drivers/gpio/gpio-kempld.c

   1 /*
   2  * Kontron PLD GPIO driver
   3  *
   4  * Copyright (c) 2010-2013 Kontron Europe GmbH
   5  * Author: Michael Brunner <michael.brunner@kontron.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License 2 as published
   9  * by the Free Software Foundation.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  */
  16
  17 #include <linux/init.h>
  18 #include <linux/kernel.h>
  19 #include <linux/module.h>
  20 #include <linux/bitops.h>
  21 #include <linux/errno.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/gpio.h>
  24 #include <linux/mfd/kempld.h>
  25
  26 #define KEMPLD_GPIO_MAX_NUM             16
  27 #define KEMPLD_GPIO_MASK(x)             (BIT((x) % 8))
  28 #define KEMPLD_GPIO_DIR_NUM(x)          (0x40 + (x) / 8)
  29 #define KEMPLD_GPIO_LVL_NUM(x)          (0x42 + (x) / 8)
  30 #define KEMPLD_GPIO_EVT_LVL_EDGE        0x46
  31 #define KEMPLD_GPIO_IEN                 0x4A
  32
  33 struct kempld_gpio_data {
  34         struct gpio_chip                chip;
  35         struct kempld_device_data       *pld;
  36 };
  37
  38 /*
  39  * Set or clear GPIO bit
  40  * kempld_get_mutex must be called prior to calling this function.
  41  */
  42 static void kempld_gpio_bitop(struct kempld_device_data *pld,
  43                               u8 reg, u8 bit, u8 val)
  44 {
  45         u8 status;
  46
  47         status = kempld_read8(pld, reg);
  48         if (val)
  49                 status |= KEMPLD_GPIO_MASK(bit);
  50         else
  51                 status &= ~KEMPLD_GPIO_MASK(bit);
  52         kempld_write8(pld, reg, status);
  53 }
  54
  55 static int kempld_gpio_get_bit(struct kempld_device_data *pld, u8 reg, u8 bit)
  56 {
  57         u8 status;
  58
  59         kempld_get_mutex(pld);
  60         status = kempld_read8(pld, reg);
  61         kempld_release_mutex(pld);
  62
  63         return !!(status & KEMPLD_GPIO_MASK(bit));
  64 }
  65
  66 static int kempld_gpio_get(struct gpio_chip *chip, unsigned offset)
  67 {
  68         struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
  69         struct kempld_device_data *pld = gpio->pld;
  70
  71         return !!kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset);
  72 }
  73
  74 static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
  75 {
  76         struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
  77         struct kempld_device_data *pld = gpio->pld;
  78
  79         kempld_get_mutex(pld);
  80         kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
  81         kempld_release_mutex(pld);
  82 }
  83
  84 static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
  85 {
  86         struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
  87         struct kempld_device_data *pld = gpio->pld;
  88
  89         kempld_get_mutex(pld);
  90         kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0);
  91         kempld_release_mutex(pld);
  92
  93         return 0;
  94 }
  95
  96 static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
  97                                         int value)
  98 {
  99         struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
 100         struct kempld_device_data *pld = gpio->pld;
 101
 102         kempld_get_mutex(pld);
 103         kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
 104         kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1);
 105         kempld_release_mutex(pld);
 106
 107         return 0;
 108 }
 109
 110 static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
 111 {
 112         struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
 113         struct kempld_device_data *pld = gpio->pld;
 114
 115         return !kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset);
 116 }
 117
 118 static int kempld_gpio_pincount(struct kempld_device_data *pld)
 119 {
 120         u16 evt, evt_back;
 121
 122         kempld_get_mutex(pld);
 123
 124         /* Backup event register as it might be already initialized */
 125         evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
 126         /* Clear event register */
 127         kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000);
 128         /* Read back event register */
 129         evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
 130         /* Restore event register */
 131         kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back);
 132
 133         kempld_release_mutex(pld);
 134
 135         return evt ? __ffs(evt) : 16;
 136 }
 137
 138 static int kempld_gpio_probe(struct platform_device *pdev)
 139 {
 140         struct device *dev = &pdev->dev;
 141         struct kempld_device_data *pld = dev_get_drvdata(dev->parent);
 142         struct kempld_platform_data *pdata = dev_get_platdata(pld->dev);
 143         struct kempld_gpio_data *gpio;
 144         struct gpio_chip *chip;
 145         int ret;
 146
 147         if (pld->info.spec_major < 2) {
 148                 dev_err(dev,
 149                         "Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n");
 150                 return -ENODEV;
 151         }
 152
 153         gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
 154         if (!gpio)
 155                 return -ENOMEM;
 156
 157         gpio->pld = pld;
 158
 159         platform_set_drvdata(pdev, gpio);
 160
 161         chip = &gpio->chip;
 162         chip->label = "gpio-kempld";
 163         chip->owner = THIS_MODULE;
 164         chip->parent = dev;
 165         chip->can_sleep = true;
 166         if (pdata && pdata->gpio_base)
 167                 chip->base = pdata->gpio_base;
 168         else
 169                 chip->base = -1;
 170         chip->direction_input = kempld_gpio_direction_input;
 171         chip->direction_output = kempld_gpio_direction_output;
 172         chip->get_direction = kempld_gpio_get_direction;
 173         chip->get = kempld_gpio_get;
 174         chip->set = kempld_gpio_set;
 175         chip->ngpio = kempld_gpio_pincount(pld);
 176         if (chip->ngpio == 0) {
 177                 dev_err(dev, "No GPIO pins detected\n");
 178                 return -ENODEV;
 179         }
 180
 181         ret = devm_gpiochip_add_data(dev, chip, gpio);
 182         if (ret) {
 183                 dev_err(dev, "Could not register GPIO chip\n");
 184                 return ret;
 185         }
 186
 187         dev_info(dev, "GPIO functionality initialized with %d pins\n",
 188                  chip->ngpio);
 189
 190         return 0;
 191 }
 192
 193 static struct platform_driver kempld_gpio_driver = {
 194         .driver = {
 195                 .name = "kempld-gpio",
 196         },
 197         .probe          = kempld_gpio_probe,
 198 };
 199
 200 module_platform_driver(kempld_gpio_driver);
 201
 202 MODULE_DESCRIPTION("KEM PLD GPIO Driver");
 203 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
 204 MODULE_LICENSE("GPL");
 205 MODULE_ALIAS("platform:kempld-gpio");