5  * SPDX-License-Identifier: Apache-2.0
27  * values must be read out by the CPU byte-by-byte. But once started,
30  * The generation time for byte 0 after starting generation (with BIAS
33  * nRF51822 - 677us
34  * nRF52810 - 248us
35  * nRF52840 - 248us
37  * The generation time for byte N >= 1 after starting generation (with
40  * nRF51822 - 677us
41  * nRF52810 - 120us
42  * nRF52840 - 120us
44  * Due to the first byte in a stream of bytes being more costly on
46  * amortize the cost of the first byte.
57  * Setting a low threshold will highly amortize the extra 120us cost
58  * of the first byte on nRF52.
64  * low or high depending on the HFCLK-usage pattern of other
69  * entropy is requested there will be no extra current-consumption for
86 	      (CONFIG_ENTROPY_NRF5_ISR_POOL_SIZE - 1)) == 0,
90 	      (CONFIG_ENTROPY_NRF5_THR_POOL_SIZE - 1)) == 0,
105 	int retval = -EAGAIN;  in random_byte_get()
122 	uint32_t last  = rngp->last;  in rng_pool_get()
123 	uint32_t mask  = rngp->mask;  in rng_pool_get()
130 	first = rngp->first_alloc;  in rng_pool_get()
133 	 * The other_read_in_progress is non-zero if rngp->first_read != first,  in rng_pool_get()
134 	 * which means that lower-priority code (which was interrupted by this  in rng_pool_get()
137 	other_read_in_progress = (rngp->first_read ^ first);  in rng_pool_get()
139 	available = (last - first) & mask;  in rng_pool_get()
148 	rngp->first_alloc = (first + len) & mask;  in rng_pool_get()
151 	while (likely(len--)) {  in rng_pool_get()
152 		*dst++ = rngp->buffer[first];  in rng_pool_get()
163 		rngp->first_read = rngp->first_alloc;  in rng_pool_get()
167 	len = dst - buf;  in rng_pool_get()
168 	available = available - len;  in rng_pool_get()
169 	if (available <= rngp->threshold) {  in rng_pool_get()
176 static int rng_pool_put(struct rng_pool *rngp, uint8_t byte)  in rng_pool_put()  argument
178 	uint8_t first = rngp->first_read;  in rng_pool_put()
179 	uint8_t last  = rngp->last;  in rng_pool_put()
180 	uint8_t mask  = rngp->mask;  in rng_pool_put()
183 	if (((last - first) & mask) == mask) {  in rng_pool_put()
184 		return -ENOBUFS;  in rng_pool_put()
187 	rngp->buffer[last] = byte;  in rng_pool_put()
188 	rngp->last = (last + 1) & mask;  in rng_pool_put()
195 	rngp->first_alloc = 0U;  in rng_pool_init()
196 	rngp->first_read  = 0U;  in rng_pool_init()
197 	rngp->last	  = 0U;  in rng_pool_init()
198 	rngp->mask	  = size - 1;  in rng_pool_init()
199 	rngp->threshold	  = threshold;  in rng_pool_init()
204 	int byte, ret;  in isr()  local
208 	byte = random_byte_get();  in isr()
209 	if (byte < 0) {  in isr()
213 	ret = rng_pool_put((struct rng_pool *)(entropy_nrf5_data.isr), byte);  in isr()
216 				   byte);  in isr()
229 	__ASSERT_NO_MSG(&entropy_nrf5_data == dev->data);  in entropy_nrf5_get_entropy()
245 		len -= bytes;  in entropy_nrf5_get_entropy()
259 	__ASSERT_NO_MSG(&entropy_nrf5_data == dev->data);  in entropy_nrf5_get_entropy_isr()
279 		 * RNG event will set the Cortex-M single-bit event register  in entropy_nrf5_get_entropy_isr()
286 			int byte;  in entropy_nrf5_get_entropy_isr()  local
293 			byte = random_byte_get();  in entropy_nrf5_get_entropy_isr()
296 			if (byte < 0) {  in entropy_nrf5_get_entropy_isr()
300 			buf[--len] = byte;  in entropy_nrf5_get_entropy_isr()
327 	__ASSERT_NO_MSG(&entropy_nrf5_data == dev->data);  in entropy_nrf5_init()