1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * LiteUART serial controller (LiteX) Driver 4 * 5 * Copyright (C) 2019-2020 Antmicro <www.antmicro.com> 6 */ 7 8 #include <linux/console.h> 9 #include <linux/litex.h> 10 #include <linux/module.h> 11 #include <linux/of.h> 12 #include <linux/of_address.h> 13 #include <linux/of_platform.h> 14 #include <linux/serial.h> 15 #include <linux/serial_core.h> 16 #include <linux/slab.h> 17 #include <linux/timer.h> 18 #include <linux/tty_flip.h> 19 #include <linux/xarray.h> 20 21 /* 22 * CSRs definitions (base address offsets + width) 23 * 24 * The definitions below are true for LiteX SoC configured for 8-bit CSR Bus, 25 * 32-bit aligned. 26 * 27 * Supporting other configurations might require new definitions or a more 28 * generic way of indexing the LiteX CSRs. 29 * 30 * For more details on how CSRs are defined and handled in LiteX, see comments 31 * in the LiteX SoC Driver: drivers/soc/litex/litex_soc_ctrl.c 32 */ 33 #define OFF_RXTX 0x00 34 #define OFF_TXFULL 0x04 35 #define OFF_RXEMPTY 0x08 36 #define OFF_EV_STATUS 0x0c 37 #define OFF_EV_PENDING 0x10 38 #define OFF_EV_ENABLE 0x14 39 40 /* events */ 41 #define EV_TX 0x1 42 #define EV_RX 0x2 43 44 struct liteuart_port { 45 struct uart_port port; 46 struct timer_list timer; 47 u32 id; 48 }; 49 50 #define to_liteuart_port(port) container_of(port, struct liteuart_port, port) 51 52 static DEFINE_XARRAY_FLAGS(liteuart_array, XA_FLAGS_ALLOC); 53 54 #ifdef CONFIG_SERIAL_LITEUART_CONSOLE 55 static struct console liteuart_console; 56 #endif 57 58 static struct uart_driver liteuart_driver = { 59 .owner = THIS_MODULE, 60 .driver_name = "liteuart", 61 .dev_name = "ttyLXU", 62 .major = 0, 63 .minor = 0, 64 .nr = CONFIG_SERIAL_LITEUART_MAX_PORTS, 65 #ifdef CONFIG_SERIAL_LITEUART_CONSOLE 66 .cons = &liteuart_console, 67 #endif 68 }; 69 70 static void liteuart_timer(struct timer_list *t) 71 { 72 struct liteuart_port *uart = from_timer(uart, t, timer); 73 struct uart_port *port = &uart->port; 74 unsigned char __iomem *membase = port->membase; 75 unsigned int flg = TTY_NORMAL; 76 int ch; 77 unsigned long status; 78 79 while ((status = !litex_read8(membase + OFF_RXEMPTY)) == 1) { 80 ch = litex_read8(membase + OFF_RXTX); 81 port->icount.rx++; 82 83 /* necessary for RXEMPTY to refresh its value */ 84 litex_write8(membase + OFF_EV_PENDING, EV_TX | EV_RX); 85 86 /* no overflow bits in status */ 87 if (!(uart_handle_sysrq_char(port, ch))) 88 uart_insert_char(port, status, 0, ch, flg); 89 90 tty_flip_buffer_push(&port->state->port); 91 } 92 93 mod_timer(&uart->timer, jiffies + uart_poll_timeout(port)); 94 } 95 96 static void liteuart_putchar(struct uart_port *port, int ch) 97 { 98 while (litex_read8(port->membase + OFF_TXFULL)) 99 cpu_relax(); 100 101 litex_write8(port->membase + OFF_RXTX, ch); 102 } 103 104 static unsigned int liteuart_tx_empty(struct uart_port *port) 105 { 106 /* not really tx empty, just checking if tx is not full */ 107 if (!litex_read8(port->membase + OFF_TXFULL)) 108 return TIOCSER_TEMT; 109 110 return 0; 111 } 112 113 static void liteuart_set_mctrl(struct uart_port *port, unsigned int mctrl) 114 { 115 /* modem control register is not present in LiteUART */ 116 } 117 118 static unsigned int liteuart_get_mctrl(struct uart_port *port) 119 { 120 return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR; 121 } 122 123 static void liteuart_stop_tx(struct uart_port *port) 124 { 125 } 126 127 static void liteuart_start_tx(struct uart_port *port) 128 { 129 struct circ_buf *xmit = &port->state->xmit; 130 unsigned char ch; 131 132 if (unlikely(port->x_char)) { 133 litex_write8(port->membase + OFF_RXTX, port->x_char); 134 port->icount.tx++; 135 port->x_char = 0; 136 } else if (!uart_circ_empty(xmit)) { 137 while (xmit->head != xmit->tail) { 138 ch = xmit->buf[xmit->tail]; 139 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1); 140 port->icount.tx++; 141 liteuart_putchar(port, ch); 142 } 143 } 144 145 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) 146 uart_write_wakeup(port); 147 } 148 149 static void liteuart_stop_rx(struct uart_port *port) 150 { 151 struct liteuart_port *uart = to_liteuart_port(port); 152 153 /* just delete timer */ 154 del_timer(&uart->timer); 155 } 156 157 static void liteuart_break_ctl(struct uart_port *port, int break_state) 158 { 159 /* LiteUART doesn't support sending break signal */ 160 } 161 162 static int liteuart_startup(struct uart_port *port) 163 { 164 struct liteuart_port *uart = to_liteuart_port(port); 165 166 /* disable events */ 167 litex_write8(port->membase + OFF_EV_ENABLE, 0); 168 169 /* prepare timer for polling */ 170 timer_setup(&uart->timer, liteuart_timer, 0); 171 mod_timer(&uart->timer, jiffies + uart_poll_timeout(port)); 172 173 return 0; 174 } 175 176 static void liteuart_shutdown(struct uart_port *port) 177 { 178 } 179 180 static void liteuart_set_termios(struct uart_port *port, struct ktermios *new, 181 struct ktermios *old) 182 { 183 unsigned int baud; 184 unsigned long flags; 185 186 spin_lock_irqsave(&port->lock, flags); 187 188 /* update baudrate */ 189 baud = uart_get_baud_rate(port, new, old, 0, 460800); 190 uart_update_timeout(port, new->c_cflag, baud); 191 192 spin_unlock_irqrestore(&port->lock, flags); 193 } 194 195 static const char *liteuart_type(struct uart_port *port) 196 { 197 return "liteuart"; 198 } 199 200 static void liteuart_release_port(struct uart_port *port) 201 { 202 } 203 204 static int liteuart_request_port(struct uart_port *port) 205 { 206 return 0; 207 } 208 209 static void liteuart_config_port(struct uart_port *port, int flags) 210 { 211 /* 212 * Driver core for serial ports forces a non-zero value for port type. 213 * Write an arbitrary value here to accommodate the serial core driver, 214 * as ID part of UAPI is redundant. 215 */ 216 port->type = 1; 217 } 218 219 static int liteuart_verify_port(struct uart_port *port, 220 struct serial_struct *ser) 221 { 222 if (port->type != PORT_UNKNOWN && ser->type != 1) 223 return -EINVAL; 224 225 return 0; 226 } 227 228 static const struct uart_ops liteuart_ops = { 229 .tx_empty = liteuart_tx_empty, 230 .set_mctrl = liteuart_set_mctrl, 231 .get_mctrl = liteuart_get_mctrl, 232 .stop_tx = liteuart_stop_tx, 233 .start_tx = liteuart_start_tx, 234 .stop_rx = liteuart_stop_rx, 235 .break_ctl = liteuart_break_ctl, 236 .startup = liteuart_startup, 237 .shutdown = liteuart_shutdown, 238 .set_termios = liteuart_set_termios, 239 .type = liteuart_type, 240 .release_port = liteuart_release_port, 241 .request_port = liteuart_request_port, 242 .config_port = liteuart_config_port, 243 .verify_port = liteuart_verify_port, 244 }; 245 246 static int liteuart_probe(struct platform_device *pdev) 247 { 248 struct liteuart_port *uart; 249 struct uart_port *port; 250 struct xa_limit limit; 251 int dev_id, ret; 252 253 /* look for aliases; auto-enumerate for free index if not found */ 254 dev_id = of_alias_get_id(pdev->dev.of_node, "serial"); 255 if (dev_id < 0) 256 limit = XA_LIMIT(0, CONFIG_SERIAL_LITEUART_MAX_PORTS); 257 else 258 limit = XA_LIMIT(dev_id, dev_id); 259 260 uart = devm_kzalloc(&pdev->dev, sizeof(struct liteuart_port), GFP_KERNEL); 261 if (!uart) 262 return -ENOMEM; 263 264 ret = xa_alloc(&liteuart_array, &dev_id, uart, limit, GFP_KERNEL); 265 if (ret) 266 return ret; 267 268 uart->id = dev_id; 269 port = &uart->port; 270 271 /* get membase */ 272 port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, NULL); 273 if (IS_ERR(port->membase)) 274 return PTR_ERR(port->membase); 275 276 /* values not from device tree */ 277 port->dev = &pdev->dev; 278 port->iotype = UPIO_MEM; 279 port->flags = UPF_BOOT_AUTOCONF; 280 port->ops = &liteuart_ops; 281 port->regshift = 2; 282 port->fifosize = 16; 283 port->iobase = 1; 284 port->type = PORT_UNKNOWN; 285 port->line = dev_id; 286 spin_lock_init(&port->lock); 287 288 return uart_add_one_port(&liteuart_driver, &uart->port); 289 } 290 291 static int liteuart_remove(struct platform_device *pdev) 292 { 293 struct uart_port *port = platform_get_drvdata(pdev); 294 struct liteuart_port *uart = to_liteuart_port(port); 295 296 xa_erase(&liteuart_array, uart->id); 297 298 return 0; 299 } 300 301 static const struct of_device_id liteuart_of_match[] = { 302 { .compatible = "litex,liteuart" }, 303 {} 304 }; 305 MODULE_DEVICE_TABLE(of, liteuart_of_match); 306 307 static struct platform_driver liteuart_platform_driver = { 308 .probe = liteuart_probe, 309 .remove = liteuart_remove, 310 .driver = { 311 .name = "liteuart", 312 .of_match_table = liteuart_of_match, 313 }, 314 }; 315 316 #ifdef CONFIG_SERIAL_LITEUART_CONSOLE 317 318 static void liteuart_console_write(struct console *co, const char *s, 319 unsigned int count) 320 { 321 struct liteuart_port *uart; 322 struct uart_port *port; 323 unsigned long flags; 324 325 uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index); 326 port = &uart->port; 327 328 spin_lock_irqsave(&port->lock, flags); 329 uart_console_write(port, s, count, liteuart_putchar); 330 spin_unlock_irqrestore(&port->lock, flags); 331 } 332 333 static int liteuart_console_setup(struct console *co, char *options) 334 { 335 struct liteuart_port *uart; 336 struct uart_port *port; 337 int baud = 115200; 338 int bits = 8; 339 int parity = 'n'; 340 int flow = 'n'; 341 342 uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index); 343 if (!uart) 344 return -ENODEV; 345 346 port = &uart->port; 347 if (!port->membase) 348 return -ENODEV; 349 350 if (options) 351 uart_parse_options(options, &baud, &parity, &bits, &flow); 352 353 return uart_set_options(port, co, baud, parity, bits, flow); 354 } 355 356 static struct console liteuart_console = { 357 .name = "liteuart", 358 .write = liteuart_console_write, 359 .device = uart_console_device, 360 .setup = liteuart_console_setup, 361 .flags = CON_PRINTBUFFER, 362 .index = -1, 363 .data = &liteuart_driver, 364 }; 365 366 static int __init liteuart_console_init(void) 367 { 368 register_console(&liteuart_console); 369 370 return 0; 371 } 372 console_initcall(liteuart_console_init); 373 374 static void early_liteuart_write(struct console *console, const char *s, 375 unsigned int count) 376 { 377 struct earlycon_device *device = console->data; 378 struct uart_port *port = &device->port; 379 380 uart_console_write(port, s, count, liteuart_putchar); 381 } 382 383 static int __init early_liteuart_setup(struct earlycon_device *device, 384 const char *options) 385 { 386 if (!device->port.membase) 387 return -ENODEV; 388 389 device->con->write = early_liteuart_write; 390 return 0; 391 } 392 393 OF_EARLYCON_DECLARE(liteuart, "litex,liteuart", early_liteuart_setup); 394 #endif /* CONFIG_SERIAL_LITEUART_CONSOLE */ 395 396 static int __init liteuart_init(void) 397 { 398 int res; 399 400 res = uart_register_driver(&liteuart_driver); 401 if (res) 402 return res; 403 404 res = platform_driver_register(&liteuart_platform_driver); 405 if (res) { 406 uart_unregister_driver(&liteuart_driver); 407 return res; 408 } 409 410 return 0; 411 } 412 413 static void __exit liteuart_exit(void) 414 { 415 platform_driver_unregister(&liteuart_platform_driver); 416 uart_unregister_driver(&liteuart_driver); 417 } 418 419 module_init(liteuart_init); 420 module_exit(liteuart_exit); 421 422 MODULE_AUTHOR("Antmicro <www.antmicro.com>"); 423 MODULE_DESCRIPTION("LiteUART serial driver"); 424 MODULE_LICENSE("GPL v2"); 425 MODULE_ALIAS("platform: liteuart"); 426