1 // SPDX-License-Identifier: GPL-2.0+
3  * NI 16550 UART Driver
5  * The National Instruments (NI) 16550 is a UART that is compatible with the
7  * for RS-485 transceiver control. This driver implements support for the
10  * Copyright 2012-2023 National Instruments Corporation
27 /* TFS - TX FIFO Size */
29 /* RFS - RX FIFO Size */
32 /* PMR - Port Mode Register */
34 /* PMR[1:0] - Port Capabilities */
37 #define NI16550_PMR_CAP_RS232		FIELD_PREP(NI16550_PMR_CAP_MASK, 1) /* RS-232 capable */
38 #define NI16550_PMR_CAP_RS485		FIELD_PREP(NI16550_PMR_CAP_MASK, 2) /* RS-485 capable */
39 #define NI16550_PMR_CAP_DUAL		FIELD_PREP(NI16550_PMR_CAP_MASK, 3) /* dual-port */
40 /* PMR[4] - Interface Mode */
45 /* PCR - Port Control Register */
48  * ---------------|----------------------|--------------------------
81 	pcr = port->serial_in(port, NI16550_PCR_OFFSET);  in ni16550_enable_transceivers()
83 	dev_dbg(port->dev, "enable transceivers: write pcr: 0x%02x\n", pcr);  in ni16550_enable_transceivers()
84 	port->serial_out(port, NI16550_PCR_OFFSET, pcr);  in ni16550_enable_transceivers()
93 	pcr = port->serial_in(port, NI16550_PCR_OFFSET);  in ni16550_disable_transceivers()
95 	dev_dbg(port->dev, "disable transceivers: write pcr: 0x%02x\n", pcr);  in ni16550_disable_transceivers()
96 	port->serial_out(port, NI16550_PCR_OFFSET, pcr);  in ni16550_disable_transceivers()
111 	if ((rs485->flags & SER_RS485_MODE_RS422) ||  in ni16550_rs485_config()
112 	    !(rs485->flags & SER_RS485_ENABLED)) {  in ni16550_rs485_config()
113 		/* RS-422 */  in ni16550_rs485_config()
115 		up->acr &= ~NI16550_ACR_AUTO_DTR_EN;  in ni16550_rs485_config()
117 		/* RS-485 2-wire Auto */  in ni16550_rs485_config()
119 		up->acr |= NI16550_ACR_AUTO_DTR_EN;  in ni16550_rs485_config()
122 	dev_dbg(port->dev, "config rs485: write pcr: 0x%02x, acr: %02x\n", pcr, up->acr);  in ni16550_rs485_config()
124 	serial_icr_write(up, UART_ACR, up->acr);  in ni16550_rs485_config()
137 	 * connected to RS-485 transceivers  in is_pmr_rs232_mode()
144 		 * If the port is dual-mode capable, then read the mode bit  in is_pmr_rs232_mode()
149 	 * If it is not dual-mode capable, then decide based on the  in is_pmr_rs232_mode()
195 	port->rs485_config = ni16550_rs485_config;  in ni16550_rs485_setup()
196 	port->rs485_supported = ni16550_rs485_supported;  in ni16550_rs485_setup()
198 	 * The hardware comes up by default in 2-wire auto mode and we  in ni16550_rs485_setup()
201 	port->rs485.flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND;  in ni16550_rs485_setup()
229 		port->iotype = UPIO_PORT;  in ni16550_get_regs()
230 		port->iobase = regs->start;  in ni16550_get_regs()
237 		port->iotype = UPIO_MEM;  in ni16550_get_regs()
238 		port->mapbase = regs->start;  in ni16550_get_regs()
239 		port->mapsize = resource_size(regs);  in ni16550_get_regs()
240 		port->flags |= UPF_IOREMAP;  in ni16550_get_regs()
242 		port->membase = devm_ioremap(&pdev->dev, port->mapbase,  in ni16550_get_regs()
243 					     port->mapsize);  in ni16550_get_regs()
244 		if (!port->membase)  in ni16550_get_regs()
245 			return -ENOMEM;  in ni16550_get_regs()
250 	dev_err(&pdev->dev, "no registers defined\n");  in ni16550_get_regs()
251 	return -EINVAL;  in ni16550_get_regs()
256  * defined, so we may read all-0s or all-1s. For such devices,
259 static u8 ni16550_read_fifo_size(struct uart_8250_port *uart, int reg)  in ni16550_read_fifo_size()  argument
261 	u8 value = serial_in(uart, reg);  in ni16550_read_fifo_size()
273 	up->mcr |= UART_MCR_CLKSEL;  in ni16550_set_mctrl()
280 	struct device *dev = &pdev->dev;  in ni16550_probe()
281 	struct uart_8250_port uart = {};  in ni16550_probe()  local
292 		return -ENOMEM;  in ni16550_probe()
294 	spin_lock_init(&uart.port.lock);  in ni16550_probe()
300 	ret = ni16550_get_regs(pdev, &uart.port);  in ni16550_probe()
305 	serial8250_set_defaults(&uart);  in ni16550_probe()
309 	uart.port.dev		= dev;  in ni16550_probe()
310 	uart.port.irq		= irq;  in ni16550_probe()
311 	uart.port.irqflags	= IRQF_SHARED;  in ni16550_probe()
312 	uart.port.flags		= UPF_SHARE_IRQ | UPF_BOOT_AUTOCONF  in ni16550_probe()
314 	uart.port.startup	= ni16550_port_startup;  in ni16550_probe()
315 	uart.port.shutdown	= ni16550_port_shutdown;  in ni16550_probe()
320 	txfifosz = ni16550_read_fifo_size(&uart, NI16550_TFS_OFFSET);  in ni16550_probe()
321 	rxfifosz = ni16550_read_fifo_size(&uart, NI16550_RFS_OFFSET);  in ni16550_probe()
323 	dev_dbg(dev, "NI 16550 has TX FIFO size %u, RX FIFO size %u\n",  in ni16550_probe()
326 	uart.port.type		= PORT_16550A;  in ni16550_probe()
327 	uart.port.fifosize	= txfifosz;  in ni16550_probe()
328 	uart.tx_loadsz		= txfifosz;  in ni16550_probe()
329 	uart.fcr		= UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10;  in ni16550_probe()
330 	uart.capabilities	= UART_CAP_FIFO | UART_CAP_AFE | UART_CAP_EFR;  in ni16550_probe()
334 	 * - static declaration in this driver (for older ACPI IDs)  in ni16550_probe()
335 	 * - a "clock-frquency" ACPI  in ni16550_probe()
337 	if (info->uartclk)  in ni16550_probe()
338 		uart.port.uartclk = info->uartclk;  in ni16550_probe()
339 	if (device_property_read_u32(dev, "clock-frequency",  in ni16550_probe()
340 				     &uart.port.uartclk)) {  in ni16550_probe()
341 		data->clk = devm_clk_get_enabled(dev, NULL);  in ni16550_probe()
342 		if (!IS_ERR(data->clk))  in ni16550_probe()
343 			uart.port.uartclk = clk_get_rate(data->clk);  in ni16550_probe()
346 	if (!uart.port.uartclk) {  in ni16550_probe()
348 		ret = -ENODEV;  in ni16550_probe()
352 	if (info->prescaler)  in ni16550_probe()
353 		prescaler = info->prescaler;  in ni16550_probe()
354 	device_property_read_u32(dev, "clock-prescaler", &prescaler);  in ni16550_probe()
357 		uart.port.set_mctrl = ni16550_set_mctrl;  in ni16550_probe()
358 		ni16550_config_prescaler(&uart, (u8)prescaler);  in ni16550_probe()
362 	 * The determination of whether or not this is an RS-485 or RS-232 port  in ni16550_probe()
363 	 * can come from the PMR (if present), otherwise we're solely an RS-485  in ni16550_probe()
366 	 * This is a device-specific property, and there are old devices in the  in ni16550_probe()
371 		rs232_property = strncmp(portmode, "RS-232", 6) == 0;  in ni16550_probe()
374 			rs232_property ? "RS-232" : "RS-485");  in ni16550_probe()
375 	} else if (info->flags & NI_HAS_PMR) {  in ni16550_probe()
376 		rs232_property = is_pmr_rs232_mode(&uart);  in ni16550_probe()
379 			rs232_property ? "RS-232" : "RS-485");  in ni16550_probe()
383 		dev_dbg(dev, "port is fixed as RS-485\n");  in ni16550_probe()
389 		 * that this is an RS-232 port, so it must be an RS-485 one.  in ni16550_probe()
391 		ni16550_rs485_setup(&uart.port);  in ni16550_probe()
394 	ret = serial8250_register_8250_port(&uart);  in ni16550_probe()
397 	data->line = ret;  in ni16550_probe()
410 	serial8250_unregister_port(data->line);  in ni16550_remove()
414 /* NI 16550 RS-485 Interface */
419 /* NI CVS-145x RS-485 Interface */
425 /* NI cRIO-904x RS-485 Interface */
427 	/* Sets UART clock rate to 22.222 MHz with 1.125 prescale */
432 /* NI sbRIO 96x8 RS-232/485 Interfaces */
434 	/* Set UART clock rate to 29.629 MHz with 1.125 prescale */
460 MODULE_DESCRIPTION("NI 16550 Driver");