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.h>
  15 #include <linux/export.h>
  16 #include <linux/acpi_gpio.h>
  17 #include <linux/acpi.h>
  18 #include <linux/interrupt.h>
  19
  20 static int acpi_gpiochip_find(struct gpio_chip *gc, void *data)
  21 {
  22         if (!gc->dev)
  23                 return false;
  24
  25         return ACPI_HANDLE(gc->dev) == data;
  26 }
  27
  28 /**
  29  * acpi_get_gpio() - Translate ACPI GPIO pin to GPIO number usable with GPIO API
  30  * @path:       ACPI GPIO controller full path name, (e.g. "\\_SB.GPO1")
  31  * @pin:        ACPI GPIO pin number (0-based, controller-relative)
  32  *
  33  * Returns GPIO number to use with Linux generic GPIO API, or errno error value
  34  */
  35
  36 int acpi_get_gpio(char *path, int pin)
  37 {
  38         struct gpio_chip *chip;
  39         acpi_handle handle;
  40         acpi_status status;
  41
  42         status = acpi_get_handle(NULL, path, &handle);
  43         if (ACPI_FAILURE(status))
  44                 return -ENODEV;
  45
  46         chip = gpiochip_find(handle, acpi_gpiochip_find);
  47         if (!chip)
  48                 return -ENODEV;
  49
  50         if (!gpio_is_valid(chip->base + pin))
  51                 return -EINVAL;
  52
  53         return chip->base + pin;
  54 }
  55 EXPORT_SYMBOL_GPL(acpi_get_gpio);
  56
  57
  58 static irqreturn_t acpi_gpio_irq_handler(int irq, void *data)
  59 {
  60         acpi_handle handle = data;
  61
  62         acpi_evaluate_object(handle, NULL, NULL, NULL);
  63
  64         return IRQ_HANDLED;
  65 }
  66
  67 /**
  68  * acpi_gpiochip_request_interrupts() - Register isr for gpio chip ACPI events
  69  * @chip:      gpio chip
  70  *
  71  * ACPI5 platforms can use GPIO signaled ACPI events. These GPIO interrupts are
  72  * handled by ACPI event methods which need to be called from the GPIO
  73  * chip's interrupt handler. acpi_gpiochip_request_interrupts finds out which
  74  * gpio pins have acpi event methods and assigns interrupt handlers that calls
  75  * the acpi event methods for those pins.
  76  *
  77  * Interrupts are automatically freed on driver detach
  78  */
  79
  80 void acpi_gpiochip_request_interrupts(struct gpio_chip *chip)
  81 {
  82         struct acpi_buffer buf = {ACPI_ALLOCATE_BUFFER, NULL};
  83         struct acpi_resource *res;
  84         acpi_handle handle, ev_handle;
  85         acpi_status status;
  86         unsigned int pin;
  87         int irq, ret;
  88         char ev_name[5];
  89
  90         if (!chip->dev || !chip->to_irq)
  91                 return;
  92
  93         handle = ACPI_HANDLE(chip->dev);
  94         if (!handle)
  95                 return;
  96
  97         status = acpi_get_event_resources(handle, &buf);
  98         if (ACPI_FAILURE(status))
  99                 return;
 100
 101         /* If a gpio interrupt has an acpi event handler method, then
 102          * set up an interrupt handler that calls the acpi event handler
 103          */
 104
 105         for (res = buf.pointer;
 106              res && (res->type != ACPI_RESOURCE_TYPE_END_TAG);
 107              res = ACPI_NEXT_RESOURCE(res)) {
 108
 109                 if (res->type != ACPI_RESOURCE_TYPE_GPIO ||
 110                     res->data.gpio.connection_type !=
 111                     ACPI_RESOURCE_GPIO_TYPE_INT)
 112                         continue;
 113
 114                 pin = res->data.gpio.pin_table[0];
 115                 if (pin > chip->ngpio)
 116                         continue;
 117
 118                 sprintf(ev_name, "_%c%02X",
 119                 res->data.gpio.triggering ? 'E' : 'L', pin);
 120
 121                 status = acpi_get_handle(handle, ev_name, &ev_handle);
 122                 if (ACPI_FAILURE(status))
 123                         continue;
 124
 125                 irq = chip->to_irq(chip, pin);
 126                 if (irq < 0)
 127                         continue;
 128
 129                 /* Assume BIOS sets the triggering, so no flags */
 130                 ret = devm_request_threaded_irq(chip->dev, irq, NULL,
 131                                           acpi_gpio_irq_handler,
 132                                           0,
 133                                           "GPIO-signaled-ACPI-event",
 134                                           ev_handle);
 135                 if (ret)
 136                         dev_err(chip->dev,
 137                                 "Failed to request IRQ %d ACPI event handler\n",
 138                                 irq);
 139         }
 140 }
 141 EXPORT_SYMBOL(acpi_gpiochip_request_interrupts);