1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Renesas Emma Mobile 8250 driver
4 *
5 * Copyright (C) 2012 Magnus Damm
6 */
7
8 #include <linux/device.h>
9 #include <linux/io.h>
10 #include <linux/module.h>
11 #include <linux/mod_devicetable.h>
12 #include <linux/serial_8250.h>
13 #include <linux/serial_reg.h>
14 #include <linux/platform_device.h>
15 #include <linux/clk.h>
16 #include <linux/slab.h>
17
18 #include "8250.h"
19
20 #define UART_DLL_EM 9
21 #define UART_DLM_EM 10
22
23 struct serial8250_em_priv {
24 struct clk *sclk;
25 int line;
26 };
27
serial8250_em_serial_out(struct uart_port * p,int offset,int value)28 static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
29 {
30 switch (offset) {
31 case UART_TX: /* TX @ 0x00 */
32 writeb(value, p->membase);
33 break;
34 case UART_FCR: /* FCR @ 0x0c (+1) */
35 case UART_LCR: /* LCR @ 0x10 (+1) */
36 case UART_MCR: /* MCR @ 0x14 (+1) */
37 case UART_SCR: /* SCR @ 0x20 (+1) */
38 writel(value, p->membase + ((offset + 1) << 2));
39 break;
40 case UART_IER: /* IER @ 0x04 */
41 value &= 0x0f; /* only 4 valid bits - not Xscale */
42 fallthrough;
43 case UART_DLL_EM: /* DLL @ 0x24 (+9) */
44 case UART_DLM_EM: /* DLM @ 0x28 (+9) */
45 writel(value, p->membase + (offset << 2));
46 }
47 }
48
serial8250_em_serial_in(struct uart_port * p,int offset)49 static unsigned int serial8250_em_serial_in(struct uart_port *p, int offset)
50 {
51 switch (offset) {
52 case UART_RX: /* RX @ 0x00 */
53 return readb(p->membase);
54 case UART_MCR: /* MCR @ 0x14 (+1) */
55 case UART_LSR: /* LSR @ 0x18 (+1) */
56 case UART_MSR: /* MSR @ 0x1c (+1) */
57 case UART_SCR: /* SCR @ 0x20 (+1) */
58 return readl(p->membase + ((offset + 1) << 2));
59 case UART_IER: /* IER @ 0x04 */
60 case UART_IIR: /* IIR @ 0x08 */
61 case UART_DLL_EM: /* DLL @ 0x24 (+9) */
62 case UART_DLM_EM: /* DLM @ 0x28 (+9) */
63 return readl(p->membase + (offset << 2));
64 }
65 return 0;
66 }
67
serial8250_em_serial_dl_read(struct uart_8250_port * up)68 static int serial8250_em_serial_dl_read(struct uart_8250_port *up)
69 {
70 return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
71 }
72
serial8250_em_serial_dl_write(struct uart_8250_port * up,int value)73 static void serial8250_em_serial_dl_write(struct uart_8250_port *up, int value)
74 {
75 serial_out(up, UART_DLL_EM, value & 0xff);
76 serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
77 }
78
serial8250_em_probe(struct platform_device * pdev)79 static int serial8250_em_probe(struct platform_device *pdev)
80 {
81 struct serial8250_em_priv *priv;
82 struct uart_8250_port up;
83 struct resource *regs;
84 int irq, ret;
85
86 irq = platform_get_irq(pdev, 0);
87 if (irq < 0)
88 return irq;
89
90 regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
91 if (!regs) {
92 dev_err(&pdev->dev, "missing registers\n");
93 return -EINVAL;
94 }
95
96 priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
97 if (!priv)
98 return -ENOMEM;
99
100 priv->sclk = devm_clk_get(&pdev->dev, "sclk");
101 if (IS_ERR(priv->sclk)) {
102 dev_err(&pdev->dev, "unable to get clock\n");
103 return PTR_ERR(priv->sclk);
104 }
105
106 memset(&up, 0, sizeof(up));
107 up.port.mapbase = regs->start;
108 up.port.irq = irq;
109 up.port.type = PORT_UNKNOWN;
110 up.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_IOREMAP;
111 up.port.dev = &pdev->dev;
112 up.port.private_data = priv;
113
114 clk_prepare_enable(priv->sclk);
115 up.port.uartclk = clk_get_rate(priv->sclk);
116
117 up.port.iotype = UPIO_MEM32;
118 up.port.serial_in = serial8250_em_serial_in;
119 up.port.serial_out = serial8250_em_serial_out;
120 up.dl_read = serial8250_em_serial_dl_read;
121 up.dl_write = serial8250_em_serial_dl_write;
122
123 ret = serial8250_register_8250_port(&up);
124 if (ret < 0) {
125 dev_err(&pdev->dev, "unable to register 8250 port\n");
126 clk_disable_unprepare(priv->sclk);
127 return ret;
128 }
129
130 priv->line = ret;
131 platform_set_drvdata(pdev, priv);
132 return 0;
133 }
134
serial8250_em_remove(struct platform_device * pdev)135 static int serial8250_em_remove(struct platform_device *pdev)
136 {
137 struct serial8250_em_priv *priv = platform_get_drvdata(pdev);
138
139 serial8250_unregister_port(priv->line);
140 clk_disable_unprepare(priv->sclk);
141 return 0;
142 }
143
144 static const struct of_device_id serial8250_em_dt_ids[] = {
145 { .compatible = "renesas,em-uart", },
146 {},
147 };
148 MODULE_DEVICE_TABLE(of, serial8250_em_dt_ids);
149
150 static struct platform_driver serial8250_em_platform_driver = {
151 .driver = {
152 .name = "serial8250-em",
153 .of_match_table = serial8250_em_dt_ids,
154 },
155 .probe = serial8250_em_probe,
156 .remove = serial8250_em_remove,
157 };
158
159 module_platform_driver(serial8250_em_platform_driver);
160
161 MODULE_AUTHOR("Magnus Damm");
162 MODULE_DESCRIPTION("Renesas Emma Mobile 8250 Driver");
163 MODULE_LICENSE("GPL v2");
164