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 
25 struct 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  */
kempld_gpio_bitop(struct kempld_device_data * pld,u8 reg,u8 bit,u8 val)34 static 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 
kempld_gpio_get_bit(struct kempld_device_data * pld,u8 reg,u8 bit)47 static 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 
kempld_gpio_get(struct gpio_chip * chip,unsigned offset)58 static 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 
kempld_gpio_set(struct gpio_chip * chip,unsigned offset,int value)66 static void kempld_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
67 {
68 	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
69 	struct kempld_device_data *pld = gpio->pld;
70 
71 	kempld_get_mutex(pld);
72 	kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
73 	kempld_release_mutex(pld);
74 }
75 
kempld_gpio_direction_input(struct gpio_chip * chip,unsigned offset)76 static int kempld_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
77 {
78 	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
79 	struct kempld_device_data *pld = gpio->pld;
80 
81 	kempld_get_mutex(pld);
82 	kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 0);
83 	kempld_release_mutex(pld);
84 
85 	return 0;
86 }
87 
kempld_gpio_direction_output(struct gpio_chip * chip,unsigned offset,int value)88 static int kempld_gpio_direction_output(struct gpio_chip *chip, unsigned offset,
89 					int value)
90 {
91 	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
92 	struct kempld_device_data *pld = gpio->pld;
93 
94 	kempld_get_mutex(pld);
95 	kempld_gpio_bitop(pld, KEMPLD_GPIO_LVL_NUM(offset), offset, value);
96 	kempld_gpio_bitop(pld, KEMPLD_GPIO_DIR_NUM(offset), offset, 1);
97 	kempld_release_mutex(pld);
98 
99 	return 0;
100 }
101 
kempld_gpio_get_direction(struct gpio_chip * chip,unsigned offset)102 static int kempld_gpio_get_direction(struct gpio_chip *chip, unsigned offset)
103 {
104 	struct kempld_gpio_data *gpio = gpiochip_get_data(chip);
105 	struct kempld_device_data *pld = gpio->pld;
106 
107 	if (kempld_gpio_get_bit(pld, KEMPLD_GPIO_DIR_NUM(offset), offset))
108 		return GPIO_LINE_DIRECTION_OUT;
109 
110 	return GPIO_LINE_DIRECTION_IN;
111 }
112 
kempld_gpio_pincount(struct kempld_device_data * pld)113 static int kempld_gpio_pincount(struct kempld_device_data *pld)
114 {
115 	u16 evt, evt_back;
116 
117 	kempld_get_mutex(pld);
118 
119 	/* Backup event register as it might be already initialized */
120 	evt_back = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
121 	/* Clear event register */
122 	kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, 0x0000);
123 	/* Read back event register */
124 	evt = kempld_read16(pld, KEMPLD_GPIO_EVT_LVL_EDGE);
125 	/* Restore event register */
126 	kempld_write16(pld, KEMPLD_GPIO_EVT_LVL_EDGE, evt_back);
127 
128 	kempld_release_mutex(pld);
129 
130 	return evt ? __ffs(evt) : 16;
131 }
132 
kempld_gpio_probe(struct platform_device * pdev)133 static int kempld_gpio_probe(struct platform_device *pdev)
134 {
135 	struct device *dev = &pdev->dev;
136 	struct kempld_device_data *pld = dev_get_drvdata(dev->parent);
137 	struct kempld_platform_data *pdata = dev_get_platdata(pld->dev);
138 	struct kempld_gpio_data *gpio;
139 	struct gpio_chip *chip;
140 	int ret;
141 
142 	if (pld->info.spec_major < 2) {
143 		dev_err(dev,
144 			"Driver only supports GPIO devices compatible to PLD spec. rev. 2.0 or higher\n");
145 		return -ENODEV;
146 	}
147 
148 	gpio = devm_kzalloc(dev, sizeof(*gpio), GFP_KERNEL);
149 	if (!gpio)
150 		return -ENOMEM;
151 
152 	gpio->pld = pld;
153 
154 	platform_set_drvdata(pdev, gpio);
155 
156 	chip = &gpio->chip;
157 	chip->label = "gpio-kempld";
158 	chip->owner = THIS_MODULE;
159 	chip->parent = dev;
160 	chip->can_sleep = true;
161 	if (pdata && pdata->gpio_base)
162 		chip->base = pdata->gpio_base;
163 	else
164 		chip->base = -1;
165 	chip->direction_input = kempld_gpio_direction_input;
166 	chip->direction_output = kempld_gpio_direction_output;
167 	chip->get_direction = kempld_gpio_get_direction;
168 	chip->get = kempld_gpio_get;
169 	chip->set = kempld_gpio_set;
170 	chip->ngpio = kempld_gpio_pincount(pld);
171 	if (chip->ngpio == 0) {
172 		dev_err(dev, "No GPIO pins detected\n");
173 		return -ENODEV;
174 	}
175 
176 	ret = devm_gpiochip_add_data(dev, chip, gpio);
177 	if (ret) {
178 		dev_err(dev, "Could not register GPIO chip\n");
179 		return ret;
180 	}
181 
182 	dev_info(dev, "GPIO functionality initialized with %d pins\n",
183 		 chip->ngpio);
184 
185 	return 0;
186 }
187 
188 static struct platform_driver kempld_gpio_driver = {
189 	.driver = {
190 		.name = "kempld-gpio",
191 	},
192 	.probe		= kempld_gpio_probe,
193 };
194 
195 module_platform_driver(kempld_gpio_driver);
196 
197 MODULE_DESCRIPTION("KEM PLD GPIO Driver");
198 MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");
199 MODULE_LICENSE("GPL");
200 MODULE_ALIAS("platform:kempld-gpio");
201