1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  *  Serial Port driver for Open Firmware platform devices
4  *
5  *    Copyright (C) 2006 Arnd Bergmann <arnd@arndb.de>, IBM Corp.
6  */
7 
8 #include <linux/bits.h>
9 #include <linux/console.h>
10 #include <linux/math.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/serial_core.h>
14 #include <linux/serial_reg.h>
15 #include <linux/of_address.h>
16 #include <linux/of_irq.h>
17 #include <linux/of_platform.h>
18 #include <linux/pm_runtime.h>
19 #include <linux/clk.h>
20 #include <linux/reset.h>
21 #include <linux/notifier.h>
22 
23 #include "8250.h"
24 
25 struct of_serial_info {
26 	struct clk *clk;
27 	struct clk *bus_clk;
28 	struct reset_control *rst;
29 	int type;
30 	int line;
31 	struct notifier_block clk_notifier;
32 };
33 
34 /* Nuvoton NPCM timeout register */
35 #define UART_NPCM_TOR          7
36 #define UART_NPCM_TOIE         BIT(7)  /* Timeout Interrupt Enable */
37 
38 static int npcm_startup(struct uart_port *port)
39 {
40 	/*
41 	 * Nuvoton calls the scratch register 'UART_TOR' (timeout
42 	 * register). Enable it, and set TIOC (timeout interrupt
43 	 * comparator) to be 0x20 for correct operation.
44 	 */
45 	serial_port_out(port, UART_NPCM_TOR, UART_NPCM_TOIE | 0x20);
46 
47 	return serial8250_do_startup(port);
48 }
49 
50 /* Nuvoton NPCM UARTs have a custom divisor calculation */
51 static unsigned int npcm_get_divisor(struct uart_port *port, unsigned int baud,
52 				     unsigned int *frac)
53 {
54 	return DIV_ROUND_CLOSEST(port->uartclk, 16 * baud + 2) - 2;
55 }
56 
57 static int npcm_setup(struct uart_port *port)
58 {
59 	port->get_divisor = npcm_get_divisor;
60 	port->startup = npcm_startup;
61 	return 0;
62 }
63 
64 static inline struct of_serial_info *clk_nb_to_info(struct notifier_block *nb)
65 {
66 	return container_of(nb, struct of_serial_info, clk_notifier);
67 }
68 
69 static int of_platform_serial_clk_notifier_cb(struct notifier_block *nb, unsigned long event,
70 					      void *data)
71 {
72 	struct of_serial_info *info = clk_nb_to_info(nb);
73 	struct uart_8250_port *port8250 = serial8250_get_port(info->line);
74 	struct clk_notifier_data *ndata = data;
75 
76 	if (event == POST_RATE_CHANGE) {
77 		serial8250_update_uartclk(&port8250->port, ndata->new_rate);
78 		return NOTIFY_OK;
79 	}
80 
81 	return NOTIFY_DONE;
82 }
83 
84 /*
85  * Fill a struct uart_port for a given device node
86  */
87 static int of_platform_serial_setup(struct platform_device *ofdev,
88 			int type, struct uart_8250_port *up,
89 			struct of_serial_info *info)
90 {
91 	struct resource resource;
92 	struct device *dev = &ofdev->dev;
93 	struct device_node *np = dev->of_node;
94 	struct uart_port *port = &up->port;
95 	u32 spd;
96 	int ret;
97 
98 	memset(port, 0, sizeof *port);
99 
100 	pm_runtime_enable(&ofdev->dev);
101 	pm_runtime_get_sync(&ofdev->dev);
102 
103 	ret = of_address_to_resource(np, 0, &resource);
104 	if (ret) {
105 		dev_err_probe(dev, ret, "invalid address\n");
106 		goto err_pmruntime;
107 	}
108 
109 	port->dev = &ofdev->dev;
110 	port->flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_FIXED_TYPE;
111 	spin_lock_init(&port->lock);
112 
113 	if (resource_type(&resource) == IORESOURCE_IO) {
114 		port->iobase = resource.start;
115 	} else {
116 		port->mapbase = resource.start;
117 		port->mapsize = resource_size(&resource);
118 		port->flags |= UPF_IOREMAP;
119 	}
120 
121 	ret = uart_read_and_validate_port_properties(port);
122 	if (ret)
123 		goto err_pmruntime;
124 
125 	/* Get clk rate through clk driver if present */
126 	if (!port->uartclk) {
127 		struct clk *bus_clk;
128 
129 		bus_clk = devm_clk_get_optional_enabled(dev, "bus");
130 		if (IS_ERR(bus_clk)) {
131 			ret = dev_err_probe(dev, PTR_ERR(bus_clk), "failed to get bus clock\n");
132 			goto err_pmruntime;
133 		}
134 
135 		/* If the bus clock is required, core clock must be named */
136 		info->clk = devm_clk_get_enabled(dev, bus_clk ? "core" : NULL);
137 		if (IS_ERR(info->clk)) {
138 			ret = dev_err_probe(dev, PTR_ERR(info->clk), "failed to get clock\n");
139 			goto err_pmruntime;
140 		}
141 
142 		info->bus_clk = bus_clk;
143 		port->uartclk = clk_get_rate(info->clk);
144 	}
145 	/* If current-speed was set, then try not to change it. */
146 	if (of_property_read_u32(np, "current-speed", &spd) == 0)
147 		port->custom_divisor = port->uartclk / (16 * spd);
148 
149 	/* Compatibility with the deprecated pxa driver and 8250_pxa drivers. */
150 	if (of_device_is_compatible(np, "mrvl,mmp-uart"))
151 		port->regshift = 2;
152 
153 	info->rst = devm_reset_control_get_optional_shared(&ofdev->dev, NULL);
154 	if (IS_ERR(info->rst)) {
155 		ret = PTR_ERR(info->rst);
156 		goto err_pmruntime;
157 	}
158 
159 	ret = reset_control_deassert(info->rst);
160 	if (ret)
161 		goto err_pmruntime;
162 
163 	port->type = type;
164 	port->rs485_config = serial8250_em485_config;
165 	port->rs485_supported = serial8250_em485_supported;
166 	up->rs485_start_tx = serial8250_em485_start_tx;
167 	up->rs485_stop_tx = serial8250_em485_stop_tx;
168 
169 	switch (type) {
170 	case PORT_RT2880:
171 		ret = rt288x_setup(port);
172 		break;
173 	case PORT_NPCM:
174 		ret = npcm_setup(port);
175 		break;
176 	default:
177 		/* Nothing to do */
178 		ret = 0;
179 		break;
180 	}
181 	if (ret)
182 		goto err_pmruntime;
183 
184 	if (IS_REACHABLE(CONFIG_SERIAL_8250_FSL) &&
185 	    (of_device_is_compatible(np, "fsl,ns16550") ||
186 	     of_device_is_compatible(np, "fsl,16550-FIFO64"))) {
187 		port->handle_irq = fsl8250_handle_irq;
188 		port->has_sysrq = IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE);
189 	}
190 
191 	return 0;
192 err_pmruntime:
193 	pm_runtime_put_sync(&ofdev->dev);
194 	pm_runtime_disable(&ofdev->dev);
195 	return ret;
196 }
197 
198 /*
199  * Try to register a serial port
200  */
201 static int of_platform_serial_probe(struct platform_device *ofdev)
202 {
203 	struct of_serial_info *info;
204 	struct uart_8250_port port8250;
205 	unsigned int port_type;
206 	u32 tx_threshold;
207 	int ret;
208 
209 	if (IS_ENABLED(CONFIG_SERIAL_8250_BCM7271) &&
210 	    of_device_is_compatible(ofdev->dev.of_node, "brcm,bcm7271-uart"))
211 		return -ENODEV;
212 
213 	port_type = (unsigned long)of_device_get_match_data(&ofdev->dev);
214 	if (port_type == PORT_UNKNOWN)
215 		return -EINVAL;
216 
217 	if (of_property_read_bool(ofdev->dev.of_node, "used-by-rtas"))
218 		return -EBUSY;
219 
220 	info = kzalloc(sizeof(*info), GFP_KERNEL);
221 	if (info == NULL)
222 		return -ENOMEM;
223 
224 	memset(&port8250, 0, sizeof(port8250));
225 	ret = of_platform_serial_setup(ofdev, port_type, &port8250, info);
226 	if (ret)
227 		goto err_free;
228 
229 	if (port8250.port.fifosize)
230 		port8250.capabilities = UART_CAP_FIFO;
231 
232 	/* Check for TX FIFO threshold & set tx_loadsz */
233 	if ((of_property_read_u32(ofdev->dev.of_node, "tx-threshold",
234 				  &tx_threshold) == 0) &&
235 	    (tx_threshold < port8250.port.fifosize))
236 		port8250.tx_loadsz = port8250.port.fifosize - tx_threshold;
237 
238 	if (of_property_read_bool(ofdev->dev.of_node, "auto-flow-control"))
239 		port8250.capabilities |= UART_CAP_AFE;
240 
241 	if (of_property_read_u32(ofdev->dev.of_node,
242 			"overrun-throttle-ms",
243 			&port8250.overrun_backoff_time_ms) != 0)
244 		port8250.overrun_backoff_time_ms = 0;
245 
246 	ret = serial8250_register_8250_port(&port8250);
247 	if (ret < 0)
248 		goto err_dispose;
249 
250 	info->type = port_type;
251 	info->line = ret;
252 	platform_set_drvdata(ofdev, info);
253 
254 	if (info->clk) {
255 		info->clk_notifier.notifier_call = of_platform_serial_clk_notifier_cb;
256 		ret = clk_notifier_register(info->clk, &info->clk_notifier);
257 		if (ret) {
258 			dev_err_probe(port8250.port.dev, ret, "Failed to set the clock notifier\n");
259 			goto err_unregister;
260 		}
261 	}
262 
263 	return 0;
264 err_unregister:
265 	serial8250_unregister_port(info->line);
266 err_dispose:
267 	pm_runtime_put_sync(&ofdev->dev);
268 	pm_runtime_disable(&ofdev->dev);
269 err_free:
270 	kfree(info);
271 	return ret;
272 }
273 
274 /*
275  * Release a line
276  */
277 static void of_platform_serial_remove(struct platform_device *ofdev)
278 {
279 	struct of_serial_info *info = platform_get_drvdata(ofdev);
280 
281 	if (info->clk)
282 		clk_notifier_unregister(info->clk, &info->clk_notifier);
283 
284 	serial8250_unregister_port(info->line);
285 
286 	reset_control_assert(info->rst);
287 	pm_runtime_put_sync(&ofdev->dev);
288 	pm_runtime_disable(&ofdev->dev);
289 	kfree(info);
290 }
291 
292 #ifdef CONFIG_PM_SLEEP
293 static int of_serial_suspend(struct device *dev)
294 {
295 	struct of_serial_info *info = dev_get_drvdata(dev);
296 	struct uart_8250_port *port8250 = serial8250_get_port(info->line);
297 	struct uart_port *port = &port8250->port;
298 
299 	serial8250_suspend_port(info->line);
300 
301 	if (!uart_console(port) || console_suspend_enabled) {
302 		pm_runtime_put_sync(dev);
303 		clk_disable_unprepare(info->clk);
304 		clk_disable_unprepare(info->bus_clk);
305 	}
306 	return 0;
307 }
308 
309 static int of_serial_resume(struct device *dev)
310 {
311 	struct of_serial_info *info = dev_get_drvdata(dev);
312 	struct uart_8250_port *port8250 = serial8250_get_port(info->line);
313 	struct uart_port *port = &port8250->port;
314 
315 	if (!uart_console(port) || console_suspend_enabled) {
316 		pm_runtime_get_sync(dev);
317 		clk_prepare_enable(info->bus_clk);
318 		clk_prepare_enable(info->clk);
319 	}
320 
321 	serial8250_resume_port(info->line);
322 
323 	return 0;
324 }
325 #endif
326 static SIMPLE_DEV_PM_OPS(of_serial_pm_ops, of_serial_suspend, of_serial_resume);
327 
328 /*
329  * A few common types, add more as needed.
330  */
331 static const struct of_device_id of_platform_serial_table[] = {
332 	{ .compatible = "ns8250",   .data = (void *)PORT_8250, },
333 	{ .compatible = "ns16450",  .data = (void *)PORT_16450, },
334 	{ .compatible = "ns16550a", .data = (void *)PORT_16550A, },
335 	{ .compatible = "ns16550",  .data = (void *)PORT_16550, },
336 	{ .compatible = "ns16750",  .data = (void *)PORT_16750, },
337 	{ .compatible = "ns16850",  .data = (void *)PORT_16850, },
338 	{ .compatible = "nxp,lpc3220-uart", .data = (void *)PORT_LPC3220, },
339 	{ .compatible = "ralink,rt2880-uart", .data = (void *)PORT_RT2880, },
340 	{ .compatible = "intel,xscale-uart", .data = (void *)PORT_XSCALE, },
341 	{ .compatible = "altr,16550-FIFO32",
342 		.data = (void *)PORT_ALTR_16550_F32, },
343 	{ .compatible = "altr,16550-FIFO64",
344 		.data = (void *)PORT_ALTR_16550_F64, },
345 	{ .compatible = "altr,16550-FIFO128",
346 		.data = (void *)PORT_ALTR_16550_F128, },
347 	{ .compatible = "fsl,16550-FIFO64",
348 		.data = (void *)PORT_16550A_FSL64, },
349 	{ .compatible = "mediatek,mtk-btif",
350 		.data = (void *)PORT_MTK_BTIF, },
351 	{ .compatible = "mrvl,mmp-uart",
352 		.data = (void *)PORT_XSCALE, },
353 	{ .compatible = "ti,da830-uart", .data = (void *)PORT_DA830, },
354 	{ .compatible = "nuvoton,wpcm450-uart", .data = (void *)PORT_NPCM, },
355 	{ .compatible = "nuvoton,npcm750-uart", .data = (void *)PORT_NPCM, },
356 	{ /* end of list */ },
357 };
358 MODULE_DEVICE_TABLE(of, of_platform_serial_table);
359 
360 static struct platform_driver of_platform_serial_driver = {
361 	.driver = {
362 		.name = "of_serial",
363 		.of_match_table = of_platform_serial_table,
364 		.pm = &of_serial_pm_ops,
365 	},
366 	.probe = of_platform_serial_probe,
367 	.remove = of_platform_serial_remove,
368 };
369 
370 module_platform_driver(of_platform_serial_driver);
371 
372 MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
373 MODULE_LICENSE("GPL");
374 MODULE_DESCRIPTION("Serial Port driver for Open Firmware platform devices");
375