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

   1 /*
   2  * Serial port driver for NXP LPC18xx/43xx UART
   3  *
   4  * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com>
   5  *
   6  * Based on 8250_mtk.c:
   7  * Copyright (c) 2014 MundoReader S.L.
   8  * Matthias Brugger <matthias.bgg@gmail.com>
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License version 2 as
  12  * published by the Free Software Foundation.
  13  *
  14  */
  15
  16 #include <linux/clk.h>
  17 #include <linux/io.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/platform_device.h>
  21
  22 #include "8250.h"
  23
  24 /* Additional LPC18xx/43xx 8250 registers and bits */
  25 #define LPC18XX_UART_RS485CTRL          (0x04c / sizeof(u32))
  26 #define  LPC18XX_UART_RS485CTRL_NMMEN   BIT(0)
  27 #define  LPC18XX_UART_RS485CTRL_DCTRL   BIT(4)
  28 #define  LPC18XX_UART_RS485CTRL_OINV    BIT(5)
  29 #define LPC18XX_UART_RS485DLY           (0x054 / sizeof(u32))
  30 #define LPC18XX_UART_RS485DLY_MAX       255
  31
  32 struct lpc18xx_uart_data {
  33         struct uart_8250_dma dma;
  34         struct clk *clk_uart;
  35         struct clk *clk_reg;
  36         int line;
  37 };
  38
  39 static int lpc18xx_rs485_config(struct uart_port *port,
  40                                 struct serial_rs485 *rs485)
  41 {
  42         struct uart_8250_port *up = up_to_u8250p(port);
  43         u32 rs485_ctrl_reg = 0;
  44         u32 rs485_dly_reg = 0;
  45         unsigned baud_clk;
  46
  47         if (rs485->flags & SER_RS485_ENABLED)
  48                 memset(rs485->padding, 0, sizeof(rs485->padding));
  49         else
  50                 memset(rs485, 0, sizeof(*rs485));
  51
  52         rs485->flags &= SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND |
  53                         SER_RS485_RTS_AFTER_SEND;
  54
  55         if (rs485->flags & SER_RS485_ENABLED) {
  56                 rs485_ctrl_reg |= LPC18XX_UART_RS485CTRL_NMMEN |
  57                                   LPC18XX_UART_RS485CTRL_DCTRL;
  58
  59                 if (rs485->flags & SER_RS485_RTS_ON_SEND) {
  60                         rs485_ctrl_reg |= LPC18XX_UART_RS485CTRL_OINV;
  61                         rs485->flags &= ~SER_RS485_RTS_AFTER_SEND;
  62                 } else {
  63                         rs485->flags |= SER_RS485_RTS_AFTER_SEND;
  64                 }
  65         }
  66
  67         if (rs485->delay_rts_after_send) {
  68                 baud_clk = port->uartclk / up->dl_read(up);
  69                 rs485_dly_reg = DIV_ROUND_UP(rs485->delay_rts_after_send
  70                                                 * baud_clk, MSEC_PER_SEC);
  71
  72                 if (rs485_dly_reg > LPC18XX_UART_RS485DLY_MAX)
  73                         rs485_dly_reg = LPC18XX_UART_RS485DLY_MAX;
  74
  75                 /* Calculate the resulting delay in ms */
  76                 rs485->delay_rts_after_send = (rs485_dly_reg * MSEC_PER_SEC)
  77                                                 / baud_clk;
  78         }
  79
  80         /* Delay RTS before send not supported */
  81         rs485->delay_rts_before_send = 0;
  82
  83         serial_out(up, LPC18XX_UART_RS485CTRL, rs485_ctrl_reg);
  84         serial_out(up, LPC18XX_UART_RS485DLY, rs485_dly_reg);
  85
  86         port->rs485 = *rs485;
  87
  88         return 0;
  89 }
  90
  91 static void lpc18xx_uart_serial_out(struct uart_port *p, int offset, int value)
  92 {
  93         /*
  94          * For DMA mode one must ensure that the UART_FCR_DMA_SELECT
  95          * bit is set when FIFO is enabled. Even if DMA is not used
  96          * setting this bit doesn't seem to affect anything.
  97          */
  98         if (offset == UART_FCR && (value & UART_FCR_ENABLE_FIFO))
  99                 value |= UART_FCR_DMA_SELECT;
 100
 101         offset = offset << p->regshift;
 102         writel(value, p->membase + offset);
 103 }
 104
 105 static int lpc18xx_serial_probe(struct platform_device *pdev)
 106 {
 107         struct lpc18xx_uart_data *data;
 108         struct uart_8250_port uart;
 109         struct resource *res;
 110         int irq, ret;
 111
 112         irq = platform_get_irq(pdev, 0);
 113         if (irq < 0) {
 114                 dev_err(&pdev->dev, "irq not found");
 115                 return irq;
 116         }
 117
 118         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 119         if (!res) {
 120                 dev_err(&pdev->dev, "memory resource not found");
 121                 return -EINVAL;
 122         }
 123
 124         memset(&uart, 0, sizeof(uart));
 125
 126         uart.port.membase = devm_ioremap(&pdev->dev, res->start,
 127                                          resource_size(res));
 128         if (!uart.port.membase)
 129                 return -ENOMEM;
 130
 131         data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
 132         if (!data)
 133                 return -ENOMEM;
 134
 135         data->clk_uart = devm_clk_get(&pdev->dev, "uartclk");
 136         if (IS_ERR(data->clk_uart)) {
 137                 dev_err(&pdev->dev, "uart clock not found\n");
 138                 return PTR_ERR(data->clk_uart);
 139         }
 140
 141         data->clk_reg = devm_clk_get(&pdev->dev, "reg");
 142         if (IS_ERR(data->clk_reg)) {
 143                 dev_err(&pdev->dev, "reg clock not found\n");
 144                 return PTR_ERR(data->clk_reg);
 145         }
 146
 147         ret = clk_prepare_enable(data->clk_reg);
 148         if (ret) {
 149                 dev_err(&pdev->dev, "unable to enable reg clock\n");
 150                 return ret;
 151         }
 152
 153         ret = clk_prepare_enable(data->clk_uart);
 154         if (ret) {
 155                 dev_err(&pdev->dev, "unable to enable uart clock\n");
 156                 goto dis_clk_reg;
 157         }
 158
 159         ret = of_alias_get_id(pdev->dev.of_node, "serial");
 160         if (ret >= 0)
 161                 uart.port.line = ret;
 162
 163         data->dma.rx_param = data;
 164         data->dma.tx_param = data;
 165
 166         spin_lock_init(&uart.port.lock);
 167         uart.port.dev = &pdev->dev;
 168         uart.port.irq = irq;
 169         uart.port.iotype = UPIO_MEM32;
 170         uart.port.mapbase = res->start;
 171         uart.port.regshift = 2;
 172         uart.port.type = PORT_16550A;
 173         uart.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE | UPF_SKIP_TEST;
 174         uart.port.uartclk = clk_get_rate(data->clk_uart);
 175         uart.port.private_data = data;
 176         uart.port.rs485_config = lpc18xx_rs485_config;
 177         uart.port.serial_out = lpc18xx_uart_serial_out;
 178
 179         uart.dma = &data->dma;
 180         uart.dma->rxconf.src_maxburst = 1;
 181         uart.dma->txconf.dst_maxburst = 1;
 182
 183         ret = serial8250_register_8250_port(&uart);
 184         if (ret < 0) {
 185                 dev_err(&pdev->dev, "unable to register 8250 port\n");
 186                 goto dis_uart_clk;
 187         }
 188
 189         data->line = ret;
 190         platform_set_drvdata(pdev, data);
 191
 192         return 0;
 193
 194 dis_uart_clk:
 195         clk_disable_unprepare(data->clk_uart);
 196 dis_clk_reg:
 197         clk_disable_unprepare(data->clk_reg);
 198         return ret;
 199 }
 200
 201 static int lpc18xx_serial_remove(struct platform_device *pdev)
 202 {
 203         struct lpc18xx_uart_data *data = platform_get_drvdata(pdev);
 204
 205         serial8250_unregister_port(data->line);
 206         clk_disable_unprepare(data->clk_uart);
 207         clk_disable_unprepare(data->clk_reg);
 208
 209         return 0;
 210 }
 211
 212 static const struct of_device_id lpc18xx_serial_match[] = {
 213         { .compatible = "nxp,lpc1850-uart" },
 214         { },
 215 };
 216 MODULE_DEVICE_TABLE(of, lpc18xx_serial_match);
 217
 218 static struct platform_driver lpc18xx_serial_driver = {
 219         .probe  = lpc18xx_serial_probe,
 220         .remove = lpc18xx_serial_remove,
 221         .driver = {
 222                 .name = "lpc18xx-uart",
 223                 .of_match_table = lpc18xx_serial_match,
 224         },
 225 };
 226 module_platform_driver(lpc18xx_serial_driver);
 227
 228 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
 229 MODULE_DESCRIPTION("Serial port driver NXP LPC18xx/43xx devices");
 230 MODULE_LICENSE("GPL v2");