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