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 };
  35
  36 static void exar_update(struct gpio_chip *chip, unsigned int reg, int val,
  37                         unsigned int offset)
  38 {
  39         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
  40         int temp;
  41
  42         mutex_lock(&exar_gpio->lock);
  43         temp = readb(exar_gpio->regs + reg);
  44         temp &= ~BIT(offset);
  45         if (val)
  46                 temp |= BIT(offset);
  47         writeb(temp, exar_gpio->regs + reg);
  48         mutex_unlock(&exar_gpio->lock);
  49 }
  50
  51 static int exar_set_direction(struct gpio_chip *chip, int direction,
  52                               unsigned int offset)
  53 {
  54         unsigned int bank = offset / 8;
  55         unsigned int addr;
  56
  57         addr = bank ? EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
  58         exar_update(chip, addr, direction, offset % 8);
  59         return 0;
  60 }
  61
  62 static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
  63                                  int value)
  64 {
  65         return exar_set_direction(chip, 0, offset);
  66 }
  67
  68 static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
  69 {
  70         return exar_set_direction(chip, 1, offset);
  71 }
  72
  73 static int exar_get(struct gpio_chip *chip, unsigned int reg)
  74 {
  75         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
  76         int value;
  77
  78         mutex_lock(&exar_gpio->lock);
  79         value = readb(exar_gpio->regs + reg);
  80         mutex_unlock(&exar_gpio->lock);
  81
  82         return !!value;
  83 }
  84
  85 static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
  86 {
  87         unsigned int bank = offset / 8;
  88         unsigned int addr;
  89         int val;
  90
  91         addr = bank ? EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
  92         val = exar_get(chip, addr) >> (offset % 8);
  93
  94         return !!val;
  95 }
  96
  97 static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
  98 {
  99         unsigned int bank = offset / 8;
 100         unsigned int addr;
 101         int val;
 102
 103         addr = bank ? EXAR_OFFSET_MPIOLVL_LO : EXAR_OFFSET_MPIOLVL_HI;
 104         val = exar_get(chip, addr) >> (offset % 8);
 105
 106         return !!val;
 107 }
 108
 109 static void exar_set_value(struct gpio_chip *chip, unsigned int offset,
 110                            int value)
 111 {
 112         unsigned int bank = offset / 8;
 113         unsigned int addr;
 114
 115         addr = bank ? EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
 116         exar_update(chip, addr, value, offset % 8);
 117 }
 118
 119 static int gpio_exar_probe(struct platform_device *pdev)
 120 {
 121         struct pci_dev *pcidev = platform_get_drvdata(pdev);
 122         struct exar_gpio_chip *exar_gpio;
 123         void __iomem *p;
 124         int index, ret;
 125
 126         if (pcidev->vendor != PCI_VENDOR_ID_EXAR)
 127                 return -ENODEV;
 128
 129         /*
 130          * Map the pci device to get the register addresses.
 131          * We will need to read and write those registers to control
 132          * the GPIO pins.
 133          * Using managed functions will save us from unmaping on exit.
 134          * As the device is enabled using managed functions by the
 135          * UART driver we can also use managed functions here.
 136          */
 137         p = pcim_iomap(pcidev, 0, 0);
 138         if (!p)
 139                 return -ENOMEM;
 140
 141         exar_gpio = devm_kzalloc(&pcidev->dev, sizeof(*exar_gpio), GFP_KERNEL);
 142         if (!exar_gpio)
 143                 return -ENOMEM;
 144
 145         mutex_init(&exar_gpio->lock);
 146
 147         index = ida_simple_get(&ida_index, 0, 0, GFP_KERNEL);
 148
 149         sprintf(exar_gpio->name, "exar_gpio%d", index);
 150         exar_gpio->gpio_chip.label = exar_gpio->name;
 151         exar_gpio->gpio_chip.parent = &pcidev->dev;
 152         exar_gpio->gpio_chip.direction_output = exar_direction_output;
 153         exar_gpio->gpio_chip.direction_input = exar_direction_input;
 154         exar_gpio->gpio_chip.get_direction = exar_get_direction;
 155         exar_gpio->gpio_chip.get = exar_get_value;
 156         exar_gpio->gpio_chip.set = exar_set_value;
 157         exar_gpio->gpio_chip.base = -1;
 158         exar_gpio->gpio_chip.ngpio = 16;
 159         exar_gpio->regs = p;
 160         exar_gpio->index = index;
 161
 162         ret = devm_gpiochip_add_data(&pcidev->dev,
 163                                      &exar_gpio->gpio_chip, exar_gpio);
 164         if (ret)
 165                 goto err_destroy;
 166
 167         platform_set_drvdata(pdev, exar_gpio);
 168
 169         return 0;
 170
 171 err_destroy:
 172         ida_simple_remove(&ida_index, index);
 173         mutex_destroy(&exar_gpio->lock);
 174         return ret;
 175 }
 176
 177 static int gpio_exar_remove(struct platform_device *pdev)
 178 {
 179         struct exar_gpio_chip *exar_gpio = platform_get_drvdata(pdev);
 180
 181         ida_simple_remove(&ida_index, exar_gpio->index);
 182         mutex_destroy(&exar_gpio->lock);
 183
 184         return 0;
 185 }
 186
 187 static struct platform_driver gpio_exar_driver = {
 188         .probe  = gpio_exar_probe,
 189         .remove = gpio_exar_remove,
 190         .driver = {
 191                 .name = DRIVER_NAME,
 192         },
 193 };
 194
 195 module_platform_driver(gpio_exar_driver);
 196
 197 MODULE_ALIAS("platform:" DRIVER_NAME);
 198 MODULE_DESCRIPTION("Exar GPIO driver");
 199 MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
 200 MODULE_LICENSE("GPL");