drivers/usb/otg/gpio_vbus.c

   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/interrupt.h>
  15 #include <linux/usb.h>
  16 #include <linux/workqueue.h>
  17
  18 #include <linux/regulator/consumer.h>
  19
  20 #include <linux/usb/gadget.h>
  21 #include <linux/usb/gpio_vbus.h>
  22 #include <linux/usb/otg.h>
  23
  24
  25 /*
  26  * A simple GPIO VBUS sensing driver for B peripheral only devices
  27  * with internal transceivers. It can control a D+ pullup GPIO and
  28  * a regulator to limit the current drawn from VBUS.
  29  *
  30  * Needs to be loaded before the UDC driver that will use it.
  31  */
  32 struct gpio_vbus_data {
  33         struct otg_transceiver otg;
  34         struct device          *dev;
  35         struct regulator       *vbus_draw;
  36         int                     vbus_draw_enabled;
  37         unsigned                mA;
  38         struct work_struct      work;
  39 };
  40
  41
  42 /*
  43  * This driver relies on "both edges" triggering.  VBUS has 100 msec to
  44  * stabilize, so the peripheral controller driver may need to cope with
  45  * some bouncing due to current surges (e.g. charging local capacitance)
  46  * and contact chatter.
  47  *
  48  * REVISIT in desperate straits, toggling between rising and falling
  49  * edges might be workable.
  50  */
  51 #define VBUS_IRQ_FLAGS \
  52         ( IRQF_SAMPLE_RANDOM | IRQF_SHARED \
  53         | IRQF_TRIGGER_RISING | IRQF_TRIGGER_FALLING )
  54
  55
  56 /* interface to regulator framework */
  57 static void set_vbus_draw(struct gpio_vbus_data *gpio_vbus, unsigned mA)
  58 {
  59         struct regulator *vbus_draw = gpio_vbus->vbus_draw;
  60         int enabled;
  61
  62         if (!vbus_draw)
  63                 return;
  64
  65         enabled = gpio_vbus->vbus_draw_enabled;
  66         if (mA) {
  67                 regulator_set_current_limit(vbus_draw, 0, 1000 * mA);
  68                 if (!enabled) {
  69                         regulator_enable(vbus_draw);
  70                         gpio_vbus->vbus_draw_enabled = 1;
  71                 }
  72         } else {
  73                 if (enabled) {
  74                         regulator_disable(vbus_draw);
  75                         gpio_vbus->vbus_draw_enabled = 0;
  76                 }
  77         }
  78         gpio_vbus->mA = mA;
  79 }
  80
  81 static int is_vbus_powered(struct gpio_vbus_mach_info *pdata)
  82 {
  83         int vbus;
  84
  85         vbus = gpio_get_value(pdata->gpio_vbus);
  86         if (pdata->gpio_vbus_inverted)
  87                 vbus = !vbus;
  88
  89         return vbus;
  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);
  96         struct gpio_vbus_mach_info *pdata = gpio_vbus->dev->platform_data;
  97         int gpio;
  98
  99         if (!gpio_vbus->otg.gadget)
 100                 return;
 101
 102         /* Peripheral controllers which manage the pullup themselves won't have
 103          * gpio_pullup configured here.  If it's configured here, we'll do what
 104          * isp1301_omap::b_peripheral() does and enable the pullup here... although
 105          * that may complicate usb_gadget_{,dis}connect() support.
 106          */
 107         gpio = pdata->gpio_pullup;
 108         if (is_vbus_powered(pdata)) {
 109                 gpio_vbus->otg.state = OTG_STATE_B_PERIPHERAL;
 110                 usb_gadget_vbus_connect(gpio_vbus->otg.gadget);
 111
 112                 /* drawing a "unit load" is *always* OK, except for OTG */
 113                 set_vbus_draw(gpio_vbus, 100);
 114
 115                 /* optionally enable D+ pullup */
 116                 if (gpio_is_valid(gpio))
 117                         gpio_set_value(gpio, !pdata->gpio_pullup_inverted);
 118         } else {
 119                 /* optionally disable D+ pullup */
 120                 if (gpio_is_valid(gpio))
 121                         gpio_set_value(gpio, pdata->gpio_pullup_inverted);
 122
 123                 set_vbus_draw(gpio_vbus, 0);
 124
 125                 usb_gadget_vbus_disconnect(gpio_vbus->otg.gadget);
 126                 gpio_vbus->otg.state = OTG_STATE_B_IDLE;
 127         }
 128 }
 129
 130 /* VBUS change IRQ handler */
 131 static irqreturn_t gpio_vbus_irq(int irq, void *data)
 132 {
 133         struct platform_device *pdev = data;
 134         struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
 135         struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
 136
 137         dev_dbg(&pdev->dev, "VBUS %s (gadget: %s)\n",
 138                 is_vbus_powered(pdata) ? "supplied" : "inactive",
 139                 gpio_vbus->otg.gadget ? gpio_vbus->otg.gadget->name : "none");
 140
 141         if (gpio_vbus->otg.gadget)
 142                 schedule_work(&gpio_vbus->work);
 143
 144         return IRQ_HANDLED;
 145 }
 146
 147 /* OTG transceiver interface */
 148
 149 /* bind/unbind the peripheral controller */
 150 static int gpio_vbus_set_peripheral(struct otg_transceiver *otg,
 151                                 struct usb_gadget *gadget)
 152 {
 153         struct gpio_vbus_data *gpio_vbus;
 154         struct gpio_vbus_mach_info *pdata;
 155         struct platform_device *pdev;
 156         int gpio, irq;
 157
 158         gpio_vbus = container_of(otg, struct gpio_vbus_data, otg);
 159         pdev = to_platform_device(gpio_vbus->dev);
 160         pdata = gpio_vbus->dev->platform_data;
 161         irq = gpio_to_irq(pdata->gpio_vbus);
 162         gpio = pdata->gpio_pullup;
 163
 164         if (!gadget) {
 165                 dev_dbg(&pdev->dev, "unregistering gadget '%s'\n",
 166                         otg->gadget->name);
 167
 168                 /* optionally disable D+ pullup */
 169                 if (gpio_is_valid(gpio))
 170                         gpio_set_value(gpio, pdata->gpio_pullup_inverted);
 171
 172                 set_vbus_draw(gpio_vbus, 0);
 173
 174                 usb_gadget_vbus_disconnect(otg->gadget);
 175                 otg->state = OTG_STATE_UNDEFINED;
 176
 177                 otg->gadget = NULL;
 178                 return 0;
 179         }
 180
 181         otg->gadget = gadget;
 182         dev_dbg(&pdev->dev, "registered gadget '%s'\n", gadget->name);
 183
 184         /* initialize connection state */
 185         gpio_vbus_irq(irq, pdev);
 186         return 0;
 187 }
 188
 189 /* effective for B devices, ignored for A-peripheral */
 190 static int gpio_vbus_set_power(struct otg_transceiver *otg, unsigned mA)
 191 {
 192         struct gpio_vbus_data *gpio_vbus;
 193
 194         gpio_vbus = container_of(otg, struct gpio_vbus_data, otg);
 195
 196         if (otg->state == OTG_STATE_B_PERIPHERAL)
 197                 set_vbus_draw(gpio_vbus, mA);
 198         return 0;
 199 }
 200
 201 /* for non-OTG B devices: set/clear transceiver suspend mode */
 202 static int gpio_vbus_set_suspend(struct otg_transceiver *otg, int suspend)
 203 {
 204         struct gpio_vbus_data *gpio_vbus;
 205
 206         gpio_vbus = container_of(otg, struct gpio_vbus_data, otg);
 207
 208         /* draw max 0 mA from vbus in suspend mode; or the previously
 209          * recorded amount of current if not suspended
 210          *
 211          * NOTE: high powered configs (mA > 100) may draw up to 2.5 mA
 212          * if they're wake-enabled ... we don't handle that yet.
 213          */
 214         return gpio_vbus_set_power(otg, suspend ? 0 : gpio_vbus->mA);
 215 }
 216
 217 /* platform driver interface */
 218
 219 static int __init gpio_vbus_probe(struct platform_device *pdev)
 220 {
 221         struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
 222         struct gpio_vbus_data *gpio_vbus;
 223         struct resource *res;
 224         int err, gpio, irq;
 225
 226         if (!pdata || !gpio_is_valid(pdata->gpio_vbus))
 227                 return -EINVAL;
 228         gpio = pdata->gpio_vbus;
 229
 230         gpio_vbus = kzalloc(sizeof(struct gpio_vbus_data), GFP_KERNEL);
 231         if (!gpio_vbus)
 232                 return -ENOMEM;
 233
 234         platform_set_drvdata(pdev, gpio_vbus);
 235         gpio_vbus->dev = &pdev->dev;
 236         gpio_vbus->otg.label = "gpio-vbus";
 237         gpio_vbus->otg.state = OTG_STATE_UNDEFINED;
 238         gpio_vbus->otg.set_peripheral = gpio_vbus_set_peripheral;
 239         gpio_vbus->otg.set_power = gpio_vbus_set_power;
 240         gpio_vbus->otg.set_suspend = gpio_vbus_set_suspend;
 241
 242         err = gpio_request(gpio, "vbus_detect");
 243         if (err) {
 244                 dev_err(&pdev->dev, "can't request vbus gpio %d, err: %d\n",
 245                         gpio, err);
 246                 goto err_gpio;
 247         }
 248         gpio_direction_input(gpio);
 249
 250         res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 251         if (res) {
 252                 irq = res->start;
 253                 res->flags &= IRQF_TRIGGER_MASK;
 254                 res->flags |= IRQF_SAMPLE_RANDOM | IRQF_SHARED;
 255         } else
 256                 irq = gpio_to_irq(gpio);
 257
 258         /* if data line pullup is in use, initialize it to "not pulling up" */
 259         gpio = pdata->gpio_pullup;
 260         if (gpio_is_valid(gpio)) {
 261                 err = gpio_request(gpio, "udc_pullup");
 262                 if (err) {
 263                         dev_err(&pdev->dev,
 264                                 "can't request pullup gpio %d, err: %d\n",
 265                                 gpio, err);
 266                         gpio_free(pdata->gpio_vbus);
 267                         goto err_gpio;
 268                 }
 269                 gpio_direction_output(gpio, pdata->gpio_pullup_inverted);
 270         }
 271
 272         err = request_irq(irq, gpio_vbus_irq, VBUS_IRQ_FLAGS,
 273                 "vbus_detect", pdev);
 274         if (err) {
 275                 dev_err(&pdev->dev, "can't request irq %i, err: %d\n",
 276                         irq, err);
 277                 goto err_irq;
 278         }
 279         INIT_WORK(&gpio_vbus->work, gpio_vbus_work);
 280
 281         /* only active when a gadget is registered */
 282         err = otg_set_transceiver(&gpio_vbus->otg);
 283         if (err) {
 284                 dev_err(&pdev->dev, "can't register transceiver, err: %d\n",
 285                         err);
 286                 goto err_otg;
 287         }
 288
 289         gpio_vbus->vbus_draw = regulator_get(&pdev->dev, "vbus_draw");
 290         if (IS_ERR(gpio_vbus->vbus_draw)) {
 291                 dev_dbg(&pdev->dev, "can't get vbus_draw regulator, err: %ld\n",
 292                         PTR_ERR(gpio_vbus->vbus_draw));
 293                 gpio_vbus->vbus_draw = NULL;
 294         }
 295
 296         return 0;
 297 err_otg:
 298         free_irq(irq, &pdev->dev);
 299 err_irq:
 300         if (gpio_is_valid(pdata->gpio_pullup))
 301                 gpio_free(pdata->gpio_pullup);
 302         gpio_free(pdata->gpio_vbus);
 303 err_gpio:
 304         platform_set_drvdata(pdev, NULL);
 305         kfree(gpio_vbus);
 306         return err;
 307 }
 308
 309 static int __exit gpio_vbus_remove(struct platform_device *pdev)
 310 {
 311         struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
 312         struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
 313         int gpio = pdata->gpio_vbus;
 314
 315         regulator_put(gpio_vbus->vbus_draw);
 316
 317         otg_set_transceiver(NULL);
 318
 319         free_irq(gpio_to_irq(gpio), &pdev->dev);
 320         if (gpio_is_valid(pdata->gpio_pullup))
 321                 gpio_free(pdata->gpio_pullup);
 322         gpio_free(gpio);
 323         platform_set_drvdata(pdev, NULL);
 324         kfree(gpio_vbus);
 325
 326         return 0;
 327 }
 328
 329 /* NOTE:  the gpio-vbus device may *NOT* be hotplugged */
 330
 331 MODULE_ALIAS("platform:gpio-vbus");
 332
 333 static struct platform_driver gpio_vbus_driver = {
 334         .driver = {
 335                 .name  = "gpio-vbus",
 336                 .owner = THIS_MODULE,
 337         },
 338         .remove  = __exit_p(gpio_vbus_remove),
 339 };
 340
 341 static int __init gpio_vbus_init(void)
 342 {
 343         return platform_driver_probe(&gpio_vbus_driver, gpio_vbus_probe);
 344 }
 345 module_init(gpio_vbus_init);
 346
 347 static void __exit gpio_vbus_exit(void)
 348 {
 349         platform_driver_unregister(&gpio_vbus_driver);
 350 }
 351 module_exit(gpio_vbus_exit);
 352
 353 MODULE_DESCRIPTION("simple GPIO controlled OTG transceiver driver");
 354 MODULE_AUTHOR("Philipp Zabel");
 355 MODULE_LICENSE("GPL");