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"); 231