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 */
65 #define RXOERR  0x02	/* OverFlow Err: Char recv but RXFULL still set */
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 circ_buf *xmit = &port->state->xmit;  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()
168 		ch = xmit->buf[xmit->tail];  in arc_serial_tx_chars()
199 	 * UART has 4 deep RX-FIFO. Driver's recongnition of this fact  in arc_serial_rx_chars()
201 	 * Upon getting a RX-Intr, such that RX-EMPTY=0, meaning data available,  in arc_serial_rx_chars()
203 	 * RX-EMPTY=1. Multiple chars being avail, with a single Interrupt,  in arc_serial_rx_chars()
204 	 * before RX-EMPTY=0, implies some sort of buffering going on in the  in arc_serial_rx_chars()
205 	 * controller, which is indeed the Rx-FIFO.  in arc_serial_rx_chars()
215 			port->icount.overrun++;  in arc_serial_rx_chars()
221 			port->icount.frame++;  in arc_serial_rx_chars()
230 		port->icount.rx++;  in arc_serial_rx_chars()
235 		tty_flip_buffer_push(&port->state->port);  in arc_serial_rx_chars()
249  * Thus Rx-interrupts are always enabled, while tx-interrupts are by default
254  *   -checks-if-tty-buffer-has-char-to-send
255  *   -writes-data-to-uart
256  *   -enable-tx-intr
258  * Once data bits are pushed out, controller raises the Tx-room-avail-Interrupt.
262  * more char in tty buffer. In case of sending, it re-enables Tx-intr. In case
289 		/* Unconditionally disable further Tx-Interrupts.  in arc_serial_isr()
319 	/* MCR not present */  in arc_serial_set_mctrl()
332 	if (request_irq(port->irq, arc_serial_isr, 0, "arc uart rx-tx", port)) {  in arc_serial_startup()
333 		dev_warn(port->dev, "Unable to attach ARC UART intr\n");  in arc_serial_startup()
334 		return -EBUSY;  in arc_serial_startup()
342 /* This is not really needed */
345 	free_irq(port->irq, port);  in arc_serial_shutdown()
359 	 * Max Baud I suppose will not be more than current 115K * 4  in arc_serial_set_termios()
360 	 * Formula for ARC UART is: hw-val = ((CLK/(BAUD*4)) -1)  in arc_serial_set_termios()
361 	 * spread over two 8-bit registers  in arc_serial_set_termios()
365 	hw_val = port->uartclk / (uart->baud * 4) - 1;  in arc_serial_set_termios()
382 	new->c_cflag &= ~(CMSPAR|CRTSCTS|CSIZE);  in arc_serial_set_termios()
383 	new->c_cflag |= CS8;  in arc_serial_set_termios()
392 	uart_update_timeout(port, new->c_cflag, baud);  in arc_serial_set_termios()
399 	return port->type == PORT_ARC ? DRIVER_NAME : NULL;  in arc_serial_type()
417 	if (port->type != PORT_UNKNOWN && ser->type != PORT_ARC)  in arc_serial_verify_port()
418 		return -EINVAL;  in arc_serial_verify_port()
429 		port->type = PORT_ARC;  in arc_serial_config_port()
486 	if (co->index < 0 || co->index >= CONFIG_SERIAL_ARC_NR_PORTS)  in arc_serial_console_setup()
487 		return -ENODEV;  in arc_serial_console_setup()
490 	 * The uart port backing the console (e.g. ttyARC1) might not have been  in arc_serial_console_setup()
493 	port = &arc_uart_ports[co->index].port;  in arc_serial_console_setup()
494 	if (!port->membase)  in arc_serial_console_setup()
495 		return -ENODEV;  in arc_serial_console_setup()
501 	 * Serial core will call port->ops->set_termios( )  in arc_serial_console_setup()
521 	struct uart_port *port = &arc_uart_ports[co->index].port;  in arc_serial_console_write()
535 	.index	= -1,
542 	struct earlycon_device *dev = con->data;  in arc_early_serial_write()
544 	uart_console_write(&dev->port, s, n, arc_serial_console_putchar);  in arc_early_serial_write()
550 	struct uart_port *port = &dev->port;  in arc_early_console_setup()
553 	if (!dev->port.membase)  in arc_early_console_setup()
554 		return -ENODEV;  in arc_early_console_setup()
556 	hw_val = port->uartclk / (dev->baud * 4) - 1;  in arc_early_console_setup()
563 	dev->con->write = arc_early_serial_write;  in arc_early_console_setup()
566 OF_EARLYCON_DECLARE(arc_uart, "snps,arc-uart", arc_early_console_setup);
572 	struct device_node *np = pdev->dev.of_node;  in arc_serial_probe()
580 		return -ENODEV;  in arc_serial_probe()
587 		dev_err(&pdev->dev, "serial%d out of range\n", dev_id);  in arc_serial_probe()
588 		return -EINVAL;  in arc_serial_probe()
592 	port = &uart->port;  in arc_serial_probe()
594 	if (of_property_read_u32(np, "clock-frequency", &val)) {  in arc_serial_probe()
595 		dev_err(&pdev->dev, "clock-frequency property NOTset\n");  in arc_serial_probe()
596 		return -EINVAL;  in arc_serial_probe()
598 	port->uartclk = val;  in arc_serial_probe()
600 	if (of_property_read_u32(np, "current-speed", &val)) {  in arc_serial_probe()
601 		dev_err(&pdev->dev, "current-speed property NOT set\n");  in arc_serial_probe()
602 		return -EINVAL;  in arc_serial_probe()
604 	uart->baud = val;  in arc_serial_probe()
606 	port->membase = devm_platform_ioremap_resource(pdev, 0);  in arc_serial_probe()
607 	if (IS_ERR(port->membase)) {  in arc_serial_probe()
609 		return PTR_ERR(port->membase);  in arc_serial_probe()
612 	port->irq = irq_of_parse_and_map(np, 0);  in arc_serial_probe()
614 	port->dev = &pdev->dev;  in arc_serial_probe()
615 	port->iotype = UPIO_MEM;  in arc_serial_probe()
616 	port->flags = UPF_BOOT_AUTOCONF;  in arc_serial_probe()
617 	port->line = dev_id;  in arc_serial_probe()
618 	port->ops = &arc_serial_pops;  in arc_serial_probe()
619 	port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_ARC_CONSOLE);  in arc_serial_probe()
621 	port->fifosize = ARC_UART_TX_FIFO_SIZE;  in arc_serial_probe()
625 	 * char or not. Explicitly setting it here, removes the subtelty  in arc_serial_probe()
627 	port->ignore_status_mask = 0;  in arc_serial_probe()
633 	{ .compatible = "snps,arc-uart" },
673 MODULE_DESCRIPTION("ARC(Synopsys) On-Chip(fpga) serial driver");