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 };
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_SAMPLE_RANDOM | IRQF_SHARED \
55 | IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING )
56
57
58 /* interface to regulator framework */
set_vbus_draw(struct gpio_vbus_data * gpio_vbus,unsigned mA)59 static void set_vbus_draw(struct gpio_vbus_data *gpio_vbus, unsigned mA)
60 {
61 struct regulator *vbus_draw = gpio_vbus->vbus_draw;
62 int enabled;
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 regulator_enable(vbus_draw);
72 gpio_vbus->vbus_draw_enabled = 1;
73 }
74 } else {
75 if (enabled) {
76 regulator_disable(vbus_draw);
77 gpio_vbus->vbus_draw_enabled = 0;
78 }
79 }
80 gpio_vbus->mA = mA;
81 }
82
is_vbus_powered(struct gpio_vbus_mach_info * pdata)83 static int is_vbus_powered(struct gpio_vbus_mach_info *pdata)
84 {
85 int vbus;
86
87 vbus = gpio_get_value(pdata->gpio_vbus);
88 if (pdata->gpio_vbus_inverted)
89 vbus = !vbus;
90
91 return vbus;
92 }
93
gpio_vbus_work(struct work_struct * work)94 static void gpio_vbus_work(struct work_struct *work)
95 {
96 struct gpio_vbus_data *gpio_vbus =
97 container_of(work, struct gpio_vbus_data, work.work);
98 struct gpio_vbus_mach_info *pdata = gpio_vbus->dev->platform_data;
99 int gpio, status;
100
101 if (!gpio_vbus->phy.otg->gadget)
102 return;
103
104 /* Peripheral controllers which manage the pullup themselves won't have
105 * gpio_pullup configured here. If it's configured here, we'll do what
106 * isp1301_omap::b_peripheral() does and enable the pullup here... although
107 * that may complicate usb_gadget_{,dis}connect() support.
108 */
109 gpio = pdata->gpio_pullup;
110 if (is_vbus_powered(pdata)) {
111 status = USB_EVENT_VBUS;
112 gpio_vbus->phy.state = OTG_STATE_B_PERIPHERAL;
113 gpio_vbus->phy.last_event = status;
114 usb_gadget_vbus_connect(gpio_vbus->phy.otg->gadget);
115
116 /* drawing a "unit load" is *always* OK, except for OTG */
117 set_vbus_draw(gpio_vbus, 100);
118
119 /* optionally enable D+ pullup */
120 if (gpio_is_valid(gpio))
121 gpio_set_value(gpio, !pdata->gpio_pullup_inverted);
122
123 atomic_notifier_call_chain(&gpio_vbus->phy.notifier,
124 status, gpio_vbus->phy.otg->gadget);
125 } else {
126 /* optionally disable D+ pullup */
127 if (gpio_is_valid(gpio))
128 gpio_set_value(gpio, pdata->gpio_pullup_inverted);
129
130 set_vbus_draw(gpio_vbus, 0);
131
132 usb_gadget_vbus_disconnect(gpio_vbus->phy.otg->gadget);
133 status = USB_EVENT_NONE;
134 gpio_vbus->phy.state = OTG_STATE_B_IDLE;
135 gpio_vbus->phy.last_event = status;
136
137 atomic_notifier_call_chain(&gpio_vbus->phy.notifier,
138 status, gpio_vbus->phy.otg->gadget);
139 }
140 }
141
142 /* VBUS change IRQ handler */
gpio_vbus_irq(int irq,void * data)143 static irqreturn_t gpio_vbus_irq(int irq, void *data)
144 {
145 struct platform_device *pdev = data;
146 struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
147 struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
148 struct usb_otg *otg = gpio_vbus->phy.otg;
149
150 dev_dbg(&pdev->dev, "VBUS %s (gadget: %s)\n",
151 is_vbus_powered(pdata) ? "supplied" : "inactive",
152 otg->gadget ? otg->gadget->name : "none");
153
154 if (otg->gadget)
155 schedule_delayed_work(&gpio_vbus->work, msecs_to_jiffies(100));
156
157 return IRQ_HANDLED;
158 }
159
160 /* OTG transceiver interface */
161
162 /* bind/unbind the peripheral controller */
gpio_vbus_set_peripheral(struct usb_otg * otg,struct usb_gadget * gadget)163 static int gpio_vbus_set_peripheral(struct usb_otg *otg,
164 struct usb_gadget *gadget)
165 {
166 struct gpio_vbus_data *gpio_vbus;
167 struct gpio_vbus_mach_info *pdata;
168 struct platform_device *pdev;
169 int gpio, irq;
170
171 gpio_vbus = container_of(otg->phy, struct gpio_vbus_data, phy);
172 pdev = to_platform_device(gpio_vbus->dev);
173 pdata = gpio_vbus->dev->platform_data;
174 irq = gpio_to_irq(pdata->gpio_vbus);
175 gpio = pdata->gpio_pullup;
176
177 if (!gadget) {
178 dev_dbg(&pdev->dev, "unregistering gadget '%s'\n",
179 otg->gadget->name);
180
181 /* optionally disable D+ pullup */
182 if (gpio_is_valid(gpio))
183 gpio_set_value(gpio, pdata->gpio_pullup_inverted);
184
185 set_vbus_draw(gpio_vbus, 0);
186
187 usb_gadget_vbus_disconnect(otg->gadget);
188 otg->phy->state = OTG_STATE_UNDEFINED;
189
190 otg->gadget = NULL;
191 return 0;
192 }
193
194 otg->gadget = gadget;
195 dev_dbg(&pdev->dev, "registered gadget '%s'\n", gadget->name);
196
197 /* initialize connection state */
198 gpio_vbus_irq(irq, pdev);
199 return 0;
200 }
201
202 /* effective for B devices, ignored for A-peripheral */
gpio_vbus_set_power(struct usb_phy * phy,unsigned mA)203 static int gpio_vbus_set_power(struct usb_phy *phy, unsigned mA)
204 {
205 struct gpio_vbus_data *gpio_vbus;
206
207 gpio_vbus = container_of(phy, struct gpio_vbus_data, phy);
208
209 if (phy->state == OTG_STATE_B_PERIPHERAL)
210 set_vbus_draw(gpio_vbus, mA);
211 return 0;
212 }
213
214 /* for non-OTG B devices: set/clear transceiver suspend mode */
gpio_vbus_set_suspend(struct usb_phy * phy,int suspend)215 static int gpio_vbus_set_suspend(struct usb_phy *phy, int suspend)
216 {
217 struct gpio_vbus_data *gpio_vbus;
218
219 gpio_vbus = container_of(phy, struct gpio_vbus_data, phy);
220
221 /* draw max 0 mA from vbus in suspend mode; or the previously
222 * recorded amount of current if not suspended
223 *
224 * NOTE: high powered configs (mA > 100) may draw up to 2.5 mA
225 * if they're wake-enabled ... we don't handle that yet.
226 */
227 return gpio_vbus_set_power(phy, suspend ? 0 : gpio_vbus->mA);
228 }
229
230 /* platform driver interface */
231
gpio_vbus_probe(struct platform_device * pdev)232 static int __init gpio_vbus_probe(struct platform_device *pdev)
233 {
234 struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
235 struct gpio_vbus_data *gpio_vbus;
236 struct resource *res;
237 int err, gpio, irq;
238
239 if (!pdata || !gpio_is_valid(pdata->gpio_vbus))
240 return -EINVAL;
241 gpio = pdata->gpio_vbus;
242
243 gpio_vbus = kzalloc(sizeof(struct gpio_vbus_data), GFP_KERNEL);
244 if (!gpio_vbus)
245 return -ENOMEM;
246
247 gpio_vbus->phy.otg = kzalloc(sizeof(struct usb_otg), GFP_KERNEL);
248 if (!gpio_vbus->phy.otg) {
249 kfree(gpio_vbus);
250 return -ENOMEM;
251 }
252
253 platform_set_drvdata(pdev, gpio_vbus);
254 gpio_vbus->dev = &pdev->dev;
255 gpio_vbus->phy.label = "gpio-vbus";
256 gpio_vbus->phy.set_power = gpio_vbus_set_power;
257 gpio_vbus->phy.set_suspend = gpio_vbus_set_suspend;
258 gpio_vbus->phy.state = OTG_STATE_UNDEFINED;
259
260 gpio_vbus->phy.otg->phy = &gpio_vbus->phy;
261 gpio_vbus->phy.otg->set_peripheral = gpio_vbus_set_peripheral;
262
263 err = gpio_request(gpio, "vbus_detect");
264 if (err) {
265 dev_err(&pdev->dev, "can't request vbus gpio %d, err: %d\n",
266 gpio, err);
267 goto err_gpio;
268 }
269 gpio_direction_input(gpio);
270
271 res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
272 if (res) {
273 irq = res->start;
274 res->flags &= IRQF_TRIGGER_MASK;
275 res->flags |= IRQF_SAMPLE_RANDOM | IRQF_SHARED;
276 } else
277 irq = gpio_to_irq(gpio);
278
279 /* if data line pullup is in use, initialize it to "not pulling up" */
280 gpio = pdata->gpio_pullup;
281 if (gpio_is_valid(gpio)) {
282 err = gpio_request(gpio, "udc_pullup");
283 if (err) {
284 dev_err(&pdev->dev,
285 "can't request pullup gpio %d, err: %d\n",
286 gpio, err);
287 gpio_free(pdata->gpio_vbus);
288 goto err_gpio;
289 }
290 gpio_direction_output(gpio, pdata->gpio_pullup_inverted);
291 }
292
293 err = request_irq(irq, gpio_vbus_irq, VBUS_IRQ_FLAGS,
294 "vbus_detect", pdev);
295 if (err) {
296 dev_err(&pdev->dev, "can't request irq %i, err: %d\n",
297 irq, err);
298 goto err_irq;
299 }
300
301 ATOMIC_INIT_NOTIFIER_HEAD(&gpio_vbus->phy.notifier);
302
303 INIT_DELAYED_WORK(&gpio_vbus->work, gpio_vbus_work);
304
305 gpio_vbus->vbus_draw = regulator_get(&pdev->dev, "vbus_draw");
306 if (IS_ERR(gpio_vbus->vbus_draw)) {
307 dev_dbg(&pdev->dev, "can't get vbus_draw regulator, err: %ld\n",
308 PTR_ERR(gpio_vbus->vbus_draw));
309 gpio_vbus->vbus_draw = NULL;
310 }
311
312 /* only active when a gadget is registered */
313 err = usb_set_transceiver(&gpio_vbus->phy);
314 if (err) {
315 dev_err(&pdev->dev, "can't register transceiver, err: %d\n",
316 err);
317 goto err_otg;
318 }
319
320 return 0;
321 err_otg:
322 free_irq(irq, &pdev->dev);
323 err_irq:
324 if (gpio_is_valid(pdata->gpio_pullup))
325 gpio_free(pdata->gpio_pullup);
326 gpio_free(pdata->gpio_vbus);
327 err_gpio:
328 platform_set_drvdata(pdev, NULL);
329 kfree(gpio_vbus->phy.otg);
330 kfree(gpio_vbus);
331 return err;
332 }
333
gpio_vbus_remove(struct platform_device * pdev)334 static int __exit gpio_vbus_remove(struct platform_device *pdev)
335 {
336 struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
337 struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
338 int gpio = pdata->gpio_vbus;
339
340 regulator_put(gpio_vbus->vbus_draw);
341
342 usb_set_transceiver(NULL);
343
344 free_irq(gpio_to_irq(gpio), &pdev->dev);
345 if (gpio_is_valid(pdata->gpio_pullup))
346 gpio_free(pdata->gpio_pullup);
347 gpio_free(gpio);
348 platform_set_drvdata(pdev, NULL);
349 kfree(gpio_vbus->phy.otg);
350 kfree(gpio_vbus);
351
352 return 0;
353 }
354
355 /* NOTE: the gpio-vbus device may *NOT* be hotplugged */
356
357 MODULE_ALIAS("platform:gpio-vbus");
358
359 static struct platform_driver gpio_vbus_driver = {
360 .driver = {
361 .name = "gpio-vbus",
362 .owner = THIS_MODULE,
363 },
364 .remove = __exit_p(gpio_vbus_remove),
365 };
366
gpio_vbus_init(void)367 static int __init gpio_vbus_init(void)
368 {
369 return platform_driver_probe(&gpio_vbus_driver, gpio_vbus_probe);
370 }
371 module_init(gpio_vbus_init);
372
gpio_vbus_exit(void)373 static void __exit gpio_vbus_exit(void)
374 {
375 platform_driver_unregister(&gpio_vbus_driver);
376 }
377 module_exit(gpio_vbus_exit);
378
379 MODULE_DESCRIPTION("simple GPIO controlled OTG transceiver driver");
380 MODULE_AUTHOR("Philipp Zabel");
381 MODULE_LICENSE("GPL");
382