1 // SPDX-License-Identifier: GPL-2.0
3 * LiteUART serial controller (LiteX) Driver
5 * Copyright (C) 2019-2020 Antmicro <www.antmicro.com>
8 #include <linux/console.h>
9 #include <linux/litex.h>
10 #include <linux/module.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>
22 * CSRs definitions (base address offsets + width)
24 * The definitions below are true for LiteX SoC configured for 8-bit CSR Bus,
27 * Supporting other configurations might require new definitions or a more
28 * generic way of indexing the LiteX CSRs.
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
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
44 struct liteuart_port {
45 struct uart_port port;
46 struct timer_list timer;
50 #define to_liteuart_port(port) container_of(port, struct liteuart_port, port)
52 static DEFINE_XARRAY_FLAGS(liteuart_array, XA_FLAGS_ALLOC);
54 #ifdef CONFIG_SERIAL_LITEUART_CONSOLE
55 static struct console liteuart_console;
58 static struct uart_driver liteuart_driver = {
60 .driver_name = "liteuart",
64 .nr = CONFIG_SERIAL_LITEUART_MAX_PORTS,
65 #ifdef CONFIG_SERIAL_LITEUART_CONSOLE
66 .cons = &liteuart_console,
70 static void liteuart_timer(struct timer_list *t)
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;
79 while ((status = !litex_read8(membase + OFF_RXEMPTY)) == 1) {
80 ch = litex_read8(membase + OFF_RXTX);
83 /* necessary for RXEMPTY to refresh its value */
84 litex_write8(membase + OFF_EV_PENDING, EV_TX | EV_RX);
86 /* no overflow bits in status */
87 if (!(uart_handle_sysrq_char(port, ch)))
88 uart_insert_char(port, status, 0, ch, flg);
90 tty_flip_buffer_push(&port->state->port);
93 mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
96 static void liteuart_putchar(struct uart_port *port, int ch)
98 while (litex_read8(port->membase + OFF_TXFULL))
101 litex_write8(port->membase + OFF_RXTX, ch);
104 static unsigned int liteuart_tx_empty(struct uart_port *port)
106 /* not really tx empty, just checking if tx is not full */
107 if (!litex_read8(port->membase + OFF_TXFULL))
113 static void liteuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
115 /* modem control register is not present in LiteUART */
118 static unsigned int liteuart_get_mctrl(struct uart_port *port)
120 return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
123 static void liteuart_stop_tx(struct uart_port *port)
127 static void liteuart_start_tx(struct uart_port *port)
129 struct circ_buf *xmit = &port->state->xmit;
132 if (unlikely(port->x_char)) {
133 litex_write8(port->membase + OFF_RXTX, port->x_char);
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);
141 liteuart_putchar(port, ch);
145 if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
146 uart_write_wakeup(port);
149 static void liteuart_stop_rx(struct uart_port *port)
151 struct liteuart_port *uart = to_liteuart_port(port);
153 /* just delete timer */
154 del_timer(&uart->timer);
157 static void liteuart_break_ctl(struct uart_port *port, int break_state)
159 /* LiteUART doesn't support sending break signal */
162 static int liteuart_startup(struct uart_port *port)
164 struct liteuart_port *uart = to_liteuart_port(port);
167 litex_write8(port->membase + OFF_EV_ENABLE, 0);
169 /* prepare timer for polling */
170 timer_setup(&uart->timer, liteuart_timer, 0);
171 mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
176 static void liteuart_shutdown(struct uart_port *port)
180 static void liteuart_set_termios(struct uart_port *port, struct ktermios *new,
181 struct ktermios *old)
186 spin_lock_irqsave(&port->lock, flags);
188 /* update baudrate */
189 baud = uart_get_baud_rate(port, new, old, 0, 460800);
190 uart_update_timeout(port, new->c_cflag, baud);
192 spin_unlock_irqrestore(&port->lock, flags);
195 static const char *liteuart_type(struct uart_port *port)
200 static void liteuart_release_port(struct uart_port *port)
204 static int liteuart_request_port(struct uart_port *port)
209 static void liteuart_config_port(struct uart_port *port, int flags)
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.
219 static int liteuart_verify_port(struct uart_port *port,
220 struct serial_struct *ser)
222 if (port->type != PORT_UNKNOWN && ser->type != 1)
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,
246 static int liteuart_probe(struct platform_device *pdev)
248 struct liteuart_port *uart;
249 struct uart_port *port;
250 struct xa_limit limit;
253 /* look for aliases; auto-enumerate for free index if not found */
254 dev_id = of_alias_get_id(pdev->dev.of_node, "serial");
256 limit = XA_LIMIT(0, CONFIG_SERIAL_LITEUART_MAX_PORTS);
258 limit = XA_LIMIT(dev_id, dev_id);
260 uart = devm_kzalloc(&pdev->dev, sizeof(struct liteuart_port), GFP_KERNEL);
264 ret = xa_alloc(&liteuart_array, &dev_id, uart, limit, GFP_KERNEL);
272 port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
273 if (IS_ERR(port->membase))
274 return PTR_ERR(port->membase);
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;
284 port->type = PORT_UNKNOWN;
286 spin_lock_init(&port->lock);
288 return uart_add_one_port(&liteuart_driver, &uart->port);
291 static int liteuart_remove(struct platform_device *pdev)
293 struct uart_port *port = platform_get_drvdata(pdev);
294 struct liteuart_port *uart = to_liteuart_port(port);
296 xa_erase(&liteuart_array, uart->id);
301 static const struct of_device_id liteuart_of_match[] = {
302 { .compatible = "litex,liteuart" },
305 MODULE_DEVICE_TABLE(of, liteuart_of_match);
307 static struct platform_driver liteuart_platform_driver = {
308 .probe = liteuart_probe,
309 .remove = liteuart_remove,
312 .of_match_table = liteuart_of_match,
316 #ifdef CONFIG_SERIAL_LITEUART_CONSOLE
318 static void liteuart_console_write(struct console *co, const char *s,
321 struct liteuart_port *uart;
322 struct uart_port *port;
325 uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index);
328 spin_lock_irqsave(&port->lock, flags);
329 uart_console_write(port, s, count, liteuart_putchar);
330 spin_unlock_irqrestore(&port->lock, flags);
333 static int liteuart_console_setup(struct console *co, char *options)
335 struct liteuart_port *uart;
336 struct uart_port *port;
342 uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index);
351 uart_parse_options(options, &baud, &parity, &bits, &flow);
353 return uart_set_options(port, co, baud, parity, bits, flow);
356 static struct console liteuart_console = {
358 .write = liteuart_console_write,
359 .device = uart_console_device,
360 .setup = liteuart_console_setup,
361 .flags = CON_PRINTBUFFER,
363 .data = &liteuart_driver,
366 static int __init liteuart_console_init(void)
368 register_console(&liteuart_console);
372 console_initcall(liteuart_console_init);
374 static void early_liteuart_write(struct console *console, const char *s,
377 struct earlycon_device *device = console->data;
378 struct uart_port *port = &device->port;
380 uart_console_write(port, s, count, liteuart_putchar);
383 static int __init early_liteuart_setup(struct earlycon_device *device,
386 if (!device->port.membase)
389 device->con->write = early_liteuart_write;
393 OF_EARLYCON_DECLARE(liteuart, "litex,liteuart", early_liteuart_setup);
394 #endif /* CONFIG_SERIAL_LITEUART_CONSOLE */
396 static int __init liteuart_init(void)
400 res = uart_register_driver(&liteuart_driver);
404 res = platform_driver_register(&liteuart_platform_driver);
406 uart_unregister_driver(&liteuart_driver);
413 static void __exit liteuart_exit(void)
415 platform_driver_unregister(&liteuart_platform_driver);
416 uart_unregister_driver(&liteuart_driver);
419 module_init(liteuart_init);
420 module_exit(liteuart_exit);
422 MODULE_AUTHOR("Antmicro <www.antmicro.com>");
423 MODULE_DESCRIPTION("LiteUART serial driver");
424 MODULE_LICENSE("GPL v2");
425 MODULE_ALIAS("platform: liteuart");