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   1 /*
   2  * Copyright © 2015 Keith Packard <keithp@keithp.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful, but
  10  * WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12  * General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License along
  15  * with this program; if not, write to the Free Software Foundation, Inc.,
  16  * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
  17  */
  18
  19 #include <ao.h>
  20 #include <ao_adc_fast.h>
  21 #include <ao_crc.h>
  22 #include <ao_trng_send.h>
  23 #include <ao_exti.h>
  24 #include <ao_power.h>
  25
  26 static struct ao_task   ao_trng_send_task;
  27 static uint8_t          trng_running;
  28 static AO_TICK_TYPE     trng_power_time;
  29
  30 #define TRNG_ENABLE_DELAY       AO_MS_TO_TICKS(100)
  31
  32 static uint8_t          random_mutex;
  33
  34 #if AO_USB_HAS_IN2
  35
  36 static struct ao_task   ao_trng_send_raw_task;
  37
  38 static void
  39 ao_trng_get_raw(uint16_t *buf)
  40 {
  41         uint16_t        i;
  42         uint16_t        t;
  43         uint16_t        v;
  44
  45         t = ao_adc_get(AO_USB_IN_SIZE>>1);      /* one 16-bit value per two output bytes */
  46         for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) {
  47                 v = ao_adc_ring[t];
  48                 *buf++ = v;
  49                 t = (t + 1) & (AO_ADC_RING_SIZE - 1);
  50         }
  51         ao_adc_ack(AO_USB_IN_SIZE>>1);
  52 }
  53
  54 static void
  55 ao_trng_send_raw(void)
  56 {
  57         static uint16_t *buffer[2];
  58         int             usb_buf_id;
  59
  60         if (!buffer[0]) {
  61                 buffer[0] = ao_usb_alloc();
  62                 buffer[1] = ao_usb_alloc();
  63                 if (!buffer[0])
  64                         ao_exit();
  65         }
  66
  67         usb_buf_id = 0;
  68
  69         for (;;) {
  70                 ao_mutex_get(&random_mutex);
  71                 if (!trng_running) {
  72                         AO_TICK_TYPE    delay;
  73
  74                         delay = trng_power_time + TRNG_ENABLE_DELAY - ao_time();
  75                         if (delay > TRNG_ENABLE_DELAY)
  76                                 delay = TRNG_ENABLE_DELAY;
  77
  78                         /* Delay long enough for the HV power supply
  79                          * to stabilize so that the first bits we read
  80                          * aren't of poor quality
  81                          */
  82                         ao_delay(delay);
  83                         trng_running = TRUE;
  84                 }
  85 #ifdef AO_LED_TRNG_RAW
  86                 ao_led_on(AO_LED_TRNG_RAW);
  87 #endif
  88                 ao_trng_get_raw(buffer[usb_buf_id]);
  89 #ifdef AO_LED_TRNG_RAW
  90                 ao_led_off(AO_LED_TRNG_RAW);
  91 #endif
  92                 ao_mutex_put(&random_mutex);
  93                 ao_usb_write2(buffer[usb_buf_id], AO_USB_IN_SIZE);
  94                 usb_buf_id = 1-usb_buf_id;
  95         }
  96 }
  97
  98 #endif
  99
 100 static uint32_t previous[AO_USB_IN_SIZE / sizeof (uint16_t)];
 101
 102 static int
 103 ao_trng_get_cooked(uint16_t *buf)
 104 {
 105         uint16_t        i;
 106         uint16_t        t;
 107         uint32_t        *rnd = (uint32_t *) ao_adc_ring;
 108         uint8_t         mismatch = 0;
 109
 110         t = ao_adc_get(AO_USB_IN_SIZE) >> 1;            /* one 16-bit value per output byte */
 111         for (i = 0; i < AO_USB_IN_SIZE / sizeof (uint16_t); i++) {
 112                 uint32_t        v;
 113
 114                 /* Fetch two values in one operation */
 115                 v = rnd[t];
 116                 if (v != previous[i]) {
 117                         mismatch = 1;
 118                         previous[i] = v;
 119                 }
 120                 t = (t + 1) & ((AO_ADC_RING_SIZE >> 1) - 1);
 121
 122                 *buf++ = ao_crc_in_32_out_16(v);
 123         }
 124         ao_adc_ack(AO_USB_IN_SIZE);
 125         return mismatch;
 126 }
 127
 128 #define AO_TRNG_START_WAIT      1024
 129 #define AO_TRNG_START_CHECK     32
 130
 131 static void
 132 ao_trng_send(void)
 133 {
 134         static uint16_t *buffer[2];
 135         int     usb_buf_id;
 136         int     good_bits;
 137         int     failed;
 138         int     s;
 139
 140         if (!buffer[0]) {
 141                 buffer[0] = ao_usb_alloc();
 142                 buffer[1] = ao_usb_alloc();
 143                 if (!buffer[0])
 144                         ao_exit();
 145         }
 146
 147         usb_buf_id = 0;
 148
 149 #ifdef AO_TRNG_ENABLE_PORT
 150         ao_gpio_set(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 1);
 151 #endif
 152         trng_power_time = ao_time();
 153
 154         ao_crc_reset();
 155
 156         ao_delay(TRNG_ENABLE_DELAY);
 157
 158         for (s = 0; s < AO_TRNG_START_WAIT; s++) {
 159                 if (ao_trng_get_cooked(buffer[0]))
 160                         break;
 161                 ao_delay(AO_MS_TO_TICKS(10));
 162         }
 163
 164         /* Validate the hardware before enabling USB */
 165         failed = 0;
 166         for (s = 0; s < AO_TRNG_START_CHECK; s++) {
 167                 if (!ao_trng_get_cooked(buffer[0])) {
 168                         failed++;
 169                         ao_delay(AO_MS_TO_TICKS(10));
 170                 }
 171         }
 172         if (failed > AO_TRNG_START_CHECK / 4)
 173                 ao_panic(AO_PANIC_DMA);
 174
 175 #if AO_USB_HAS_IN2
 176         ao_add_task(&ao_trng_send_raw_task, ao_trng_send_raw, "trng_send_raw");
 177 #endif
 178
 179 #ifdef AO_USB_START_DISABLED
 180         ao_usb_enable();
 181 #endif
 182
 183         for (;;) {
 184                 ao_mutex_get(&random_mutex);
 185                 if (!trng_running) {
 186                         AO_TICK_TYPE    delay;
 187
 188                         delay = trng_power_time + TRNG_ENABLE_DELAY - ao_time();
 189                         if (delay > TRNG_ENABLE_DELAY)
 190                                 delay = TRNG_ENABLE_DELAY;
 191
 192                         /* Delay long enough for the HV power supply
 193                          * to stabilize so that the first bits we read
 194                          * aren't of poor quality
 195                          */
 196                         ao_delay(delay);
 197                         trng_running = TRUE;
 198                 }
 199 #ifdef AO_LED_TRNG_COOKED
 200                 ao_led_on(AO_LED_TRNG_COOKED);
 201 #endif
 202                 good_bits = ao_trng_get_cooked(buffer[usb_buf_id]);
 203 #ifdef AO_LED_TRNG_COOKED
 204                 ao_led_off(AO_LED_TRNG_COOKED);
 205 #endif
 206                 ao_mutex_put(&random_mutex);
 207                 if (good_bits) {
 208                         ao_usb_write(buffer[usb_buf_id], AO_USB_IN_SIZE);
 209                         usb_buf_id = 1-usb_buf_id;
 210                         failed = 0;
 211                 } else {
 212                         failed++;
 213                         ao_delay(AO_MS_TO_TICKS(10));
 214                         if (failed > 10) {
 215                                 ao_usb_disable();
 216                                 ao_panic(AO_PANIC_DMA);
 217                         }
 218                 }
 219         }
 220 }
 221
 222 #if AO_POWER_MANAGEMENT
 223
 224 static void ao_trng_suspend(void *arg)
 225 {
 226         (void) arg;
 227 #ifdef AO_TRNG_ENABLE_PORT
 228         ao_gpio_set(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 0);
 229 #endif
 230         trng_running = FALSE;
 231 }
 232
 233 static void ao_trng_resume(void *arg)
 234 {
 235         (void) arg;
 236 #ifdef AO_TRNG_ENABLE_PORT
 237         ao_gpio_set(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 1);
 238 #endif
 239         trng_power_time = ao_time();
 240 }
 241
 242 static struct ao_power ao_trng_power = {
 243         .suspend = ao_trng_suspend,
 244         .resume = ao_trng_resume
 245 };
 246
 247 #endif
 248
 249 void
 250 ao_trng_send_init(void)
 251 {
 252 #ifdef AO_TRNG_ENABLE_PORT
 253         ao_enable_output(AO_TRNG_ENABLE_PORT, AO_TRNG_ENABLE_BIT, AO_TRNG_ENABLE_PIN, 0);
 254         ao_power_register(&ao_trng_power);
 255 #endif
 256         ao_enable_input(AO_RAW_PORT, AO_RAW_BIT, AO_EXTI_MODE_PULL_UP);
 257         ao_add_task(&ao_trng_send_task, ao_trng_send, "trng_send");
 258 }