git.gag.com Git - fw/altos/blob - src/samd21/ao_serial_samd21.c

   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         uint64_t        top = (uint64_t) ao_usart_speeds[speed] << (4 + 16);
  93         uint16_t        baud = (uint16_t) (65536 - (top + AO_SYSCLK/2) / AO_SYSCLK);
  94
  95         usart->reg->baud = baud;
  96 }
  97
  98 static void
  99 ao_usart_init(struct ao_samd21_usart *usart, bool hw_flow, uint8_t id)
 100 {
 101         struct samd21_sercom *reg = usart->reg;
 102
 103         (void) hw_flow;
 104
 105         /* Send a clock along */
 106         samd21_gclk_clkctrl(0, SAMD21_GCLK_CLKCTRL_ID_SERCOM0_CORE + id);
 107
 108         samd21_nvic_set_enable(SAMD21_NVIC_ISR_SERCOM0_POS + id);
 109         samd21_nvic_set_priority(SAMD21_NVIC_ISR_SERCOM0_POS + id, 4);
 110
 111         /* enable */
 112         samd21_pm.apbcmask |= (1 << (SAMD21_PM_APBCMASK_SERCOM0 + id));
 113
 114         /* Reset */
 115         reg->ctrla = (1 << SAMD21_SERCOM_CTRLA_SWRST);
 116
 117         while ((reg->ctrla & (1 << SAMD21_SERCOM_CTRLA_SWRST)) ||
 118                (reg->syncbusy & (1 << SAMD21_SERCOM_SYNCBUSY_SWRST)))
 119                 ;
 120
 121         reg->ctrlb = ((0 << SAMD21_SERCOM_CTRLB_CHSIZE) |
 122                       (0 << SAMD21_SERCOM_CTRLB_SBMODE) |
 123                       (0 << SAMD21_SERCOM_CTRLB_COLDEN) |
 124                       (0 << SAMD21_SERCOM_CTRLB_SFDE) |
 125                       (0 << SAMD21_SERCOM_CTRLB_ENC) |
 126                       (0 << SAMD21_SERCOM_CTRLB_PMODE) |
 127                       (1 << SAMD21_SERCOM_CTRLB_TXEN) |
 128                       (1 << SAMD21_SERCOM_CTRLB_RXEN) |
 129                       (3 << SAMD21_SERCOM_CTRLB_FIFOCLR));
 130
 131         ao_usart_set_speed(usart, AO_SERIAL_SPEED_9600);
 132
 133         /* finish setup and enable the hardware */
 134         reg->ctrla = ((0 << SAMD21_SERCOM_CTRLA_SWRST) |
 135                       (1 << SAMD21_SERCOM_CTRLA_ENABLE) |
 136                       (1 << SAMD21_SERCOM_CTRLA_MODE) |
 137                       (1 << SAMD21_SERCOM_CTRLA_RUNSTDBY) |
 138                       (0 << SAMD21_SERCOM_CTRLA_IBON) |
 139                       (0 << SAMD21_SERCOM_CTRLA_SAMPR) |
 140                       (1 << SAMD21_SERCOM_CTRLA_TXPO) | /* pad[2] */
 141                       (3 << SAMD21_SERCOM_CTRLA_RXPO) | /* pad[3] */
 142                       (0 << SAMD21_SERCOM_CTRLA_SAMPA) |
 143                       (0 << SAMD21_SERCOM_CTRLA_FORM) | /* no parity */
 144                       (0 << SAMD21_SERCOM_CTRLA_CMODE) | /* async */
 145                       (0 << SAMD21_SERCOM_CTRLA_CPOL) |
 146                       (1 << SAMD21_SERCOM_CTRLA_DORD)); /* LSB first */
 147
 148         /* Enable receive interrupt */
 149         reg->intenset = (1 << SAMD21_SERCOM_INTFLAG_RXC);
 150 }
 151
 152 static int
 153 _ao_usart_pollchar(struct ao_samd21_usart *usart)
 154 {
 155         int     c;
 156
 157         if (ao_fifo_empty(usart->rx_fifo))
 158                 c = AO_READ_AGAIN;
 159         else {
 160                 uint8_t u;
 161                 ao_fifo_remove(usart->rx_fifo, u);
 162                 if ((usart->reg->intenset & (1 << SAMD21_SERCOM_INTFLAG_RXC)) == 0) {
 163                         if (ao_fifo_barely(usart->rx_fifo))
 164                                 usart->reg->intenset = (1 << SAMD21_SERCOM_INTFLAG_RXC);
 165                 }
 166 #if HAS_SERIAL_SW_FLOW
 167                 /* If we've cleared RTS, check if there's space now and turn it back on */
 168                 if (usart->gpio_rts && usart->rts == 0 && ao_fifo_barely(usart->rx_fifo)) {
 169                         ao_gpio_set(usart->gpio_rts, usart->pin_rts, foo, 0);
 170                         usart->rts = 1;
 171                 }
 172 #endif
 173                 c = u;
 174         }
 175         return c;
 176 }
 177
 178 static char
 179 ao_usart_getchar(struct ao_samd21_usart *usart)
 180 {
 181         int c;
 182         ao_arch_block_interrupts();
 183         while ((c = _ao_usart_pollchar(usart)) == AO_READ_AGAIN)
 184                 ao_sleep(&usart->rx_fifo);
 185         ao_arch_release_interrupts();
 186         return (char) c;
 187 }
 188
 189 static void
 190 ao_usart_putchar(struct ao_samd21_usart *usart, char c)
 191 {
 192         ao_arch_block_interrupts();
 193         while (ao_fifo_full(usart->tx_fifo))
 194                 ao_sleep(&usart->tx_fifo);
 195         ao_fifo_insert(usart->tx_fifo, c);
 196         _ao_usart_tx_start(usart);
 197         ao_arch_release_interrupts();
 198 }
 199
 200 static void
 201 ao_usart_drain(struct ao_samd21_usart *usart)
 202 {
 203         ao_arch_block_interrupts();
 204         while (!ao_fifo_empty(usart->tx_fifo) || usart->tx_running) {
 205                 usart->draining = 1;
 206                 ao_sleep(&usart->tx_fifo);
 207         }
 208         ao_arch_release_interrupts();
 209 }
 210
 211 #if HAS_SERIAL_0
 212
 213 struct ao_samd21_usart ao_samd21_usart0;
 214
 215 void samd21_sercom0_isr(void) { ao_usart_isr(&ao_samd21_usart0, USE_SERIAL_0_STDIN); }
 216
 217 char
 218 ao_serial0_getchar(void)
 219 {
 220         return ao_usart_getchar(&ao_samd21_usart0);
 221 }
 222
 223 void
 224 ao_serial0_putchar(char c)
 225 {
 226         ao_usart_putchar(&ao_samd21_usart0, c);
 227 }
 228
 229 int
 230 _ao_serial0_pollchar(void)
 231 {
 232         return _ao_usart_pollchar(&ao_samd21_usart0);
 233 }
 234
 235 void
 236 ao_serial0_drain(void)
 237 {
 238         ao_usart_drain(&ao_samd21_usart0);
 239 }
 240
 241 void
 242 ao_serial0_set_speed(uint8_t speed)
 243 {
 244         ao_usart_drain(&ao_samd21_usart0);
 245         ao_usart_set_speed(&ao_samd21_usart0, speed);
 246 }
 247 #endif  /* HAS_SERIAL_0 */
 248
 249 #if HAS_SERIAL_1
 250
 251 struct ao_samd21_usart ao_samd21_usart1;
 252
 253 void samd21_sercom1_isr(void) { ao_usart_isr(&ao_samd21_usart1, USE_SERIAL_1_STDIN); }
 254
 255 char
 256 ao_serial1_getchar(void)
 257 {
 258         return ao_usart_getchar(&ao_samd21_usart1);
 259 }
 260
 261 void
 262 ao_serial1_putchar(char c)
 263 {
 264         ao_usart_putchar(&ao_samd21_usart1, c);
 265 }
 266
 267 int
 268 _ao_serial1_pollchar(void)
 269 {
 270         return _ao_usart_pollchar(&ao_samd21_usart1);
 271 }
 272
 273 void
 274 ao_serial1_drain(void)
 275 {
 276         ao_usart_drain(&ao_samd21_usart1);
 277 }
 278
 279 void
 280 ao_serial1_set_speed(uint8_t speed)
 281 {
 282         ao_usart_drain(&ao_samd21_usart1);
 283         ao_usart_set_speed(&ao_samd21_usart1, speed);
 284 }
 285 #endif  /* HAS_SERIAL_1 */
 286
 287 void
 288 ao_serial_init(void)
 289 {
 290 #if HAS_SERIAL_0
 291
 292 #if SERIAL_0_PA10_PA11
 293         /* Pin settings */
 294         ao_enable_port(&samd21_port_a);
 295         samd21_port_pmux_set(&samd21_port_a, 10, SAMD21_PORT_PMUX_FUNC_C);
 296         samd21_port_pmux_set(&samd21_port_a, 11, SAMD21_PORT_PMUX_FUNC_C);
 297 #else
 298 #error "No SERIAL_0 port configuration specified"
 299 #endif
 300
 301         ao_samd21_usart0.reg = &samd21_sercom0;
 302         ao_usart_init(&ao_samd21_usart0, 0, 0);
 303
 304 #if USE_SERIAL_0_STDIN
 305         ao_add_stdio(_ao_serial0_pollchar,
 306                      ao_serial0_putchar,
 307                      NULL);
 308 #endif
 309 #endif
 310 #if HAS_SERIAL_1
 311
 312 #if SERIAL_1_PA00_PA01
 313         /* Pin settings */
 314         ao_enable_port(&samd21_port_a);
 315         samd21_port_pmux_set(&samd21_port_a, 0, SAMD21_PORT_PMUX_FUNC_D);
 316         samd21_port_pmux_set(&samd21_port_a, 1, SAMD21_PORT_PMUX_FUNC_D);
 317 #else
 318 #error "No SERIAL_1 port configuration specified"
 319 #endif
 320
 321         ao_samd21_usart1.reg = &samd21_sercom1;
 322         ao_usart_init(&ao_samd21_usart1, 0, 0);
 323
 324 #if USE_SERIAL_1_STDIN
 325         ao_add_stdio(_ao_serial1_pollchar,
 326                      ao_serial1_putchar,
 327                      NULL);
 328 #endif
 329 #endif
 330 }