xref: /linux/drivers/usb/phy/phy-gpio-vbus-usb.c (revision 24bce201d79807b668bf9d9e0aca801c5c0d5f78) 
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * gpio-vbus.c - simple GPIO VBUS sensing driver for B peripheral devices
4  *
5  * Copyright (c) 2008 Philipp Zabel <philipp.zabel@gmail.com>
6  */
7 
8 #include <linux/kernel.h>
9 #include <linux/platform_device.h>
10 #include <linux/gpio/consumer.h>
11 #include <linux/module.h>
12 #include <linux/slab.h>
13 #include <linux/interrupt.h>
14 #include <linux/usb.h>
15 #include <linux/workqueue.h>
16 
17 #include <linux/regulator/consumer.h>
18 
19 #include <linux/usb/gadget.h>
20 #include <linux/usb/otg.h>
21 
22 
23 /*
24  * A simple GPIO VBUS sensing driver for B peripheral only devices
25  * with internal transceivers. It can control a D+ pullup GPIO and
26  * a regulator to limit the current drawn from VBUS.
27  *
28  * Needs to be loaded before the UDC driver that will use it.
29  */
30 struct gpio_vbus_data {
31 	struct gpio_desc	*vbus_gpiod;
32 	struct gpio_desc	*pullup_gpiod;
33 	struct usb_phy		phy;
34 	struct device          *dev;
35 	struct regulator       *vbus_draw;
36 	int			vbus_draw_enabled;
37 	unsigned		mA;
38 	struct delayed_work	work;
39 	int			vbus;
40 	int			irq;
41 };
42 
43 
44 /*
45  * This driver relies on "both edges" triggering.  VBUS has 100 msec to
46  * stabilize, so the peripheral controller driver may need to cope with
47  * some bouncing due to current surges (e.g. charging local capacitance)
48  * and contact chatter.
49  *
50  * REVISIT in desperate straits, toggling between rising and falling
51  * edges might be workable.
52  */
53 #define VBUS_IRQ_FLAGS \
54 	(IRQF_SHARED | IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING)
55 
56 
57 /* interface to regulator framework */
58 static void set_vbus_draw(struct gpio_vbus_data *gpio_vbus, unsigned mA)
59 {
60 	struct regulator *vbus_draw = gpio_vbus->vbus_draw;
61 	int enabled;
62 	int ret;
63 
64 	if (!vbus_draw)
65 		return;
66 
67 	enabled = gpio_vbus->vbus_draw_enabled;
68 	if (mA) {
69 		regulator_set_current_limit(vbus_draw, 0, 1000 * mA);
70 		if (!enabled) {
71 			ret = regulator_enable(vbus_draw);
72 			if (ret < 0)
73 				return;
74 			gpio_vbus->vbus_draw_enabled = 1;
75 		}
76 	} else {
77 		if (enabled) {
78 			ret = regulator_disable(vbus_draw);
79 			if (ret < 0)
80 				return;
81 			gpio_vbus->vbus_draw_enabled = 0;
82 		}
83 	}
84 	gpio_vbus->mA = mA;
85 }
86 
87 static int is_vbus_powered(struct gpio_vbus_data *gpio_vbus)
88 {
89 	return gpiod_get_value(gpio_vbus->vbus_gpiod);
90 }
91 
92 static void gpio_vbus_work(struct work_struct *work)
93 {
94 	struct gpio_vbus_data *gpio_vbus =
95 		container_of(work, struct gpio_vbus_data, work.work);
96 	int status, vbus;
97 
98 	if (!gpio_vbus->phy.otg->gadget)
99 		return;
100 
101 	vbus = is_vbus_powered(gpio_vbus);
102 	if ((vbus ^ gpio_vbus->vbus) == 0)
103 		return;
104 	gpio_vbus->vbus = vbus;
105 
106 	/* Peripheral controllers which manage the pullup themselves won't have
107 	 * a pullup GPIO configured here.  If it's configured here, we'll do
108 	 * what isp1301_omap::b_peripheral() does and enable the pullup here...
109 	 * although that may complicate usb_gadget_{,dis}connect() support.
110 	 */
111 
112 	if (vbus) {
113 		status = USB_EVENT_VBUS;
114 		gpio_vbus->phy.otg->state = OTG_STATE_B_PERIPHERAL;
115 		gpio_vbus->phy.last_event = status;
116 		usb_gadget_vbus_connect(gpio_vbus->phy.otg->gadget);
117 
118 		/* drawing a "unit load" is *always* OK, except for OTG */
119 		set_vbus_draw(gpio_vbus, 100);
120 
121 		/* optionally enable D+ pullup */
122 		if (gpio_vbus->pullup_gpiod)
123 			gpiod_set_value(gpio_vbus->pullup_gpiod, 1);
124 
125 		atomic_notifier_call_chain(&gpio_vbus->phy.notifier,
126 					   status, gpio_vbus->phy.otg->gadget);
127 		usb_phy_set_event(&gpio_vbus->phy, USB_EVENT_ENUMERATED);
128 	} else {
129 		/* optionally disable D+ pullup */
130 		if (gpio_vbus->pullup_gpiod)
131 			gpiod_set_value(gpio_vbus->pullup_gpiod, 0);
132 
133 		set_vbus_draw(gpio_vbus, 0);
134 
135 		usb_gadget_vbus_disconnect(gpio_vbus->phy.otg->gadget);
136 		status = USB_EVENT_NONE;
137 		gpio_vbus->phy.otg->state = OTG_STATE_B_IDLE;
138 		gpio_vbus->phy.last_event = status;
139 
140 		atomic_notifier_call_chain(&gpio_vbus->phy.notifier,
141 					   status, gpio_vbus->phy.otg->gadget);
142 		usb_phy_set_event(&gpio_vbus->phy, USB_EVENT_NONE);
143 	}
144 }
145 
146 /* VBUS change IRQ handler */
147 static irqreturn_t gpio_vbus_irq(int irq, void *data)
148 {
149 	struct platform_device *pdev = data;
150 	struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
151 	struct usb_otg *otg = gpio_vbus->phy.otg;
152 
153 	dev_dbg(&pdev->dev, "VBUS %s (gadget: %s)\n",
154 		is_vbus_powered(gpio_vbus) ? "supplied" : "inactive",
155 		otg->gadget ? otg->gadget->name : "none");
156 
157 	if (otg->gadget)
158 		schedule_delayed_work(&gpio_vbus->work, msecs_to_jiffies(100));
159 
160 	return IRQ_HANDLED;
161 }
162 
163 /* OTG transceiver interface */
164 
165 /* bind/unbind the peripheral controller */
166 static int gpio_vbus_set_peripheral(struct usb_otg *otg,
167 					struct usb_gadget *gadget)
168 {
169 	struct gpio_vbus_data *gpio_vbus;
170 	struct platform_device *pdev;
171 
172 	gpio_vbus = container_of(otg->usb_phy, struct gpio_vbus_data, phy);
173 	pdev = to_platform_device(gpio_vbus->dev);
174 
175 	if (!gadget) {
176 		dev_dbg(&pdev->dev, "unregistering gadget '%s'\n",
177 			otg->gadget->name);
178 
179 		/* optionally disable D+ pullup */
180 		if (gpio_vbus->pullup_gpiod)
181 			gpiod_set_value(gpio_vbus->pullup_gpiod, 0);
182 
183 		set_vbus_draw(gpio_vbus, 0);
184 
185 		usb_gadget_vbus_disconnect(otg->gadget);
186 		otg->state = OTG_STATE_UNDEFINED;
187 
188 		otg->gadget = NULL;
189 		return 0;
190 	}
191 
192 	otg->gadget = gadget;
193 	dev_dbg(&pdev->dev, "registered gadget '%s'\n", gadget->name);
194 
195 	/* initialize connection state */
196 	gpio_vbus->vbus = 0; /* start with disconnected */
197 	gpio_vbus_irq(gpio_vbus->irq, pdev);
198 	return 0;
199 }
200 
201 /* effective for B devices, ignored for A-peripheral */
202 static int gpio_vbus_set_power(struct usb_phy *phy, unsigned mA)
203 {
204 	struct gpio_vbus_data *gpio_vbus;
205 
206 	gpio_vbus = container_of(phy, struct gpio_vbus_data, phy);
207 
208 	if (phy->otg->state == OTG_STATE_B_PERIPHERAL)
209 		set_vbus_draw(gpio_vbus, mA);
210 	return 0;
211 }
212 
213 /* for non-OTG B devices: set/clear transceiver suspend mode */
214 static int gpio_vbus_set_suspend(struct usb_phy *phy, int suspend)
215 {
216 	struct gpio_vbus_data *gpio_vbus;
217 
218 	gpio_vbus = container_of(phy, struct gpio_vbus_data, phy);
219 
220 	/* draw max 0 mA from vbus in suspend mode; or the previously
221 	 * recorded amount of current if not suspended
222 	 *
223 	 * NOTE: high powered configs (mA > 100) may draw up to 2.5 mA
224 	 * if they're wake-enabled ... we don't handle that yet.
225 	 */
226 	return gpio_vbus_set_power(phy, suspend ? 0 : gpio_vbus->mA);
227 }
228 
229 /* platform driver interface */
230 
231 static int gpio_vbus_probe(struct platform_device *pdev)
232 {
233 	struct gpio_vbus_data *gpio_vbus;
234 	struct resource *res;
235 	struct device *dev = &pdev->dev;
236 	int err, irq;
237 	unsigned long irqflags;
238 
239 	gpio_vbus = devm_kzalloc(&pdev->dev, sizeof(struct gpio_vbus_data),
240 				 GFP_KERNEL);
241 	if (!gpio_vbus)
242 		return -ENOMEM;
243 
244 	gpio_vbus->phy.otg = devm_kzalloc(&pdev->dev, sizeof(struct usb_otg),
245 					  GFP_KERNEL);
246 	if (!gpio_vbus->phy.otg)
247 		return -ENOMEM;
248 
249 	platform_set_drvdata(pdev, gpio_vbus);
250 	gpio_vbus->dev = &pdev->dev;
251 	gpio_vbus->phy.label = "gpio-vbus";
252 	gpio_vbus->phy.dev = gpio_vbus->dev;
253 	gpio_vbus->phy.set_power = gpio_vbus_set_power;
254 	gpio_vbus->phy.set_suspend = gpio_vbus_set_suspend;
255 
256 	gpio_vbus->phy.otg->state = OTG_STATE_UNDEFINED;
257 	gpio_vbus->phy.otg->usb_phy = &gpio_vbus->phy;
258 	gpio_vbus->phy.otg->set_peripheral = gpio_vbus_set_peripheral;
259 
260 	/* Look up the VBUS sensing GPIO */
261 	gpio_vbus->vbus_gpiod = devm_gpiod_get(dev, "vbus", GPIOD_IN);
262 	if (IS_ERR(gpio_vbus->vbus_gpiod)) {
263 		err = PTR_ERR(gpio_vbus->vbus_gpiod);
264 		dev_err(&pdev->dev, "can't request vbus gpio, err: %d\n", err);
265 		return err;
266 	}
267 	gpiod_set_consumer_name(gpio_vbus->vbus_gpiod, "vbus_detect");
268 
269 	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
270 	if (res) {
271 		irq = res->start;
272 		irqflags = (res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED;
273 	} else {
274 		irq = gpiod_to_irq(gpio_vbus->vbus_gpiod);
275 		irqflags = VBUS_IRQ_FLAGS;
276 	}
277 
278 	gpio_vbus->irq = irq;
279 
280 	/*
281 	 * The VBUS sensing GPIO should have a pulldown, which will normally be
282 	 * part of a resistor ladder turning a 4.0V-5.25V level on VBUS into a
283 	 * value the GPIO detects as active. Some systems will use comparators.
284 	 * Get the optional D+ or D- pullup GPIO. If the data line pullup is
285 	 * in use, initialize it to "not pulling up"
286 	 */
287 	gpio_vbus->pullup_gpiod = devm_gpiod_get_optional(dev, "pullup",
288 							  GPIOD_OUT_LOW);
289 	if (IS_ERR(gpio_vbus->pullup_gpiod)) {
290 		err = PTR_ERR(gpio_vbus->pullup_gpiod);
291 		dev_err(&pdev->dev, "can't request pullup gpio, err: %d\n",
292 			err);
293 		return err;
294 	}
295 	if (gpio_vbus->pullup_gpiod)
296 		gpiod_set_consumer_name(gpio_vbus->pullup_gpiod, "udc_pullup");
297 
298 	err = devm_request_irq(&pdev->dev, irq, gpio_vbus_irq, irqflags,
299 			       "vbus_detect", pdev);
300 	if (err) {
301 		dev_err(&pdev->dev, "can't request irq %i, err: %d\n",
302 			irq, err);
303 		return err;
304 	}
305 
306 	INIT_DELAYED_WORK(&gpio_vbus->work, gpio_vbus_work);
307 
308 	gpio_vbus->vbus_draw = devm_regulator_get(&pdev->dev, "vbus_draw");
309 	if (IS_ERR(gpio_vbus->vbus_draw)) {
310 		dev_dbg(&pdev->dev, "can't get vbus_draw regulator, err: %ld\n",
311 			PTR_ERR(gpio_vbus->vbus_draw));
312 		gpio_vbus->vbus_draw = NULL;
313 	}
314 
315 	/* only active when a gadget is registered */
316 	err = usb_add_phy(&gpio_vbus->phy, USB_PHY_TYPE_USB2);
317 	if (err) {
318 		dev_err(&pdev->dev, "can't register transceiver, err: %d\n",
319 			err);
320 		return err;
321 	}
322 
323 	/* TODO: wakeup could be enabled here with device_init_wakeup(dev, 1) */
324 
325 	return 0;
326 }
327 
328 static int gpio_vbus_remove(struct platform_device *pdev)
329 {
330 	struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
331 
332 	device_init_wakeup(&pdev->dev, 0);
333 	cancel_delayed_work_sync(&gpio_vbus->work);
334 
335 	usb_remove_phy(&gpio_vbus->phy);
336 
337 	return 0;
338 }
339 
340 #ifdef CONFIG_PM
341 static int gpio_vbus_pm_suspend(struct device *dev)
342 {
343 	struct gpio_vbus_data *gpio_vbus = dev_get_drvdata(dev);
344 
345 	if (device_may_wakeup(dev))
346 		enable_irq_wake(gpio_vbus->irq);
347 
348 	return 0;
349 }
350 
351 static int gpio_vbus_pm_resume(struct device *dev)
352 {
353 	struct gpio_vbus_data *gpio_vbus = dev_get_drvdata(dev);
354 
355 	if (device_may_wakeup(dev))
356 		disable_irq_wake(gpio_vbus->irq);
357 
358 	return 0;
359 }
360 
361 static const struct dev_pm_ops gpio_vbus_dev_pm_ops = {
362 	.suspend	= gpio_vbus_pm_suspend,
363 	.resume		= gpio_vbus_pm_resume,
364 };
365 #endif
366 
367 MODULE_ALIAS("platform:gpio-vbus");
368 
369 static struct platform_driver gpio_vbus_driver = {
370 	.driver = {
371 		.name  = "gpio-vbus",
372 #ifdef CONFIG_PM
373 		.pm = &gpio_vbus_dev_pm_ops,
374 #endif
375 	},
376 	.probe		= gpio_vbus_probe,
377 	.remove		= gpio_vbus_remove,
378 };
379 
380 module_platform_driver(gpio_vbus_driver);
381 
382 MODULE_DESCRIPTION("simple GPIO controlled OTG transceiver driver");
383 MODULE_AUTHOR("Philipp Zabel");
384 MODULE_LICENSE("GPL");
385