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/bits.h>
9 #include <linux/console.h>
10 #include <linux/interrupt.h>
11 #include <linux/litex.h>
12 #include <linux/module.h>
14 #include <linux/of_address.h>
15 #include <linux/of_platform.h>
16 #include <linux/serial.h>
17 #include <linux/serial_core.h>
18 #include <linux/slab.h>
19 #include <linux/timer.h>
20 #include <linux/tty_flip.h>
21 #include <linux/xarray.h>
24 * CSRs definitions (base address offsets + width)
26 * The definitions below are true for LiteX SoC configured for 8-bit CSR Bus,
29 * Supporting other configurations might require new definitions or a more
30 * generic way of indexing the LiteX CSRs.
32 * For more details on how CSRs are defined and handled in LiteX, see comments
33 * in the LiteX SoC Driver: drivers/soc/litex/litex_soc_ctrl.c
36 #define OFF_TXFULL 0x04
37 #define OFF_RXEMPTY 0x08
38 #define OFF_EV_STATUS 0x0c
39 #define OFF_EV_PENDING 0x10
40 #define OFF_EV_ENABLE 0x14
46 struct liteuart_port {
47 struct uart_port port;
48 struct timer_list timer;
53 #define to_liteuart_port(port) container_of(port, struct liteuart_port, port)
55 static DEFINE_XARRAY_FLAGS(liteuart_array, XA_FLAGS_ALLOC);
57 #ifdef CONFIG_SERIAL_LITEUART_CONSOLE
58 static struct console liteuart_console;
61 static struct uart_driver liteuart_driver = {
63 .driver_name = KBUILD_MODNAME,
67 .nr = CONFIG_SERIAL_LITEUART_MAX_PORTS,
68 #ifdef CONFIG_SERIAL_LITEUART_CONSOLE
69 .cons = &liteuart_console,
73 static void liteuart_update_irq_reg(struct uart_port *port, bool set, u8 mask)
75 struct liteuart_port *uart = to_liteuart_port(port);
78 uart->irq_reg |= mask;
80 uart->irq_reg &= ~mask;
83 litex_write8(port->membase + OFF_EV_ENABLE, uart->irq_reg);
86 static void liteuart_stop_tx(struct uart_port *port)
88 liteuart_update_irq_reg(port, false, EV_TX);
91 static void liteuart_start_tx(struct uart_port *port)
93 liteuart_update_irq_reg(port, true, EV_TX);
96 static void liteuart_stop_rx(struct uart_port *port)
98 struct liteuart_port *uart = to_liteuart_port(port);
100 /* just delete timer */
101 del_timer(&uart->timer);
104 static void liteuart_rx_chars(struct uart_port *port)
106 unsigned char __iomem *membase = port->membase;
109 while (!litex_read8(membase + OFF_RXEMPTY)) {
110 ch = litex_read8(membase + OFF_RXTX);
113 /* necessary for RXEMPTY to refresh its value */
114 litex_write8(membase + OFF_EV_PENDING, EV_RX);
116 /* no overflow bits in status */
117 if (!(uart_handle_sysrq_char(port, ch)))
118 uart_insert_char(port, 1, 0, ch, TTY_NORMAL);
121 tty_flip_buffer_push(&port->state->port);
124 static void liteuart_tx_chars(struct uart_port *port)
128 uart_port_tx(port, ch,
129 !litex_read8(port->membase + OFF_TXFULL),
130 litex_write8(port->membase + OFF_RXTX, ch));
133 static irqreturn_t liteuart_interrupt(int irq, void *data)
135 struct liteuart_port *uart = data;
136 struct uart_port *port = &uart->port;
141 * if polling, the context would be "in_serving_softirq", so use
142 * irq[save|restore] spin_lock variants to cover all possibilities
144 spin_lock_irqsave(&port->lock, flags);
145 isr = litex_read8(port->membase + OFF_EV_PENDING) & uart->irq_reg;
147 liteuart_rx_chars(port);
149 liteuart_tx_chars(port);
150 spin_unlock_irqrestore(&port->lock, flags);
152 return IRQ_RETVAL(isr);
155 static void liteuart_timer(struct timer_list *t)
157 struct liteuart_port *uart = from_timer(uart, t, timer);
158 struct uart_port *port = &uart->port;
160 liteuart_interrupt(0, port);
161 mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
164 static unsigned int liteuart_tx_empty(struct uart_port *port)
166 /* not really tx empty, just checking if tx is not full */
167 if (!litex_read8(port->membase + OFF_TXFULL))
173 static void liteuart_set_mctrl(struct uart_port *port, unsigned int mctrl)
175 /* modem control register is not present in LiteUART */
178 static unsigned int liteuart_get_mctrl(struct uart_port *port)
180 return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
183 static int liteuart_startup(struct uart_port *port)
185 struct liteuart_port *uart = to_liteuart_port(port);
190 ret = request_irq(port->irq, liteuart_interrupt, 0,
191 KBUILD_MODNAME, uart);
194 "line %d irq %d failed: switch to polling\n",
195 port->line, port->irq);
200 spin_lock_irqsave(&port->lock, flags);
201 /* only enabling rx irqs during startup */
202 liteuart_update_irq_reg(port, true, EV_RX);
203 spin_unlock_irqrestore(&port->lock, flags);
206 timer_setup(&uart->timer, liteuart_timer, 0);
207 mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
213 static void liteuart_shutdown(struct uart_port *port)
215 struct liteuart_port *uart = to_liteuart_port(port);
218 spin_lock_irqsave(&port->lock, flags);
219 liteuart_update_irq_reg(port, false, EV_RX | EV_TX);
220 spin_unlock_irqrestore(&port->lock, flags);
223 free_irq(port->irq, port);
225 del_timer_sync(&uart->timer);
228 static void liteuart_set_termios(struct uart_port *port, struct ktermios *new,
229 const struct ktermios *old)
234 spin_lock_irqsave(&port->lock, flags);
236 /* update baudrate */
237 baud = uart_get_baud_rate(port, new, old, 0, 460800);
238 uart_update_timeout(port, new->c_cflag, baud);
240 spin_unlock_irqrestore(&port->lock, flags);
243 static const char *liteuart_type(struct uart_port *port)
248 static void liteuart_config_port(struct uart_port *port, int flags)
251 * Driver core for serial ports forces a non-zero value for port type.
252 * Write an arbitrary value here to accommodate the serial core driver,
253 * as ID part of UAPI is redundant.
258 static int liteuart_verify_port(struct uart_port *port,
259 struct serial_struct *ser)
261 if (port->type != PORT_UNKNOWN && ser->type != 1)
267 static const struct uart_ops liteuart_ops = {
268 .tx_empty = liteuart_tx_empty,
269 .set_mctrl = liteuart_set_mctrl,
270 .get_mctrl = liteuart_get_mctrl,
271 .stop_tx = liteuart_stop_tx,
272 .start_tx = liteuart_start_tx,
273 .stop_rx = liteuart_stop_rx,
274 .startup = liteuart_startup,
275 .shutdown = liteuart_shutdown,
276 .set_termios = liteuart_set_termios,
277 .type = liteuart_type,
278 .config_port = liteuart_config_port,
279 .verify_port = liteuart_verify_port,
282 static int liteuart_probe(struct platform_device *pdev)
284 struct liteuart_port *uart;
285 struct uart_port *port;
286 struct xa_limit limit;
289 uart = devm_kzalloc(&pdev->dev, sizeof(struct liteuart_port), GFP_KERNEL);
296 port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);
297 if (IS_ERR(port->membase))
298 return PTR_ERR(port->membase);
300 ret = platform_get_irq_optional(pdev, 0);
301 if (ret < 0 && ret != -ENXIO)
306 /* look for aliases; auto-enumerate for free index if not found */
307 dev_id = of_alias_get_id(pdev->dev.of_node, "serial");
309 limit = XA_LIMIT(0, CONFIG_SERIAL_LITEUART_MAX_PORTS);
311 limit = XA_LIMIT(dev_id, dev_id);
313 ret = xa_alloc(&liteuart_array, &dev_id, uart, limit, GFP_KERNEL);
318 /* values not from device tree */
319 port->dev = &pdev->dev;
320 port->iotype = UPIO_MEM;
321 port->flags = UPF_BOOT_AUTOCONF;
322 port->ops = &liteuart_ops;
324 port->type = PORT_UNKNOWN;
326 spin_lock_init(&port->lock);
328 platform_set_drvdata(pdev, port);
330 ret = uart_add_one_port(&liteuart_driver, &uart->port);
337 xa_erase(&liteuart_array, uart->id);
342 static int liteuart_remove(struct platform_device *pdev)
344 struct uart_port *port = platform_get_drvdata(pdev);
345 struct liteuart_port *uart = to_liteuart_port(port);
347 uart_remove_one_port(&liteuart_driver, port);
348 xa_erase(&liteuart_array, uart->id);
353 static const struct of_device_id liteuart_of_match[] = {
354 { .compatible = "litex,liteuart" },
357 MODULE_DEVICE_TABLE(of, liteuart_of_match);
359 static struct platform_driver liteuart_platform_driver = {
360 .probe = liteuart_probe,
361 .remove = liteuart_remove,
363 .name = KBUILD_MODNAME,
364 .of_match_table = liteuart_of_match,
368 #ifdef CONFIG_SERIAL_LITEUART_CONSOLE
370 static void liteuart_putchar(struct uart_port *port, unsigned char ch)
372 while (litex_read8(port->membase + OFF_TXFULL))
375 litex_write8(port->membase + OFF_RXTX, ch);
378 static void liteuart_console_write(struct console *co, const char *s,
381 struct liteuart_port *uart;
382 struct uart_port *port;
385 uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index);
388 spin_lock_irqsave(&port->lock, flags);
389 uart_console_write(port, s, count, liteuart_putchar);
390 spin_unlock_irqrestore(&port->lock, flags);
393 static int liteuart_console_setup(struct console *co, char *options)
395 struct liteuart_port *uart;
396 struct uart_port *port;
402 uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index);
411 uart_parse_options(options, &baud, &parity, &bits, &flow);
413 return uart_set_options(port, co, baud, parity, bits, flow);
416 static struct console liteuart_console = {
417 .name = KBUILD_MODNAME,
418 .write = liteuart_console_write,
419 .device = uart_console_device,
420 .setup = liteuart_console_setup,
421 .flags = CON_PRINTBUFFER,
423 .data = &liteuart_driver,
426 static int __init liteuart_console_init(void)
428 register_console(&liteuart_console);
432 console_initcall(liteuart_console_init);
434 static void early_liteuart_write(struct console *console, const char *s,
437 struct earlycon_device *device = console->data;
438 struct uart_port *port = &device->port;
440 uart_console_write(port, s, count, liteuart_putchar);
443 static int __init early_liteuart_setup(struct earlycon_device *device,
446 if (!device->port.membase)
449 device->con->write = early_liteuart_write;
453 OF_EARLYCON_DECLARE(liteuart, "litex,liteuart", early_liteuart_setup);
454 #endif /* CONFIG_SERIAL_LITEUART_CONSOLE */
456 static int __init liteuart_init(void)
460 res = uart_register_driver(&liteuart_driver);
464 res = platform_driver_register(&liteuart_platform_driver);
466 uart_unregister_driver(&liteuart_driver);
471 static void __exit liteuart_exit(void)
473 platform_driver_unregister(&liteuart_platform_driver);
474 uart_unregister_driver(&liteuart_driver);
477 module_init(liteuart_init);
478 module_exit(liteuart_exit);
480 MODULE_AUTHOR("Antmicro <www.antmicro.com>");
481 MODULE_DESCRIPTION("LiteUART serial driver");
482 MODULE_LICENSE("GPL v2");
483 MODULE_ALIAS("platform:liteuart");