drivers/gpio/gpiolib-acpi.c

   1 /*
   2  * ACPI helpers for GPIO API
   3  *
   4  * Copyright (C) 2012, Intel Corporation
   5  * Authors: Mathias Nyman <mathias.nyman@linux.intel.com>
   6  *          Mika Westerberg <mika.westerberg@linux.intel.com>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/errno.h>
  14 #include <linux/gpio/consumer.h>
  15 #include <linux/gpio/driver.h>
  16 #include <linux/export.h>
  17 #include <linux/acpi.h>
  18 #include <linux/interrupt.h>
  19
  20 #include "gpiolib.h"
  21
  22 struct acpi_gpio_evt_pin {
  23         struct list_head node;
  24         acpi_handle *evt_handle;
  25         unsigned int pin;
  26         unsigned int irq;
  27 };
  28
  29 static int acpi_gpiochip_find(struct gpio_chip *gc, void *data)
  30 {
  31         if (!gc->dev)
  32                 return false;
  33
  34         return ACPI_HANDLE(gc->dev) == data;
  35 }
  36
  37 /**
  38  * acpi_get_gpiod() - Translate ACPI GPIO pin to GPIO descriptor usable with GPIO API
  39  * @path:       ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1")
  40  * @pin:        ACPI GPIO pin number (0-based, controller-relative)
  41  *
  42  * Returns GPIO descriptor to use with Linux generic GPIO API, or ERR_PTR
  43  * error value
  44  */
  45
  46 static struct gpio_desc *acpi_get_gpiod(char *path, int pin)
  47 {
  48         struct gpio_chip *chip;
  49         acpi_handle handle;
  50         acpi_status status;
  51
  52         status = acpi_get_handle(NULL, path, &handle);
  53         if (ACPI_FAILURE(status))
  54                 return ERR_PTR(-ENODEV);
  55
  56         chip = gpiochip_find(handle, acpi_gpiochip_find);
  57         if (!chip)
  58                 return ERR_PTR(-ENODEV);
  59
  60         if (pin < 0 || pin > chip->ngpio)
  61                 return ERR_PTR(-EINVAL);
  62
  63         return gpio_to_desc(chip->base + pin);
  64 }
  65
  66 static irqreturn_t acpi_gpio_irq_handler(int irq, void *data)
  67 {
  68         acpi_handle handle = data;
  69
  70         acpi_evaluate_object(handle, NULL, NULL, NULL);
  71
  72         return IRQ_HANDLED;
  73 }
  74
  75 static irqreturn_t acpi_gpio_irq_handler_evt(int irq, void *data)
  76 {
  77         struct acpi_gpio_evt_pin *evt_pin = data;
  78
  79         acpi_execute_simple_method(evt_pin->evt_handle, NULL, evt_pin->pin);
  80
  81         return IRQ_HANDLED;
  82 }
  83
  84 static void acpi_gpio_evt_dh(acpi_handle handle, void *data)
  85 {
  86         /* The address of this function is used as a key. */
  87 }
  88
  89 /**
  90  * acpi_gpiochip_request_interrupts() - Register isr for gpio chip ACPI events
  91  * @chip:      gpio chip
  92  *
  93  * ACPI5 platforms can use GPIO signaled ACPI events. These GPIO interrupts are
  94  * handled by ACPI event methods which need to be called from the GPIO
  95  * chip's interrupt handler. acpi_gpiochip_request_interrupts finds out which
  96  * gpio pins have acpi event methods and assigns interrupt handlers that calls
  97  * the acpi event methods for those pins.
  98  */
  99 static void acpi_gpiochip_request_interrupts(struct gpio_chip *chip)
 100 {
 101         struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
 102         struct acpi_resource *res;
 103         acpi_handle handle, evt_handle;
 104         struct list_head *evt_pins = NULL;
 105         acpi_status status;
 106         unsigned int pin;
 107         int irq, ret;
 108         char ev_name[5];
 109
 110         if (!chip->dev || !chip->to_irq)
 111                 return;
 112
 113         handle = ACPI_HANDLE(chip->dev);
 114         if (!handle)
 115                 return;
 116
 117         status = acpi_get_event_resources(handle, &buf);
 118         if (ACPI_FAILURE(status))
 119                 return;
 120
 121         status = acpi_get_handle(handle, "_EVT", &evt_handle);
 122         if (ACPI_SUCCESS(status)) {
 123                 evt_pins = kzalloc(sizeof(*evt_pins), GFP_KERNEL);
 124                 if (evt_pins) {
 125                         INIT_LIST_HEAD(evt_pins);
 126                         status = acpi_attach_data(handle, acpi_gpio_evt_dh,
 127                                                   evt_pins);
 128                         if (ACPI_FAILURE(status)) {
 129                                 kfree(evt_pins);
 130                                 evt_pins = NULL;
 131                         }
 132                 }
 133         }
 134
 135         /*
 136          * If a GPIO interrupt has an ACPI event handler method, or _EVT is
 137          * present, set up an interrupt handler that calls the ACPI event
 138          * handler.
 139          */
 140         for (res = buf.pointer;
 141              res && (res->type != ACPI_RESOURCE_TYPE_END_TAG);
 142              res = ACPI_NEXT_RESOURCE(res)) {
 143                 irq_handler_t handler = NULL;
 144                 void *data;
 145
 146                 if (res->type != ACPI_RESOURCE_TYPE_GPIO ||
 147                     res->data.gpio.connection_type !=
 148                     ACPI_RESOURCE_GPIO_TYPE_INT)
 149                         continue;
 150
 151                 pin = res->data.gpio.pin_table[0];
 152                 if (pin > chip->ngpio)
 153                         continue;
 154
 155                 irq = chip->to_irq(chip, pin);
 156                 if (irq < 0)
 157                         continue;
 158
 159                 if (pin <= 255) {
 160                         acpi_handle ev_handle;
 161
 162                         sprintf(ev_name, "_%c%02X",
 163                                 res->data.gpio.triggering ? 'E' : 'L', pin);
 164                         status = acpi_get_handle(handle, ev_name, &ev_handle);
 165                         if (ACPI_SUCCESS(status)) {
 166                                 handler = acpi_gpio_irq_handler;
 167                                 data = ev_handle;
 168                         }
 169                 }
 170                 if (!handler && evt_pins) {
 171                         struct acpi_gpio_evt_pin *evt_pin;
 172
 173                         evt_pin = kzalloc(sizeof(*evt_pin), GFP_KERNEL);
 174                         if (!evt_pin)
 175                                 continue;
 176
 177                         list_add_tail(&evt_pin->node, evt_pins);
 178                         evt_pin->evt_handle = evt_handle;
 179                         evt_pin->pin = pin;
 180                         evt_pin->irq = irq;
 181                         handler = acpi_gpio_irq_handler_evt;
 182                         data = evt_pin;
 183                 }
 184                 if (!handler)
 185                         continue;
 186
 187                 /* Assume BIOS sets the triggering, so no flags */
 188                 ret = devm_request_threaded_irq(chip->dev, irq, NULL, handler,
 189                                                 0, "GPIO-signaled-ACPI-event",
 190                                                 data);
 191                 if (ret)
 192                         dev_err(chip->dev,
 193                                 "Failed to request IRQ %d ACPI event handler\n",
 194                                 irq);
 195         }
 196 }
 197
 198 /**
 199  * acpi_gpiochip_free_interrupts() - Free GPIO _EVT ACPI event interrupts.
 200  * @chip:      gpio chip
 201  *
 202  * Free interrupts associated with the _EVT method for the given GPIO chip.
 203  *
 204  * The remaining ACPI event interrupts associated with the chip are freed
 205  * automatically.
 206  */
 207 static void acpi_gpiochip_free_interrupts(struct gpio_chip *chip)
 208 {
 209         acpi_handle handle;
 210         acpi_status status;
 211         struct list_head *evt_pins;
 212         struct acpi_gpio_evt_pin *evt_pin, *ep;
 213
 214         if (!chip->dev || !chip->to_irq)
 215                 return;
 216
 217         handle = ACPI_HANDLE(chip->dev);
 218         if (!handle)
 219                 return;
 220
 221         status = acpi_get_data(handle, acpi_gpio_evt_dh, (void **)&evt_pins);
 222         if (ACPI_FAILURE(status))
 223                 return;
 224
 225         list_for_each_entry_safe_reverse(evt_pin, ep, evt_pins, node) {
 226                 devm_free_irq(chip->dev, evt_pin->irq, evt_pin);
 227                 list_del(&evt_pin->node);
 228                 kfree(evt_pin);
 229         }
 230
 231         acpi_detach_data(handle, acpi_gpio_evt_dh);
 232         kfree(evt_pins);
 233 }
 234
 235 struct acpi_gpio_lookup {
 236         struct acpi_gpio_info info;
 237         int index;
 238         struct gpio_desc *desc;
 239         int n;
 240 };
 241
 242 static int acpi_find_gpio(struct acpi_resource *ares, void *data)
 243 {
 244         struct acpi_gpio_lookup *lookup = data;
 245
 246         if (ares->type != ACPI_RESOURCE_TYPE_GPIO)
 247                 return 1;
 248
 249         if (lookup->n++ == lookup->index && !lookup->desc) {
 250                 const struct acpi_resource_gpio *agpio = &ares->data.gpio;
 251
 252                 lookup->desc = acpi_get_gpiod(agpio->resource_source.string_ptr,
 253                                               agpio->pin_table[0]);
 254                 lookup->info.gpioint =
 255                         agpio->connection_type == ACPI_RESOURCE_GPIO_TYPE_INT;
 256                 lookup->info.active_low =
 257                         agpio->polarity == ACPI_ACTIVE_LOW;
 258         }
 259
 260         return 1;
 261 }
 262
 263 /**
 264  * acpi_get_gpiod_by_index() - get a GPIO descriptor from device resources
 265  * @dev: pointer to a device to get GPIO from
 266  * @index: index of GpioIo/GpioInt resource (starting from %0)
 267  * @info: info pointer to fill in (optional)
 268  *
 269  * Function goes through ACPI resources for @dev and based on @index looks
 270  * up a GpioIo/GpioInt resource, translates it to the Linux GPIO descriptor,
 271  * and returns it. @index matches GpioIo/GpioInt resources only so if there
 272  * are total %3 GPIO resources, the index goes from %0 to %2.
 273  *
 274  * If the GPIO cannot be translated or there is an error an ERR_PTR is
 275  * returned.
 276  *
 277  * Note: if the GPIO resource has multiple entries in the pin list, this
 278  * function only returns the first.
 279  */
 280 struct gpio_desc *acpi_get_gpiod_by_index(struct device *dev, int index,
 281                                           struct acpi_gpio_info *info)
 282 {
 283         struct acpi_gpio_lookup lookup;
 284         struct list_head resource_list;
 285         struct acpi_device *adev;
 286         acpi_handle handle;
 287         int ret;
 288
 289         if (!dev)
 290                 return ERR_PTR(-EINVAL);
 291
 292         handle = ACPI_HANDLE(dev);
 293         if (!handle || acpi_bus_get_device(handle, &adev))
 294                 return ERR_PTR(-ENODEV);
 295
 296         memset(&lookup, 0, sizeof(lookup));
 297         lookup.index = index;
 298
 299         INIT_LIST_HEAD(&resource_list);
 300         ret = acpi_dev_get_resources(adev, &resource_list, acpi_find_gpio,
 301                                      &lookup);
 302         if (ret < 0)
 303                 return ERR_PTR(ret);
 304
 305         acpi_dev_free_resource_list(&resource_list);
 306
 307         if (lookup.desc && info)
 308                 *info = lookup.info;
 309
 310         return lookup.desc ? lookup.desc : ERR_PTR(-ENOENT);
 311 }
 312
 313 void acpi_gpiochip_add(struct gpio_chip *chip)
 314 {
 315         acpi_gpiochip_request_interrupts(chip);
 316 }
 317
 318 void acpi_gpiochip_remove(struct gpio_chip *chip)
 319 {
 320         acpi_gpiochip_free_interrupts(chip);
 321 }