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drivers: entropy: Introduce ISR-specific entropy function

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In order to address the requirements of the kernel boot process, an
optional ISR-specific function is declared to allow entropy collection
outside of thread mode and without using any kernel primitives. It also
includes a parameter to optionally busy-wait for hardware entropy
generation.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
This commit is contained in:
Carles Cufi 2018-05-24 20:10:53 +02:00 committed by Andrew Boie
parent 29599f6d80
commit 668e31f7db
1 changed files with 41 additions and 3 deletions
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44
include/entropy.h
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@ -36,13 +36,24 @@ extern "C" {
typedef int (*entropy_get_entropy_t)(struct device *dev,
u8_t *buffer,
u16_t length);
/**
* @typedef entropy_get_entropy_isr_t
* @brief Callback API to get entropy from an ISR.
*
* See entropy_get_entropy_isr() for argument description
*/
typedef int (*entropy_get_entropy_isr_t)(struct device *dev,
u8_t *buffer,
u16_t length,
u32_t flags);
struct entropy_driver_api {
entropy_get_entropy_t get_entropy;
entropy_get_entropy_t get_entropy;
entropy_get_entropy_isr_t get_entropy_isr;
};
/**
* @brief Fills a buffer with entropy.
* @brief Fills a buffer with entropy. Blocks if required in order to
* generate the necessary random data.
*
* @param dev Pointer to the entropy device.
* @param buffer Buffer to fill with entropy.
@ -64,6 +75,33 @@ static inline int _impl_entropy_get_entropy(struct device *dev,
return api->get_entropy(dev, buffer, length);
}
/* Busy-wait for random data to be ready */
#define ENTROPY_BUSYWAIT BIT(0)
/**
* @brief Fills a buffer with entropy in a non-blocking or busy-wait manner.
* Callable from ISRs.
*
* @param dev Pointer to the device structure.
* @param buffer Buffer to fill with entropy.
* @param length Buffer length.
* @param flags Flags to modify the behavior of the call.
* @retval number of bytes filled with entropy or -error.
*/
static inline int entropy_get_entropy_isr(struct device *dev,
u8_t *buffer,
u16_t length,
u32_t flags)
{
const struct entropy_driver_api *api = dev->driver_api;
if (!api->get_entropy_isr) {
return -ENOTSUP;
}
return api->get_entropy_isr(dev, buffer, length, flags);
}
#ifdef __cplusplus
}
#endif