drivers/gpio/gpio-loongson.c

   1 /*
   2  *  Loongson-2F/3A/3B GPIO Support
   3  *
   4  *  Copyright (c) 2008 Richard Liu,  STMicroelectronics  <richard.liu@st.com>
   5  *  Copyright (c) 2008-2010 Arnaud Patard <apatard@mandriva.com>
   6  *  Copyright (c) 2013 Hongbing Hu <huhb@lemote.com>
   7  *  Copyright (c) 2014 Huacai Chen <chenhc@lemote.com>
   8  *
   9  *  This program is free software; you can redistribute it and/or modify
  10  *  it under the terms of the GNU General Public License as published by
  11  *  the Free Software Foundation; either version 2 of the License, or
  12  *  (at your option) any later version.
  13  */
  14
  15 #include <linux/kernel.h>
  16 #include <linux/init.h>
  17 #include <linux/module.h>
  18 #include <linux/spinlock.h>
  19 #include <linux/err.h>
  20 #include <linux/gpio/driver.h>
  21 #include <linux/platform_device.h>
  22 #include <linux/bitops.h>
  23 #include <asm/types.h>
  24 #include <loongson.h>
  25
  26 #define STLS2F_N_GPIO           4
  27 #define STLS3A_N_GPIO           16
  28
  29 #ifdef CONFIG_CPU_LOONGSON3
  30 #define LOONGSON_N_GPIO STLS3A_N_GPIO
  31 #else
  32 #define LOONGSON_N_GPIO STLS2F_N_GPIO
  33 #endif
  34
  35 /*
  36  * Offset into the register where we read lines, we write them from offset 0.
  37  * This offset is the only thing that stand between us and using
  38  * GPIO_GENERIC.
  39  */
  40 #define LOONGSON_GPIO_IN_OFFSET 16
  41
  42 static DEFINE_SPINLOCK(gpio_lock);
  43
  44 static int loongson_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
  45 {
  46         u32 val;
  47
  48         spin_lock(&gpio_lock);
  49         val = LOONGSON_GPIODATA;
  50         spin_unlock(&gpio_lock);
  51
  52         return !!(val & BIT(gpio + LOONGSON_GPIO_IN_OFFSET));
  53 }
  54
  55 static void loongson_gpio_set_value(struct gpio_chip *chip,
  56                 unsigned gpio, int value)
  57 {
  58         u32 val;
  59
  60         spin_lock(&gpio_lock);
  61         val = LOONGSON_GPIODATA;
  62         if (value)
  63                 val |= BIT(gpio);
  64         else
  65                 val &= ~BIT(gpio);
  66         LOONGSON_GPIODATA = val;
  67         spin_unlock(&gpio_lock);
  68 }
  69
  70 static int loongson_gpio_direction_input(struct gpio_chip *chip, unsigned gpio)
  71 {
  72         u32 temp;
  73
  74         spin_lock(&gpio_lock);
  75         temp = LOONGSON_GPIOIE;
  76         temp |= BIT(gpio);
  77         LOONGSON_GPIOIE = temp;
  78         spin_unlock(&gpio_lock);
  79
  80         return 0;
  81 }
  82
  83 static int loongson_gpio_direction_output(struct gpio_chip *chip,
  84                 unsigned gpio, int level)
  85 {
  86         u32 temp;
  87
  88         loongson_gpio_set_value(chip, gpio, level);
  89         spin_lock(&gpio_lock);
  90         temp = LOONGSON_GPIOIE;
  91         temp &= ~BIT(gpio);
  92         LOONGSON_GPIOIE = temp;
  93         spin_unlock(&gpio_lock);
  94
  95         return 0;
  96 }
  97
  98 static int loongson_gpio_probe(struct platform_device *pdev)
  99 {
 100         struct gpio_chip *gc;
 101         struct device *dev = &pdev->dev;
 102
 103         gc = devm_kzalloc(dev, sizeof(*gc), GFP_KERNEL);
 104         if (!gc)
 105                 return -ENOMEM;
 106
 107         gc->label = "loongson-gpio-chip";
 108         gc->base = 0;
 109         gc->ngpio = LOONGSON_N_GPIO;
 110         gc->get = loongson_gpio_get_value;
 111         gc->set = loongson_gpio_set_value;
 112         gc->direction_input = loongson_gpio_direction_input;
 113         gc->direction_output = loongson_gpio_direction_output;
 114
 115         return gpiochip_add_data(gc, NULL);
 116 }
 117
 118 static struct platform_driver loongson_gpio_driver = {
 119         .driver = {
 120                 .name = "loongson-gpio",
 121         },
 122         .probe = loongson_gpio_probe,
 123 };
 124
 125 static int __init loongson_gpio_setup(void)
 126 {
 127         struct platform_device *pdev;
 128         int ret;
 129
 130         ret = platform_driver_register(&loongson_gpio_driver);
 131         if (ret) {
 132                 pr_err("error registering loongson GPIO driver\n");
 133                 return ret;
 134         }
 135
 136         pdev = platform_device_register_simple("loongson-gpio", -1, NULL, 0);
 137         return PTR_ERR_OR_ZERO(pdev);
 138 }
 139 postcore_initcall(loongson_gpio_setup);