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/config.h>
  35 #include <linux/kernel.h>
  36 #include <linux/init.h>
  37 #include <linux/platform_device.h>
  38 #include <linux/spinlock.h>
  39 #include <linux/leds.h>
  40 #include <asm/arch/hardware.h>
  41
  42 extern spinlock_t gpio_lock;
  43
  44 /* Up to 16 gpio lines are possible. */
  45 #define GPIO_MAX 16
  46 static struct ixp4xxgpioled_device {
  47         struct led_classdev ancestor;
  48         int               flags;
  49 } ixp4xxgpioled_devices[GPIO_MAX];
  50
  51 void ixp4xxgpioled_brightness_set(struct led_classdev *pled,
  52                                 enum led_brightness value)
  53 {
  54         const struct ixp4xxgpioled_device *const ixp4xx_dev =
  55                 container_of(pled, struct ixp4xxgpioled_device, ancestor);
  56         const u32 gpio_pin = ixp4xx_dev - ixp4xxgpioled_devices;
  57
  58         if (gpio_pin < GPIO_MAX && ixp4xx_dev->ancestor.name != 0) {
  59                 /* Set or clear the 'gpio_pin' bit according to the style
  60                  * and the required setting (value > 0 == on)
  61                  */
  62                 const int gpio_value =
  63                         (value > 0) == (ixp4xx_dev->flags != IXP4XX_GPIO_LOW) ?
  64                                 IXP4XX_GPIO_HIGH : IXP4XX_GPIO_LOW;
  65
  66                 {
  67                         unsigned long flags;
  68                         spin_lock_irqsave(&gpio_lock, flags);
  69                         gpio_line_set(gpio_pin, gpio_value);
  70                         spin_unlock_irqrestore(&gpio_lock, flags);
  71                 }
  72         }
  73 }
  74
  75 /* LEDs are described in resources, the following iterates over the valid
  76  * LED resources.
  77  */
  78 #define for_all_leds(i, pdev) \
  79         for (i=0; i<pdev->num_resources; ++i) \
  80                 if (pdev->resource[i].start < GPIO_MAX && \
  81                         pdev->resource[i].name != 0)
  82
  83 /* The following applies 'operation' to each LED from the given platform,
  84  * the function always returns 0 to allow tail call elimination.
  85  */
  86 static int apply_to_all_leds(struct platform_device *pdev,
  87         void (*operation)(struct led_classdev *pled))
  88 {
  89         int i;
  90
  91         for_all_leds(i, pdev)
  92                 operation(&ixp4xxgpioled_devices[pdev->resource[i].start].ancestor);
  93         return 0;
  94 }
  95
  96 #ifdef CONFIG_PM
  97 static int ixp4xxgpioled_suspend(struct platform_device *pdev,
  98                                 pm_message_t state)
  99 {
 100         return apply_to_all_leds(pdev, led_classdev_suspend);
 101 }
 102
 103 static int ixp4xxgpioled_resume(struct platform_device *pdev)
 104 {
 105         return apply_to_all_leds(pdev, led_classdev_resume);
 106 }
 107 #endif
 108
 109 static void ixp4xxgpioled_remove_one_led(struct led_classdev *pled)
 110 {
 111         led_classdev_unregister(pled);
 112         pled->name = 0;
 113 }
 114
 115 static int ixp4xxgpioled_remove(struct platform_device *pdev)
 116 {
 117         return apply_to_all_leds(pdev, ixp4xxgpioled_remove_one_led);
 118 }
 119
 120 static int ixp4xxgpioled_probe(struct platform_device *pdev)
 121 {
 122         /* The board level has to tell the driver where the
 123          * LEDs are connected - there is no way to find out
 124          * electrically.  It must also say whether the GPIO
 125          * lines are active high or active low.
 126          *
 127          * To do this read the num_resources (the number of
 128          * LEDs) and the struct resource (the data for each
 129          * LED).  The name comes from the resource, and it
 130          * isn't copied.
 131          */
 132         int i;
 133
 134         for_all_leds(i, pdev) {
 135                 const u8 gpio_pin = pdev->resource[i].start;
 136                 int      rc;
 137
 138                 if (ixp4xxgpioled_devices[gpio_pin].ancestor.name == 0) {
 139                         unsigned long flags;
 140
 141                         spin_lock_irqsave(&gpio_lock, flags);
 142                         gpio_line_config(gpio_pin, IXP4XX_GPIO_OUT);
 143                         /* The config can, apparently, reset the state,
 144                          * I suspect the gpio line may be an input and
 145                          * the config may cause the line to be latched,
 146                          * so the setting depends on how the LED is
 147                          * connected to the line (which affects how it
 148                          * floats if not driven).
 149                          */
 150                         gpio_line_set(gpio_pin, IXP4XX_GPIO_HIGH);
 151                         spin_unlock_irqrestore(&gpio_lock, flags);
 152
 153                         ixp4xxgpioled_devices[gpio_pin].flags =
 154                                 pdev->resource[i].flags & IORESOURCE_BITS;
 155
 156                         ixp4xxgpioled_devices[gpio_pin].ancestor.name =
 157                                 pdev->resource[i].name;
 158
 159                         /* This is how a board manufacturer makes the LED
 160                          * come on on reset - the GPIO line will be high, so
 161                          * make the LED light when the line is low...
 162                          */
 163                         if (ixp4xxgpioled_devices[gpio_pin].flags != IXP4XX_GPIO_LOW)
 164                                 ixp4xxgpioled_devices[gpio_pin].ancestor.brightness = 100;
 165                         else
 166                                 ixp4xxgpioled_devices[gpio_pin].ancestor.brightness = 0;
 167
 168                         ixp4xxgpioled_devices[gpio_pin].ancestor.flags = 0;
 169
 170                         ixp4xxgpioled_devices[gpio_pin].ancestor.brightness_set =
 171                                 ixp4xxgpioled_brightness_set;
 172
 173                         ixp4xxgpioled_devices[gpio_pin].ancestor.default_trigger = 0;
 174                 }
 175
 176                 rc = led_classdev_register(&pdev->dev,
 177                                 &ixp4xxgpioled_devices[gpio_pin].ancestor);
 178                 if (rc < 0) {
 179                         ixp4xxgpioled_devices[gpio_pin].ancestor.name = 0;
 180                         ixp4xxgpioled_remove(pdev);
 181                         return rc;
 182                 }
 183         }
 184
 185         return 0;
 186 }
 187
 188 static struct platform_driver ixp4xxgpioled_driver = {
 189         .probe   = ixp4xxgpioled_probe,
 190         .remove  = ixp4xxgpioled_remove,
 191 #ifdef CONFIG_PM
 192         .suspend = ixp4xxgpioled_suspend,
 193         .resume  = ixp4xxgpioled_resume,
 194 #endif
 195         .driver  = {
 196                 .name = "IXP4XX-GPIO-LED",
 197         },
 198 };
 199
 200 static int __init ixp4xxgpioled_init(void)
 201 {
 202         return platform_driver_register(&ixp4xxgpioled_driver);
 203 }
 204
 205 static void __exit ixp4xxgpioled_exit(void)
 206 {
 207         platform_driver_unregister(&ixp4xxgpioled_driver);
 208 }
 209
 210 module_init(ixp4xxgpioled_init);
 211 module_exit(ixp4xxgpioled_exit);
 212
 213 MODULE_AUTHOR("John Bowler <jbowler@acm.org>");
 214 MODULE_DESCRIPTION("IXP4XX GPIO LED driver");
 215 MODULE_LICENSE("Dual MIT/GPL");