  * @return a 32-bit number
  */
-uint32_t z_impl_sys_rand32_get(void)
+static inline uint32_t rand32_get(void)
 {
 	/* initial seed value */
 	static uint64_t state = (uint64_t)CONFIG_TIMER_RANDOM_INITIAL_STATE;
@@ -64,7 +64,7 @@ void z_impl_sys_rand_get(void *dst, size_t outlen)
 	uint32_t ret;
 
 	while (outlen) {
-		ret = sys_rand32_get();
+		ret = rand32_get();
 		blocksize = MIN(outlen, sizeof(ret));
 		(void)memcpy((void *)udst, &ret, blocksize);
 		udst += blocksize;

subsys/random/rand32_xoshiro128.c

@@ -91,15 +91,6 @@ static uint32_t xoshiro128_next(void)
 	return result;
 }
 
-uint32_t z_impl_sys_rand32_get(void)
-{
-	if (unlikely(!initialized)) {
-		xoshiro128_init_state();
-	}
-
-	return xoshiro128_next();
-}
-
 void z_impl_sys_rand_get(void *dst, size_t outlen)
 {
 	size_t blocks = outlen / sizeof(uint32_t);