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 */
34struct 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 */
60static 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
89static 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
100static 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.otg->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		usb_phy_set_event(&gpio_vbus->phy, USB_EVENT_ENUMERATED);
138	} else {
139		/* optionally disable D+ pullup */
140		if (gpio_is_valid(gpio))
141			gpio_set_value(gpio, pdata->gpio_pullup_inverted);
142
143		set_vbus_draw(gpio_vbus, 0);
144
145		usb_gadget_vbus_disconnect(gpio_vbus->phy.otg->gadget);
146		status = USB_EVENT_NONE;
147		gpio_vbus->phy.otg->state = OTG_STATE_B_IDLE;
148		gpio_vbus->phy.last_event = status;
149
150		atomic_notifier_call_chain(&gpio_vbus->phy.notifier,
151					   status, gpio_vbus->phy.otg->gadget);
152		usb_phy_set_event(&gpio_vbus->phy, USB_EVENT_NONE);
153	}
154}
155
156/* VBUS change IRQ handler */
157static irqreturn_t gpio_vbus_irq(int irq, void *data)
158{
159	struct platform_device *pdev = data;
160	struct gpio_vbus_mach_info *pdata = dev_get_platdata(&pdev->dev);
161	struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
162	struct usb_otg *otg = gpio_vbus->phy.otg;
163
164	dev_dbg(&pdev->dev, "VBUS %s (gadget: %s)\n",
165		is_vbus_powered(pdata) ? "supplied" : "inactive",
166		otg->gadget ? otg->gadget->name : "none");
167
168	if (otg->gadget)
169		schedule_delayed_work(&gpio_vbus->work, msecs_to_jiffies(100));
170
171	return IRQ_HANDLED;
172}
173
174/* OTG transceiver interface */
175
176/* bind/unbind the peripheral controller */
177static int gpio_vbus_set_peripheral(struct usb_otg *otg,
178					struct usb_gadget *gadget)
179{
180	struct gpio_vbus_data *gpio_vbus;
181	struct gpio_vbus_mach_info *pdata;
182	struct platform_device *pdev;
183	int gpio;
184
185	gpio_vbus = container_of(otg->usb_phy, struct gpio_vbus_data, phy);
186	pdev = to_platform_device(gpio_vbus->dev);
187	pdata = dev_get_platdata(gpio_vbus->dev);
188	gpio = pdata->gpio_pullup;
189
190	if (!gadget) {
191		dev_dbg(&pdev->dev, "unregistering gadget '%s'\n",
192			otg->gadget->name);
193
194		/* optionally disable D+ pullup */
195		if (gpio_is_valid(gpio))
196			gpio_set_value(gpio, pdata->gpio_pullup_inverted);
197
198		set_vbus_draw(gpio_vbus, 0);
199
200		usb_gadget_vbus_disconnect(otg->gadget);
201		otg->state = OTG_STATE_UNDEFINED;
202
203		otg->gadget = NULL;
204		return 0;
205	}
206
207	otg->gadget = gadget;
208	dev_dbg(&pdev->dev, "registered gadget '%s'\n", gadget->name);
209
210	/* initialize connection state */
211	gpio_vbus->vbus = 0; /* start with disconnected */
212	gpio_vbus_irq(gpio_vbus->irq, pdev);
213	return 0;
214}
215
216/* effective for B devices, ignored for A-peripheral */
217static int gpio_vbus_set_power(struct usb_phy *phy, unsigned mA)
218{
219	struct gpio_vbus_data *gpio_vbus;
220
221	gpio_vbus = container_of(phy, struct gpio_vbus_data, phy);
222
223	if (phy->otg->state == OTG_STATE_B_PERIPHERAL)
224		set_vbus_draw(gpio_vbus, mA);
225	return 0;
226}
227
228/* for non-OTG B devices: set/clear transceiver suspend mode */
229static int gpio_vbus_set_suspend(struct usb_phy *phy, int suspend)
230{
231	struct gpio_vbus_data *gpio_vbus;
232
233	gpio_vbus = container_of(phy, struct gpio_vbus_data, phy);
234
235	/* draw max 0 mA from vbus in suspend mode; or the previously
236	 * recorded amount of current if not suspended
237	 *
238	 * NOTE: high powered configs (mA > 100) may draw up to 2.5 mA
239	 * if they're wake-enabled ... we don't handle that yet.
240	 */
241	return gpio_vbus_set_power(phy, suspend ? 0 : gpio_vbus->mA);
242}
243
244/* platform driver interface */
245
246static int gpio_vbus_probe(struct platform_device *pdev)
247{
248	struct gpio_vbus_mach_info *pdata = dev_get_platdata(&pdev->dev);
249	struct gpio_vbus_data *gpio_vbus;
250	struct resource *res;
251	int err, gpio, irq;
252	unsigned long irqflags;
253
254	if (!pdata || !gpio_is_valid(pdata->gpio_vbus))
255		return -EINVAL;
256	gpio = pdata->gpio_vbus;
257
258	gpio_vbus = devm_kzalloc(&pdev->dev, sizeof(struct gpio_vbus_data),
259				 GFP_KERNEL);
260	if (!gpio_vbus)
261		return -ENOMEM;
262
263	gpio_vbus->phy.otg = devm_kzalloc(&pdev->dev, sizeof(struct usb_otg),
264					  GFP_KERNEL);
265	if (!gpio_vbus->phy.otg)
266		return -ENOMEM;
267
268	platform_set_drvdata(pdev, gpio_vbus);
269	gpio_vbus->dev = &pdev->dev;
270	gpio_vbus->phy.label = "gpio-vbus";
271	gpio_vbus->phy.dev = gpio_vbus->dev;
272	gpio_vbus->phy.set_power = gpio_vbus_set_power;
273	gpio_vbus->phy.set_suspend = gpio_vbus_set_suspend;
274
275	gpio_vbus->phy.otg->state = OTG_STATE_UNDEFINED;
276	gpio_vbus->phy.otg->usb_phy = &gpio_vbus->phy;
277	gpio_vbus->phy.otg->set_peripheral = gpio_vbus_set_peripheral;
278
279	err = devm_gpio_request(&pdev->dev, gpio, "vbus_detect");
280	if (err) {
281		dev_err(&pdev->dev, "can't request vbus gpio %d, err: %d\n",
282			gpio, err);
283		return err;
284	}
285	gpio_direction_input(gpio);
286
287	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
288	if (res) {
289		irq = res->start;
290		irqflags = (res->flags & IRQF_TRIGGER_MASK) | IRQF_SHARED;
291	} else {
292		irq = gpio_to_irq(gpio);
293		irqflags = VBUS_IRQ_FLAGS;
294	}
295
296	gpio_vbus->irq = irq;
297
298	/* if data line pullup is in use, initialize it to "not pulling up" */
299	gpio = pdata->gpio_pullup;
300	if (gpio_is_valid(gpio)) {
301		err = devm_gpio_request(&pdev->dev, gpio, "udc_pullup");
302		if (err) {
303			dev_err(&pdev->dev,
304				"can't request pullup gpio %d, err: %d\n",
305				gpio, err);
306			return err;
307		}
308		gpio_direction_output(gpio, pdata->gpio_pullup_inverted);
309	}
310
311	err = devm_request_irq(&pdev->dev, irq, gpio_vbus_irq, irqflags,
312			       "vbus_detect", pdev);
313	if (err) {
314		dev_err(&pdev->dev, "can't request irq %i, err: %d\n",
315			irq, err);
316		return err;
317	}
318
319	INIT_DELAYED_WORK(&gpio_vbus->work, gpio_vbus_work);
320
321	gpio_vbus->vbus_draw = devm_regulator_get(&pdev->dev, "vbus_draw");
322	if (IS_ERR(gpio_vbus->vbus_draw)) {
323		dev_dbg(&pdev->dev, "can't get vbus_draw regulator, err: %ld\n",
324			PTR_ERR(gpio_vbus->vbus_draw));
325		gpio_vbus->vbus_draw = NULL;
326	}
327
328	/* only active when a gadget is registered */
329	err = usb_add_phy(&gpio_vbus->phy, USB_PHY_TYPE_USB2);
330	if (err) {
331		dev_err(&pdev->dev, "can't register transceiver, err: %d\n",
332			err);
333		return err;
334	}
335
336	device_init_wakeup(&pdev->dev, pdata->wakeup);
337
338	return 0;
339}
340
341static int gpio_vbus_remove(struct platform_device *pdev)
342{
343	struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
344
345	device_init_wakeup(&pdev->dev, 0);
346	cancel_delayed_work_sync(&gpio_vbus->work);
347
348	usb_remove_phy(&gpio_vbus->phy);
349
350	return 0;
351}
352
353#ifdef CONFIG_PM
354static int gpio_vbus_pm_suspend(struct device *dev)
355{
356	struct gpio_vbus_data *gpio_vbus = dev_get_drvdata(dev);
357
358	if (device_may_wakeup(dev))
359		enable_irq_wake(gpio_vbus->irq);
360
361	return 0;
362}
363
364static int gpio_vbus_pm_resume(struct device *dev)
365{
366	struct gpio_vbus_data *gpio_vbus = dev_get_drvdata(dev);
367
368	if (device_may_wakeup(dev))
369		disable_irq_wake(gpio_vbus->irq);
370
371	return 0;
372}
373
374static const struct dev_pm_ops gpio_vbus_dev_pm_ops = {
375	.suspend	= gpio_vbus_pm_suspend,
376	.resume		= gpio_vbus_pm_resume,
377};
378#endif
379
380MODULE_ALIAS("platform:gpio-vbus");
381
382static struct platform_driver gpio_vbus_driver = {
383	.driver = {
384		.name  = "gpio-vbus",
385#ifdef CONFIG_PM
386		.pm = &gpio_vbus_dev_pm_ops,
387#endif
388	},
389	.probe		= gpio_vbus_probe,
390	.remove		= gpio_vbus_remove,
391};
392
393module_platform_driver(gpio_vbus_driver);
394
395MODULE_DESCRIPTION("simple GPIO controlled OTG transceiver driver");
396MODULE_AUTHOR("Philipp Zabel");
397MODULE_LICENSE("GPL");
398