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
  7#define DEFAULT_SYMBOL_NAMESPACE "GPIO_IDIO_16"
  8
  9#include <linux/bits.h>
 10#include <linux/device.h>
 11#include <linux/err.h>
 12#include <linux/export.h>
 13#include <linux/gpio/regmap.h>
 14#include <linux/module.h>
 15#include <linux/regmap.h>
 16#include <linux/types.h>
 17
 18#include "gpio-idio-16.h"
 19
 20#define IDIO_16_DAT_BASE 0x0
 21#define IDIO_16_OUT_BASE IDIO_16_DAT_BASE
 22#define IDIO_16_IN_BASE (IDIO_16_DAT_BASE + 1)
 23#define IDIO_16_CLEAR_INTERRUPT 0x1
 24#define IDIO_16_ENABLE_IRQ 0x2
 25#define IDIO_16_DEACTIVATE_INPUT_FILTERS 0x3
 26#define IDIO_16_DISABLE_IRQ IDIO_16_ENABLE_IRQ
 27#define IDIO_16_INTERRUPT_STATUS 0x6
 28
 29#define IDIO_16_NGPIO 32
 30#define IDIO_16_NGPIO_PER_REG 8
 31#define IDIO_16_REG_STRIDE 4
 32
 33struct idio_16_data {
 34	struct regmap *map;
 35	unsigned int irq_mask;
 36};
 37
 38static int idio_16_handle_mask_sync(const int index, const unsigned int mask_buf_def,
 39				    const unsigned int mask_buf, void *const irq_drv_data)
 40{
 41	struct idio_16_data *const data = irq_drv_data;
 42	const unsigned int prev_mask = data->irq_mask;
 43	int err;
 44	unsigned int val;
 45
 46	/* exit early if no change since the previous mask */
 47	if (mask_buf == prev_mask)
 48		return 0;
 49
 50	/* remember the current mask for the next mask sync */
 51	data->irq_mask = mask_buf;
 52
 53	/* if all previously masked, enable interrupts when unmasking */
 54	if (prev_mask == mask_buf_def) {
 55		err = regmap_write(data->map, IDIO_16_CLEAR_INTERRUPT, 0x00);
 56		if (err)
 57			return err;
 58		return regmap_read(data->map, IDIO_16_ENABLE_IRQ, &val);
 59	}
 60
 61	/* if all are currently masked, disable interrupts */
 62	if (mask_buf == mask_buf_def)
 63		return regmap_write(data->map, IDIO_16_DISABLE_IRQ, 0x00);
 64
 65	return 0;
 66}
 67
 68static int idio_16_reg_mask_xlate(struct gpio_regmap *const gpio, const unsigned int base,
 69				  const unsigned int offset, unsigned int *const reg,
 70				  unsigned int *const mask)
 71{
 72	unsigned int stride;
 73
 74	/* Input lines start at GPIO 16 */
 75	if (offset < 16) {
 76		stride = offset / IDIO_16_NGPIO_PER_REG;
 77		*reg = IDIO_16_OUT_BASE + stride * IDIO_16_REG_STRIDE;
 78	} else {
 79		stride = (offset - 16) / IDIO_16_NGPIO_PER_REG;
 80		*reg = IDIO_16_IN_BASE + stride * IDIO_16_REG_STRIDE;
 81	}
 82
 83	*mask = BIT(offset % IDIO_16_NGPIO_PER_REG);
 84
 85	return 0;
 86}
 87
 88static const char *idio_16_names[IDIO_16_NGPIO] = {
 89	"OUT0", "OUT1", "OUT2", "OUT3", "OUT4", "OUT5", "OUT6", "OUT7",
 90	"OUT8", "OUT9", "OUT10", "OUT11", "OUT12", "OUT13", "OUT14", "OUT15",
 91	"IIN0", "IIN1", "IIN2", "IIN3", "IIN4", "IIN5", "IIN6", "IIN7",
 92	"IIN8", "IIN9", "IIN10", "IIN11", "IIN12", "IIN13", "IIN14", "IIN15",
 93};
 94
 95/**
 96 * devm_idio_16_regmap_register - Register an IDIO-16 GPIO device
 97 * @dev:	device that is registering this IDIO-16 GPIO device
 98 * @config:	configuration for idio_16_regmap_config
 99 *
100 * Registers an IDIO-16 GPIO device. Returns 0 on success and negative error number on failure.
101 */
102int devm_idio_16_regmap_register(struct device *const dev,
103				 const struct idio_16_regmap_config *const config)
104{
105	struct gpio_regmap_config gpio_config = {};
106	int err;
107	struct idio_16_data *data;
108	struct regmap_irq_chip *chip;
109	struct regmap_irq_chip_data *chip_data;
110
111	if (!config->parent)
112		return -EINVAL;
113
114	if (!config->map)
115		return -EINVAL;
116
117	if (!config->regmap_irqs)
118		return -EINVAL;
119
120	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
121	if (!data)
122		return -ENOMEM;
123	data->map = config->map;
124
125	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
126	if (!chip)
127		return -ENOMEM;
128
129	chip->name = dev_name(dev);
130	chip->status_base = IDIO_16_INTERRUPT_STATUS;
131	chip->mask_base = IDIO_16_ENABLE_IRQ;
132	chip->ack_base = IDIO_16_CLEAR_INTERRUPT;
133	chip->no_status = config->no_status;
134	chip->num_regs = 1;
135	chip->irqs = config->regmap_irqs;
136	chip->num_irqs = config->num_regmap_irqs;
137	chip->handle_mask_sync = idio_16_handle_mask_sync;
138	chip->irq_drv_data = data;
139
140	/* Disable IRQ to prevent spurious interrupts before we're ready */
141	err = regmap_write(data->map, IDIO_16_DISABLE_IRQ, 0x00);
142	if (err)
143		return err;
144
145	err = devm_regmap_add_irq_chip(dev, data->map, config->irq, 0, 0, chip, &chip_data);
146	if (err)
147		return dev_err_probe(dev, err, "IRQ registration failed\n");
148
149	if (config->filters) {
150		/* Deactivate input filters */
151		err = regmap_write(data->map, IDIO_16_DEACTIVATE_INPUT_FILTERS, 0x00);
152		if (err)
153			return err;
154	}
155
156	gpio_config.parent = config->parent;
157	gpio_config.regmap = data->map;
158	gpio_config.ngpio = IDIO_16_NGPIO;
159	gpio_config.names = idio_16_names;
160	gpio_config.reg_dat_base = GPIO_REGMAP_ADDR(IDIO_16_DAT_BASE);
161	gpio_config.reg_set_base = GPIO_REGMAP_ADDR(IDIO_16_DAT_BASE);
162	gpio_config.ngpio_per_reg = IDIO_16_NGPIO_PER_REG;
163	gpio_config.reg_stride = IDIO_16_REG_STRIDE;
164	gpio_config.irq_domain = regmap_irq_get_domain(chip_data);
165	gpio_config.reg_mask_xlate = idio_16_reg_mask_xlate;
166
167	return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));
168}
169EXPORT_SYMBOL_GPL(devm_idio_16_regmap_register);
170
171MODULE_AUTHOR("William Breathitt Gray");
172MODULE_DESCRIPTION("ACCES IDIO-16 GPIO Library");
173MODULE_LICENSE("GPL");