// SPDX-License-Identifier: GPL-2.0/* * LiteUART serial controller (LiteX) Driver * * Copyright (C) 2019-2020 Antmicro <www.antmicro.com> */ #include <linux/bits.h>#include <linux/console.h>#include <linux/interrupt.h>#include <linux/litex.h>#include <linux/module.h>#include <linux/of.h>#include <linux/platform_device.h>#include <linux/serial.h>#include <linux/serial_core.h>#include <linux/slab.h>#include <linux/timer.h>#include <linux/tty_flip.h>#include <linux/xarray.h> /* * CSRs definitions (base address offsets + width) * * The definitions below are true for LiteX SoC configured for 8-bit CSR Bus, * 32-bit aligned. * * Supporting other configurations might require new definitions or a more * generic way of indexing the LiteX CSRs. * * For more details on how CSRs are defined and handled in LiteX, see comments * in the LiteX SoC Driver: drivers/soc/litex/litex_soc_ctrl.c */#define OFF_RXTX	0x00#define OFF_TXFULL	0x04#define OFF_RXEMPTY	0x08#define OFF_EV_STATUS	0x0c#define OFF_EV_PENDING	0x10#define OFF_EV_ENABLE	0x14 /* events */#define EV_TX		BIT(0)#define EV_RX		BIT(1) struct liteuart_port {	struct uart_port port;	struct timer_list timer;	u8 irq_reg;}; #define to_liteuart_port(port)	container_of(port, struct liteuart_port, port) static DEFINE_XARRAY_FLAGS(liteuart_array, XA_FLAGS_ALLOC); #ifdef CONFIG_SERIAL_LITEUART_CONSOLEstatic struct console liteuart_console;#endif static struct uart_driver liteuart_driver = {	.owner = THIS_MODULE,	.driver_name = KBUILD_MODNAME,	.dev_name = "ttyLXU",	.major = 0,	.minor = 0,	.nr = CONFIG_SERIAL_LITEUART_MAX_PORTS,#ifdef CONFIG_SERIAL_LITEUART_CONSOLE	.cons = &liteuart_console,#endif}; static void liteuart_update_irq_reg(struct uart_port *port, bool set, u8 mask){	struct liteuart_port *uart = to_liteuart_port(port); 	if (set)		uart->irq_reg |= mask;	else		uart->irq_reg &= ~mask; 	if (port->irq)		litex_write8(port->membase + OFF_EV_ENABLE, uart->irq_reg);} static void liteuart_stop_tx(struct uart_port *port){	liteuart_update_irq_reg(port, false, EV_TX);} static void liteuart_start_tx(struct uart_port *port){	liteuart_update_irq_reg(port, true, EV_TX);} static void liteuart_stop_rx(struct uart_port *port){	struct liteuart_port *uart = to_liteuart_port(port); 	/* just delete timer */	timer_delete(&uart->timer);} static void liteuart_rx_chars(struct uart_port *port){	unsigned char __iomem *membase = port->membase;	u8 ch; 	while (!litex_read8(membase + OFF_RXEMPTY)) {		ch = litex_read8(membase + OFF_RXTX);		port->icount.rx++; 		/* necessary for RXEMPTY to refresh its value */		litex_write8(membase + OFF_EV_PENDING, EV_RX); 		/* no overflow bits in status */		if (!(uart_handle_sysrq_char(port, ch)))			uart_insert_char(port, 1, 0, ch, TTY_NORMAL);	} 	tty_flip_buffer_push(&port->state->port);} static void liteuart_tx_chars(struct uart_port *port){	u8 ch; 	uart_port_tx(port, ch,		!litex_read8(port->membase + OFF_TXFULL),		litex_write8(port->membase + OFF_RXTX, ch));} static irqreturn_t liteuart_interrupt(int irq, void *data){	struct liteuart_port *uart = data;	struct uart_port *port = &uart->port;	unsigned long flags;	u8 isr; 	/*	 * if polling, the context would be "in_serving_softirq", so use	 * irq[save|restore] spin_lock variants to cover all possibilities	 */	uart_port_lock_irqsave(port, &flags);	isr = litex_read8(port->membase + OFF_EV_PENDING) & uart->irq_reg;	if (isr & EV_RX)		liteuart_rx_chars(port);	if (isr & EV_TX)		liteuart_tx_chars(port);	uart_port_unlock_irqrestore(port, flags); 	return IRQ_RETVAL(isr);} static void liteuart_timer(struct timer_list *t){	struct liteuart_port *uart = timer_container_of(uart, t, timer);	struct uart_port *port = &uart->port; 	liteuart_interrupt(0, port);	mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));} static unsigned int liteuart_tx_empty(struct uart_port *port){	/* not really tx empty, just checking if tx is not full */	if (!litex_read8(port->membase + OFF_TXFULL))		return TIOCSER_TEMT; 	return 0;} static void liteuart_set_mctrl(struct uart_port *port, unsigned int mctrl){	/* modem control register is not present in LiteUART */} static unsigned int liteuart_get_mctrl(struct uart_port *port){	return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;} static int liteuart_startup(struct uart_port *port){	struct liteuart_port *uart = to_liteuart_port(port);	unsigned long flags;	int ret; 	if (port->irq) {		ret = request_irq(port->irq, liteuart_interrupt, 0,				  KBUILD_MODNAME, uart);		if (ret) {			dev_warn(port->dev,				"line %d irq %d failed: switch to polling\n",				port->line, port->irq);			port->irq = 0;		}	} 	uart_port_lock_irqsave(port, &flags);	/* only enabling rx irqs during startup */	liteuart_update_irq_reg(port, true, EV_RX);	uart_port_unlock_irqrestore(port, flags); 	if (!port->irq) {		timer_setup(&uart->timer, liteuart_timer, 0);		mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));	} 	return 0;} static void liteuart_shutdown(struct uart_port *port){	struct liteuart_port *uart = to_liteuart_port(port);	unsigned long flags; 	uart_port_lock_irqsave(port, &flags);	liteuart_update_irq_reg(port, false, EV_RX | EV_TX);	uart_port_unlock_irqrestore(port, flags); 	if (port->irq)		free_irq(port->irq, port);	else		timer_delete_sync(&uart->timer);} static void liteuart_set_termios(struct uart_port *port, struct ktermios *new,				 const struct ktermios *old){	unsigned int baud;	unsigned long flags; 	uart_port_lock_irqsave(port, &flags); 	/* update baudrate */	baud = uart_get_baud_rate(port, new, old, 0, 460800);	uart_update_timeout(port, new->c_cflag, baud); 	uart_port_unlock_irqrestore(port, flags);} static const char *liteuart_type(struct uart_port *port){	return "liteuart";} static void liteuart_config_port(struct uart_port *port, int flags){	/*	 * Driver core for serial ports forces a non-zero value for port type.	 * Write an arbitrary value here to accommodate the serial core driver,	 * as ID part of UAPI is redundant.	 */	port->type = 1;} static int liteuart_verify_port(struct uart_port *port,				struct serial_struct *ser){	if (port->type != PORT_UNKNOWN && ser->type != 1)		return -EINVAL; 	return 0;} static const struct uart_ops liteuart_ops = {	.tx_empty	= liteuart_tx_empty,	.set_mctrl	= liteuart_set_mctrl,	.get_mctrl	= liteuart_get_mctrl,	.stop_tx	= liteuart_stop_tx,	.start_tx	= liteuart_start_tx,	.stop_rx	= liteuart_stop_rx,	.startup	= liteuart_startup,	.shutdown	= liteuart_shutdown,	.set_termios	= liteuart_set_termios,	.type		= liteuart_type,	.config_port	= liteuart_config_port,	.verify_port	= liteuart_verify_port,}; static int liteuart_probe(struct platform_device *pdev){	struct liteuart_port *uart;	struct uart_port *port;	struct xa_limit limit;	int dev_id, ret; 	uart = devm_kzalloc(&pdev->dev, sizeof(struct liteuart_port), GFP_KERNEL);	if (!uart)		return -ENOMEM; 	port = &uart->port; 	/* get membase */	port->membase = devm_platform_get_and_ioremap_resource(pdev, 0, NULL);	if (IS_ERR(port->membase))		return PTR_ERR(port->membase); 	ret = platform_get_irq_optional(pdev, 0);	if (ret < 0 && ret != -ENXIO)		return ret;	if (ret > 0)		port->irq = ret; 	/* look for aliases; auto-enumerate for free index if not found */	dev_id = of_alias_get_id(pdev->dev.of_node, "serial");	if (dev_id < 0)		limit = XA_LIMIT(0, CONFIG_SERIAL_LITEUART_MAX_PORTS);	else		limit = XA_LIMIT(dev_id, dev_id); 	ret = xa_alloc(&liteuart_array, &dev_id, uart, limit, GFP_KERNEL);	if (ret)		return ret; 	/* values not from device tree */	port->dev = &pdev->dev;	port->iotype = UPIO_MEM;	port->flags = UPF_BOOT_AUTOCONF;	port->ops = &liteuart_ops;	port->fifosize = 16;	port->type = PORT_UNKNOWN;	port->line = dev_id;	spin_lock_init(&port->lock); 	platform_set_drvdata(pdev, port); 	ret = uart_add_one_port(&liteuart_driver, &uart->port);	if (ret)		goto err_erase_id; 	return 0; err_erase_id:	xa_erase(&liteuart_array, dev_id); 	return ret;} static void liteuart_remove(struct platform_device *pdev){	struct uart_port *port = platform_get_drvdata(pdev);	unsigned int line = port->line; 	uart_remove_one_port(&liteuart_driver, port);	xa_erase(&liteuart_array, line);} static const struct of_device_id liteuart_of_match[] = {	{ .compatible = "litex,liteuart" },	{}};MODULE_DEVICE_TABLE(of, liteuart_of_match); static struct platform_driver liteuart_platform_driver = {	.probe = liteuart_probe,	.remove = liteuart_remove,	.driver = {		.name = KBUILD_MODNAME,		.of_match_table = liteuart_of_match,	},}; #ifdef CONFIG_SERIAL_LITEUART_CONSOLE static void liteuart_putchar(struct uart_port *port, unsigned char ch){	while (litex_read8(port->membase + OFF_TXFULL))		cpu_relax(); 	litex_write8(port->membase + OFF_RXTX, ch);} static void liteuart_console_write(struct console *co, const char *s,	unsigned int count){	struct liteuart_port *uart;	struct uart_port *port;	unsigned long flags; 	uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index);	port = &uart->port; 	uart_port_lock_irqsave(port, &flags);	uart_console_write(port, s, count, liteuart_putchar);	uart_port_unlock_irqrestore(port, flags);} static int liteuart_console_setup(struct console *co, char *options){	struct liteuart_port *uart;	struct uart_port *port;	int baud = 115200;	int bits = 8;	int parity = 'n';	int flow = 'n'; 	uart = (struct liteuart_port *)xa_load(&liteuart_array, co->index);	if (!uart)		return -ENODEV; 	port = &uart->port;	if (!port->membase)		return -ENODEV; 	if (options)		uart_parse_options(options, &baud, &parity, &bits, &flow); 	return uart_set_options(port, co, baud, parity, bits, flow);} static struct console liteuart_console = {	.name = KBUILD_MODNAME,	.write = liteuart_console_write,	.device = uart_console_device,	.setup = liteuart_console_setup,	.flags = CON_PRINTBUFFER,	.index = -1,	.data = &liteuart_driver,}; static int __init liteuart_console_init(void){	register_console(&liteuart_console); 	return 0;}console_initcall(liteuart_console_init); static void early_liteuart_write(struct console *console, const char *s,				    unsigned int count){	struct earlycon_device *device = console->data;	struct uart_port *port = &device->port; 	uart_console_write(port, s, count, liteuart_putchar);} static int __init early_liteuart_setup(struct earlycon_device *device,				       const char *options){	if (!device->port.membase)		return -ENODEV; 	device->con->write = early_liteuart_write;	return 0;} OF_EARLYCON_DECLARE(liteuart, "litex,liteuart", early_liteuart_setup);#endif /* CONFIG_SERIAL_LITEUART_CONSOLE */ static int __init liteuart_init(void){	int res; 	res = uart_register_driver(&liteuart_driver);	if (res)		return res; 	res = platform_driver_register(&liteuart_platform_driver);	if (res)		uart_unregister_driver(&liteuart_driver); 	return res;} static void __exit liteuart_exit(void){	platform_driver_unregister(&liteuart_platform_driver);	uart_unregister_driver(&liteuart_driver);} module_init(liteuart_init);module_exit(liteuart_exit); MODULE_AUTHOR("Antmicro <www.antmicro.com>");MODULE_DESCRIPTION("LiteUART serial driver");MODULE_LICENSE("GPL v2");MODULE_ALIAS("platform:liteuart");