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/*
* 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");
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