xref: /openbmc/linux/drivers/tty/serial/8250/8250_em.c (revision b245aa0c)
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 
17 #include "8250.h"
18 
19 #define UART_DLL_EM 9
20 #define UART_DLM_EM 10
21 #define UART_HCR0_EM 11
22 
23 /*
24  * A high value for UART_FCR_EM avoids overlapping with existing UART_*
25  * register defines. UART_FCR_EM_HW is the real HW register offset.
26  */
27 #define UART_FCR_EM 0x10003
28 #define UART_FCR_EM_HW 3
29 
30 #define UART_HCR0_EM_SW_RESET	BIT(7) /* SW Reset */
31 
32 struct serial8250_em_priv {
33 	int line;
34 };
35 
serial8250_em_serial_out_helper(struct uart_port * p,int offset,int value)36 static void serial8250_em_serial_out_helper(struct uart_port *p, int offset,
37 					    int value)
38 {
39 	switch (offset) {
40 	case UART_TX: /* TX @ 0x00 */
41 		writeb(value, p->membase);
42 		break;
43 	case UART_LCR: /* LCR @ 0x10 (+1) */
44 	case UART_MCR: /* MCR @ 0x14 (+1) */
45 	case UART_SCR: /* SCR @ 0x20 (+1) */
46 		writel(value, p->membase + ((offset + 1) << 2));
47 		break;
48 	case UART_FCR_EM:
49 		writel(value, p->membase + (UART_FCR_EM_HW << 2));
50 		break;
51 	case UART_IER: /* IER @ 0x04 */
52 		value &= 0x0f; /* only 4 valid bits - not Xscale */
53 		fallthrough;
54 	case UART_DLL_EM: /* DLL @ 0x24 (+9) */
55 	case UART_DLM_EM: /* DLM @ 0x28 (+9) */
56 	case UART_HCR0_EM: /* HCR0 @ 0x2c */
57 		writel(value, p->membase + (offset << 2));
58 		break;
59 	}
60 }
61 
serial8250_em_serial_in(struct uart_port * p,int offset)62 static unsigned int serial8250_em_serial_in(struct uart_port *p, int offset)
63 {
64 	switch (offset) {
65 	case UART_RX: /* RX @ 0x00 */
66 		return readb(p->membase);
67 	case UART_LCR: /* LCR @ 0x10 (+1) */
68 	case UART_MCR: /* MCR @ 0x14 (+1) */
69 	case UART_LSR: /* LSR @ 0x18 (+1) */
70 	case UART_MSR: /* MSR @ 0x1c (+1) */
71 	case UART_SCR: /* SCR @ 0x20 (+1) */
72 		return readl(p->membase + ((offset + 1) << 2));
73 	case UART_FCR_EM:
74 		return readl(p->membase + (UART_FCR_EM_HW << 2));
75 	case UART_IER: /* IER @ 0x04 */
76 	case UART_IIR: /* IIR @ 0x08 */
77 	case UART_DLL_EM: /* DLL @ 0x24 (+9) */
78 	case UART_DLM_EM: /* DLM @ 0x28 (+9) */
79 	case UART_HCR0_EM: /* HCR0 @ 0x2c */
80 		return readl(p->membase + (offset << 2));
81 	}
82 	return 0;
83 }
84 
serial8250_em_reg_update(struct uart_port * p,int off,int value)85 static void serial8250_em_reg_update(struct uart_port *p, int off, int value)
86 {
87 	unsigned int ier, fcr, lcr, mcr, hcr0;
88 
89 	ier = serial8250_em_serial_in(p, UART_IER);
90 	fcr = serial8250_em_serial_in(p, UART_FCR_EM);
91 	lcr = serial8250_em_serial_in(p, UART_LCR);
92 	mcr = serial8250_em_serial_in(p, UART_MCR);
93 	hcr0 = serial8250_em_serial_in(p, UART_HCR0_EM);
94 
95 	serial8250_em_serial_out_helper(p, UART_FCR_EM, fcr |
96 							UART_FCR_CLEAR_RCVR |
97 							UART_FCR_CLEAR_XMIT);
98 	serial8250_em_serial_out_helper(p, UART_HCR0_EM, hcr0 |
99 							 UART_HCR0_EM_SW_RESET);
100 	serial8250_em_serial_out_helper(p, UART_HCR0_EM, hcr0 &
101 							 ~UART_HCR0_EM_SW_RESET);
102 
103 	switch (off) {
104 	case UART_FCR_EM:
105 		fcr = value;
106 		break;
107 	case UART_LCR:
108 		lcr = value;
109 		break;
110 	case UART_MCR:
111 		mcr = value;
112 		break;
113 	}
114 
115 	serial8250_em_serial_out_helper(p, UART_IER, ier);
116 	serial8250_em_serial_out_helper(p, UART_FCR_EM, fcr);
117 	serial8250_em_serial_out_helper(p, UART_MCR, mcr);
118 	serial8250_em_serial_out_helper(p, UART_LCR, lcr);
119 	serial8250_em_serial_out_helper(p, UART_HCR0_EM, hcr0);
120 }
121 
serial8250_em_serial_out(struct uart_port * p,int offset,int value)122 static void serial8250_em_serial_out(struct uart_port *p, int offset, int value)
123 {
124 	switch (offset) {
125 	case UART_TX:
126 	case UART_SCR:
127 	case UART_IER:
128 	case UART_DLL_EM:
129 	case UART_DLM_EM:
130 		serial8250_em_serial_out_helper(p, offset, value);
131 		break;
132 	case UART_FCR:
133 		serial8250_em_reg_update(p, UART_FCR_EM, value);
134 		break;
135 	case UART_LCR:
136 	case UART_MCR:
137 		serial8250_em_reg_update(p, offset, value);
138 		break;
139 	}
140 }
141 
serial8250_em_serial_dl_read(struct uart_8250_port * up)142 static u32 serial8250_em_serial_dl_read(struct uart_8250_port *up)
143 {
144 	return serial_in(up, UART_DLL_EM) | serial_in(up, UART_DLM_EM) << 8;
145 }
146 
serial8250_em_serial_dl_write(struct uart_8250_port * up,u32 value)147 static void serial8250_em_serial_dl_write(struct uart_8250_port *up, u32 value)
148 {
149 	serial_out(up, UART_DLL_EM, value & 0xff);
150 	serial_out(up, UART_DLM_EM, value >> 8 & 0xff);
151 }
152 
serial8250_em_probe(struct platform_device * pdev)153 static int serial8250_em_probe(struct platform_device *pdev)
154 {
155 	struct serial8250_em_priv *priv;
156 	struct device *dev = &pdev->dev;
157 	struct uart_8250_port up;
158 	struct resource *regs;
159 	struct clk *sclk;
160 	int irq, ret;
161 
162 	irq = platform_get_irq(pdev, 0);
163 	if (irq < 0)
164 		return irq;
165 
166 	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
167 	if (!regs)
168 		return dev_err_probe(dev, -EINVAL, "missing registers\n");
169 
170 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
171 	if (!priv)
172 		return -ENOMEM;
173 
174 	sclk = devm_clk_get_enabled(dev, "sclk");
175 	if (IS_ERR(sclk))
176 		return dev_err_probe(dev, PTR_ERR(sclk), "unable to get clock\n");
177 
178 	memset(&up, 0, sizeof(up));
179 	up.port.mapbase = regs->start;
180 	up.port.irq = irq;
181 	up.port.type = PORT_16750;
182 	up.port.flags = UPF_FIXED_PORT | UPF_IOREMAP | UPF_FIXED_TYPE;
183 	up.port.dev = dev;
184 	up.port.private_data = priv;
185 
186 	up.port.uartclk = clk_get_rate(sclk);
187 
188 	up.port.iotype = UPIO_MEM32;
189 	up.port.serial_in = serial8250_em_serial_in;
190 	up.port.serial_out = serial8250_em_serial_out;
191 	up.dl_read = serial8250_em_serial_dl_read;
192 	up.dl_write = serial8250_em_serial_dl_write;
193 
194 	ret = serial8250_register_8250_port(&up);
195 	if (ret < 0)
196 		return dev_err_probe(dev, ret, "unable to register 8250 port\n");
197 
198 	priv->line = ret;
199 	platform_set_drvdata(pdev, priv);
200 	return 0;
201 }
202 
serial8250_em_remove(struct platform_device * pdev)203 static int serial8250_em_remove(struct platform_device *pdev)
204 {
205 	struct serial8250_em_priv *priv = platform_get_drvdata(pdev);
206 
207 	serial8250_unregister_port(priv->line);
208 	return 0;
209 }
210 
211 static const struct of_device_id serial8250_em_dt_ids[] = {
212 	{ .compatible = "renesas,em-uart", },
213 	{},
214 };
215 MODULE_DEVICE_TABLE(of, serial8250_em_dt_ids);
216 
217 static struct platform_driver serial8250_em_platform_driver = {
218 	.driver = {
219 		.name		= "serial8250-em",
220 		.of_match_table = serial8250_em_dt_ids,
221 	},
222 	.probe			= serial8250_em_probe,
223 	.remove			= serial8250_em_remove,
224 };
225 
226 module_platform_driver(serial8250_em_platform_driver);
227 
228 MODULE_AUTHOR("Magnus Damm");
229 MODULE_DESCRIPTION("Renesas Emma Mobile 8250 Driver");
230 MODULE_LICENSE("GPL v2");
231