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