altos/chaoskey: Add support for flipping between raw and cooked bits

Plug the 'force bootloader' thing onto the board while it's running
and it will generate raw bits instead of running them through the CRC
to whiten. Useful for validating the raw hardware.

Signed-off-by: Keith Packard <keithp@keithp.com>

2 files changed, 50 insertions, 12 deletions

diff --git a/src/chaoskey-v0.1/ao_pins.h b/src/chaoskey-v0.1/ao_pins.h
index 8f3eb7b1..95d9a576 100644
--- a/src/chaoskey-v0.1/ao_pins.h
+++ b/src/chaoskey-v0.1/ao_pins.h
@@ -67,6 +67,11 @@
 #define AO_CRC_INIT	0xffffffff
 
 /* TRNG */
-#define AO_LED_TRNG_ACTIVE	AO_LED_GREEN
+#define AO_LED_TRNG_COOKED	AO_LED_GREEN
+#define AO_LED_TRNG_RAW		AO_LED_RED
+
+/* Mode pin */
+#define AO_RAW_PORT		(&stm_gpioa)
+#define AO_RAW_BIT		15
 
 #endif /* _AO_PINS_H_ */
diff --git a/src/drivers/ao_trng_send.c b/src/drivers/ao_trng_send.c
index bac6035c..64c016b2 100644
--- a/src/drivers/ao_trng_send.c
+++ b/src/drivers/ao_trng_send.c
@@ -19,17 +19,48 @@
 #include <ao_adc_fast.h>
 #include <ao_crc.h>
 #include <ao_trng_send.h>
+#include <ao_exti.h>
 
 static void
-ao_trng_send(void)
+ao_trng_send_raw(uint16_t *buf)
+{
+	uint16_t	i;
+	uint16_t	t;
+	uint16_t	*rnd = (uint16_t *) ao_adc_ring;
+
+	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++) {
+		*buf++ = rnd[t];
+		t = (t + 1) & (AO_ADC_RING_SIZE - 1);
+	}
+}
+
+static void
+ao_trng_send_cooked(uint16_t *buf)
 {
-	static uint16_t	*buffer[2];
-	int		usb_buf_id;
 	uint16_t	i;
-	uint16_t	*buf;
 	uint16_t	t;
 	uint32_t	*rnd = (uint32_t *) ao_adc_ring;
 
+	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++) {
+		*buf++ = ao_crc_in_32_out_16(rnd[t]);
+		t = (t + 1) & ((AO_ADC_RING_SIZE>>1) - 1);
+	}
+}
+
+static inline int
+ao_send_raw(void)
+{
+	return !ao_gpio_get(AO_RAW_PORT, AO_RAW_BIT, AO_RAW_PIN);
+}
+
+static void
+ao_trng_send(void)
+{
+	static uint16_t	*buffer[2];
+	int	usb_buf_id;
+
 	if (!buffer[0]) {
 		buffer[0] = ao_usb_alloc();
 		buffer[1] = ao_usb_alloc();
@@ -42,15 +73,16 @@ ao_trng_send(void)
 	ao_crc_reset();
 
 	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);
+		if (ao_send_raw()) {
+			ao_led_on(AO_LED_TRNG_RAW);
+			ao_trng_send_raw(buffer[usb_buf_id]);
+			ao_led_off(AO_LED_TRNG_RAW);
+		} else {
+			ao_led_on(AO_LED_TRNG_COOKED);
+			ao_trng_send_cooked(buffer[usb_buf_id]);
+			ao_led_off(AO_LED_TRNG_COOKED);
 		}
 		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;
 	}
@@ -61,5 +93,6 @@ static struct ao_task ao_trng_send_task;
 void
 ao_trng_send_init(void)
 {
+	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");
 }