1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
4  */
5 
6 #include <linux/clk.h>
7 #include <linux/console.h>
8 #include <linux/io.h>
9 #include <linux/module.h>
10 #include <linux/of.h>
11 #include <linux/platform_device.h>
12 
13 #include "8250.h"
14 
15 /*
16  * This hardware is similar to 8250, but its register map is a bit different:
17  *   - MMIO32 (regshift = 2)
18  *   - FCR is not at 2, but 3
19  *   - LCR and MCR are not at 3 and 4, they share 4
20  *   - No SCR (Instead, CHAR can be used as a scratch register)
21  *   - Divisor latch at 9, no divisor latch access bit
22  */
23 
24 #define UNIPHIER_UART_REGSHIFT		2
25 
26 /* bit[15:8] = CHAR, bit[7:0] = FCR */
27 #define UNIPHIER_UART_CHAR_FCR		(3 << (UNIPHIER_UART_REGSHIFT))
28 /* bit[15:8] = LCR, bit[7:0] = MCR */
29 #define UNIPHIER_UART_LCR_MCR		(4 << (UNIPHIER_UART_REGSHIFT))
30 /* Divisor Latch Register */
31 #define UNIPHIER_UART_DLR		(9 << (UNIPHIER_UART_REGSHIFT))
32 
33 struct uniphier8250_priv {
34 	int line;
35 	struct clk *clk;
36 	spinlock_t atomic_write_lock;
37 };
38 
39 #ifdef CONFIG_SERIAL_8250_CONSOLE
uniphier_early_console_setup(struct earlycon_device * device,const char * options)40 static int __init uniphier_early_console_setup(struct earlycon_device *device,
41 					       const char *options)
42 {
43 	if (!device->port.membase)
44 		return -ENODEV;
45 
46 	/* This hardware always expects MMIO32 register interface. */
47 	device->port.iotype = UPIO_MEM32;
48 	device->port.regshift = UNIPHIER_UART_REGSHIFT;
49 
50 	/*
51 	 * Do not touch the divisor register in early_serial8250_setup();
52 	 * we assume it has been initialized by a boot loader.
53 	 */
54 	device->baud = 0;
55 
56 	return early_serial8250_setup(device, options);
57 }
58 OF_EARLYCON_DECLARE(uniphier, "socionext,uniphier-uart",
59 		    uniphier_early_console_setup);
60 #endif
61 
62 /*
63  * The register map is slightly different from that of 8250.
64  * IO callbacks must be overridden for correct access to FCR, LCR, MCR and SCR.
65  */
uniphier_serial_in(struct uart_port * p,int offset)66 static unsigned int uniphier_serial_in(struct uart_port *p, int offset)
67 {
68 	unsigned int valshift = 0;
69 
70 	switch (offset) {
71 	case UART_SCR:
72 		/* No SCR for this hardware.  Use CHAR as a scratch register */
73 		valshift = 8;
74 		offset = UNIPHIER_UART_CHAR_FCR;
75 		break;
76 	case UART_LCR:
77 		valshift = 8;
78 		fallthrough;
79 	case UART_MCR:
80 		offset = UNIPHIER_UART_LCR_MCR;
81 		break;
82 	default:
83 		offset <<= UNIPHIER_UART_REGSHIFT;
84 		break;
85 	}
86 
87 	/*
88 	 * The return value must be masked with 0xff because some registers
89 	 * share the same offset that must be accessed by 32-bit write/read.
90 	 * 8 or 16 bit access to this hardware result in unexpected behavior.
91 	 */
92 	return (readl(p->membase + offset) >> valshift) & 0xff;
93 }
94 
uniphier_serial_out(struct uart_port * p,int offset,int value)95 static void uniphier_serial_out(struct uart_port *p, int offset, int value)
96 {
97 	unsigned int valshift = 0;
98 	bool normal = false;
99 
100 	switch (offset) {
101 	case UART_SCR:
102 		/* No SCR for this hardware.  Use CHAR as a scratch register */
103 		valshift = 8;
104 		fallthrough;
105 	case UART_FCR:
106 		offset = UNIPHIER_UART_CHAR_FCR;
107 		break;
108 	case UART_LCR:
109 		valshift = 8;
110 		/* Divisor latch access bit does not exist. */
111 		value &= ~UART_LCR_DLAB;
112 		fallthrough;
113 	case UART_MCR:
114 		offset = UNIPHIER_UART_LCR_MCR;
115 		break;
116 	default:
117 		offset <<= UNIPHIER_UART_REGSHIFT;
118 		normal = true;
119 		break;
120 	}
121 
122 	if (normal) {
123 		writel(value, p->membase + offset);
124 	} else {
125 		/*
126 		 * Special case: two registers share the same address that
127 		 * must be 32-bit accessed.  As this is not longer atomic safe,
128 		 * take a lock just in case.
129 		 */
130 		struct uniphier8250_priv *priv = p->private_data;
131 		unsigned long flags;
132 		u32 tmp;
133 
134 		spin_lock_irqsave(&priv->atomic_write_lock, flags);
135 		tmp = readl(p->membase + offset);
136 		tmp &= ~(0xff << valshift);
137 		tmp |= value << valshift;
138 		writel(tmp, p->membase + offset);
139 		spin_unlock_irqrestore(&priv->atomic_write_lock, flags);
140 	}
141 }
142 
143 /*
144  * This hardware does not have the divisor latch access bit.
145  * The divisor latch register exists at different address.
146  * Override dl_read/write callbacks.
147  */
uniphier_serial_dl_read(struct uart_8250_port * up)148 static int uniphier_serial_dl_read(struct uart_8250_port *up)
149 {
150 	return readl(up->port.membase + UNIPHIER_UART_DLR);
151 }
152 
uniphier_serial_dl_write(struct uart_8250_port * up,int value)153 static void uniphier_serial_dl_write(struct uart_8250_port *up, int value)
154 {
155 	writel(value, up->port.membase + UNIPHIER_UART_DLR);
156 }
157 
uniphier_uart_probe(struct platform_device * pdev)158 static int uniphier_uart_probe(struct platform_device *pdev)
159 {
160 	struct device *dev = &pdev->dev;
161 	struct uart_8250_port up;
162 	struct uniphier8250_priv *priv;
163 	struct resource *regs;
164 	void __iomem *membase;
165 	int irq;
166 	int ret;
167 
168 	regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
169 	if (!regs) {
170 		dev_err(dev, "failed to get memory resource\n");
171 		return -EINVAL;
172 	}
173 
174 	membase = devm_ioremap(dev, regs->start, resource_size(regs));
175 	if (!membase)
176 		return -ENOMEM;
177 
178 	irq = platform_get_irq(pdev, 0);
179 	if (irq < 0)
180 		return irq;
181 
182 	priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
183 	if (!priv)
184 		return -ENOMEM;
185 
186 	memset(&up, 0, sizeof(up));
187 
188 	ret = of_alias_get_id(dev->of_node, "serial");
189 	if (ret < 0) {
190 		dev_err(dev, "failed to get alias id\n");
191 		return ret;
192 	}
193 	up.port.line = ret;
194 
195 	priv->clk = devm_clk_get(dev, NULL);
196 	if (IS_ERR(priv->clk)) {
197 		dev_err(dev, "failed to get clock\n");
198 		return PTR_ERR(priv->clk);
199 	}
200 
201 	ret = clk_prepare_enable(priv->clk);
202 	if (ret)
203 		return ret;
204 
205 	up.port.uartclk = clk_get_rate(priv->clk);
206 
207 	spin_lock_init(&priv->atomic_write_lock);
208 
209 	up.port.dev = dev;
210 	up.port.private_data = priv;
211 	up.port.mapbase = regs->start;
212 	up.port.mapsize = resource_size(regs);
213 	up.port.membase = membase;
214 	up.port.irq = irq;
215 
216 	up.port.type = PORT_16550A;
217 	up.port.iotype = UPIO_MEM32;
218 	up.port.fifosize = 64;
219 	up.port.regshift = UNIPHIER_UART_REGSHIFT;
220 	up.port.flags = UPF_FIXED_PORT | UPF_FIXED_TYPE;
221 	up.capabilities = UART_CAP_FIFO;
222 
223 	if (of_property_read_bool(dev->of_node, "auto-flow-control"))
224 		up.capabilities |= UART_CAP_AFE;
225 
226 	up.port.serial_in = uniphier_serial_in;
227 	up.port.serial_out = uniphier_serial_out;
228 	up.dl_read = uniphier_serial_dl_read;
229 	up.dl_write = uniphier_serial_dl_write;
230 
231 	ret = serial8250_register_8250_port(&up);
232 	if (ret < 0) {
233 		dev_err(dev, "failed to register 8250 port\n");
234 		clk_disable_unprepare(priv->clk);
235 		return ret;
236 	}
237 	priv->line = ret;
238 
239 	platform_set_drvdata(pdev, priv);
240 
241 	return 0;
242 }
243 
uniphier_uart_remove(struct platform_device * pdev)244 static int uniphier_uart_remove(struct platform_device *pdev)
245 {
246 	struct uniphier8250_priv *priv = platform_get_drvdata(pdev);
247 
248 	serial8250_unregister_port(priv->line);
249 	clk_disable_unprepare(priv->clk);
250 
251 	return 0;
252 }
253 
uniphier_uart_suspend(struct device * dev)254 static int __maybe_unused uniphier_uart_suspend(struct device *dev)
255 {
256 	struct uniphier8250_priv *priv = dev_get_drvdata(dev);
257 	struct uart_8250_port *up = serial8250_get_port(priv->line);
258 
259 	serial8250_suspend_port(priv->line);
260 
261 	if (!uart_console(&up->port) || console_suspend_enabled)
262 		clk_disable_unprepare(priv->clk);
263 
264 	return 0;
265 }
266 
uniphier_uart_resume(struct device * dev)267 static int __maybe_unused uniphier_uart_resume(struct device *dev)
268 {
269 	struct uniphier8250_priv *priv = dev_get_drvdata(dev);
270 	struct uart_8250_port *up = serial8250_get_port(priv->line);
271 	int ret;
272 
273 	if (!uart_console(&up->port) || console_suspend_enabled) {
274 		ret = clk_prepare_enable(priv->clk);
275 		if (ret)
276 			return ret;
277 	}
278 
279 	serial8250_resume_port(priv->line);
280 
281 	return 0;
282 }
283 
284 static const struct dev_pm_ops uniphier_uart_pm_ops = {
285 	SET_SYSTEM_SLEEP_PM_OPS(uniphier_uart_suspend, uniphier_uart_resume)
286 };
287 
288 static const struct of_device_id uniphier_uart_match[] = {
289 	{ .compatible = "socionext,uniphier-uart" },
290 	{ /* sentinel */ }
291 };
292 MODULE_DEVICE_TABLE(of, uniphier_uart_match);
293 
294 static struct platform_driver uniphier_uart_platform_driver = {
295 	.probe		= uniphier_uart_probe,
296 	.remove		= uniphier_uart_remove,
297 	.driver = {
298 		.name	= "uniphier-uart",
299 		.of_match_table = uniphier_uart_match,
300 		.pm = &uniphier_uart_pm_ops,
301 	},
302 };
303 module_platform_driver(uniphier_uart_platform_driver);
304 
305 MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
306 MODULE_DESCRIPTION("UniPhier UART driver");
307 MODULE_LICENSE("GPL");
308