diff options
Diffstat (limited to 'src/drivers/ao_trng_send.c')
| -rw-r--r-- | src/drivers/ao_trng_send.c | 228 |
1 files changed, 214 insertions, 14 deletions
diff --git a/src/drivers/ao_trng_send.c b/src/drivers/ao_trng_send.c index bac6035c..171a345f 100644 --- a/src/drivers/ao_trng_send.c +++ b/src/drivers/ao_trng_send.c @@ -19,47 +19,247 @@ #include <ao_adc_fast.h> #include <ao_crc.h> #include <ao_trng_send.h> +#include <ao_exti.h> +#include <ao_power.h> + +static struct ao_task ao_trng_send_task, ao_trng_send_raw_task; +static uint8_t trng_running; +static AO_TICK_TYPE trng_power_time; + +#define TRNG_ENABLE_DELAY AO_MS_TO_TICKS(100) + +static uint8_t random_mutex; static void -ao_trng_send(void) +ao_trng_get_raw(uint16_t *buf) +{ + uint16_t i; + uint16_t t; + uint16_t v; + + t = ao_adc_get(AO_USB_IN_SIZE>>1); /* one 16-bit value per two output bytes */ + for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) { + v = ao_adc_ring[t]; + *buf++ = v; + t = (t + 1) & (AO_ADC_RING_SIZE - 1); + } + ao_adc_ack(AO_USB_IN_SIZE>>1); +} + +static void +ao_trng_send_raw(void) { static uint16_t *buffer[2]; int usb_buf_id; + + if (!buffer[0]) { + buffer[0] = ao_usb_alloc(); + buffer[1] = ao_usb_alloc(); + if (!buffer[0]) + ao_exit(); + } + + usb_buf_id = 0; + + for (;;) { + ao_mutex_get(&random_mutex); + if (!trng_running) { + AO_TICK_TYPE delay; + + delay = trng_power_time + TRNG_ENABLE_DELAY - ao_time(); + if (delay > TRNG_ENABLE_DELAY) + delay = TRNG_ENABLE_DELAY; + + /* Delay long enough for the HV power supply + * to stabilize so that the first bits we read + * aren't of poor quality + */ + ao_delay(delay); + trng_running = TRUE; + } +#ifdef AO_LED_TRNG_RAW + ao_led_on(AO_LED_TRNG_RAW); +#endif + ao_trng_get_raw(buffer[usb_buf_id]); +#ifdef AO_LED_TRNG_RAW + ao_led_off(AO_LED_TRNG_RAW); +#endif + ao_mutex_put(&random_mutex); + ao_usb_write2(buffer[usb_buf_id], AO_USB_IN_SIZE); + usb_buf_id = 1-usb_buf_id; + } +} + +/* Make sure there's at least 8 bits of variance in the samples */ +#define MIN_VARIANCE (128 * 128) + +/* Make sure the signal is spread around a bit */ +#define MAX_VARIANCE (512 * 512) + +#define ADD_STATS(value) do { \ + sum += (value); \ + sum2 += (value) * (value); \ + } while(0) + +#define VARIANCE(n) ((sum2 - (sum / (n) * sum)) / (n)) + +static int +ao_trng_get_cooked(uint16_t *buf) +{ uint16_t i; - uint16_t *buf; uint16_t t; uint32_t *rnd = (uint32_t *) ao_adc_ring; + int32_t sum, sum2, var; + + sum = sum2 = 0; + t = ao_adc_get(AO_USB_IN_SIZE) >> 1; /* one 16-bit value per output byte */ + for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) { + uint32_t v; + uint16_t v1, v2; + + /* Fetch two values in one operation */ + v = rnd[t]; + t = (t + 1) & ((AO_ADC_RING_SIZE >> 1) - 1); + + *buf++ = ao_crc_in_32_out_16(v); + + v1 = v; + v2 = v >> 16; + + ADD_STATS(v1); + ADD_STATS(v2); + } + ao_adc_ack(AO_USB_IN_SIZE); + var = VARIANCE(2 * AO_USB_IN_SIZE / sizeof (uint16_t)); + return var >= MIN_VARIANCE && var <= MAX_VARIANCE; +} + +#define AO_TRNG_START_WAIT 1024 +#define AO_TRNG_START_CHECK 32 + +static void +ao_trng_send(void) +{ + static uint16_t *buffer[2]; + int usb_buf_id; + int good_bits; + int failed; + int s; if (!buffer[0]) { buffer[0] = ao_usb_alloc(); buffer[1] = ao_usb_alloc(); if (!buffer[0]) - return; + ao_exit(); } usb_buf_id = 0; +#ifdef AO_TRNG_ENABLE_PORT + ao_gpio_set(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 1); +#endif + trng_power_time = ao_time(); + ao_crc_reset(); + ao_delay(TRNG_ENABLE_DELAY); + + for (s = 0; s < AO_TRNG_START_WAIT; s++) { + if (ao_trng_get_cooked(buffer[0])) + break; + ao_delay(AO_MS_TO_TICKS(10)); + } + + /* Validate the hardware before enabling USB */ + failed = 0; + for (s = 0; s < AO_TRNG_START_CHECK; s++) { + if (!ao_trng_get_cooked(buffer[0])) { + failed++; + ao_delay(AO_MS_TO_TICKS(10)); + } + } + if (failed > AO_TRNG_START_CHECK / 4) + ao_panic(AO_PANIC_DMA); + + ao_add_task(&ao_trng_send_raw_task, ao_trng_send_raw, "trng_send_raw"); + +#ifdef AO_USB_START_DISABLED + ao_usb_enable(); +#endif + for (;;) { - ao_led_on(AO_LED_TRNG_ACTIVE); - t = ao_adc_get(AO_USB_IN_SIZE) >> 1; /* one 16-bit value per output byte */ - buf = buffer[usb_buf_id]; - for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) { - *buf++ = ao_crc_in_32_out_16(rnd[t]); - t = (t + 1) & ((AO_ADC_RING_SIZE>>1) - 1); + ao_mutex_get(&random_mutex); + if (!trng_running) { + AO_TICK_TYPE delay; + + delay = trng_power_time + TRNG_ENABLE_DELAY - ao_time(); + if (delay > TRNG_ENABLE_DELAY) + delay = TRNG_ENABLE_DELAY; + + /* Delay long enough for the HV power supply + * to stabilize so that the first bits we read + * aren't of poor quality + */ + ao_delay(delay); + trng_running = TRUE; + } +#ifdef AO_LED_TRNG_COOKED + ao_led_on(AO_LED_TRNG_COOKED); +#endif + good_bits = ao_trng_get_cooked(buffer[usb_buf_id]); +#ifdef AO_LED_TRNG_COOKED + ao_led_off(AO_LED_TRNG_COOKED); +#endif + ao_mutex_put(&random_mutex); + if (good_bits) { + ao_usb_write(buffer[usb_buf_id], AO_USB_IN_SIZE); + usb_buf_id = 1-usb_buf_id; + failed = 0; + } else { + failed++; + ao_delay(AO_MS_TO_TICKS(10)); + if (failed > 10) { + ao_usb_disable(); + ao_panic(AO_PANIC_DMA); + } } - ao_adc_ack(AO_USB_IN_SIZE); - ao_led_off(AO_LED_TRNG_ACTIVE); - ao_usb_write(buffer[usb_buf_id], AO_USB_IN_SIZE); - usb_buf_id = 1-usb_buf_id; } } -static struct ao_task ao_trng_send_task; +#if AO_POWER_MANAGEMENT + +static void ao_trng_suspend(void *arg) +{ + (void) arg; +#ifdef AO_TRNG_ENABLE_PORT + ao_gpio_set(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 0); +#endif + trng_running = FALSE; +} + +static void ao_trng_resume(void *arg) +{ + (void) arg; +#ifdef AO_TRNG_ENABLE_PORT + ao_gpio_set(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 1); +#endif + trng_power_time = ao_time(); +} + +static struct ao_power ao_trng_power = { + .suspend = ao_trng_suspend, + .resume = ao_trng_resume +}; + +#endif void ao_trng_send_init(void) { +#ifdef AO_TRNG_ENABLE_PORT + ao_enable_output(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 0); + ao_power_register(&ao_trng_power); +#endif + ao_enable_input(AO_RAW_PORT, AO_RAW_BIT, AO_EXTI_MODE_PULL_UP); ao_add_task(&ao_trng_send_task, ao_trng_send, "trng_send"); } |