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 resource *mem;
 39};
 40
 41static int men_z127_debounce(struct gpio_chip *gc, unsigned gpio,
 42			     unsigned debounce)
 43{
 44	struct men_z127_gpio *priv = gpiochip_get_data(gc);
 45	struct device *dev = gc->parent;
 46	unsigned int rnd;
 47	u32 db_en, db_cnt;
 48
 49	if (!MEN_Z127_DB_IN_RANGE(debounce)) {
 50		dev_err(dev, "debounce value %u out of range", debounce);
 51		return -EINVAL;
 52	}
 53
 54	if (debounce > 0) {
 55		/* round up or down depending on MSB-1 */
 56		rnd = fls(debounce) - 1;
 57
 58		if (rnd && (debounce & BIT(rnd - 1)))
 59			debounce = round_up(debounce, MEN_Z127_DB_MIN_US);
 60		else
 61			debounce = round_down(debounce, MEN_Z127_DB_MIN_US);
 62
 63		if (debounce > MEN_Z127_DB_MAX_US)
 64			debounce = MEN_Z127_DB_MAX_US;
 65
 66		/* 50us per register unit */
 67		debounce /= 50;
 68	}
 69
 70	spin_lock(&gc->bgpio_lock);
 71
 72	db_en = readl(priv->reg_base + MEN_Z127_DBER);
 73
 74	if (debounce == 0) {
 75		db_en &= ~BIT(gpio);
 76		db_cnt = 0;
 77	} else {
 78		db_en |= BIT(gpio);
 79		db_cnt = debounce;
 80	}
 81
 82	writel(db_en, priv->reg_base + MEN_Z127_DBER);
 83	writel(db_cnt, priv->reg_base + GPIO_TO_DBCNT_REG(gpio));
 84
 85	spin_unlock(&gc->bgpio_lock);
 86
 87	return 0;
 88}
 89
 90static int men_z127_set_single_ended(struct gpio_chip *gc,
 91				     unsigned offset,
 92				     enum pin_config_param param)
 93{
 94	struct men_z127_gpio *priv = gpiochip_get_data(gc);
 95	u32 od_en;
 96
 97	spin_lock(&gc->bgpio_lock);
 98	od_en = readl(priv->reg_base + MEN_Z127_ODER);
 99
100	if (param == PIN_CONFIG_DRIVE_OPEN_DRAIN)
101		od_en |= BIT(offset);
102	else
103		/* Implicitly PIN_CONFIG_DRIVE_PUSH_PULL */
104		od_en &= ~BIT(offset);
105
106	writel(od_en, priv->reg_base + MEN_Z127_ODER);
107	spin_unlock(&gc->bgpio_lock);
108
109	return 0;
110}
111
112static int men_z127_set_config(struct gpio_chip *gc, unsigned offset,
113			       unsigned long config)
114{
115	enum pin_config_param param = pinconf_to_config_param(config);
116
117	switch (param) {
118	case PIN_CONFIG_DRIVE_OPEN_DRAIN:
119	case PIN_CONFIG_DRIVE_PUSH_PULL:
120		return men_z127_set_single_ended(gc, offset, param);
121
122	case PIN_CONFIG_INPUT_DEBOUNCE:
123		return men_z127_debounce(gc, offset,
124			pinconf_to_config_argument(config));
125
126	default:
127		break;
128	}
129
130	return -ENOTSUPP;
131}
132
133static int men_z127_probe(struct mcb_device *mdev,
134			  const struct mcb_device_id *id)
135{
136	struct men_z127_gpio *men_z127_gpio;
137	struct device *dev = &mdev->dev;
138	int ret;
139
140	men_z127_gpio = devm_kzalloc(dev, sizeof(struct men_z127_gpio),
141				     GFP_KERNEL);
142	if (!men_z127_gpio)
143		return -ENOMEM;
144
145	men_z127_gpio->mem = mcb_request_mem(mdev, dev_name(dev));
146	if (IS_ERR(men_z127_gpio->mem)) {
147		dev_err(dev, "failed to request device memory");
148		return PTR_ERR(men_z127_gpio->mem);
149	}
150
151	men_z127_gpio->reg_base = ioremap(men_z127_gpio->mem->start,
152					  resource_size(men_z127_gpio->mem));
153	if (men_z127_gpio->reg_base == NULL) {
154		ret = -ENXIO;
155		goto err_release;
156	}
157
158	mcb_set_drvdata(mdev, men_z127_gpio);
159
160	ret = bgpio_init(&men_z127_gpio->gc, &mdev->dev, 4,
161			 men_z127_gpio->reg_base + MEN_Z127_PSR,
162			 men_z127_gpio->reg_base + MEN_Z127_CTRL,
163			 NULL,
164			 men_z127_gpio->reg_base + MEN_Z127_GPIODR,
165			 NULL, 0);
166	if (ret)
167		goto err_unmap;
168
169	men_z127_gpio->gc.set_config = men_z127_set_config;
170
171	ret = gpiochip_add_data(&men_z127_gpio->gc, men_z127_gpio);
172	if (ret) {
173		dev_err(dev, "failed to register MEN 16Z127 GPIO controller");
174		goto err_unmap;
175	}
176
177	dev_info(dev, "MEN 16Z127 GPIO driver registered");
178
179	return 0;
180
181err_unmap:
182	iounmap(men_z127_gpio->reg_base);
183err_release:
184	mcb_release_mem(men_z127_gpio->mem);
185	return ret;
186}
187
188static void men_z127_remove(struct mcb_device *mdev)
189{
190	struct men_z127_gpio *men_z127_gpio = mcb_get_drvdata(mdev);
191
192	gpiochip_remove(&men_z127_gpio->gc);
193	iounmap(men_z127_gpio->reg_base);
194	mcb_release_mem(men_z127_gpio->mem);
195}
196
197static const struct mcb_device_id men_z127_ids[] = {
198	{ .device = 0x7f },
199	{ }
200};
201MODULE_DEVICE_TABLE(mcb, men_z127_ids);
202
203static struct mcb_driver men_z127_driver = {
204	.driver = {
205		.name = "z127-gpio",
206	},
207	.probe = men_z127_probe,
208	.remove = men_z127_remove,
209	.id_table = men_z127_ids,
210};
211module_mcb_driver(men_z127_driver);
212
213MODULE_AUTHOR("Andreas Werner <andreas.werner@men.de>");
214MODULE_DESCRIPTION("MEN 16z127 GPIO Controller");
215MODULE_LICENSE("GPL v2");
216MODULE_ALIAS("mcb:16z127");