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
lpc18xx_rs485_config(struct uart_port * port,struct ktermios * termios,struct serial_rs485 * rs485)35 static int lpc18xx_rs485_config(struct uart_port *port, struct ktermios *termios,
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 rs485_ctrl_reg |= LPC18XX_UART_RS485CTRL_NMMEN |
45 LPC18XX_UART_RS485CTRL_DCTRL;
46
47 if (rs485->flags & SER_RS485_RTS_ON_SEND)
48 rs485_ctrl_reg |= LPC18XX_UART_RS485CTRL_OINV;
49 }
50
51 if (rs485->delay_rts_after_send) {
52 baud_clk = port->uartclk / up->dl_read(up);
53 rs485_dly_reg = DIV_ROUND_UP(rs485->delay_rts_after_send
54 * baud_clk, MSEC_PER_SEC);
55
56 if (rs485_dly_reg > LPC18XX_UART_RS485DLY_MAX)
57 rs485_dly_reg = LPC18XX_UART_RS485DLY_MAX;
58
59 /* Calculate the resulting delay in ms */
60 rs485->delay_rts_after_send = (rs485_dly_reg * MSEC_PER_SEC)
61 / baud_clk;
62 }
63
64 serial_out(up, LPC18XX_UART_RS485CTRL, rs485_ctrl_reg);
65 serial_out(up, LPC18XX_UART_RS485DLY, rs485_dly_reg);
66
67 return 0;
68 }
69
lpc18xx_uart_serial_out(struct uart_port * p,int offset,int value)70 static void lpc18xx_uart_serial_out(struct uart_port *p, int offset, int value)
71 {
72 /*
73 * For DMA mode one must ensure that the UART_FCR_DMA_SELECT
74 * bit is set when FIFO is enabled. Even if DMA is not used
75 * setting this bit doesn't seem to affect anything.
76 */
77 if (offset == UART_FCR && (value & UART_FCR_ENABLE_FIFO))
78 value |= UART_FCR_DMA_SELECT;
79
80 offset = offset << p->regshift;
81 writel(value, p->membase + offset);
82 }
83
84 static const struct serial_rs485 lpc18xx_rs485_supported = {
85 .flags = SER_RS485_ENABLED | SER_RS485_RTS_ON_SEND | SER_RS485_RTS_AFTER_SEND,
86 .delay_rts_after_send = 1,
87 /* Delay RTS before send is not supported */
88 };
89
lpc18xx_serial_probe(struct platform_device * pdev)90 static int lpc18xx_serial_probe(struct platform_device *pdev)
91 {
92 struct lpc18xx_uart_data *data;
93 struct uart_8250_port uart;
94 struct resource *res;
95 int ret;
96
97 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
98 if (!res) {
99 dev_err(&pdev->dev, "memory resource not found");
100 return -EINVAL;
101 }
102
103 memset(&uart, 0, sizeof(uart));
104
105 uart.port.membase = devm_ioremap(&pdev->dev, res->start,
106 resource_size(res));
107 if (!uart.port.membase)
108 return -ENOMEM;
109
110 data = devm_kzalloc(&pdev->dev, sizeof(*data), GFP_KERNEL);
111 if (!data)
112 return -ENOMEM;
113
114 data->clk_uart = devm_clk_get(&pdev->dev, "uartclk");
115 if (IS_ERR(data->clk_uart)) {
116 dev_err(&pdev->dev, "uart clock not found\n");
117 return PTR_ERR(data->clk_uart);
118 }
119
120 data->clk_reg = devm_clk_get(&pdev->dev, "reg");
121 if (IS_ERR(data->clk_reg)) {
122 dev_err(&pdev->dev, "reg clock not found\n");
123 return PTR_ERR(data->clk_reg);
124 }
125
126 ret = clk_prepare_enable(data->clk_reg);
127 if (ret) {
128 dev_err(&pdev->dev, "unable to enable reg clock\n");
129 return ret;
130 }
131
132 ret = clk_prepare_enable(data->clk_uart);
133 if (ret) {
134 dev_err(&pdev->dev, "unable to enable uart clock\n");
135 goto dis_clk_reg;
136 }
137
138 data->dma.rx_param = data;
139 data->dma.tx_param = data;
140
141 spin_lock_init(&uart.port.lock);
142 uart.port.dev = &pdev->dev;
143 uart.port.mapbase = res->start;
144 uart.port.type = PORT_16550A;
145 uart.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE | UPF_SKIP_TEST;
146 uart.port.uartclk = clk_get_rate(data->clk_uart);
147 uart.port.private_data = data;
148 uart.port.rs485_config = lpc18xx_rs485_config;
149 uart.port.rs485_supported = lpc18xx_rs485_supported;
150 uart.port.serial_out = lpc18xx_uart_serial_out;
151
152 ret = uart_read_port_properties(&uart.port);
153 if (ret)
154 goto dis_uart_clk;
155
156 uart.port.iotype = UPIO_MEM32;
157 uart.port.regshift = 2;
158
159 uart.dma = &data->dma;
160 uart.dma->rxconf.src_maxburst = 1;
161 uart.dma->txconf.dst_maxburst = 1;
162
163 ret = serial8250_register_8250_port(&uart);
164 if (ret < 0) {
165 dev_err(&pdev->dev, "unable to register 8250 port\n");
166 goto dis_uart_clk;
167 }
168
169 data->line = ret;
170 platform_set_drvdata(pdev, data);
171
172 return 0;
173
174 dis_uart_clk:
175 clk_disable_unprepare(data->clk_uart);
176 dis_clk_reg:
177 clk_disable_unprepare(data->clk_reg);
178 return ret;
179 }
180
lpc18xx_serial_remove(struct platform_device * pdev)181 static void lpc18xx_serial_remove(struct platform_device *pdev)
182 {
183 struct lpc18xx_uart_data *data = platform_get_drvdata(pdev);
184
185 serial8250_unregister_port(data->line);
186 clk_disable_unprepare(data->clk_uart);
187 clk_disable_unprepare(data->clk_reg);
188 }
189
190 static const struct of_device_id lpc18xx_serial_match[] = {
191 { .compatible = "nxp,lpc1850-uart" },
192 { },
193 };
194 MODULE_DEVICE_TABLE(of, lpc18xx_serial_match);
195
196 static struct platform_driver lpc18xx_serial_driver = {
197 .probe = lpc18xx_serial_probe,
198 .remove_new = lpc18xx_serial_remove,
199 .driver = {
200 .name = "lpc18xx-uart",
201 .of_match_table = lpc18xx_serial_match,
202 },
203 };
204 module_platform_driver(lpc18xx_serial_driver);
205
206 MODULE_AUTHOR("Joachim Eastwood <manabian@gmail.com>");
207 MODULE_DESCRIPTION("Serial port driver NXP LPC18xx/43xx devices");
208 MODULE_LICENSE("GPL v2");
209