drivers/gpio/gpio-exar.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * GPIO driver for Exar XR17V35X chip
   4  *
   5  * Copyright (C) 2015 Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>
   6  */
   7
   8 #include <linux/bitops.h>
   9 #include <linux/device.h>
  10 #include <linux/gpio/driver.h>
  11 #include <linux/idr.h>
  12 #include <linux/init.h>
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/pci.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/regmap.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 /*
  25  * The Device Configuration and UART Configuration Registers
  26  * for each UART channel take 1KB of memory address space.
  27  */
  28 #define EXAR_UART_CHANNEL_SIZE 0x400
  29
  30 #define DRIVER_NAME "gpio_exar"
  31
  32 static DEFINE_IDA(ida_index);
  33
  34 struct exar_gpio_chip {
  35         struct gpio_chip gpio_chip;
  36         struct regmap *regmap;
  37         int index;
  38         char name[20];
  39         unsigned int first_pin;
  40         /*
  41          * The offset to the cascaded device's (if existing)
  42          * Device Configuration Registers.
  43          */
  44         unsigned int cascaded_offset;
  45 };
  46
  47 static unsigned int
  48 exar_offset_to_sel_addr(struct exar_gpio_chip *exar_gpio, unsigned int offset)
  49 {
  50         unsigned int pin = exar_gpio->first_pin + (offset % 16);
  51         unsigned int cascaded = offset / 16;
  52         unsigned int addr = pin / 8 ? EXAR_OFFSET_MPIOSEL_HI : EXAR_OFFSET_MPIOSEL_LO;
  53
  54         return addr + (cascaded ? exar_gpio->cascaded_offset : 0);
  55 }
  56
  57 static unsigned int
  58 exar_offset_to_lvl_addr(struct exar_gpio_chip *exar_gpio, unsigned int offset)
  59 {
  60         unsigned int pin = exar_gpio->first_pin + (offset % 16);
  61         unsigned int cascaded = offset / 16;
  62         unsigned int addr = pin / 8 ? EXAR_OFFSET_MPIOLVL_HI : EXAR_OFFSET_MPIOLVL_LO;
  63
  64         return addr + (cascaded ? exar_gpio->cascaded_offset : 0);
  65 }
  66
  67 static unsigned int
  68 exar_offset_to_bit(struct exar_gpio_chip *exar_gpio, unsigned int offset)
  69 {
  70         unsigned int pin = exar_gpio->first_pin + (offset % 16);
  71
  72         return pin % 8;
  73 }
  74
  75 static int exar_get_direction(struct gpio_chip *chip, unsigned int offset)
  76 {
  77         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
  78         unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
  79         unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
  80
  81         if (regmap_test_bits(exar_gpio->regmap, addr, BIT(bit)))
  82                 return GPIO_LINE_DIRECTION_IN;
  83
  84         return GPIO_LINE_DIRECTION_OUT;
  85 }
  86
  87 static int exar_get_value(struct gpio_chip *chip, unsigned int offset)
  88 {
  89         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
  90         unsigned int addr = exar_offset_to_lvl_addr(exar_gpio, offset);
  91         unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
  92
  93         return !!(regmap_test_bits(exar_gpio->regmap, 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 = exar_offset_to_lvl_addr(exar_gpio, offset);
 101         unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
 102         unsigned int bit_value = value ? BIT(bit) : 0;
 103
 104         /*
 105          * regmap_write_bits() forces value to be written when an external
 106          * pull up/down might otherwise indicate value was already set.
 107          */
 108         regmap_write_bits(exar_gpio->regmap, addr, BIT(bit), bit_value);
 109 }
 110
 111 static int exar_direction_output(struct gpio_chip *chip, unsigned int offset,
 112                                  int value)
 113 {
 114         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
 115         unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
 116         unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
 117
 118         exar_set_value(chip, offset, value);
 119         regmap_clear_bits(exar_gpio->regmap, addr, BIT(bit));
 120
 121         return 0;
 122 }
 123
 124 static int exar_direction_input(struct gpio_chip *chip, unsigned int offset)
 125 {
 126         struct exar_gpio_chip *exar_gpio = gpiochip_get_data(chip);
 127         unsigned int addr = exar_offset_to_sel_addr(exar_gpio, offset);
 128         unsigned int bit = exar_offset_to_bit(exar_gpio, offset);
 129
 130         regmap_set_bits(exar_gpio->regmap, addr, BIT(bit));
 131
 132         return 0;
 133 }
 134
 135 static void exar_devm_ida_free(void *data)
 136 {
 137         struct exar_gpio_chip *exar_gpio = data;
 138
 139         ida_free(&ida_index, exar_gpio->index);
 140 }
 141
 142 static const struct regmap_config exar_regmap_config = {
 143         .name           = "exar-gpio",
 144         .reg_bits       = 16,
 145         .val_bits       = 8,
 146         .io_port        = true,
 147 };
 148
 149 static int gpio_exar_probe(struct platform_device *pdev)
 150 {
 151         struct device *dev = &pdev->dev;
 152         struct pci_dev *pcidev = to_pci_dev(dev->parent);
 153         struct exar_gpio_chip *exar_gpio;
 154         u32 first_pin, ngpios;
 155         void __iomem *p;
 156         int index, ret;
 157
 158         /*
 159          * The UART driver must have mapped region 0 prior to registering this
 160          * device - use it.
 161          */
 162         p = pcim_iomap_table(pcidev)[0];
 163         if (!p)
 164                 return -ENOMEM;
 165
 166         ret = device_property_read_u32(dev, "exar,first-pin", &first_pin);
 167         if (ret)
 168                 return ret;
 169
 170         ret = device_property_read_u32(dev, "ngpios", &ngpios);
 171         if (ret)
 172                 return ret;
 173
 174         exar_gpio = devm_kzalloc(dev, sizeof(*exar_gpio), GFP_KERNEL);
 175         if (!exar_gpio)
 176                 return -ENOMEM;
 177
 178         /*
 179          * If cascaded, secondary xr17v354 or xr17v358 have the same amount
 180          * of MPIOs as their primaries and the last 4 bits of the primary's
 181          * PCI Device ID is the number of its UART channels.
 182          */
 183         if (pcidev->device & GENMASK(15, 12)) {
 184                 ngpios += ngpios;
 185                 exar_gpio->cascaded_offset = (pcidev->device & GENMASK(3, 0)) *
 186                                 EXAR_UART_CHANNEL_SIZE;
 187         }
 188
 189         /*
 190          * We don't need to check the return values of mmio regmap operations (unless
 191          * the regmap has a clock attached which is not the case here).
 192          */
 193         exar_gpio->regmap = devm_regmap_init_mmio(dev, p, &exar_regmap_config);
 194         if (IS_ERR(exar_gpio->regmap))
 195                 return PTR_ERR(exar_gpio->regmap);
 196
 197         index = ida_alloc(&ida_index, GFP_KERNEL);
 198         if (index < 0)
 199                 return index;
 200
 201         ret = devm_add_action_or_reset(dev, exar_devm_ida_free, exar_gpio);
 202         if (ret)
 203                 return ret;
 204
 205         sprintf(exar_gpio->name, "exar_gpio%d", index);
 206         exar_gpio->gpio_chip.label = exar_gpio->name;
 207         exar_gpio->gpio_chip.parent = dev;
 208         exar_gpio->gpio_chip.direction_output = exar_direction_output;
 209         exar_gpio->gpio_chip.direction_input = exar_direction_input;
 210         exar_gpio->gpio_chip.get_direction = exar_get_direction;
 211         exar_gpio->gpio_chip.get = exar_get_value;
 212         exar_gpio->gpio_chip.set = exar_set_value;
 213         exar_gpio->gpio_chip.base = -1;
 214         exar_gpio->gpio_chip.ngpio = ngpios;
 215         exar_gpio->index = index;
 216         exar_gpio->first_pin = first_pin;
 217
 218         ret = devm_gpiochip_add_data(dev, &exar_gpio->gpio_chip, exar_gpio);
 219         if (ret)
 220                 return ret;
 221
 222         return 0;
 223 }
 224
 225 static struct platform_driver gpio_exar_driver = {
 226         .probe  = gpio_exar_probe,
 227         .driver = {
 228                 .name = DRIVER_NAME,
 229         },
 230 };
 231
 232 module_platform_driver(gpio_exar_driver);
 233
 234 MODULE_ALIAS("platform:" DRIVER_NAME);
 235 MODULE_DESCRIPTION("Exar GPIO driver");
 236 MODULE_AUTHOR("Sudip Mukherjee <sudip.mukherjee@codethink.co.uk>");
 237 MODULE_LICENSE("GPL");