drivers/gpio/gpio-exar.c

   1 /*
   2  * GPIO driver for Exar XR17V35X chip
   3  *
   4  * Copyright (C) 2015 Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
   5  *
   6  * This program is free software; you can redistribute it and/or modify
   7  * it under the terms of the GNU General Public License version 2 as
   8  * published by the Free Software Foundation.
   9  */
  10 #include <linux/bitops.h>
  11 #include <linux/device.h>
  12 #include <linux/gpio/driver.h>
  13 #include <linux/init.h>
  14 #include <linux/kernel.h>
  15 #include <linux/module.h>
  16 #include <linux/pci.h>
  17 #include <linux/platform_device.h>
  18
  19 #define EXAR_OFFSET_MPIOLVL_LO 0x90
  20 #define EXAR_OFFSET_MPIOSEL_LO 0x93
  21 #define EXAR_OFFSET_MPIOLVL_HI 0x96
  22 #define EXAR_OFFSET_MPIOSEL_HI 0x99
  23
  24 #define DRIVER_NAME "gpio_exar"
  25
  26 static DEFINE_IDA(ida_index);
  27
  28 struct exar_gpio_chip {
  29         struct gpio_chip gpio_chip;
  30         struct mutex lock;
  31         int index;
  32         void __iomem *regs;
  33         char name[20];
  34         unsigned int first_pin;
  35 };
  36
  37 static void exar_update(struct gpio_chip *chip, unsigned int reg, int val,
  38                         unsigned int offset)
  39 {
  40         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
  41         int temp;
  42
  43         mutex_lock(&exar_gpio->lock);
  44         temp = readb(exar_gpio->regs + reg);
  45         temp &= ~BIT(offset);
  46         if (val)
  47                 temp |= BIT(offset);
  48         writeb(temp, exar_gpio->regs + reg);
  49         mutex_unlock(&exar_gpio->lock);
  50 }
  51
  52 static int exar_set_direction(struct gpio_chip *chip, int direction,
  53                               unsigned int offset)
  54 {
  55         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
  56         unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
  57                 EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
  58         unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
  59
  60         exar_update(chip, addr, direction, bit);
  61         return 0;
  62 }
  63
  64 static int exar_get(struct gpio_chip *chip, unsigned int reg)
  65 {
  66         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
  67         int value;
  68
  69         mutex_lock(&exar_gpio->lock);
  70         value = readb(exar_gpio->regs + reg);
  71         mutex_unlock(&exar_gpio->lock);
  72
  73         return value;
  74 }
  75
  76 static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
  77 {
  78         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
  79         unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
  80                 EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
  81         unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
  82
  83         return !!(exar_get(chip, addr) & BIT(bit));
  84 }
  85
  86 static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
  87 {
  88         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
  89         unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
  90                 EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
  91         unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
  92
  93         return !!(exar_get(chip, addr) & BIT(bit));
  94 }
  95
  96 static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
  97                            int value)
  98 {
  99         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
 100         unsigned int addr = (offset + exar_gpio->first_pin) / 8 ?
 101                 EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
 102         unsigned int bit  = (offset + exar_gpio->first_pin) % 8;
 103
 104         exar_update(chip, addr, value, bit);
 105 }
 106
 107 static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
 108                                  int value)
 109 {
 110         exar_set_value(chip, offset, value);
 111         return exar_set_direction(chip, 0, offset);
 112 }
 113
 114 static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
 115 {
 116         return exar_set_direction(chip, 1, offset);
 117 }
 118
 119 static int gpio_exar_probe(struct platform_device *pdev)
 120 {
 121         struct pci_dev *pcidev = to_pci_dev(pdev->dev.parent);
 122         struct exar_gpio_chip *exar_gpio;
 123         u32 first_pin, ngpios;
 124         void __iomem *p;
 125         int index, ret;
 126
 127         /*
 128          * The UART driver must have mapped region 0 prior to registering this
 129          * device - use it.
 130          */
 131         p = pcim_iomap_table(pcidev)[0];
 132         if (!p)
 133                 return -ENOMEM;
 134
 135         ret = device_property_read_u32(&pdev->dev, "exar,first-pin",
 136                                        &first_pin);
 137         if (ret)
 138                 return ret;
 139
 140         ret = device_property_read_u32(&pdev->dev, "ngpios", &ngpios);
 141         if (ret)
 142                 return ret;
 143
 144         exar_gpio = devm_kzalloc(&pdev->dev, sizeof(*exar_gpio), GFP_KERNEL);
 145         if (!exar_gpio)
 146                 return -ENOMEM;
 147
 148         mutex_init(&exar_gpio->lock);
 149
 150         index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL);
 151         if (index < 0) {
 152                 ret = index;
 153                 goto err_mutex_destroy;
 154         }
 155
 156         sprintf(exar_gpio->name, "exar_gpio%d", index);
 157         exar_gpio->gpio_chip.label = exar_gpio->name;
 158         exar_gpio->gpio_chip.parent = &pdev->dev;
 159         exar_gpio->gpio_chip.direction_output = exar_direction_output;
 160         exar_gpio->gpio_chip.direction_input = exar_direction_input;
 161         exar_gpio->gpio_chip.get_direction = exar_get_direction;
 162         exar_gpio->gpio_chip.get = exar_get_value;
 163         exar_gpio->gpio_chip.set = exar_set_value;
 164         exar_gpio->gpio_chip.base = -1;
 165         exar_gpio->gpio_chip.ngpio = ngpios;
 166         exar_gpio->regs = p;
 167         exar_gpio->index = index;
 168         exar_gpio->first_pin = first_pin;
 169
 170         ret = devm_gpiochip_add_data(&pdev->dev,
 171                                      &exar_gpio->gpio_chip, exar_gpio);
 172         if (ret)
 173                 goto err_destroy;
 174
 175         platform_set_drvdata(pdev, exar_gpio);
 176
 177         return 0;
 178
 179 err_destroy:
 180         ida_simple_remove(&ida_index, index);
 181 err_mutex_destroy:
 182         mutex_destroy(&exar_gpio->lock);
 183         return ret;
 184 }
 185
 186 static int gpio_exar_remove(struct platform_device *pdev)
 187 {
 188         struct exar_gpio_chip *exar_gpio = platform_get_drvdata(pdev);
 189
 190         ida_simple_remove(&ida_index, exar_gpio->index);
 191         mutex_destroy(&exar_gpio->lock);
 192
 193         return 0;
 194 }
 195
 196 static struct platform_driver gpio_exar_driver = {
 197         .probe  = gpio_exar_probe,
 198         .remove = gpio_exar_remove,
 199         .driver = {
 200                 .name = DRIVER_NAME,
 201         },
 202 };
 203
 204 module_platform_driver(gpio_exar_driver);
 205
 206 MODULE_ALIAS("platform:" DRIVER_NAME);
 207 MODULE_DESCRIPTION("Exar GPIO driver");
 208 MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
 209 MODULE_LICENSE("GPL");