1/*
  2 * MEN 16Z127 GPIO driver
  3 *
  4 * Copyright (C) 2016 MEN Mikroelektronik GmbH (www.men.de)
  5 *
  6 * This program is free software; you can redistribute it and/or modify it
  7 * under the terms of the GNU General Public License as published by the Free
  8 * Software Foundation; version 2 of the License.
  9 */
 10
 11#include <linux/kernel.h>
 12#include <linux/module.h>
 13#include <linux/io.h>
 14#include <linux/err.h>
 15#include <linux/mcb.h>
 16#include <linux/bitops.h>
 17#include <linux/gpio/driver.h>
 18
 19#define MEN_Z127_CTRL	0x00
 20#define MEN_Z127_PSR	0x04
 21#define MEN_Z127_IRQR	0x08
 22#define MEN_Z127_GPIODR	0x0c
 23#define MEN_Z127_IER1	0x10
 24#define MEN_Z127_IER2	0x14
 25#define MEN_Z127_DBER	0x18
 26#define MEN_Z127_ODER	0x1C
 27#define GPIO_TO_DBCNT_REG(gpio)	((gpio * 4) + 0x80)
 28
 29#define MEN_Z127_DB_MIN_US	50
 30/* 16 bit compare register. Each bit represents 50us */
 31#define MEN_Z127_DB_MAX_US	(0xffff * MEN_Z127_DB_MIN_US)
 32#define MEN_Z127_DB_IN_RANGE(db)	((db >= MEN_Z127_DB_MIN_US) && \
 33					 (db <= MEN_Z127_DB_MAX_US))
 34
 35struct men_z127_gpio {
 36	struct gpio_chip gc;
 37	void __iomem *reg_base;
 38	struct mcb_device *mdev;
 39	struct resource *mem;
 40};
 41
 42static int men_z127_debounce(struct gpio_chip *gc, unsigned gpio,
 43			     unsigned debounce)
 44{
 45	struct men_z127_gpio *priv = gpiochip_get_data(gc);
 46	struct device *dev = &priv->mdev->dev;
 47	unsigned int rnd;
 48	u32 db_en, db_cnt;
 49
 50	if (!MEN_Z127_DB_IN_RANGE(debounce)) {
 51		dev_err(dev, "debounce value %u out of range", debounce);
 52		return -EINVAL;
 53	}
 54
 55	if (debounce > 0) {
 56		/* round up or down depending on MSB-1 */
 57		rnd = fls(debounce) - 1;
 58
 59		if (rnd && (debounce & BIT(rnd - 1)))
 60			debounce = round_up(debounce, MEN_Z127_DB_MIN_US);
 61		else
 62			debounce = round_down(debounce, MEN_Z127_DB_MIN_US);
 63
 64		if (debounce > MEN_Z127_DB_MAX_US)
 65			debounce = MEN_Z127_DB_MAX_US;
 66
 67		/* 50us per register unit */
 68		debounce /= 50;
 69	}
 70
 71	spin_lock(&gc->bgpio_lock);
 72
 73	db_en = readl(priv->reg_base + MEN_Z127_DBER);
 74
 75	if (debounce == 0) {
 76		db_en &= ~BIT(gpio);
 77		db_cnt = 0;
 78	} else {
 79		db_en |= BIT(gpio);
 80		db_cnt = debounce;
 81	}
 82
 83	writel(db_en, priv->reg_base + MEN_Z127_DBER);
 84	writel(db_cnt, priv->reg_base + GPIO_TO_DBCNT_REG(gpio));
 85
 86	spin_unlock(&gc->bgpio_lock);
 87
 88	return 0;
 89}
 90
 91static int men_z127_request(struct gpio_chip *gc, unsigned gpio_pin)
 92{
 93	struct men_z127_gpio *priv = gpiochip_get_data(gc);
 94	u32 od_en;
 95
 96	if (gpio_pin >= gc->ngpio)
 97		return -EINVAL;
 98
 99	spin_lock(&gc->bgpio_lock);
100	od_en = readl(priv->reg_base + MEN_Z127_ODER);
101
102	if (gpiochip_line_is_open_drain(gc, gpio_pin))
103		od_en |= BIT(gpio_pin);
104	else
105		od_en &= ~BIT(gpio_pin);
106
107	writel(od_en, priv->reg_base + MEN_Z127_ODER);
108	spin_unlock(&gc->bgpio_lock);
109
110	return 0;
111}
112
113static int men_z127_probe(struct mcb_device *mdev,
114			  const struct mcb_device_id *id)
115{
116	struct men_z127_gpio *men_z127_gpio;
117	struct device *dev = &mdev->dev;
118	int ret;
119
120	men_z127_gpio = devm_kzalloc(dev, sizeof(struct men_z127_gpio),
121				     GFP_KERNEL);
122	if (!men_z127_gpio)
123		return -ENOMEM;
124
125	men_z127_gpio->mem = mcb_request_mem(mdev, dev_name(dev));
126	if (IS_ERR(men_z127_gpio->mem)) {
127		dev_err(dev, "failed to request device memory");
128		return PTR_ERR(men_z127_gpio->mem);
129	}
130
131	men_z127_gpio->reg_base = ioremap(men_z127_gpio->mem->start,
132					  resource_size(men_z127_gpio->mem));
133	if (men_z127_gpio->reg_base == NULL) {
134		ret = -ENXIO;
135		goto err_release;
136	}
137
138	men_z127_gpio->mdev = mdev;
139	mcb_set_drvdata(mdev, men_z127_gpio);
140
141	ret = bgpio_init(&men_z127_gpio->gc, &mdev->dev, 4,
142			 men_z127_gpio->reg_base + MEN_Z127_PSR,
143			 men_z127_gpio->reg_base + MEN_Z127_CTRL,
144			 NULL,
145			 men_z127_gpio->reg_base + MEN_Z127_GPIODR,
146			 NULL, 0);
147	if (ret)
148		goto err_unmap;
149
150	men_z127_gpio->gc.set_debounce = men_z127_debounce;
151	men_z127_gpio->gc.request = men_z127_request;
152
153	ret = gpiochip_add_data(&men_z127_gpio->gc, men_z127_gpio);
154	if (ret) {
155		dev_err(dev, "failed to register MEN 16Z127 GPIO controller");
156		goto err_unmap;
157	}
158
159	dev_info(dev, "MEN 16Z127 GPIO driver registered");
160
161	return 0;
162
163err_unmap:
164	iounmap(men_z127_gpio->reg_base);
165err_release:
166	mcb_release_mem(men_z127_gpio->mem);
167	return ret;
168}
169
170static void men_z127_remove(struct mcb_device *mdev)
171{
172	struct men_z127_gpio *men_z127_gpio = mcb_get_drvdata(mdev);
173
174	gpiochip_remove(&men_z127_gpio->gc);
175	iounmap(men_z127_gpio->reg_base);
176	mcb_release_mem(men_z127_gpio->mem);
177}
178
179static const struct mcb_device_id men_z127_ids[] = {
180	{ .device = 0x7f },
181	{ }
182};
183MODULE_DEVICE_TABLE(mcb, men_z127_ids);
184
185static struct mcb_driver men_z127_driver = {
186	.driver = {
187		.name = "z127-gpio",
188		.owner = THIS_MODULE,
189	},
190	.probe = men_z127_probe,
191	.remove = men_z127_remove,
192	.id_table = men_z127_ids,
193};
194module_mcb_driver(men_z127_driver);
195
196MODULE_AUTHOR("Andreas Werner <andreas.werner@men.de>");
197MODULE_DESCRIPTION("MEN 16z127 GPIO Controller");
198MODULE_LICENSE("GPL v2");
199MODULE_ALIAS("mcb:16z127");