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
32struct idio_16_data {
33	struct regmap *map;
34	unsigned int irq_mask;
35};
36
37static 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
67static 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
87static 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 */
101int 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}
168EXPORT_SYMBOL_GPL(devm_idio_16_regmap_register);
169
170MODULE_AUTHOR("William Breathitt Gray");
171MODULE_DESCRIPTION("ACCES IDIO-16 GPIO Library");
172MODULE_LICENSE("GPL");
173