1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Serial port driver for NXP LPC18xx/43xx UART 4 * 5 * Copyright (C) 2015 Joachim Eastwood <manabian@gmail.com> 6 * 7 * Based on 8250_mtk.c: 8 * Copyright (c) 2014 MundoReader S.L. 9 * Matthias Brugger <matthias.bgg@gmail.com> 10 */ 11 12 #include <linux/clk.h> 13 #include <linux/io.h> 14 #include <linux/module.h> 15 #include <linux/of.h> 16 #include <linux/platform_device.h> 17 18 #include "8250.h" 19 20 /* Additional LPC18xx/43xx 8250 registers and bits */ 21 #define LPC18XX_UART_RS485CTRL (0x04c / sizeof(u32)) 22 #define LPC18XX_UART_RS485CTRL_NMMEN BIT(0) 23 #define LPC18XX_UART_RS485CTRL_DCTRL BIT(4) 24 #define LPC18XX_UART_RS485CTRL_OINV BIT(5) 25 #define LPC18XX_UART_RS485DLY (0x054 / sizeof(u32)) 26 #define LPC18XX_UART_RS485DLY_MAX 255 27 28 struct lpc18xx_uart_data { 29 struct uart_8250_dma dma; 30 struct clk *clk_uart; 31 struct clk *clk_reg; 32 int line; 33 }; 34 35 static int lpc18xx_rs485_config(struct uart_port *port, 36 struct serial_rs485 *rs485) 37 { 38 struct uart_8250_port *up = up_to_u8250p(port); 39 u32 rs485_ctrl_reg = 0; 40 u32 rs485_dly_reg = 0; 41 unsigned baud_clk; 42 43 if (rs485->flags & SER_RS485_ENABLED) 44 memset(rs485->padding, 0, sizeof(rs485->padding)); 45 else 46 memset(rs485, 0, sizeof(*rs485)); 47 48 rs485->flags &= SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | 49 SER_RS485_RTS_AFTER_SEND; 50 51 if (rs485->flags & SER_RS485_ENABLED) { 52 rs485_ctrl_reg |= LPC18XX_UART_RS485CTRL_NMMEN | 53 LPC18XX_UART_RS485CTRL_DCTRL; 54 55 if (rs485->flags & SER_RS485_RTS_ON_SEND) { 56 rs485_ctrl_reg |= LPC18XX_UART_RS485CTRL_OINV; 57 rs485->flags &= ~SER_RS485_RTS_AFTER_SEND; 58 } else { 59 rs485->flags |= SER_RS485_RTS_AFTER_SEND; 60 } 61 } 62 63 if (rs485->delay_rts_after_send) { 64 baud_clk = port->uartclk / up->dl_read(up); 65 rs485_dly_reg = DIV_ROUND_UP(rs485->delay_rts_after_send 66 * baud_clk, MSEC_PER_SEC); 67 68 if (rs485_dly_reg > LPC18XX_UART_RS485DLY_MAX) 69 rs485_dly_reg = LPC18XX_UART_RS485DLY_MAX; 70 71 /* Calculate the resulting delay in ms */ 72 rs485->delay_rts_after_send = (rs485_dly_reg * MSEC_PER_SEC) 73 / baud_clk; 74 } 75 76 /* Delay RTS before send not supported */ 77 rs485->delay_rts_before_send = 0; 78 79 serial_out(up, LPC18XX_UART_RS485CTRL, rs485_ctrl_reg); 80 serial_out(up, LPC18XX_UART_RS485DLY, rs485_dly_reg); 81 82 port->rs485 = *rs485; 83 84 return 0; 85 } 86 87 static void lpc18xx_uart_serial_out(struct uart_port *p, int offset, int value) 88 { 89 /* 90 * For DMA mode one must ensure that the UART_FCR_DMA_SELECT 91 * bit is set when FIFO is enabled. Even if DMA is not used 92 * setting this bit doesn't seem to affect anything. 93 */ 94 if (offset == UART_FCR && (value & UART_FCR_ENABLE_FIFO)) 95 value |= UART_FCR_DMA_SELECT; 96 97 offset = offset << p->regshift; 98 writel(value, p->membase + offset); 99 } 100 101 static int lpc18xx_serial_probe(struct platform_device *pdev) 102 { 103 struct lpc18xx_uart_data *data; 104 struct uart_8250_port uart; 105 struct resource *res; 106 int irq, ret; 107 108 irq = platform_get_irq(pdev, 0); 109 if (irq < 0) { 110 dev_err(&pdev->dev, "irq not found"); 111 return irq; 112 } 113 114 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 115 if (!res) { 116 dev_err(&pdev->dev, "memory resource not found"); 117 return -EINVAL; 118 } 119 120 memset(&uart, 0, sizeof(uart)); 121 122 uart.port.membase = devm_ioremap(&pdev->dev, res->start, 123 resource_size(res)); 124 if (!uart.port.membase) 125 return -ENOMEM; 126 127 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL); 128 if (!data) 129 return -ENOMEM; 130 131 data->clk_uart = devm_clk_get(&pdev->dev, "uartclk"); 132 if (IS_ERR(data->clk_uart)) { 133 dev_err(&pdev->dev, "uart clock not found\n"); 134 return PTR_ERR(data->clk_uart); 135 } 136 137 data->clk_reg = devm_clk_get(&pdev->dev, "reg"); 138 if (IS_ERR(data->clk_reg)) { 139 dev_err(&pdev->dev, "reg clock not found\n"); 140 return PTR_ERR(data->clk_reg); 141 } 142 143 ret = clk_prepare_enable(data->clk_reg); 144 if (ret) { 145 dev_err(&pdev->dev, "unable to enable reg clock\n"); 146 return ret; 147 } 148 149 ret = clk_prepare_enable(data->clk_uart); 150 if (ret) { 151 dev_err(&pdev->dev, "unable to enable uart clock\n"); 152 goto dis_clk_reg; 153 } 154 155 ret = of_alias_get_id(pdev->dev.of_node, "serial"); 156 if (ret >= 0) 157 uart.port.line = ret; 158 159 data->dma.rx_param = data; 160 data->dma.tx_param = data; 161 162 spin_lock_init(&uart.port.lock); 163 uart.port.dev = &pdev->dev; 164 uart.port.irq = irq; 165 uart.port.iotype = UPIO_MEM32; 166 uart.port.mapbase = res->start; 167 uart.port.regshift = 2; 168 uart.port.type = PORT_16550A; 169 uart.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE | UPF_SKIP_TEST; 170 uart.port.uartclk = clk_get_rate(data->clk_uart); 171 uart.port.private_data = data; 172 uart.port.rs485_config = lpc18xx_rs485_config; 173 uart.port.serial_out = lpc18xx_uart_serial_out; 174 175 uart.dma = &data->dma; 176 uart.dma->rxconf.src_maxburst = 1; 177 uart.dma->txconf.dst_maxburst = 1; 178 179 ret = serial8250_register_8250_port(&uart); 180 if (ret < 0) { 181 dev_err(&pdev->dev, "unable to register 8250 port\n"); 182 goto dis_uart_clk; 183 } 184 185 data->line = ret; 186 platform_set_drvdata(pdev, data); 187 188 return 0; 189 190 dis_uart_clk: 191 clk_disable_unprepare(data->clk_uart); 192 dis_clk_reg: 193 clk_disable_unprepare(data->clk_reg); 194 return ret; 195 } 196 197 static int lpc18xx_serial_remove(struct platform_device *pdev) 198 { 199 struct lpc18xx_uart_data *data = platform_get_drvdata(pdev); 200 201 serial8250_unregister_port(data->line); 202 clk_disable_unprepare(data->clk_uart); 203 clk_disable_unprepare(data->clk_reg); 204 205 return 0; 206 } 207 208 static const struct of_device_id lpc18xx_serial_match[] = { 209 { .compatible = "nxp,lpc1850-uart" }, 210 { }, 211 }; 212 MODULE_DEVICE_TABLE(of, lpc18xx_serial_match); 213 214 static struct platform_driver lpc18xx_serial_driver = { 215 .probe = lpc18xx_serial_probe, 216 .remove = lpc18xx_serial_remove, 217 .driver = { 218 .name = "lpc18xx-uart", 219 .of_match_table = lpc18xx_serial_match, 220 }, 221 }; 222 module_platform_driver(lpc18xx_serial_driver); 223 224 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>"); 225 MODULE_DESCRIPTION("Serial port driver NXP LPC18xx/43xx devices"); 226 MODULE_LICENSE("GPL v2"); 227