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/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 otg_transceiver otg;
  36         struct device          *dev;
  37         struct regulator       *vbus_draw;
  38         int                     vbus_draw_enabled;
  39         unsigned                mA;
  40         struct work_struct      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 */
  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
  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
  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);
  98         struct gpio_vbus_mach_info *pdata = gpio_vbus->dev->platform_data;
  99         int gpio;
 100
 101         if (!gpio_vbus->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                 gpio_vbus->otg.state = OTG_STATE_B_PERIPHERAL;
 112                 usb_gadget_vbus_connect(gpio_vbus->otg.gadget);
 113
 114                 /* drawing a "unit load" is *always* OK, except for OTG */
 115                 set_vbus_draw(gpio_vbus, 100);
 116
 117                 /* optionally enable D+ pullup */
 118                 if (gpio_is_valid(gpio))
 119                         gpio_set_value(gpio, !pdata->gpio_pullup_inverted);
 120         } else {
 121                 /* optionally disable D+ pullup */
 122                 if (gpio_is_valid(gpio))
 123                         gpio_set_value(gpio, pdata->gpio_pullup_inverted);
 124
 125                 set_vbus_draw(gpio_vbus, 0);
 126
 127                 usb_gadget_vbus_disconnect(gpio_vbus->otg.gadget);
 128                 gpio_vbus->otg.state = OTG_STATE_B_IDLE;
 129         }
 130 }
 131
 132 /* VBUS change IRQ handler */
 133 static irqreturn_t gpio_vbus_irq(int irq, void *data)
 134 {
 135         struct platform_device *pdev = data;
 136         struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
 137         struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
 138
 139         dev_dbg(&pdev->dev, "VBUS %s (gadget: %s)\n",
 140                 is_vbus_powered(pdata) ? "supplied" : "inactive",
 141                 gpio_vbus->otg.gadget ? gpio_vbus->otg.gadget->name : "none");
 142
 143         if (gpio_vbus->otg.gadget)
 144                 schedule_work(&gpio_vbus->work);
 145
 146         return IRQ_HANDLED;
 147 }
 148
 149 /* OTG transceiver interface */
 150
 151 /* bind/unbind the peripheral controller */
 152 static int gpio_vbus_set_peripheral(struct otg_transceiver *otg,
 153                                 struct usb_gadget *gadget)
 154 {
 155         struct gpio_vbus_data *gpio_vbus;
 156         struct gpio_vbus_mach_info *pdata;
 157         struct platform_device *pdev;
 158         int gpio, irq;
 159
 160         gpio_vbus = container_of(otg, struct gpio_vbus_data, otg);
 161         pdev = to_platform_device(gpio_vbus->dev);
 162         pdata = gpio_vbus->dev->platform_data;
 163         irq = gpio_to_irq(pdata->gpio_vbus);
 164         gpio = pdata->gpio_pullup;
 165
 166         if (!gadget) {
 167                 dev_dbg(&pdev->dev, "unregistering gadget '%s'\n",
 168                         otg->gadget->name);
 169
 170                 /* optionally disable D+ pullup */
 171                 if (gpio_is_valid(gpio))
 172                         gpio_set_value(gpio, pdata->gpio_pullup_inverted);
 173
 174                 set_vbus_draw(gpio_vbus, 0);
 175
 176                 usb_gadget_vbus_disconnect(otg->gadget);
 177                 otg->state = OTG_STATE_UNDEFINED;
 178
 179                 otg->gadget = NULL;
 180                 return 0;
 181         }
 182
 183         otg->gadget = gadget;
 184         dev_dbg(&pdev->dev, "registered gadget '%s'\n", gadget->name);
 185
 186         /* initialize connection state */
 187         gpio_vbus_irq(irq, pdev);
 188         return 0;
 189 }
 190
 191 /* effective for B devices, ignored for A-peripheral */
 192 static int gpio_vbus_set_power(struct otg_transceiver *otg, unsigned mA)
 193 {
 194         struct gpio_vbus_data *gpio_vbus;
 195
 196         gpio_vbus = container_of(otg, struct gpio_vbus_data, otg);
 197
 198         if (otg->state == OTG_STATE_B_PERIPHERAL)
 199                 set_vbus_draw(gpio_vbus, mA);
 200         return 0;
 201 }
 202
 203 /* for non-OTG B devices: set/clear transceiver suspend mode */
 204 static int gpio_vbus_set_suspend(struct otg_transceiver *otg, int suspend)
 205 {
 206         struct gpio_vbus_data *gpio_vbus;
 207
 208         gpio_vbus = container_of(otg, struct gpio_vbus_data, otg);
 209
 210         /* draw max 0 mA from vbus in suspend mode; or the previously
 211          * recorded amount of current if not suspended
 212          *
 213          * NOTE: high powered configs (mA > 100) may draw up to 2.5 mA
 214          * if they're wake-enabled ... we don't handle that yet.
 215          */
 216         return gpio_vbus_set_power(otg, suspend ? 0 : gpio_vbus->mA);
 217 }
 218
 219 /* platform driver interface */
 220
 221 static int __init gpio_vbus_probe(struct platform_device *pdev)
 222 {
 223         struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
 224         struct gpio_vbus_data *gpio_vbus;
 225         struct resource *res;
 226         int err, gpio, irq;
 227
 228         if (!pdata || !gpio_is_valid(pdata->gpio_vbus))
 229                 return -EINVAL;
 230         gpio = pdata->gpio_vbus;
 231
 232         gpio_vbus = kzalloc(sizeof(struct gpio_vbus_data), GFP_KERNEL);
 233         if (!gpio_vbus)
 234                 return -ENOMEM;
 235
 236         platform_set_drvdata(pdev, gpio_vbus);
 237         gpio_vbus->dev = &pdev->dev;
 238         gpio_vbus->otg.label = "gpio-vbus";
 239         gpio_vbus->otg.state = OTG_STATE_UNDEFINED;
 240         gpio_vbus->otg.set_peripheral = gpio_vbus_set_peripheral;
 241         gpio_vbus->otg.set_power = gpio_vbus_set_power;
 242         gpio_vbus->otg.set_suspend = gpio_vbus_set_suspend;
 243
 244         err = gpio_request(gpio, "vbus_detect");
 245         if (err) {
 246                 dev_err(&pdev->dev, "can't request vbus gpio %d, err: %d\n",
 247                         gpio, err);
 248                 goto err_gpio;
 249         }
 250         gpio_direction_input(gpio);
 251
 252         res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
 253         if (res) {
 254                 irq = res->start;
 255                 res->flags &= IRQF_TRIGGER_MASK;
 256                 res->flags |= IRQF_SAMPLE_RANDOM | IRQF_SHARED;
 257         } else
 258                 irq = gpio_to_irq(gpio);
 259
 260         /* if data line pullup is in use, initialize it to "not pulling up" */
 261         gpio = pdata->gpio_pullup;
 262         if (gpio_is_valid(gpio)) {
 263                 err = gpio_request(gpio, "udc_pullup");
 264                 if (err) {
 265                         dev_err(&pdev->dev,
 266                                 "can't request pullup gpio %d, err: %d\n",
 267                                 gpio, err);
 268                         gpio_free(pdata->gpio_vbus);
 269                         goto err_gpio;
 270                 }
 271                 gpio_direction_output(gpio, pdata->gpio_pullup_inverted);
 272         }
 273
 274         err = request_irq(irq, gpio_vbus_irq, VBUS_IRQ_FLAGS,
 275                 "vbus_detect", pdev);
 276         if (err) {
 277                 dev_err(&pdev->dev, "can't request irq %i, err: %d\n",
 278                         irq, err);
 279                 goto err_irq;
 280         }
 281         INIT_WORK(&gpio_vbus->work, gpio_vbus_work);
 282
 283         gpio_vbus->vbus_draw = regulator_get(&pdev->dev, "vbus_draw");
 284         if (IS_ERR(gpio_vbus->vbus_draw)) {
 285                 dev_dbg(&pdev->dev, "can't get vbus_draw regulator, err: %ld\n",
 286                         PTR_ERR(gpio_vbus->vbus_draw));
 287                 gpio_vbus->vbus_draw = NULL;
 288         }
 289
 290         /* only active when a gadget is registered */
 291         err = otg_set_transceiver(&gpio_vbus->otg);
 292         if (err) {
 293                 dev_err(&pdev->dev, "can't register transceiver, err: %d\n",
 294                         err);
 295                 goto err_otg;
 296         }
 297
 298         return 0;
 299 err_otg:
 300         free_irq(irq, &pdev->dev);
 301 err_irq:
 302         if (gpio_is_valid(pdata->gpio_pullup))
 303                 gpio_free(pdata->gpio_pullup);
 304         gpio_free(pdata->gpio_vbus);
 305 err_gpio:
 306         platform_set_drvdata(pdev, NULL);
 307         kfree(gpio_vbus);
 308         return err;
 309 }
 310
 311 static int __exit gpio_vbus_remove(struct platform_device *pdev)
 312 {
 313         struct gpio_vbus_data *gpio_vbus = platform_get_drvdata(pdev);
 314         struct gpio_vbus_mach_info *pdata = pdev->dev.platform_data;
 315         int gpio = pdata->gpio_vbus;
 316
 317         regulator_put(gpio_vbus->vbus_draw);
 318
 319         otg_set_transceiver(NULL);
 320
 321         free_irq(gpio_to_irq(gpio), &pdev->dev);
 322         if (gpio_is_valid(pdata->gpio_pullup))
 323                 gpio_free(pdata->gpio_pullup);
 324         gpio_free(gpio);
 325         platform_set_drvdata(pdev, NULL);
 326         kfree(gpio_vbus);
 327
 328         return 0;
 329 }
 330
 331 /* NOTE:  the gpio-vbus device may *NOT* be hotplugged */
 332
 333 MODULE_ALIAS("platform:gpio-vbus");
 334
 335 static struct platform_driver gpio_vbus_driver = {
 336         .driver = {
 337                 .name  = "gpio-vbus",
 338                 .owner = THIS_MODULE,
 339         },
 340         .remove  = __exit_p(gpio_vbus_remove),
 341 };
 342
 343 static int __init gpio_vbus_init(void)
 344 {
 345         return platform_driver_probe(&gpio_vbus_driver, gpio_vbus_probe);
 346 }
 347 module_init(gpio_vbus_init);
 348
 349 static void __exit gpio_vbus_exit(void)
 350 {
 351         platform_driver_unregister(&gpio_vbus_driver);
 352 }
 353 module_exit(gpio_vbus_exit);
 354
 355 MODULE_DESCRIPTION("simple GPIO controlled OTG transceiver driver");
 356 MODULE_AUTHOR("Philipp Zabel");
 357 MODULE_LICENSE("GPL");