drivers/leds/leds-ixp4xx-gpio.c

   1 /*
   2  * IXP4XX GPIO driver LED driver
   3  *
   4  * Author: John Bowler <jbowler@acm.org>
   5  *
   6  * Copyright (c) 2006 John Bowler
   7  *
   8  * Permission is hereby granted, free of charge, to any
   9  * person obtaining a copy of this software and associated
  10  * documentation files (the "Software"), to deal in the
  11  * Software without restriction, including without
  12  * limitation the rights to use, copy, modify, merge,
  13  * publish, distribute, sublicense, and/or sell copies of
  14  * the Software, and to permit persons to whom the
  15  * Software is furnished to do so, subject to the
  16  * following conditions:
  17  *
  18  * The above copyright notice and this permission notice
  19  * shall be included in all copies or substantial portions
  20  * of the Software.
  21  *
  22  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
  23  * ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
  24  * TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
  25  * PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
  26  * SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR
  27  * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
  28  * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  29  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  30  * OTHER DEALINGS IN THE SOFTWARE.
  31  *
  32  */
  33
  34 #include <linux/kernel.h>
  35 #include <linux/init.h>
  36 #include <linux/platform_device.h>
  37 #include <linux/spinlock.h>
  38 #include <linux/leds.h>
  39 #include <asm/arch/hardware.h>
  40
  41 extern spinlock_t gpio_lock;
  42
  43 /* Up to 16 gpio lines are possible. */
  44 #define GPIO_MAX 16
  45 static struct ixp4xxgpioled_device {
  46         struct led_classdev ancestor;
  47         int               flags;
  48 } ixp4xxgpioled_devices[GPIO_MAX];
  49
  50 void ixp4xxgpioled_brightness_set(struct led_classdev *pled,
  51                                 enum led_brightness value)
  52 {
  53         const struct ixp4xxgpioled_device *const ixp4xx_dev =
  54                 container_of(pled, struct ixp4xxgpioled_device, ancestor);
  55         const u32 gpio_pin = ixp4xx_dev - ixp4xxgpioled_devices;
  56
  57         if (gpio_pin < GPIO_MAX && ixp4xx_dev->ancestor.name != 0) {
  58                 /* Set or clear the 'gpio_pin' bit according to the style
  59                  * and the required setting (value > 0 == on)
  60                  */
  61                 const int gpio_value =
  62                         (value > 0) == (ixp4xx_dev->flags != IXP4XX_GPIO_LOW) ?
  63                                 IXP4XX_GPIO_HIGH : IXP4XX_GPIO_LOW;
  64
  65                 {
  66                         unsigned long flags;
  67                         spin_lock_irqsave(&gpio_lock, flags);
  68                         gpio_line_set(gpio_pin, gpio_value);
  69                         spin_unlock_irqrestore(&gpio_lock, flags);
  70                 }
  71         }
  72 }
  73
  74 /* LEDs are described in resources, the following iterates over the valid
  75  * LED resources.
  76  */
  77 #define for_all_leds(i, pdev) \
  78         for (i=0; i<pdev->num_resources; ++i) \
  79                 if (pdev->resource[i].start < GPIO_MAX && \
  80                         pdev->resource[i].name != 0)
  81
  82 /* The following applies 'operation' to each LED from the given platform,
  83  * the function always returns 0 to allow tail call elimination.
  84  */
  85 static int apply_to_all_leds(struct platform_device *pdev,
  86         void (*operation)(struct led_classdev *pled))
  87 {
  88         int i;
  89
  90         for_all_leds(i, pdev)
  91                 operation(&ixp4xxgpioled_devices[pdev->resource[i].start].ancestor);
  92         return 0;
  93 }
  94
  95 #ifdef CONFIG_PM
  96 static int ixp4xxgpioled_suspend(struct platform_device *pdev,
  97                                 pm_message_t state)
  98 {
  99         return apply_to_all_leds(pdev, led_classdev_suspend);
 100 }
 101
 102 static int ixp4xxgpioled_resume(struct platform_device *pdev)
 103 {
 104         return apply_to_all_leds(pdev, led_classdev_resume);
 105 }
 106 #endif
 107
 108 static void ixp4xxgpioled_remove_one_led(struct led_classdev *pled)
 109 {
 110         led_classdev_unregister(pled);
 111         pled->name = 0;
 112 }
 113
 114 static int ixp4xxgpioled_remove(struct platform_device *pdev)
 115 {
 116         return apply_to_all_leds(pdev, ixp4xxgpioled_remove_one_led);
 117 }
 118
 119 static int ixp4xxgpioled_probe(struct platform_device *pdev)
 120 {
 121         /* The board level has to tell the driver where the
 122          * LEDs are connected - there is no way to find out
 123          * electrically.  It must also say whether the GPIO
 124          * lines are active high or active low.
 125          *
 126          * To do this read the num_resources (the number of
 127          * LEDs) and the struct resource (the data for each
 128          * LED).  The name comes from the resource, and it
 129          * isn't copied.
 130          */
 131         int i;
 132
 133         for_all_leds(i, pdev) {
 134                 const u8 gpio_pin = pdev->resource[i].start;
 135                 int      rc;
 136
 137                 if (ixp4xxgpioled_devices[gpio_pin].ancestor.name == 0) {
 138                         unsigned long flags;
 139
 140                         spin_lock_irqsave(&gpio_lock, flags);
 141                         gpio_line_config(gpio_pin, IXP4XX_GPIO_OUT);
 142                         /* The config can, apparently, reset the state,
 143                          * I suspect the gpio line may be an input and
 144                          * the config may cause the line to be latched,
 145                          * so the setting depends on how the LED is
 146                          * connected to the line (which affects how it
 147                          * floats if not driven).
 148                          */
 149                         gpio_line_set(gpio_pin, IXP4XX_GPIO_HIGH);
 150                         spin_unlock_irqrestore(&gpio_lock, flags);
 151
 152                         ixp4xxgpioled_devices[gpio_pin].flags =
 153                                 pdev->resource[i].flags & IORESOURCE_BITS;
 154
 155                         ixp4xxgpioled_devices[gpio_pin].ancestor.name =
 156                                 pdev->resource[i].name;
 157
 158                         /* This is how a board manufacturer makes the LED
 159                          * come on on reset - the GPIO line will be high, so
 160                          * make the LED light when the line is low...
 161                          */
 162                         if (ixp4xxgpioled_devices[gpio_pin].flags != IXP4XX_GPIO_LOW)
 163                                 ixp4xxgpioled_devices[gpio_pin].ancestor.brightness = 100;
 164                         else
 165                                 ixp4xxgpioled_devices[gpio_pin].ancestor.brightness = 0;
 166
 167                         ixp4xxgpioled_devices[gpio_pin].ancestor.flags = 0;
 168
 169                         ixp4xxgpioled_devices[gpio_pin].ancestor.brightness_set =
 170                                 ixp4xxgpioled_brightness_set;
 171
 172                         ixp4xxgpioled_devices[gpio_pin].ancestor.default_trigger = 0;
 173                 }
 174
 175                 rc = led_classdev_register(&pdev->dev,
 176                                 &ixp4xxgpioled_devices[gpio_pin].ancestor);
 177                 if (rc < 0) {
 178                         ixp4xxgpioled_devices[gpio_pin].ancestor.name = 0;
 179                         ixp4xxgpioled_remove(pdev);
 180                         return rc;
 181                 }
 182         }
 183
 184         return 0;
 185 }
 186
 187 static struct platform_driver ixp4xxgpioled_driver = {
 188         .probe   = ixp4xxgpioled_probe,
 189         .remove  = ixp4xxgpioled_remove,
 190 #ifdef CONFIG_PM
 191         .suspend = ixp4xxgpioled_suspend,
 192         .resume  = ixp4xxgpioled_resume,
 193 #endif
 194         .driver  = {
 195                 .name = "IXP4XX-GPIO-LED",
 196         },
 197 };
 198
 199 static int __init ixp4xxgpioled_init(void)
 200 {
 201         return platform_driver_register(&ixp4xxgpioled_driver);
 202 }
 203
 204 static void __exit ixp4xxgpioled_exit(void)
 205 {
 206         platform_driver_unregister(&ixp4xxgpioled_driver);
 207 }
 208
 209 module_init(ixp4xxgpioled_init);
 210 module_exit(ixp4xxgpioled_exit);
 211
 212 MODULE_AUTHOR("John Bowler <jbowler@acm.org>");
 213 MODULE_DESCRIPTION("IXP4XX GPIO LED driver");
 214 MODULE_LICENSE("Dual MIT/GPL");