1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * SAMA5D2 PIOBU GPIO controller
4  *
5  * Copyright (C) 2018 Microchip Technology Inc. and its subsidiaries
6  *
7  * Author: Andrei Stefanescu <andrei.stefanescu@microchip.com>
8  *
9  */
10 #include <linux/bits.h>
11 #include <linux/gpio/driver.h>
12 #include <linux/init.h>
13 #include <linux/kernel.h>
14 #include <linux/mfd/syscon.h>
15 #include <linux/module.h>
16 #include <linux/of.h>
17 #include <linux/platform_device.h>
18 #include <linux/regmap.h>
19 
20 #define PIOBU_NUM 8
21 #define PIOBU_REG_SIZE 4
22 
23 /*
24  * backup mode protection register for tamper detection
25  * normal mode protection register for tamper detection
26  * wakeup signal generation
27  */
28 #define PIOBU_BMPR 0x7C
29 #define PIOBU_NMPR 0x80
30 #define PIOBU_WKPR 0x90
31 
32 #define PIOBU_BASE 0x18 /* PIOBU offset from SECUMOD base register address. */
33 
34 #define PIOBU_DET_OFFSET 16
35 
36 /* In the datasheet this bit is called OUTPUT */
37 #define PIOBU_DIRECTION BIT(8)
38 #define PIOBU_OUT BIT(8)
39 #define PIOBU_IN 0
40 
41 #define PIOBU_SOD BIT(9)
42 #define PIOBU_PDS BIT(10)
43 
44 #define PIOBU_HIGH BIT(9)
45 #define PIOBU_LOW 0
46 
47 struct sama5d2_piobu {
48 	struct gpio_chip chip;
49 	struct regmap *regmap;
50 };
51 
52 /**
53  * sama5d2_piobu_setup_pin() - prepares a pin for set_direction call
54  *
55  * Do not consider pin for tamper detection (normal and backup modes)
56  * Do not consider pin as tamper wakeup interrupt source
57  */
58 static int sama5d2_piobu_setup_pin(struct gpio_chip *chip, unsigned int pin)
59 {
60 	int ret;
61 	struct sama5d2_piobu *piobu = container_of(chip, struct sama5d2_piobu,
62 						   chip);
63 	unsigned int mask = BIT(PIOBU_DET_OFFSET + pin);
64 
65 	ret = regmap_update_bits(piobu->regmap, PIOBU_BMPR, mask, 0);
66 	if (ret)
67 		return ret;
68 
69 	ret = regmap_update_bits(piobu->regmap, PIOBU_NMPR, mask, 0);
70 	if (ret)
71 		return ret;
72 
73 	return regmap_update_bits(piobu->regmap, PIOBU_WKPR, mask, 0);
74 }
75 
76 /**
77  * sama5d2_piobu_write_value() - writes value & mask at the pin's PIOBU register
78  */
79 static int sama5d2_piobu_write_value(struct gpio_chip *chip, unsigned int pin,
80 				     unsigned int mask, unsigned int value)
81 {
82 	int reg;
83 	struct sama5d2_piobu *piobu = container_of(chip, struct sama5d2_piobu,
84 						   chip);
85 
86 	reg = PIOBU_BASE + pin * PIOBU_REG_SIZE;
87 
88 	return regmap_update_bits(piobu->regmap, reg, mask, value);
89 }
90 
91 /**
92  * sama5d2_piobu_read_value() - read the value with masking from the pin's PIOBU
93  *			      register
94  */
95 static int sama5d2_piobu_read_value(struct gpio_chip *chip, unsigned int pin,
96 				    unsigned int mask)
97 {
98 	struct sama5d2_piobu *piobu = container_of(chip, struct sama5d2_piobu,
99 						   chip);
100 	unsigned int val, reg;
101 	int ret;
102 
103 	reg = PIOBU_BASE + pin * PIOBU_REG_SIZE;
104 	ret = regmap_read(piobu->regmap, reg, &val);
105 	if (ret < 0)
106 		return ret;
107 
108 	return val & mask;
109 }
110 
111 /**
112  * sama5d2_piobu_get_direction() - gpiochip get_direction
113  */
114 static int sama5d2_piobu_get_direction(struct gpio_chip *chip,
115 				       unsigned int pin)
116 {
117 	int ret = sama5d2_piobu_read_value(chip, pin, PIOBU_DIRECTION);
118 
119 	if (ret < 0)
120 		return ret;
121 
122 	return (ret == PIOBU_IN) ? 1 : 0;
123 }
124 
125 /**
126  * sama5d2_piobu_direction_input() - gpiochip direction_input
127  */
128 static int sama5d2_piobu_direction_input(struct gpio_chip *chip,
129 					 unsigned int pin)
130 {
131 	return sama5d2_piobu_write_value(chip, pin, PIOBU_DIRECTION, PIOBU_IN);
132 }
133 
134 /**
135  * sama5d2_piobu_direction_output() - gpiochip direction_output
136  */
137 static int sama5d2_piobu_direction_output(struct gpio_chip *chip,
138 					  unsigned int pin, int value)
139 {
140 	unsigned int val = PIOBU_OUT;
141 
142 	if (value)
143 		val |= PIOBU_HIGH;
144 
145 	return sama5d2_piobu_write_value(chip, pin, PIOBU_DIRECTION | PIOBU_SOD,
146 					 val);
147 }
148 
149 /**
150  * sama5d2_piobu_get() - gpiochip get
151  */
152 static int sama5d2_piobu_get(struct gpio_chip *chip, unsigned int pin)
153 {
154 	/* if pin is input, read value from PDS else read from SOD */
155 	int ret = sama5d2_piobu_get_direction(chip, pin);
156 
157 	if (ret == 1)
158 		ret = sama5d2_piobu_read_value(chip, pin, PIOBU_PDS);
159 	else if (!ret)
160 		ret = sama5d2_piobu_read_value(chip, pin, PIOBU_SOD);
161 
162 	if (ret < 0)
163 		return ret;
164 
165 	return !!ret;
166 }
167 
168 /**
169  * sama5d2_piobu_set() - gpiochip set
170  */
171 static void sama5d2_piobu_set(struct gpio_chip *chip, unsigned int pin,
172 			      int value)
173 {
174 	if (!value)
175 		value = PIOBU_LOW;
176 	else
177 		value = PIOBU_HIGH;
178 
179 	sama5d2_piobu_write_value(chip, pin, PIOBU_SOD, value);
180 }
181 
182 static int sama5d2_piobu_probe(struct platform_device *pdev)
183 {
184 	struct sama5d2_piobu *piobu;
185 	int ret, i;
186 
187 	piobu = devm_kzalloc(&pdev->dev, sizeof(*piobu), GFP_KERNEL);
188 	if (!piobu)
189 		return -ENOMEM;
190 
191 	platform_set_drvdata(pdev, piobu);
192 	piobu->chip.label = pdev->name;
193 	piobu->chip.parent = &pdev->dev;
194 	piobu->chip.of_node = pdev->dev.of_node;
195 	piobu->chip.owner = THIS_MODULE,
196 	piobu->chip.get_direction = sama5d2_piobu_get_direction,
197 	piobu->chip.direction_input = sama5d2_piobu_direction_input,
198 	piobu->chip.direction_output = sama5d2_piobu_direction_output,
199 	piobu->chip.get = sama5d2_piobu_get,
200 	piobu->chip.set = sama5d2_piobu_set,
201 	piobu->chip.base = -1,
202 	piobu->chip.ngpio = PIOBU_NUM,
203 	piobu->chip.can_sleep = 0,
204 
205 	piobu->regmap = syscon_node_to_regmap(pdev->dev.of_node);
206 	if (IS_ERR(piobu->regmap)) {
207 		dev_err(&pdev->dev, "Failed to get syscon regmap %ld\n",
208 			PTR_ERR(piobu->regmap));
209 		return PTR_ERR(piobu->regmap);
210 	}
211 
212 	ret = devm_gpiochip_add_data(&pdev->dev, &piobu->chip, piobu);
213 	if (ret) {
214 		dev_err(&pdev->dev, "Failed to add gpiochip %d\n", ret);
215 		return ret;
216 	}
217 
218 	for (i = 0; i < PIOBU_NUM; ++i) {
219 		ret = sama5d2_piobu_setup_pin(&piobu->chip, i);
220 		if (ret) {
221 			dev_err(&pdev->dev, "Failed to setup pin: %d %d\n",
222 				i, ret);
223 			return ret;
224 		}
225 	}
226 
227 	return 0;
228 }
229 
230 static const struct of_device_id sama5d2_piobu_ids[] = {
231 	{ .compatible = "atmel,sama5d2-secumod" },
232 	{},
233 };
234 MODULE_DEVICE_TABLE(of, sama5d2_piobu_ids);
235 
236 static struct platform_driver sama5d2_piobu_driver = {
237 	.driver = {
238 		.name		= "sama5d2-piobu",
239 		.of_match_table	= of_match_ptr(sama5d2_piobu_ids)
240 	},
241 	.probe = sama5d2_piobu_probe,
242 };
243 
244 module_platform_driver(sama5d2_piobu_driver);
245 
246 MODULE_VERSION("1.0");
247 MODULE_LICENSE("GPL v2");
248 MODULE_DESCRIPTION("SAMA5D2 PIOBU controller driver");
249 MODULE_AUTHOR("Andrei Stefanescu <andrei.stefanescu@microchip.com>");
250