gpio-kempld.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Kontron PLD GPIO driver
  4 *
  5 * Copyright (c) 2010-2013 Kontron Europe GmbH
  6 * Author: Michael Brunner <michael.brunner@kontron.com>
  7 */
  8
  9#include <linux/init.h>
 10#include <linux/kernel.h>
 11#include <linux/module.h>
 12#include <linux/bitops.h>
 13#include <linux/errno.h>
 14#include <linux/platform_device.h>
 15#include <linux/gpio/driver.h>
 16#include <linux/mfd/kempld.h>
 17
 18#define KEMPLD_GPIO_MAX_NUM		16
 19#define KEMPLD_GPIO_MASK(x)		(BIT((x) % 8))
 20#define KEMPLD_GPIO_DIR_NUM(x)		(0x40 + (x) / 8)
 21#define KEMPLD_GPIO_LVL_NUM(x)		(0x42 + (x) / 8)
 22#define KEMPLD_GPIO_EVT_LVL_EDGE	0x46
 23#define KEMPLD_GPIO_IEN			0x4A
 24
 25struct kempld_gpio_data {
 26	struct gpio_chip		chip;
 27	struct kempld_device_data	*pld;
 28};
 29
 30/*
 31 * Set or clear GPIO bit
 32 * kempld_get_mutex must be called prior to calling this function.
 33 */
 34static void kempld_gpio_bitop(struct kempld_device_data *pld,
 35			      u8 reg, u8 bit, u8 val)
 36{
 37	u8 status;
 38
 39	status = kempld_read8(pld, reg);
 40	if (val)
 41		status |= KEMPLD_GPIO_MASK(bit);
 42	else
 43		status &= ~KEMPLD_GPIO_MASK(bit);
 44	kempld_write8(pld, reg, status);
 45}
 46
 47static int kempld_gpio_get_bit(struct kempld_device_data *pld, u8 reg, u8 bit)
 48{
 49	u8 status;
 50
 51	kempld_get_mutex(pld);
 52	status = kempld_read8(pld, reg);
 53	kempld_release_mutex(pld);
 54
 55	return !!(status & KEMPLD_GPIO_MASK(bit));
 56}
 57
 58static int kempld_gpio_get(struct gpio_chip *chip, unsigned offset)
 59{
 60	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
 61	struct kempld_device_data *pld = gpio->pld;
 62
 63	return !!kempld_gpio_get_bit(pld, KEMPLD_GPIO_LVL_NUM(offset), offset);
 64}
 65
 66static int kempld_gpio_set(struct gpio_chip *chip, unsigned int offset,
 67			   int value)
 68{
 69	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
 70	struct kempld_device_data *pld = gpio->pld;
 71
 72	kempld_get_mutex(pld);
 73	kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
 74	kempld_release_mutex(pld);
 75
 76	return 0;
 77}
 78
 79static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
 80{
 81	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
 82	struct kempld_device_data *pld = gpio->pld;
 83
 84	kempld_get_mutex(pld);
 85	kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0);
 86	kempld_release_mutex(pld);
 87
 88	return 0;
 89}
 90
 91static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
 92					int value)
 93{
 94	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
 95	struct kempld_device_data *pld = gpio->pld;
 96
 97	kempld_get_mutex(pld);
 98	kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
 99	kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1);
100	kempld_release_mutex(pld);
101
102	return 0;
103}
104
105static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
106{
107	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
108	struct kempld_device_data *pld = gpio->pld;
109
110	if (kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset))
111		return GPIO_LINE_DIRECTION_OUT;
112
113	return GPIO_LINE_DIRECTION_IN;
114}
115
116static int kempld_gpio_pincount(struct kempld_device_data *pld)
117{
118	u16 evt, evt_back;
119
120	kempld_get_mutex(pld);
121
122	/* Backup event register as it might be already initialized */
123	evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
124	/* Clear event register */
125	kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000);
126	/* Read back event register */
127	evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
128	/* Restore event register */
129	kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back);
130
131	kempld_release_mutex(pld);
132
133	return evt ? __ffs(evt) : 16;
134}
135
136static int kempld_gpio_probe(struct platform_device *pdev)
137{
138	struct device *dev = &pdev->dev;
139	struct kempld_device_data *pld = dev_get_drvdata(dev->parent);
140	struct kempld_platform_data *pdata = dev_get_platdata(pld->dev);
141	struct kempld_gpio_data *gpio;
142	struct gpio_chip *chip;
143	int ret;
144
145	if (pld->info.spec_major < 2) {
146		dev_err(dev,
147			"Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n");
148		return -ENODEV;
149	}
150
151	gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
152	if (!gpio)
153		return -ENOMEM;
154
155	gpio->pld = pld;
156
157	platform_set_drvdata(pdev, gpio);
158
159	chip = &gpio->chip;
160	chip->label = "gpio-kempld";
161	chip->owner = THIS_MODULE;
162	chip->parent = dev;
163	chip->can_sleep = true;
164	if (pdata && pdata->gpio_base)
165		chip->base = pdata->gpio_base;
166	else
167		chip->base = -1;
168	chip->direction_input = kempld_gpio_direction_input;
169	chip->direction_output = kempld_gpio_direction_output;
170	chip->get_direction = kempld_gpio_get_direction;
171	chip->get = kempld_gpio_get;
172	chip->set = kempld_gpio_set;
173	chip->ngpio = kempld_gpio_pincount(pld);
174	if (chip->ngpio == 0) {
175		dev_err(dev, "No GPIO pins detected\n");
176		return -ENODEV;
177	}
178
179	ret = devm_gpiochip_add_data(dev, chip, gpio);
180	if (ret) {
181		dev_err(dev, "Could not register GPIO chip\n");
182		return ret;
183	}
184
185	dev_info(dev, "GPIO functionality initialized with %d pins\n",
186		 chip->ngpio);
187
188	return 0;
189}
190
191static struct platform_driver kempld_gpio_driver = {
192	.driver = {
193		.name = "kempld-gpio",
194	},
195	.probe		= kempld_gpio_probe,
196};
197
198module_platform_driver(kempld_gpio_driver);
199
200MODULE_DESCRIPTION("KEM PLD GPIO Driver");
201MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
202MODULE_LICENSE("GPL");
203MODULE_ALIAS("platform:kempld-gpio");