1 /*
2  * gpio-vbus.c - simple GPIO VBUS sensing driver for B peripheral devices
3  *
4  * Copyright (c) 2008 Philipp Zabel <philipp.zabel@gmail.com>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License version 2 as
8  * published by the Free Software Foundation.
9  */
10 
11 #include <linux/kernel.h>
12 #include <linux/platform_device.h>
13 #include <linux/gpio.h>
14 #include <linux/module.h>
15 #include <linux/slab.h>
16 #include <linux/interrupt.h>
17 #include <linux/usb.h>
18 #include <linux/workqueue.h>
19 
20 #include <linux/regulator/consumer.h>
21 
22 #include <linux/usb/gadget.h>
23 #include <linux/usb/gpio_vbus.h>
24 #include <linux/usb/otg.h>
25 
26 
27 /*
28  * A simple GPIO VBUS sensing driver for B peripheral only devices
29  * with internal transceivers. It can control a D+ pullup GPIO and
30  * a regulator to limit the current drawn from VBUS.
31  *
32  * Needs to be loaded before the UDC driver that will use it.
33  */
34 struct gpio_vbus_data {
35 	struct usb_phy		phy;
36 	struct device          *dev;
37 	struct regulator       *vbus_draw;
38 	int			vbus_draw_enabled;
39 	unsigned		mA;
40 	struct delayed_work	work;
41 	int			vbus;
42 	int			irq;
43 };
44 
45 
46 /*
47  * This driver relies on "both edges" triggering.  VBUS has 100 msec to
48  * stabilize, so the peripheral controller driver may need to cope with
49  * some bouncing due to current surges (e.g. charging local capacitance)
50  * and contact chatter.
51  *
52  * REVISIT in desperate straits, toggling between rising and falling
53  * edges might be workable.
54  */
55 #define VBUS_IRQ_FLAGS \
56 	(IRQF_SHARED | IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING)
57 
58 
59 /* interface to regulator framework */
60 static void set_vbus_draw(struct gpio_vbus_data *gpio_vbus, unsigned mA)
61 {
62 	struct regulator *vbus_draw = gpio_vbus->vbus_draw;
63 	int enabled;
64 	int ret;
65 
66 	if (!vbus_draw)
67 		return;
68 
69 	enabled = gpio_vbus->vbus_draw_enabled;
70 	if (mA) {
71 		regulator_set_current_limit(vbus_draw, 0, 1000 * mA);
72 		if (!enabled) {
73 			ret = regulator_enable(vbus_draw);
74 			if (ret < 0)
75 				return;
76 			gpio_vbus->vbus_draw_enabled = 1;
77 		}
78 	} else {
79 		if (enabled) {
80 			ret = regulator_disable(vbus_draw);
81 			if (ret < 0)
82 				return;
83 			gpio_vbus->vbus_draw_enabled = 0;
84 		}
85 	}
86 	gpio_vbus->mA = mA;
87 }
88 
89 static int is_vbus_powered(struct gpio_vbus_mach_info *pdata)
90 {
91 	int vbus;
92 
93 	vbus = gpio_get_value(pdata->gpio_vbus);
94 	if (pdata->gpio_vbus_inverted)
95 		vbus = !vbus;
96 
97 	return vbus;
98 }
99 
100 static void gpio_vbus_work(struct work_struct *work)
101 {
102 	struct gpio_vbus_data *gpio_vbus =
103 		container_of(work, struct gpio_vbus_data, work.work);
104 	struct gpio_vbus_mach_info *pdata = dev_get_platdata(gpio_vbus->dev);
105 	int gpio, status, vbus;
106 
107 	if (!gpio_vbus->phy.otg->gadget)
108 		return;
109 
110 	vbus = is_vbus_powered(pdata);
111 	if ((vbus ^ gpio_vbus->vbus) == 0)
112 		return;
113 	gpio_vbus->vbus = vbus;
114 
115 	/* Peripheral controllers which manage the pullup themselves won't have
116 	 * gpio_pullup configured here.  If it's configured here, we'll do what
117 	 * isp1301_omap::b_peripheral() does and enable the pullup here... although
118 	 * that may complicate usb_gadget_{,dis}connect() support.
119 	 */
120 	gpio = pdata->gpio_pullup;
121 
122 	if (vbus) {
123 		status = USB_EVENT_VBUS;
124 		gpio_vbus->phy.state = OTG_STATE_B_PERIPHERAL;
125 		gpio_vbus->phy.last_event = status;
126 		usb_gadget_vbus_connect(gpio_vbus->phy.otg->gadget);
127 
128 		/* drawing a "unit load" is *always* OK, except for OTG */
129 		set_vbus_draw(gpio_vbus, 100);
130 
131 		/* optionally enable D+ pullup */
132 		if (gpio_is_valid(gpio))
133 			gpio_set_value(gpio, !pdata->gpio_pullup_inverted);
134 
135 		atomic_notifier_call_chain(&gpio_vbus->phy.notifier,
136 					   status, gpio_vbus->phy.otg->gadget);
137 	} else {
138 		/* optionally disable D+ pullup */
139 		if (gpio_is_valid(gpio))
140 			gpio_set_value(gpio, pdata->gpio_pullup_inverted);
141 
142 		set_vbus_draw(gpio_vbus, 0);
143 
144 		usb_gadget_vbus_disconnect(gpio_vbus->phy.otg->gadget);
145 		status = USB_EVENT_NONE;
146 		gpio_vbus->phy.state = OTG_STATE_B_IDLE;
147 		gpio_vbus->phy.last_event = status;
148 
149 		atomic_notifier_call_chain(&gpio_vbus->phy.notifier,
150 					   status, gpio_vbus->phy.otg->gadget);
151 	}
152 }
153 
154 /* VBUS change IRQ handler */
155 static irqreturn_t gpio_vbus_irq(int irq, void *data)
156 {
157 	struct platform_device *pdev = data;
158 	struct gpio_vbus_mach_info *pdata = dev_get_platdata(&pdev->dev);
159 	struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
160 	struct usb_otg *otg = gpio_vbus->phy.otg;
161 
162 	dev_dbg(&pdev->dev, "VBUS %s (gadget: %s)\n",
163 		is_vbus_powered(pdata) ? "supplied" : "inactive",
164 		otg->gadget ? otg->gadget->name : "none");
165 
166 	if (otg->gadget)
167 		schedule_delayed_work(&gpio_vbus->work, msecs_to_jiffies(100));
168 
169 	return IRQ_HANDLED;
170 }
171 
172 /* OTG transceiver interface */
173 
174 /* bind/unbind the peripheral controller */
175 static int gpio_vbus_set_peripheral(struct usb_otg *otg,
176 					struct usb_gadget *gadget)
177 {
178 	struct gpio_vbus_data *gpio_vbus;
179 	struct gpio_vbus_mach_info *pdata;
180 	struct platform_device *pdev;
181 	int gpio;
182 
183 	gpio_vbus = container_of(otg->phy, struct gpio_vbus_data, phy);
184 	pdev = to_platform_device(gpio_vbus->dev);
185 	pdata = dev_get_platdata(gpio_vbus->dev);
186 	gpio = pdata->gpio_pullup;
187 
188 	if (!gadget) {
189 		dev_dbg(&pdev->dev, "unregistering gadget '%s'\n",
190 			otg->gadget->name);
191 
192 		/* optionally disable D+ pullup */
193 		if (gpio_is_valid(gpio))
194 			gpio_set_value(gpio, pdata->gpio_pullup_inverted);
195 
196 		set_vbus_draw(gpio_vbus, 0);
197 
198 		usb_gadget_vbus_disconnect(otg->gadget);
199 		otg->phy->state = OTG_STATE_UNDEFINED;
200 
201 		otg->gadget = NULL;
202 		return 0;
203 	}
204 
205 	otg->gadget = gadget;
206 	dev_dbg(&pdev->dev, "registered gadget '%s'\n", gadget->name);
207 
208 	/* initialize connection state */
209 	gpio_vbus->vbus = 0; /* start with disconnected */
210 	gpio_vbus_irq(gpio_vbus->irq, pdev);
211 	return 0;
212 }
213 
214 /* effective for B devices, ignored for A-peripheral */
215 static int gpio_vbus_set_power(struct usb_phy *phy, unsigned mA)
216 {
217 	struct gpio_vbus_data *gpio_vbus;
218 
219 	gpio_vbus = container_of(phy, struct gpio_vbus_data, phy);
220 
221 	if (phy->state == OTG_STATE_B_PERIPHERAL)
222 		set_vbus_draw(gpio_vbus, mA);
223 	return 0;
224 }
225 
226 /* for non-OTG B devices: set/clear transceiver suspend mode */
227 static int gpio_vbus_set_suspend(struct usb_phy *phy, int suspend)
228 {
229 	struct gpio_vbus_data *gpio_vbus;
230 
231 	gpio_vbus = container_of(phy, struct gpio_vbus_data, phy);
232 
233 	/* draw max 0 mA from vbus in suspend mode; or the previously
234 	 * recorded amount of current if not suspended
235 	 *
236 	 * NOTE: high powered configs (mA > 100) may draw up to 2.5 mA
237 	 * if they're wake-enabled ... we don't handle that yet.
238 	 */
239 	return gpio_vbus_set_power(phy, suspend ? 0 : gpio_vbus->mA);
240 }
241 
242 /* platform driver interface */
243 
244 static int gpio_vbus_probe(struct platform_device *pdev)
245 {
246 	struct gpio_vbus_mach_info *pdata = dev_get_platdata(&pdev->dev);
247 	struct gpio_vbus_data *gpio_vbus;
248 	struct resource *res;
249 	int err, gpio, irq;
250 	unsigned long irqflags;
251 
252 	if (!pdata || !gpio_is_valid(pdata->gpio_vbus))
253 		return -EINVAL;
254 	gpio = pdata->gpio_vbus;
255 
256 	gpio_vbus = devm_kzalloc(&pdev->dev, sizeof(struct gpio_vbus_data),
257 				 GFP_KERNEL);
258 	if (!gpio_vbus)
259 		return -ENOMEM;
260 
261 	gpio_vbus->phy.otg = devm_kzalloc(&pdev->dev, sizeof(struct usb_otg),
262 					  GFP_KERNEL);
263 	if (!gpio_vbus->phy.otg)
264 		return -ENOMEM;
265 
266 	platform_set_drvdata(pdev, gpio_vbus);
267 	gpio_vbus->dev = &pdev->dev;
268 	gpio_vbus->phy.label = "gpio-vbus";
269 	gpio_vbus->phy.dev = gpio_vbus->dev;
270 	gpio_vbus->phy.set_power = gpio_vbus_set_power;
271 	gpio_vbus->phy.set_suspend = gpio_vbus_set_suspend;
272 	gpio_vbus->phy.state = OTG_STATE_UNDEFINED;
273 
274 	gpio_vbus->phy.otg->phy = &gpio_vbus->phy;
275 	gpio_vbus->phy.otg->set_peripheral = gpio_vbus_set_peripheral;
276 
277 	err = devm_gpio_request(&pdev->dev, gpio, "vbus_detect");
278 	if (err) {
279 		dev_err(&pdev->dev, "can't request vbus gpio %d, err: %d\n",
280 			gpio, err);
281 		return err;
282 	}
283 	gpio_direction_input(gpio);
284 
285 	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
286 	if (res) {
287 		irq = res->start;
288 		irqflags = (res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED;
289 	} else {
290 		irq = gpio_to_irq(gpio);
291 		irqflags = VBUS_IRQ_FLAGS;
292 	}
293 
294 	gpio_vbus->irq = irq;
295 
296 	/* if data line pullup is in use, initialize it to "not pulling up" */
297 	gpio = pdata->gpio_pullup;
298 	if (gpio_is_valid(gpio)) {
299 		err = devm_gpio_request(&pdev->dev, gpio, "udc_pullup");
300 		if (err) {
301 			dev_err(&pdev->dev,
302 				"can't request pullup gpio %d, err: %d\n",
303 				gpio, err);
304 			return err;
305 		}
306 		gpio_direction_output(gpio, pdata->gpio_pullup_inverted);
307 	}
308 
309 	err = devm_request_irq(&pdev->dev, irq, gpio_vbus_irq, irqflags,
310 			       "vbus_detect", pdev);
311 	if (err) {
312 		dev_err(&pdev->dev, "can't request irq %i, err: %d\n",
313 			irq, err);
314 		return err;
315 	}
316 
317 	INIT_DELAYED_WORK(&gpio_vbus->work, gpio_vbus_work);
318 
319 	gpio_vbus->vbus_draw = devm_regulator_get(&pdev->dev, "vbus_draw");
320 	if (IS_ERR(gpio_vbus->vbus_draw)) {
321 		dev_dbg(&pdev->dev, "can't get vbus_draw regulator, err: %ld\n",
322 			PTR_ERR(gpio_vbus->vbus_draw));
323 		gpio_vbus->vbus_draw = NULL;
324 	}
325 
326 	/* only active when a gadget is registered */
327 	err = usb_add_phy(&gpio_vbus->phy, USB_PHY_TYPE_USB2);
328 	if (err) {
329 		dev_err(&pdev->dev, "can't register transceiver, err: %d\n",
330 			err);
331 		return err;
332 	}
333 
334 	device_init_wakeup(&pdev->dev, pdata->wakeup);
335 
336 	return 0;
337 }
338 
339 static int gpio_vbus_remove(struct platform_device *pdev)
340 {
341 	struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
342 
343 	device_init_wakeup(&pdev->dev, 0);
344 	cancel_delayed_work_sync(&gpio_vbus->work);
345 
346 	usb_remove_phy(&gpio_vbus->phy);
347 
348 	return 0;
349 }
350 
351 #ifdef CONFIG_PM
352 static int gpio_vbus_pm_suspend(struct device *dev)
353 {
354 	struct gpio_vbus_data *gpio_vbus = dev_get_drvdata(dev);
355 
356 	if (device_may_wakeup(dev))
357 		enable_irq_wake(gpio_vbus->irq);
358 
359 	return 0;
360 }
361 
362 static int gpio_vbus_pm_resume(struct device *dev)
363 {
364 	struct gpio_vbus_data *gpio_vbus = dev_get_drvdata(dev);
365 
366 	if (device_may_wakeup(dev))
367 		disable_irq_wake(gpio_vbus->irq);
368 
369 	return 0;
370 }
371 
372 static const struct dev_pm_ops gpio_vbus_dev_pm_ops = {
373 	.suspend	= gpio_vbus_pm_suspend,
374 	.resume		= gpio_vbus_pm_resume,
375 };
376 #endif
377 
378 MODULE_ALIAS("platform:gpio-vbus");
379 
380 static struct platform_driver gpio_vbus_driver = {
381 	.driver = {
382 		.name  = "gpio-vbus",
383 		.owner = THIS_MODULE,
384 #ifdef CONFIG_PM
385 		.pm = &gpio_vbus_dev_pm_ops,
386 #endif
387 	},
388 	.probe		= gpio_vbus_probe,
389 	.remove		= gpio_vbus_remove,
390 };
391 
392 module_platform_driver(gpio_vbus_driver);
393 
394 MODULE_DESCRIPTION("simple GPIO controlled OTG transceiver driver");
395 MODULE_AUTHOR("Philipp Zabel");
396 MODULE_LICENSE("GPL");
397