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   1 /*
   2  * Copyright © 2019 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
  15 #include <ao.h>
  16
  17 static int
  18 _ao_usart_tx_start(struct ao_samd21_usart *usart)
  19 {
  20         if (!ao_fifo_empty(usart->tx_fifo)) {
  21 #if HAS_SERIAL_SW_FLOW
  22                 if (usart->gpio_cts && ao_gpio_get(usart->gpio_cts, usart->pin_cts, foo) == 1) {
  23                         ao_exti_enable(usart->gpio_cts, usart->pin_cts);
  24                         return 0;
  25                 }
  26 #endif
  27                 if (usart->reg->intflag & (1 << SAMD21_SERCOM_INTFLAG_DRE))
  28                 {
  29                         usart->tx_running = 1;
  30                         usart->reg->intenset = (1 << SAMD21_SERCOM_INTFLAG_DRE) | (1 << SAMD21_SERCOM_INTFLAG_TXC);
  31                         ao_fifo_remove(usart->tx_fifo, usart->reg->data);
  32                         ao_wakeup(&usart->tx_fifo);
  33                         return 1;
  34                 }
  35         }
  36         return 0;
  37 }
  38
  39 static void
  40 _ao_usart_rx(struct ao_samd21_usart *usart, int is_stdin)
  41 {
  42         if (usart->reg->intflag & (1 << SAMD21_SERCOM_INTFLAG_RXC)) {
  43                 if (!ao_fifo_full(usart->rx_fifo)) {
  44                         ao_fifo_insert(usart->rx_fifo, usart->reg->data);
  45                         ao_wakeup(&usart->rx_fifo);
  46                         if (is_stdin)
  47                                 ao_wakeup(&ao_stdin_ready);
  48 #if HAS_SERIAL_SW_FLOW
  49                         /* If the fifo is nearly full, turn off RTS and wait
  50                          * for it to drain a bunch
  51                          */
  52                         if (usart->gpio_rts && ao_fifo_mostly(usart->rx_fifo)) {
  53                                 ao_gpio_set(usart->gpio_rts, usart->pin_rts, usart->pin_rts, 1);
  54                                 usart->rts = 0;
  55                         }
  56 #endif
  57                 } else {
  58                         usart->reg->intenclr = (1 << SAMD21_SERCOM_INTFLAG_RXC);
  59                 }
  60         }
  61 }
  62
  63 static void
  64 ao_usart_isr(struct ao_samd21_usart *usart, int is_stdin)
  65 {
  66         _ao_usart_rx(usart, is_stdin);
  67
  68         if (!_ao_usart_tx_start(usart))
  69                 usart->reg->intenclr = (1 << SAMD21_SERCOM_INTFLAG_DRE);
  70
  71         if (usart->reg->intflag & (1 << SAMD21_SERCOM_INTFLAG_TXC)) {
  72                 usart->tx_running = 0;
  73                 usart->reg->intenclr = (1 << SAMD21_SERCOM_INTFLAG_TXC);
  74                 if (usart->draining) {
  75                         usart->draining = 0;
  76                         ao_wakeup(&usart->tx_fifo);
  77                 }
  78         }
  79 }
  80
  81 static const uint32_t ao_usart_speeds[] = {
  82         [AO_SERIAL_SPEED_4800] = 4800,
  83         [AO_SERIAL_SPEED_9600] = 9600,
  84         [AO_SERIAL_SPEED_19200] = 19200,
  85         [AO_SERIAL_SPEED_57600] = 57600,
  86         [AO_SERIAL_SPEED_115200] = 115200,
  87 };
  88
  89 static void
  90 ao_usart_set_speed(struct ao_samd21_usart *usart, uint8_t speed)
  91 {
  92         struct samd21_sercom *reg = usart->reg;
  93         uint64_t        top = (uint64_t) ao_usart_speeds[speed] << (4 + 16);
  94         uint16_t        baud = (uint16_t) (65536 - (top + AO_SYSCLK/2) / AO_SYSCLK);
  95         uint32_t        ctrla = reg->ctrla;
  96
  97         if (ctrla & (1UL << SAMD21_SERCOM_CTRLA_ENABLE)) {
  98                 usart->reg->ctrla = ctrla & ~(1UL << SAMD21_SERCOM_CTRLA_ENABLE);
  99                 while (reg->syncbusy & (1 << SAMD21_SERCOM_SYNCBUSY_ENABLE))
 100                         ;
 101         }
 102         usart->reg->baud = baud;
 103         if (ctrla & (1UL << SAMD21_SERCOM_CTRLA_ENABLE)) {
 104                 usart->reg->ctrla = ctrla;
 105                 while (reg->syncbusy & (1 << SAMD21_SERCOM_SYNCBUSY_ENABLE))
 106                         ;
 107         }
 108 }
 109
 110 static void
 111 ao_usart_init(struct ao_samd21_usart *usart, bool hw_flow, uint8_t id, uint8_t txpo, uint8_t rxpo)
 112 {
 113         struct samd21_sercom *reg = usart->reg;
 114
 115         (void) hw_flow;
 116
 117         /* Send a clock along */
 118         samd21_gclk_clkctrl(0, SAMD21_GCLK_CLKCTRL_ID_SERCOM0_CORE + id);
 119
 120         samd21_nvic_set_enable(SAMD21_NVIC_ISR_SERCOM0_POS + id);
 121         samd21_nvic_set_priority(SAMD21_NVIC_ISR_SERCOM0_POS + id, 4);
 122
 123         /* enable */
 124         samd21_pm.apbcmask |= (1 << (SAMD21_PM_APBCMASK_SERCOM0 + id));
 125
 126         /* Reset */
 127         reg->ctrla = (1 << SAMD21_SERCOM_CTRLA_SWRST);
 128
 129         while ((reg->ctrla & (1 << SAMD21_SERCOM_CTRLA_SWRST)) ||
 130                (reg->syncbusy & (1 << SAMD21_SERCOM_SYNCBUSY_SWRST)))
 131                 ;
 132
 133         reg->ctrlb = ((0 << SAMD21_SERCOM_CTRLB_CHSIZE) |
 134                       (0 << SAMD21_SERCOM_CTRLB_SBMODE) |
 135                       (0 << SAMD21_SERCOM_CTRLB_COLDEN) |
 136                       (0 << SAMD21_SERCOM_CTRLB_SFDE) |
 137                       (0 << SAMD21_SERCOM_CTRLB_ENC) |
 138                       (0 << SAMD21_SERCOM_CTRLB_PMODE) |
 139                       (1 << SAMD21_SERCOM_CTRLB_TXEN) |
 140                       (1 << SAMD21_SERCOM_CTRLB_RXEN) |
 141                       (3 << SAMD21_SERCOM_CTRLB_FIFOCLR));
 142
 143         ao_usart_set_speed(usart, AO_SERIAL_SPEED_9600);
 144
 145         /* finish setup and enable the hardware */
 146         reg->ctrla = ((0 << SAMD21_SERCOM_CTRLA_SWRST) |
 147                       (1 << SAMD21_SERCOM_CTRLA_ENABLE) |
 148                       (1 << SAMD21_SERCOM_CTRLA_MODE) |
 149                       (1 << SAMD21_SERCOM_CTRLA_RUNSTDBY) |
 150                       (0 << SAMD21_SERCOM_CTRLA_IBON) |
 151                       (0 << SAMD21_SERCOM_CTRLA_SAMPR) |
 152                       (txpo << SAMD21_SERCOM_CTRLA_TXPO) |      /* pad[2] */
 153                       (rxpo << SAMD21_SERCOM_CTRLA_RXPO) |      /* pad[3] */
 154                       (0 << SAMD21_SERCOM_CTRLA_SAMPA) |
 155                       (0 << SAMD21_SERCOM_CTRLA_FORM) | /* no parity */
 156                       (0 << SAMD21_SERCOM_CTRLA_CMODE) | /* async */
 157                       (0 << SAMD21_SERCOM_CTRLA_CPOL) |
 158                       (1 << SAMD21_SERCOM_CTRLA_DORD)); /* LSB first */
 159
 160         while (reg->syncbusy & (1 << SAMD21_SERCOM_SYNCBUSY_ENABLE))
 161                 ;
 162
 163         /* Enable receive interrupt */
 164         reg->intenset = (1 << SAMD21_SERCOM_INTFLAG_RXC);
 165 }
 166
 167 static int
 168 _ao_usart_pollchar(struct ao_samd21_usart *usart)
 169 {
 170         int     c;
 171
 172         if (ao_fifo_empty(usart->rx_fifo))
 173                 c = AO_READ_AGAIN;
 174         else {
 175                 uint8_t u;
 176                 ao_fifo_remove(usart->rx_fifo, u);
 177                 if ((usart->reg->intenset & (1 << SAMD21_SERCOM_INTFLAG_RXC)) == 0) {
 178                         if (ao_fifo_barely(usart->rx_fifo))
 179                                 usart->reg->intenset = (1 << SAMD21_SERCOM_INTFLAG_RXC);
 180                 }
 181 #if HAS_SERIAL_SW_FLOW
 182                 /* If we've cleared RTS, check if there's space now and turn it back on */
 183                 if (usart->gpio_rts && usart->rts == 0 && ao_fifo_barely(usart->rx_fifo)) {
 184                         ao_gpio_set(usart->gpio_rts, usart->pin_rts, foo, 0);
 185                         usart->rts = 1;
 186                 }
 187 #endif
 188                 c = u;
 189         }
 190         return c;
 191 }
 192
 193 static char
 194 ao_usart_getchar(struct ao_samd21_usart *usart)
 195 {
 196         int c;
 197         ao_arch_block_interrupts();
 198         while ((c = _ao_usart_pollchar(usart)) == AO_READ_AGAIN)
 199                 ao_sleep(&usart->rx_fifo);
 200         ao_arch_release_interrupts();
 201         return (char) c;
 202 }
 203
 204 static void
 205 ao_usart_putchar(struct ao_samd21_usart *usart, char c)
 206 {
 207         ao_arch_block_interrupts();
 208         while (ao_fifo_full(usart->tx_fifo))
 209                 ao_sleep(&usart->tx_fifo);
 210         ao_fifo_insert(usart->tx_fifo, c);
 211         _ao_usart_tx_start(usart);
 212         ao_arch_release_interrupts();
 213 }
 214
 215 static void
 216 ao_usart_drain(struct ao_samd21_usart *usart)
 217 {
 218         ao_arch_block_interrupts();
 219         while (!ao_fifo_empty(usart->tx_fifo) || usart->tx_running) {
 220                 usart->draining = 1;
 221                 ao_sleep(&usart->tx_fifo);
 222         }
 223         ao_arch_release_interrupts();
 224 }
 225
 226 #if HAS_SERIAL_0
 227
 228 struct ao_samd21_usart ao_samd21_usart0;
 229
 230 void samd21_sercom0_isr(void) { ao_usart_isr(&ao_samd21_usart0, USE_SERIAL_0_STDIN); }
 231
 232 char
 233 ao_serial0_getchar(void)
 234 {
 235         return ao_usart_getchar(&ao_samd21_usart0);
 236 }
 237
 238 void
 239 ao_serial0_putchar(char c)
 240 {
 241         ao_usart_putchar(&ao_samd21_usart0, c);
 242 }
 243
 244 int
 245 _ao_serial0_pollchar(void)
 246 {
 247         return _ao_usart_pollchar(&ao_samd21_usart0);
 248 }
 249
 250 void
 251 ao_serial0_drain(void)
 252 {
 253         ao_usart_drain(&ao_samd21_usart0);
 254 }
 255
 256 void
 257 ao_serial0_set_speed(uint8_t speed)
 258 {
 259         ao_usart_drain(&ao_samd21_usart0);
 260         ao_usart_set_speed(&ao_samd21_usart0, speed);
 261 }
 262 #endif  /* HAS_SERIAL_0 */
 263
 264 #if HAS_SERIAL_1
 265
 266 struct ao_samd21_usart ao_samd21_usart1;
 267
 268 void samd21_sercom1_isr(void) { ao_usart_isr(&ao_samd21_usart1, USE_SERIAL_1_STDIN); }
 269
 270 char
 271 ao_serial1_getchar(void)
 272 {
 273         return ao_usart_getchar(&ao_samd21_usart1);
 274 }
 275
 276 void
 277 ao_serial1_putchar(char c)
 278 {
 279         ao_usart_putchar(&ao_samd21_usart1, c);
 280 }
 281
 282 int
 283 _ao_serial1_pollchar(void)
 284 {
 285         return _ao_usart_pollchar(&ao_samd21_usart1);
 286 }
 287
 288 void
 289 ao_serial1_drain(void)
 290 {
 291         ao_usart_drain(&ao_samd21_usart1);
 292 }
 293
 294 void
 295 ao_serial1_set_speed(uint8_t speed)
 296 {
 297         ao_usart_drain(&ao_samd21_usart1);
 298         ao_usart_set_speed(&ao_samd21_usart1, speed);
 299 }
 300 #endif  /* HAS_SERIAL_1 */
 301
 302 void
 303 ao_serial_init(void)
 304 {
 305         uint8_t txpo, rxpo;
 306 #if HAS_SERIAL_0
 307
 308 #if SERIAL_0_PA10_PA11
 309         /* Pin settings */
 310         ao_enable_port(&samd21_port_a);
 311         samd21_port_pmux_set(&samd21_port_a, 10, SAMD21_PORT_PMUX_FUNC_C);
 312         samd21_port_pmux_set(&samd21_port_a, 11, SAMD21_PORT_PMUX_FUNC_C);
 313         txpo = SAMD21_SERCOM_CTRLA_TXPO_TX_2; /* pad 2 */
 314         rxpo = SAMD21_SERCOM_CTRLA_RXPO_RX_3; /* pad 3 */
 315 #else
 316 #error "No SERIAL_0 port configuration specified"
 317 #endif
 318
 319         ao_samd21_usart0.reg = &samd21_sercom0;
 320         ao_usart_init(&ao_samd21_usart0, 0, 0, txpo, rxpo);
 321
 322 #if USE_SERIAL_0_STDIN
 323         ao_add_stdio(_ao_serial0_pollchar,
 324                      ao_serial0_putchar,
 325                      NULL);
 326 #endif
 327 #endif
 328 #if HAS_SERIAL_1
 329
 330 #if SERIAL_1_PA00_PA01
 331         /* Pin settings */
 332         ao_enable_port(&samd21_port_a);
 333         samd21_port_pmux_set(&samd21_port_a, 0, SAMD21_PORT_PMUX_FUNC_D);
 334         samd21_port_pmux_set(&samd21_port_a, 1, SAMD21_PORT_PMUX_FUNC_D);
 335         txpo = SAMD21_SERCOM_CTRLA_TXPO_TX_0;
 336         rxpo = SAMD21_SERCOM_CTRLA_RXPO_RX_1;
 337 #else
 338 #error "No SERIAL_1 port configuration specified"
 339 #endif
 340
 341         ao_samd21_usart1.reg = &samd21_sercom1;
 342         ao_usart_init(&ao_samd21_usart1, 0, 1, txpo, rxpo);
 343
 344 #if USE_SERIAL_1_STDIN
 345         ao_add_stdio(_ao_serial1_pollchar,
 346                      ao_serial1_putchar,
 347                      NULL);
 348 #endif
 349 #endif
 350 }