1 // SPDX-License-Identifier: GPL-2.0
3  * ARC On-Chip(fpga) UART Driver
5  * Copyright (C) 2010-2012 Synopsys, Inc. (www.synopsys.com)
8  *  -Decoupled the driver from arch/arc
10  *    +Using early_platform_xxx() for early console (thx to mach-shmobile/xxx)
13  *  -Is uart_tx_stopped() not done in tty write path as it has already been
17  *  -New Serial Core based ARC UART driver
18  *  -Derived largely from blackfin driver albiet with some major tweaks
21  *  -check if sysreq works
42  * UART Register set (this is not a Standards Compliant IP)
58 #define RXEMPTY 0x20	/* Receive FIFO Empty: No char receivede */
59 #define TXEMPTY 0x80	/* Transmit FIFO Empty, thus char can be written into */
64 #define RXFERR  0x01	/* Frame Error: Stop Bit not detected */
68 #define RBASE(port, reg)      (port->membase + reg)
108 #define DRIVER_NAME	"arc-uart"
136  * Return TIOCSER_TEMT when transmitter is not busy.
150  * Driver internal routine, used by both tty(serial core) as well as tx-isr
151  *  -Called under spinlock in either cases
152  *  -also tty->flow.stopped has already been checked
158 	struct tty_port *tport = &port->state->port;  in arc_serial_tx_chars()
162 	if (unlikely(port->x_char)) {  in arc_serial_tx_chars()
163 		UART_SET_DATA(port, port->x_char);  in arc_serial_tx_chars()
164 		port->icount.tx++;  in arc_serial_tx_chars()
165 		port->x_char = 0;  in arc_serial_tx_chars()
178 	if (kfifo_len(&tport->xmit_fifo) < WAKEUP_CHARS)  in arc_serial_tx_chars()
197 	 * UART has 4 deep RX-FIFO. Driver's recongnition of this fact  in arc_serial_rx_chars()
199 	 * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,  in arc_serial_rx_chars()
201 	 * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,  in arc_serial_rx_chars()
202 	 * before RX-EMPTY=0, implies some sort of buffering going on in the  in arc_serial_rx_chars()
203 	 * controller, which is indeed the Rx-FIFO.  in arc_serial_rx_chars()
213 			port->icount.overrun++;  in arc_serial_rx_chars()
219 			port->icount.frame++;  in arc_serial_rx_chars()
228 		port->icount.rx++;  in arc_serial_rx_chars()
233 		tty_flip_buffer_push(&port->state->port);  in arc_serial_rx_chars()
247  * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
250  * When tty has some data to send out, serial core calls driver's start_tx
252  *   -checks-if-tty-buffer-has-char-to-send
253  *   -writes-data-to-uart
254  *   -enable-tx-intr
256  * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
258  * be the last char to send, before settling down into the quiet polled mode).
259  * It then calls the exact routine used by tty layer write to send out any
260  * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
287 		/* Unconditionally disable further Tx-Interrupts.  in arc_serial_isr()
309 	 *  (CTS) Clear To Send  in arc_serial_get_mctrl()
317 	/* MCR not present */  in arc_serial_set_mctrl()
330 	if (request_irq(port->irq, arc_serial_isr, 0, "arc uart rx-tx", port)) {  in arc_serial_startup()
331 		dev_warn(port->dev, "Unable to attach ARC UART intr\n");  in arc_serial_startup()
332 		return -EBUSY;  in arc_serial_startup()
340 /* This is not really needed */
343 	free_irq(port->irq, port);  in arc_serial_shutdown()
357 	 * Max Baud I suppose will not be more than current 115K * 4  in arc_serial_set_termios()
358 	 * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)  in arc_serial_set_termios()
359 	 * spread over two 8-bit registers  in arc_serial_set_termios()
363 	hw_val = port->uartclk / (uart->baud * 4) - 1;  in arc_serial_set_termios()
380 	new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);  in arc_serial_set_termios()
381 	new->c_cflag |= CS8;  in arc_serial_set_termios()
390 	uart_update_timeout(port, new->c_cflag, baud);  in arc_serial_set_termios()
397 	return port->type == PORT_ARC ? DRIVER_NAME : NULL;  in arc_serial_type()
415 	if (port->type != PORT_UNKNOWN && ser->type != PORT_ARC)  in arc_serial_verify_port()
416 		return -EINVAL;  in arc_serial_verify_port()
427 		port->type = PORT_ARC;  in arc_serial_config_port()
484 	if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)  in arc_serial_console_setup()
485 		return -ENODEV;  in arc_serial_console_setup()
488 	 * The uart port backing the console (e.g. ttyARC1) might not have been  in arc_serial_console_setup()
491 	port = &arc_uart_ports[co->index].port;  in arc_serial_console_setup()
492 	if (!port->membase)  in arc_serial_console_setup()
493 		return -ENODEV;  in arc_serial_console_setup()
499 	 * Serial core will call port->ops->set_termios( )  in arc_serial_console_setup()
519 	struct uart_port *port = &arc_uart_ports[co->index].port;  in arc_serial_console_write()
533 	.index	= -1,
540 	struct earlycon_device *dev = con->data;  in arc_early_serial_write()
542 	uart_console_write(&dev->port, s, n, arc_serial_console_putchar);  in arc_early_serial_write()
548 	struct uart_port *port = &dev->port;  in arc_early_console_setup()
551 	if (!dev->port.membase)  in arc_early_console_setup()
552 		return -ENODEV;  in arc_early_console_setup()
554 	hw_val = port->uartclk / (dev->baud * 4) - 1;  in arc_early_console_setup()
561 	dev->con->write = arc_early_serial_write;  in arc_early_console_setup()
564 OF_EARLYCON_DECLARE(arc_uart, "snps,arc-uart", arc_early_console_setup);
570 	struct device_node *np = pdev->dev.of_node;  in arc_serial_probe()
578 		return -ENODEV;  in arc_serial_probe()
585 		dev_err(&pdev->dev, "serial%d out of range\n", dev_id);  in arc_serial_probe()
586 		return -EINVAL;  in arc_serial_probe()
590 	port = &uart->port;  in arc_serial_probe()
592 	if (of_property_read_u32(np, "clock-frequency", &val)) {  in arc_serial_probe()
593 		dev_err(&pdev->dev, "clock-frequency property NOTset\n");  in arc_serial_probe()
594 		return -EINVAL;  in arc_serial_probe()
596 	port->uartclk = val;  in arc_serial_probe()
598 	if (of_property_read_u32(np, "current-speed", &val)) {  in arc_serial_probe()
599 		dev_err(&pdev->dev, "current-speed property NOT set\n");  in arc_serial_probe()
600 		return -EINVAL;  in arc_serial_probe()
602 	uart->baud = val;  in arc_serial_probe()
604 	port->membase = devm_platform_ioremap_resource(pdev, 0);  in arc_serial_probe()
605 	if (IS_ERR(port->membase)) {  in arc_serial_probe()
607 		return PTR_ERR(port->membase);  in arc_serial_probe()
610 	port->irq = irq_of_parse_and_map(np, 0);  in arc_serial_probe()
612 	port->dev = &pdev->dev;  in arc_serial_probe()
613 	port->iotype = UPIO_MEM;  in arc_serial_probe()
614 	port->flags = UPF_BOOT_AUTOCONF;  in arc_serial_probe()
615 	port->line = dev_id;  in arc_serial_probe()
616 	port->ops = &arc_serial_pops;  in arc_serial_probe()
617 	port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_ARC_CONSOLE);  in arc_serial_probe()
619 	port->fifosize = ARC_UART_TX_FIFO_SIZE;  in arc_serial_probe()
623 	 * char or not. Explicitly setting it here, removes the subtelty  in arc_serial_probe()
625 	port->ignore_status_mask = 0;  in arc_serial_probe()
631 	{ .compatible = "snps,arc-uart" },
671 MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");