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Commit d2aef35a authored by Joachim Eastwood's avatar Joachim Eastwood Committed by Greg Kroah-Hartman
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serial: 8250: add LPC18xx/43xx UART driver 



Serial port driver for the 8250-based UART found on LPC18xx/43xx
devices. The UART is 16550A compatible with additional features
like RS485 support, synchronous mode, IrDA, and DMA.

For now only basic UART and RS485 operation is supported.

Signed-off-by: default avatarJoachim Eastwood <manabian@gmail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 1a8d2903

drivers/tty/serial/8250/8250_lpc18xx.c

0 → 100644
+230 −0
Original line number Diff line number Diff line 
/*

 * Serial port driver for NXP LPC18xx/43xx UART

 *

 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>

 *

 * Based on 8250_mtk.c:

 * Copyright (c) 2014 MundoReader S.L.

 * Matthias Brugger <matthias.bgg@gmail.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License version 2 as

 * published by the Free Software Foundation.

 *

 */



#include <linux/clk.h>

#include <linux/io.h>

#include <linux/module.h>

#include <linux/of.h>

#include <linux/platform_device.h>



#include "8250.h"



/* Additional LPC18xx/43xx 8250 registers and bits */

#define LPC18XX_UART_RS485CTRL		(0x04c / sizeof(u32))

#define  LPC18XX_UART_RS485CTRL_NMMEN	BIT(0)

#define  LPC18XX_UART_RS485CTRL_DCTRL	BIT(4)

#define  LPC18XX_UART_RS485CTRL_OINV	BIT(5)

#define LPC18XX_UART_RS485DLY		(0x054 / sizeof(u32))

#define LPC18XX_UART_RS485DLY_MAX	255



struct lpc18xx_uart_data {

	struct uart_8250_dma dma;

	struct clk *clk_uart;

	struct clk *clk_reg;

	int line;

};



static int lpc18xx_rs485_config(struct uart_port *port,

				struct serial_rs485 *rs485)

{

	struct uart_8250_port *up = up_to_u8250p(port);

	u32 rs485_ctrl_reg = 0;

	u32 rs485_dly_reg = 0;

	unsigned baud_clk;



	if (rs485->flags & SER_RS485_ENABLED)

		memset(rs485->padding, 0, sizeof(rs485->padding));

	else

		memset(rs485, 0, sizeof(*rs485));



	rs485->flags &= SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND |

			SER_RS485_RTS_AFTER_SEND;



	if (rs485->flags & SER_RS485_ENABLED) {

		rs485_ctrl_reg |= LPC18XX_UART_RS485CTRL_NMMEN |

				  LPC18XX_UART_RS485CTRL_DCTRL;



		if (rs485->flags & SER_RS485_RTS_ON_SEND) {

			rs485_ctrl_reg |= LPC18XX_UART_RS485CTRL_OINV;

			rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;

		} else {

			rs485->flags |= SER_RS485_RTS_AFTER_SEND;

		}

	}



	if (rs485->delay_rts_after_send) {

		baud_clk = port->uartclk / up->dl_read(up);

		rs485_dly_reg = DIV_ROUND_UP(rs485->delay_rts_after_send

						* baud_clk, MSEC_PER_SEC);



		if (rs485_dly_reg > LPC18XX_UART_RS485DLY_MAX)

			rs485_dly_reg = LPC18XX_UART_RS485DLY_MAX;



		/* Calculate the resulting delay in ms */

		rs485->delay_rts_after_send = (rs485_dly_reg * MSEC_PER_SEC)

						/ baud_clk;

	}



	/* Delay RTS before send not supported */

	rs485->delay_rts_before_send = 0;



	serial_out(up, LPC18XX_UART_RS485CTRL, rs485_ctrl_reg);

	serial_out(up, LPC18XX_UART_RS485DLY, rs485_dly_reg);



	port->rs485 = *rs485;



	return 0;

}



static void lpc18xx_uart_serial_out(struct uart_port *p, int offset, int value)

{

	/*

	 * For DMA mode one must ensure that the UART_FCR_DMA_SELECT

	 * bit is set when FIFO is enabled. Even if DMA is not used

	 * setting this bit doesn't seem to affect anything.

	 */

	if (offset == UART_FCR && (value & UART_FCR_ENABLE_FIFO))

		value |= UART_FCR_DMA_SELECT;



	offset = offset << p->regshift;

	writel(value, p->membase + offset);

}



static int lpc18xx_serial_probe(struct platform_device *pdev)

{

	struct lpc18xx_uart_data *data;

	struct uart_8250_port uart;

	struct resource *res;

	int irq, ret;



	irq = platform_get_irq(pdev, 0);

	if (irq < 0) {

		dev_err(&pdev->dev, "irq not found");

		return irq;

	}



	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	if (!res) {

		dev_err(&pdev->dev, "memory resource not found");

		return -EINVAL;

	}



	memset(&uart, 0, sizeof(uart));



	uart.port.membase = devm_ioremap(&pdev->dev, res->start,

					 resource_size(res));

	if (!uart.port.membase)

		return -ENOMEM;



	data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);

	if (!data)

		return -ENOMEM;



	data->clk_uart = devm_clk_get(&pdev->dev, "uartclk");

	if (IS_ERR(data->clk_uart)) {

		dev_err(&pdev->dev, "uart clock not found\n");

		return PTR_ERR(data->clk_uart);

	}



	data->clk_reg = devm_clk_get(&pdev->dev, "reg");

	if (IS_ERR(data->clk_reg)) {

		dev_err(&pdev->dev, "reg clock not found\n");

		return PTR_ERR(data->clk_reg);

	}



	ret = clk_prepare_enable(data->clk_reg);

	if (ret) {

		dev_err(&pdev->dev, "unable to enable reg clock\n");

		return ret;

	}



	ret = clk_prepare_enable(data->clk_uart);

	if (ret) {

		dev_err(&pdev->dev, "unable to enable uart clock\n");

		goto dis_clk_reg;

	}



	ret = of_alias_get_id(pdev->dev.of_node, "serial");

	if (ret >= 0)

		uart.port.line = ret;



	data->dma.rx_param = data;

	data->dma.tx_param = data;



	spin_lock_init(&uart.port.lock);

	uart.port.dev = &pdev->dev;

	uart.port.irq = irq;

	uart.port.iotype = UPIO_MEM32;

	uart.port.mapbase = res->start;

	uart.port.regshift = 2;

	uart.port.type = PORT_16550A;

	uart.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE | UPF_SKIP_TEST;

	uart.port.uartclk = clk_get_rate(data->clk_uart);

	uart.port.private_data = data;

	uart.port.rs485_config = lpc18xx_rs485_config;

	uart.port.serial_out = lpc18xx_uart_serial_out;



	uart.dma = &data->dma;

	uart.dma->rxconf.src_maxburst = 1;

	uart.dma->txconf.dst_maxburst = 1;



	ret = serial8250_register_8250_port(&uart);

	if (ret < 0) {

		dev_err(&pdev->dev, "unable to register 8250 port\n");

		goto dis_uart_clk;

	}



	data->line = ret;

	platform_set_drvdata(pdev, data);



	return 0;



dis_uart_clk:

	clk_disable_unprepare(data->clk_uart);

dis_clk_reg:

	clk_disable_unprepare(data->clk_reg);

	return ret;

}



static int lpc18xx_serial_remove(struct platform_device *pdev)

{

	struct lpc18xx_uart_data *data = platform_get_drvdata(pdev);



	serial8250_unregister_port(data->line);

	clk_disable_unprepare(data->clk_uart);

	clk_disable_unprepare(data->clk_reg);



	return 0;

}



static const struct of_device_id lpc18xx_serial_match[] = {

	{ .compatible = "nxp,lpc1850-uart" },

	{ },

};

MODULE_DEVICE_TABLE(of, lpc18xx_serial_match);



static struct platform_driver lpc18xx_serial_driver = {

	.probe  = lpc18xx_serial_probe,

	.remove = lpc18xx_serial_remove,

	.driver = {

		.name = "lpc18xx-uart",

		.of_match_table = lpc18xx_serial_match,

	},

};

module_platform_driver(lpc18xx_serial_driver);



MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");

MODULE_DESCRIPTION("Serial port driver NXP LPC18xx/43xx devices");

MODULE_LICENSE("GPL v2");

drivers/tty/serial/8250/Kconfig

+8 −0
Original line number Diff line number Diff line
@@ -336,6 +336,14 @@ config SERIAL_8250_FINTEK 
	  LPC to 4 UART. This device has some RS485 functionality not available

	  through the PNP driver. If unsure, say N.



config SERIAL_8250_LPC18XX

	bool "NXP LPC18xx/43xx serial port support"

	depends on SERIAL_8250 && OF && (ARCH_LPC18XX || COMPILE_TEST)

	default ARCH_LPC18XX

	help

	  If you have a LPC18xx/43xx based board and want to use the

	  serial port, say Y to this option. If unsure, say Y.



config SERIAL_8250_MT6577

	bool "Mediatek serial port support"

	depends on SERIAL_8250 && ARCH_MEDIATEK

drivers/tty/serial/8250/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -22,5 +22,6 @@ obj-$(CONFIG_SERIAL_8250_DW) += 8250_dw.o 
obj-$(CONFIG_SERIAL_8250_EM)		+= 8250_em.o

obj-$(CONFIG_SERIAL_8250_OMAP)		+= 8250_omap.o

obj-$(CONFIG_SERIAL_8250_FINTEK)	+= 8250_fintek.o

obj-$(CONFIG_SERIAL_8250_LPC18XX)	+= 8250_lpc18xx.o

obj-$(CONFIG_SERIAL_8250_MT6577)	+= 8250_mtk.o

obj-$(CONFIG_SERIAL_8250_UNIPHIER)	+= 8250_uniphier.o