drivers/gpio/gpio-idio-16.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * GPIO library for the ACCES IDIO-16 family
   4  * Copyright (C) 2022 William Breathitt Gray
   5  */
   6 #include <linux/bits.h>
   7 #include <linux/device.h>
   8 #include <linux/err.h>
   9 #include <linux/export.h>
  10 #include <linux/gpio/regmap.h>
  11 #include <linux/module.h>
  12 #include <linux/regmap.h>
  13 #include <linux/types.h>
  14
  15 #include "gpio-idio-16.h"
  16
  17 #define DEFAULT_SYMBOL_NAMESPACE GPIO_IDIO_16
  18
  19 #define IDIO_16_DAT_BASE 0x0
  20 #define IDIO_16_OUT_BASE IDIO_16_DAT_BASE
  21 #define IDIO_16_IN_BASE (IDIO_16_DAT_BASE + 1)
  22 #define IDIO_16_CLEAR_INTERRUPT 0x1
  23 #define IDIO_16_ENABLE_IRQ 0x2
  24 #define IDIO_16_DEACTIVATE_INPUT_FILTERS 0x3
  25 #define IDIO_16_DISABLE_IRQ IDIO_16_ENABLE_IRQ
  26 #define IDIO_16_INTERRUPT_STATUS 0x6
  27
  28 #define IDIO_16_NGPIO 32
  29 #define IDIO_16_NGPIO_PER_REG 8
  30 #define IDIO_16_REG_STRIDE 4
  31
  32 struct idio_16_data {
  33         struct regmap *map;
  34         unsigned int irq_mask;
  35 };
  36
  37 static int idio_16_handle_mask_sync(const int index, const unsigned int mask_buf_def,
  38                                     const unsigned int mask_buf, void *const irq_drv_data)
  39 {
  40         struct idio_16_data *const data = irq_drv_data;
  41         const unsigned int prev_mask = data->irq_mask;
  42         int err;
  43         unsigned int val;
  44
  45         /* exit early if no change since the previous mask */
  46         if (mask_buf == prev_mask)
  47                 return 0;
  48
  49         /* remember the current mask for the next mask sync */
  50         data->irq_mask = mask_buf;
  51
  52         /* if all previously masked, enable interrupts when unmasking */
  53         if (prev_mask == mask_buf_def) {
  54                 err = regmap_write(data->map, IDIO_16_CLEAR_INTERRUPT, 0x00);
  55                 if (err)
  56                         return err;
  57                 return regmap_read(data->map, IDIO_16_ENABLE_IRQ, &val);
  58         }
  59
  60         /* if all are currently masked, disable interrupts */
  61         if (mask_buf == mask_buf_def)
  62                 return regmap_write(data->map, IDIO_16_DISABLE_IRQ, 0x00);
  63
  64         return 0;
  65 }
  66
  67 static int idio_16_reg_mask_xlate(struct gpio_regmap *const gpio, const unsigned int base,
  68                                   const unsigned int offset, unsigned int *const reg,
  69                                   unsigned int *const mask)
  70 {
  71         unsigned int stride;
  72
  73         /* Input lines start at GPIO 16 */
  74         if (offset < 16) {
  75                 stride = offset / IDIO_16_NGPIO_PER_REG;
  76                 *reg = IDIO_16_OUT_BASE + stride * IDIO_16_REG_STRIDE;
  77         } else {
  78                 stride = (offset - 16) / IDIO_16_NGPIO_PER_REG;
  79                 *reg = IDIO_16_IN_BASE + stride * IDIO_16_REG_STRIDE;
  80         }
  81
  82         *mask = BIT(offset % IDIO_16_NGPIO_PER_REG);
  83
  84         return 0;
  85 }
  86
  87 static const char *idio_16_names[IDIO_16_NGPIO] = {
  88         "OUT0", "OUT1", "OUT2", "OUT3", "OUT4", "OUT5", "OUT6", "OUT7",
  89         "OUT8", "OUT9", "OUT10", "OUT11", "OUT12", "OUT13", "OUT14", "OUT15",
  90         "IIN0", "IIN1", "IIN2", "IIN3", "IIN4", "IIN5", "IIN6", "IIN7",
  91         "IIN8", "IIN9", "IIN10", "IIN11", "IIN12", "IIN13", "IIN14", "IIN15",
  92 };
  93
  94 /**
  95  * devm_idio_16_regmap_register - Register an IDIO-16 GPIO device
  96  * @dev:        device that is registering this IDIO-16 GPIO device
  97  * @config:     configuration for idio_16_regmap_config
  98  *
  99  * Registers an IDIO-16 GPIO device. Returns 0 on success and negative error number on failure.
 100  */
 101 int devm_idio_16_regmap_register(struct device *const dev,
 102                                  const struct idio_16_regmap_config *const config)
 103 {
 104         struct gpio_regmap_config gpio_config = {};
 105         int err;
 106         struct idio_16_data *data;
 107         struct regmap_irq_chip *chip;
 108         struct regmap_irq_chip_data *chip_data;
 109
 110         if (!config->parent)
 111                 return -EINVAL;
 112
 113         if (!config->map)
 114                 return -EINVAL;
 115
 116         if (!config->regmap_irqs)
 117                 return -EINVAL;
 118
 119         data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 120         if (!data)
 121                 return -ENOMEM;
 122         data->map = config->map;
 123
 124         chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
 125         if (!chip)
 126                 return -ENOMEM;
 127
 128         chip->name = dev_name(dev);
 129         chip->status_base = IDIO_16_INTERRUPT_STATUS;
 130         chip->mask_base = IDIO_16_ENABLE_IRQ;
 131         chip->ack_base = IDIO_16_CLEAR_INTERRUPT;
 132         chip->no_status = config->no_status;
 133         chip->num_regs = 1;
 134         chip->irqs = config->regmap_irqs;
 135         chip->num_irqs = config->num_regmap_irqs;
 136         chip->handle_mask_sync = idio_16_handle_mask_sync;
 137         chip->irq_drv_data = data;
 138
 139         /* Disable IRQ to prevent spurious interrupts before we're ready */
 140         err = regmap_write(data->map, IDIO_16_DISABLE_IRQ, 0x00);
 141         if (err)
 142                 return err;
 143
 144         err = devm_regmap_add_irq_chip(dev, data->map, config->irq, 0, 0, chip, &chip_data);
 145         if (err)
 146                 return dev_err_probe(dev, err, "IRQ registration failed\n");
 147
 148         if (config->filters) {
 149                 /* Deactivate input filters */
 150                 err = regmap_write(data->map, IDIO_16_DEACTIVATE_INPUT_FILTERS, 0x00);
 151                 if (err)
 152                         return err;
 153         }
 154
 155         gpio_config.parent = config->parent;
 156         gpio_config.regmap = data->map;
 157         gpio_config.ngpio = IDIO_16_NGPIO;
 158         gpio_config.names = idio_16_names;
 159         gpio_config.reg_dat_base = GPIO_REGMAP_ADDR(IDIO_16_DAT_BASE);
 160         gpio_config.reg_set_base = GPIO_REGMAP_ADDR(IDIO_16_DAT_BASE);
 161         gpio_config.ngpio_per_reg = IDIO_16_NGPIO_PER_REG;
 162         gpio_config.reg_stride = IDIO_16_REG_STRIDE;
 163         gpio_config.irq_domain = regmap_irq_get_domain(chip_data);
 164         gpio_config.reg_mask_xlate = idio_16_reg_mask_xlate;
 165
 166         return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));
 167 }
 168 EXPORT_SYMBOL_GPL(devm_idio_16_regmap_register);
 169
 170 MODULE_AUTHOR("William Breathitt Gray");
 171 MODULE_DESCRIPTION("ACCES IDIO-16 GPIO Library");
 172 MODULE_LICENSE("GPL");