Merge pull request #2664 from utzig/kinetis-trng-refactor
Updates to the kinetis TRNG driver
diff --git a/hw/drivers/trng/trng_kinetis/src/trng_kinetis.c b/hw/drivers/trng/trng_kinetis/src/trng_kinetis.c
index 7f38cdf..dfab99d 100644
--- a/hw/drivers/trng/trng_kinetis/src/trng_kinetis.c
+++ b/hw/drivers/trng/trng_kinetis/src/trng_kinetis.c
@@ -35,6 +35,22 @@
do { \
(base)->MCTL |= (TRNG_MCTL_PRGM_MASK | TRNG_MCTL_ERR_MASK); \
} while (0)
+#define TRNG_CLEAR_AND_ENABLE_INTS(base) \
+ do { \
+ (base)->INT_CTRL &= ~(TRNG_INT_CTRL_HW_ERR_MASK | \
+ TRNG_INT_CTRL_ENT_VAL_MASK); \
+ (base)->INT_MASK |= TRNG_INT_MASK_HW_ERR_MASK | \
+ TRNG_INT_MASK_ENT_VAL_MASK; \
+ } while (0)
+#define TRNG_CLEAR_AND_ENABLE_ENTROPY_INT(base) \
+ do { \
+ (base)->INT_CTRL &= ~TRNG_INT_CTRL_ENT_VAL_MASK; \
+ (base)->INT_MASK |= TRNG_INT_MASK_ENT_VAL_MASK; \
+ } while (0)
+#define TRNG_DISABLE_ENTROPY_INT(base) \
+ do { \
+ (base)->INT_MASK &= ~TRNG_INT_MASK_ENT_VAL_MASK; \
+ } while (0)
#else
#error "Unsupported TRNG interface"
#endif
@@ -42,33 +58,80 @@
#include "trng/trng.h"
#include "trng_kinetis/trng_kinetis.h"
-static uint8_t rng_cache[ MYNEWT_VAL(KINETIS_TRNG_CACHE_LEN) ];
-static uint16_t rng_cache_out;
-static uint16_t rng_cache_in;
-static struct os_mutex rng_cache_mu;
-static os_stack_t *pstack;
+#define TRNG_CACHE_LEN MYNEWT_VAL(KINETIS_TRNG_CACHE_LEN)
+static struct {
+ uint16_t out;
+ uint16_t in;
+ uint16_t used;
+ struct os_mutex mu;
+ uint8_t cache[TRNG_CACHE_LEN];
+} rng_state;
+static_assert(sizeof(rng_state.cache) == TRNG_CACHE_LEN,
+ "Must fix TRNG_CACHE_LEN usage");
+#define CACHE_OUT(x) \
+ do { \
+ (x) = rng_state.cache[rng_state.out]; \
+ rng_state.out = (rng_state.out + 1) % TRNG_CACHE_LEN; \
+ rng_state.used--; \
+ } while (0)
+#define CACHE_IN(x) \
+ do { \
+ rng_state.cache[rng_state.in] = (x); \
+ rng_state.in = (rng_state.in + 1) % TRNG_CACHE_LEN; \
+ rng_state.used++; \
+ } while (0)
+#define IS_CACHE_FULL() (rng_state.used == TRNG_CACHE_LEN)
+#define IS_CACHE_EMPTY() (rng_state.used == 0)
+#define CACHE_INIT() \
+ do { \
+ rng_state.out = 0; \
+ rng_state.in = 0; \
+ rng_state.used = 0; \
+ } while (0)
+#define CACHE_LOCK() os_mutex_pend(&rng_state.mu, OS_TIMEOUT_NEVER)
+#define CACHE_UNLOCK() os_mutex_release(&rng_state.mu)
+#define CACHE_INIT_LOCK() os_mutex_init(&rng_state.mu)
+
+#if USE_RNGA
static bool running;
+#endif
static struct os_eventq rng_evtq;
+static struct os_event evt = {0};
#define TRNG_POLLER_PRIO (8)
#define TRNG_POLLER_STACK_SIZE OS_STACK_ALIGN(64)
-static struct os_task poller_task;
+static struct os_task trng_poller_task;
+OS_TASK_STACK_DEFINE(trng_poller_stack, TRNG_POLLER_STACK_SIZE);
-static inline void
+#if USE_TRNG
+static void
+trng_irq_handler(void)
+{
+ if (TRNG0->MCTL & TRNG_MCTL_ERR_MASK) {
+ TRNG0->MCTL |= TRNG_MCTL_ERR_MASK;
+ }
+
+ if (TRNG0->INT_CTRL & TRNG_INT_CTRL_HW_ERR_MASK) {
+ TRNG0->INT_CTRL &= ~TRNG_INT_CTRL_HW_ERR_MASK;
+ }
+
+ if (TRNG0->INT_CTRL & TRNG_INT_CTRL_ENT_VAL_MASK) {
+ TRNG_DISABLE_ENTROPY_INT(TRNG0);
+ (void)os_eventq_put(&rng_evtq, &evt);
+ }
+}
+#endif
+
+static void
kinetis_trng_start(void)
{
- struct os_event evt;
-
#if USE_RNGA
RNGA_SetMode(RNG, kRNGA_ModeNormal);
+ running = true;
+ (void)os_eventq_put(&rng_evtq, &evt);
#elif USE_TRNG
TRNG_START(TRNG0);
#endif
- running = true;
-
- evt.ev_queued = 0;
- evt.ev_arg = NULL;
- (void)os_eventq_put(&rng_evtq, &evt);
}
static inline void
@@ -76,47 +139,35 @@
{
#if USE_RNGA
RNGA_SetMode(RNG, kRNGA_ModeSleep);
+ running = false;
#elif USE_TRNG
TRNG_STOP(TRNG0);
#endif
-
- running = false;
}
static size_t
kinetis_trng_read(struct trng_dev *trng, void *ptr, size_t size)
{
size_t num_read;
+ uint8_t *u8p;
- os_mutex_pend(&rng_cache_mu, OS_TIMEOUT_NEVER);
+ num_read = 0;
+ u8p = (uint8_t *)ptr;
- if (rng_cache_out <= rng_cache_in) {
- size = min(size, rng_cache_in - rng_cache_out);
- memcpy(ptr, &rng_cache[rng_cache_out], size);
- num_read = size;
- } else if (rng_cache_out + size <= sizeof(rng_cache)) {
- memcpy(ptr, &rng_cache[rng_cache_out], size);
- num_read = size;
- } else {
- num_read = sizeof(rng_cache) - rng_cache_out;
- memcpy(ptr, &rng_cache[rng_cache_out], num_read);
+ CACHE_LOCK();
- size -= num_read;
- ptr += num_read;
-
- size = min(size, rng_cache_in);
- memcpy(ptr, rng_cache, size);
- num_read += size;
+ while (!IS_CACHE_EMPTY() && size) {
+ CACHE_OUT(*u8p++);
+ num_read++;
+ size--;
}
- rng_cache_out = (rng_cache_out + num_read) % sizeof(rng_cache);
+ CACHE_UNLOCK();
if (num_read > 0) {
kinetis_trng_start();
}
- os_mutex_release(&rng_cache_mu);
-
return num_read;
}
@@ -146,31 +197,39 @@
int rc;
while (1) {
- if (running) {
+#if USE_TRNG
+ (void)os_eventq_get(&rng_evtq);
+#endif
+
#if USE_RNGA
+ if (running) {
rc = RNGA_GetRandomData(RNG, data, sizeof(uint32_t));
#else
rc = TRNG_GetRandomData(TRNG0, data, sizeof(uint32_t));
#endif
if (rc == 0) {
- os_mutex_pend(&rng_cache_mu, OS_TIMEOUT_NEVER);
+ CACHE_LOCK();
+
for (i = 0; i < 4; i++) {
- rng_cache[rng_cache_in++] = data[i];
-
- if (rng_cache_in >= sizeof(rng_cache)) {
- rng_cache_in = 0;
- }
-
- if ((rng_cache_in + 1) % sizeof(rng_cache) == rng_cache_out) {
+ if (IS_CACHE_FULL()) {
kinetis_trng_stop();
break;
}
+
+ CACHE_IN(data[i]);
}
- os_mutex_release(&rng_cache_mu);
+
+ CACHE_UNLOCK();
+
+#if USE_TRNG
+ TRNG_CLEAR_AND_ENABLE_ENTROPY_INT(TRNG0);
+#endif
}
+#if USE_RNGA
} else {
(void)os_eventq_get(&rng_evtq);
}
+#endif
}
}
@@ -179,22 +238,28 @@
{
struct trng_dev *trng;
#if USE_TRNG
- trng_config_t default_config;
+ trng_config_t trng_config;
#endif
trng = (struct trng_dev *)dev;
assert(trng);
if (!(dev->od_flags & OS_DEV_F_STATUS_OPEN)) {
- rng_cache_out = 0;
- rng_cache_in = 0;
+ CACHE_INIT();
#if USE_RNGA
RNGA_Init(RNG);
RNGA_Seed(RNG, SIM->UIDL);
+
#elif USE_TRNG
- (void)TRNG_GetDefaultConfig(&default_config);
- TRNG_Init(TRNG0, &default_config);
+ NVIC_SetVector(TRNG0_IRQn, (uint32_t)trng_irq_handler);
+ NVIC_EnableIRQ(TRNG0_IRQn);
+
+ (void)TRNG_GetDefaultConfig(&trng_config);
+ trng_config.entropyDelay = MYNEWT_VAL(KINETIS_TRNG_ENTROPY_DELAY);
+ TRNG_Init(TRNG0, &trng_config);
+
+ TRNG_CLEAR_AND_ENABLE_INTS(TRNG0);
#endif
kinetis_trng_start();
@@ -218,13 +283,11 @@
trng->interface.read = kinetis_trng_read;
os_eventq_init(&rng_evtq);
- os_mutex_init(&rng_cache_mu);
+ CACHE_INIT_LOCK();
- pstack = malloc(sizeof(os_stack_t) * TRNG_POLLER_STACK_SIZE);
- assert(pstack);
-
- rc = os_task_init(&poller_task, "trng_poller", trng_poller_handler, NULL,
- TRNG_POLLER_PRIO, OS_WAIT_FOREVER, pstack, TRNG_POLLER_STACK_SIZE);
+ rc = os_task_init(&trng_poller_task, "trng_poller", trng_poller_handler, NULL,
+ TRNG_POLLER_PRIO, OS_WAIT_FOREVER, trng_poller_stack,
+ TRNG_POLLER_STACK_SIZE);
if (rc) {
return rc;
}
diff --git a/hw/drivers/trng/trng_kinetis/syscfg.yml b/hw/drivers/trng/trng_kinetis/syscfg.yml
index 7c72a7b..dc01492 100644
--- a/hw/drivers/trng/trng_kinetis/syscfg.yml
+++ b/hw/drivers/trng/trng_kinetis/syscfg.yml
@@ -30,3 +30,10 @@
value: 0
restrictions:
- '!KINETIS_TRNG_USE_RNGA'
+ KINETIS_TRNG_ENTROPY_DELAY:
+ description: >
+ The configured number is the length, in system clocks, of each
+ entropy sample taken. The default value is 3200, but it can be
+ reduced for faster sample generation, given the compromise of
+ generating worse entropy.
+ value: 3200
