drivers: sam: entropy: implement get_entropy_isr
The commit contributes the implementation of get_entropy_isr API function for the SAM entropy driver. The implementation is similar to get_entropy, with the difference that it does not invoke k_yield() when called with the ENTROPY_BUSYWAIT options flag set. When the function is invoked without the ENTROPY_BUSYWAIT flag, it simply returns whatever data is available, without busy waiting on the RNG herdware. Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>
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75f9512755
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1 changed files with 70 additions and 6 deletions
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@ -18,7 +18,7 @@ struct trng_sam_dev_cfg {
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#define DEV_CFG(dev) \
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((const struct trng_sam_dev_cfg *const)(dev)->config->config_info)
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static int entropy_sam_wait_ready(Trng *const trng)
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static int entropy_sam_wait_ready(Trng * const trng, u32_t flags)
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{
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/* According to the reference manual, the generator provides
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* one 32-bit random value every 84 peripheral clock cycles.
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@ -36,14 +36,23 @@ static int entropy_sam_wait_ready(Trng *const trng)
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return -ETIMEDOUT;
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}
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k_yield();
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if ((flags & ENTROPY_BUSYWAIT) == 0U) {
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/* This internal function is used by both get_entropy,
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* and get_entropy_isr APIs. The later may call this
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* function with the ENTROPY_BUSYWAIT flag set. In
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* that case make no assumption that the kernel is
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* initialized when the function is called; so, just
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* do busy-wait for the random data to be ready.
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*/
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k_yield();
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}
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}
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return 0;
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}
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static int entropy_sam_get_entropy(struct device *dev, u8_t *buffer,
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u16_t length)
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static int entropy_sam_get_entropy_internal(struct device *dev, u8_t *buffer,
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u16_t length, u32_t flags)
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{
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Trng *const trng = DEV_CFG(dev)->regs;
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@ -52,7 +61,7 @@ static int entropy_sam_get_entropy(struct device *dev, u8_t *buffer,
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u32_t value;
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int res;
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res = entropy_sam_wait_ready(trng);
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res = entropy_sam_wait_ready(trng, flags);
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if (res < 0) {
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return res;
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}
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@ -68,6 +77,60 @@ static int entropy_sam_get_entropy(struct device *dev, u8_t *buffer,
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return 0;
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}
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static int entropy_sam_get_entropy(struct device *dev, u8_t *buffer,
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u16_t length)
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{
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return entropy_sam_get_entropy_internal(dev, buffer, length, 0);
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}
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static int entropy_sam_get_entropy_isr(struct device *dev, u8_t *buffer,
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u16_t length, u32_t flags)
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{
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u16_t cnt = length;
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if ((flags & ENTROPY_BUSYWAIT) == 0U) {
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/* No busy wait; return whatever data is available. */
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Trng * const trng = DEV_CFG(dev)->regs;
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do {
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size_t to_copy;
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u32_t value;
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if (!(trng->TRNG_ISR & TRNG_ISR_DATRDY)) {
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/* Data not ready */
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break;
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}
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value = trng->TRNG_ODATA;
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to_copy = MIN(length, sizeof(value));
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memcpy(buffer, &value, to_copy);
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buffer += to_copy;
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length -= to_copy;
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} while (length > 0);
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return cnt - length;
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} else {
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/* Allowed to busy-wait */
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int ret =
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entropy_sam_get_entropy_internal(dev,
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buffer, length, flags);
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if (ret == 0) {
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/* Data retrieved successfully. */
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return cnt;
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}
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return ret;
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}
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}
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static int entropy_sam_init(struct device *dev)
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{
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Trng *const trng = DEV_CFG(dev)->regs;
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@ -82,7 +145,8 @@ static int entropy_sam_init(struct device *dev)
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}
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static const struct entropy_driver_api entropy_sam_api = {
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.get_entropy = entropy_sam_get_entropy
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.get_entropy = entropy_sam_get_entropy,
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.get_entropy_isr = entropy_sam_get_entropy_isr
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};
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static const struct trng_sam_dev_cfg trng_sam_cfg = {
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