It's a major reorganization.

In order to add FIDO2 support, we need to reorganize some USB/CCID calls to specific area (named driver).
Thus, pico-hsm-sdk has two drivers:
- CCID driver implements APDU over USB/CCID ISO-7816 standard procedures.
- HID driver implements APDU over HID.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>

src/rng/hwrng.c

@@ -0,0 +1,182 @@
+/*
+ * This file is part of the Pico HSM SDK distribution (https://github.com/polhenarejos/pico-hsm-sdk).
+ * Copyright (c) 2022 Pol Henarejos.
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, version 3.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <stdint.h>
+#include <string.h>
+#include <stdio.h>
+#include "pico/stdlib.h"
+
+#include "hwrng.h"
+#include "hardware/structs/rosc.h"
+#include "hardware/gpio.h"
+#include "hardware/adc.h"
+#include "pico/unique_id.h"
+
+#include "pico/time.h"
+static inline uint32_t board_millis(void)
+{
+    return to_ms_since_boot(get_absolute_time());
+}
+
+void adc_start() {
+    adc_init();
+    adc_gpio_init(27);
+    adc_select_input(1);
+}
+
+void adc_stop() {
+}
+
+static uint64_t random_word = 0xcbf29ce484222325;
+static uint8_t ep_round = 0;
+
+static void ep_init() {
+    random_word = 0xcbf29ce484222325;
+    ep_round = 0;
+}
+
+/* Here, we assume a little endian architecture.  */
+static int ep_process () {
+    if (ep_round == 0) {
+        ep_init();
+    }
+    uint64_t word = 0x0;
+    for (int n = 0; n < 64; n++) {
+        uint8_t bit1, bit2;
+        do
+        {
+            bit1 = rosc_hw->randombit&0xff;
+            //sleep_ms(1);
+            bit2 = rosc_hw->randombit&0xff;
+        } while(bit1 == bit2);
+        word = (word << 1) | bit1;
+    }
+    random_word ^= word^board_millis()^adc_read();
+    random_word *= 0x00000100000001B3;
+    if (++ep_round == 8) {
+        ep_round = 0;
+        return 2; //2 words
+    }
+    return 0;
+}
+
+static const uint32_t *ep_output() {
+    return (uint32_t *)&random_word;
+}
+
+struct rng_rb {
+    uint32_t *buf;
+    uint8_t head, tail;
+    uint8_t size;
+    unsigned int full :1;
+    unsigned int empty :1;
+};
+
+static void rb_init(struct rng_rb *rb, uint32_t *p, uint8_t size) {
+    rb->buf = p;
+    rb->size = size;
+    rb->head = rb->tail = 0;
+    rb->full = 0;
+    rb->empty = 1;
+}
+
+static void rb_add(struct rng_rb *rb, uint32_t v) {
+    rb->buf[rb->tail++] = v;
+    if (rb->tail == rb->size)
+        rb->tail = 0;
+    if (rb->tail == rb->head)
+        rb->full = 1;
+    rb->empty = 0;
+}
+
+static uint32_t rb_del(struct rng_rb *rb) {
+    uint32_t v = rb->buf[rb->head++];
+
+    if (rb->head == rb->size)
+        rb->head = 0;
+    if (rb->head == rb->tail)
+        rb->empty = 1;
+    rb->full = 0;
+
+    return v;
+}
+
+static struct rng_rb the_ring_buffer;
+
+void *neug_task() {
+    struct rng_rb *rb = &the_ring_buffer;
+
+    int n;
+
+    if ((n = ep_process())) {
+	    int i;
+	    const uint32_t *vp;
+
+	    vp = ep_output();
+
+	    for (i = 0; i < n; i++) {
+	        rb_add (rb, *vp++);
+	        if (rb->full)
+		        break;
+	    }
+	}
+
+    return NULL;
+}
+
+void neug_init(uint32_t *buf, uint8_t size) {
+    pico_unique_board_id_t unique_id;
+    pico_get_unique_board_id(&unique_id);
+    struct rng_rb *rb = &the_ring_buffer;
+
+    rb_init(rb, buf, size);
+
+    adc_start();
+
+    ep_init();
+}
+
+void neug_flush(void) {
+    struct rng_rb *rb = &the_ring_buffer;
+
+    while (!rb->empty)
+        rb_del (rb);
+}
+
+uint32_t neug_get() {
+    struct rng_rb *rb = &the_ring_buffer;
+    uint32_t v;
+
+    while (rb->empty)
+        neug_task();
+    v = rb_del(rb);
+
+    return v;
+}
+
+void neug_wait_full(void) { //should be called only on core1
+    struct rng_rb *rb = &the_ring_buffer;
+
+    while (!rb->full) {
+        sleep_ms(1);
+    }
+}
+
+void neug_fini(void) {
+    neug_get();
+}
+