8250_of.c

  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
 25struct 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
 38static 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 */
 51static 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
 57static 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
 64static 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
 69static 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 */
 87static 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;
192err_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 */
201static 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;
264err_unregister:
265	serial8250_unregister_port(info->line);
266err_dispose:
267	pm_runtime_put_sync(&ofdev->dev);
268	pm_runtime_disable(&ofdev->dev);
269err_free:
270	kfree(info);
271	return ret;
272}
273
274/*
275 * Release a line
276 */
277static 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
293static 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
309static 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
326static 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 */
331static 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};
358MODULE_DEVICE_TABLE(of, of_platform_serial_table);
359
360static 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
370module_platform_driver(of_platform_serial_driver);
371
372MODULE_AUTHOR("Arnd Bergmann <arnd@arndb.de>");
373MODULE_LICENSE("GPL");
374MODULE_DESCRIPTION("Serial Port driver for Open Firmware platform devices");