1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Loongson-2F/3A/3B GPIO Support
4 *
5 * Copyright (c) 2008 Richard Liu, STMicroelectronics <richard.liu@st.com>
6 * Copyright (c) 2008-2010 Arnaud Patard <apatard@mandriva.com>
7 * Copyright (c) 2013 Hongbing Hu <huhb@lemote.com>
8 * Copyright (c) 2014 Huacai Chen <chenhc@lemote.com>
9 */
10
11#include <linux/kernel.h>
12#include <linux/init.h>
13#include <linux/module.h>
14#include <linux/spinlock.h>
15#include <linux/err.h>
16#include <linux/gpio/driver.h>
17#include <linux/platform_device.h>
18#include <linux/bitops.h>
19#include <asm/types.h>
20#include <loongson.h>
21
22#define STLS2F_N_GPIO 4
23#define STLS3A_N_GPIO 16
24
25#ifdef CONFIG_CPU_LOONGSON64
26#define LOONGSON_N_GPIO STLS3A_N_GPIO
27#else
28#define LOONGSON_N_GPIO STLS2F_N_GPIO
29#endif
30
31/*
32 * Offset into the register where we read lines, we write them from offset 0.
33 * This offset is the only thing that stand between us and using
34 * GPIO_GENERIC.
35 */
36#define LOONGSON_GPIO_IN_OFFSET 16
37
38static DEFINE_SPINLOCK(gpio_lock);
39
40static int loongson_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
41{
42 u32 val;
43
44 spin_lock(lock: &gpio_lock);
45 val = LOONGSON_GPIODATA;
46 spin_unlock(lock: &gpio_lock);
47
48 return !!(val & BIT(gpio + LOONGSON_GPIO_IN_OFFSET));
49}
50
51static void loongson_gpio_set_value(struct gpio_chip *chip,
52 unsigned gpio, int value)
53{
54 u32 val;
55
56 spin_lock(lock: &gpio_lock);
57 val = LOONGSON_GPIODATA;
58 if (value)
59 val |= BIT(gpio);
60 else
61 val &= ~BIT(gpio);
62 LOONGSON_GPIODATA = val;
63 spin_unlock(lock: &gpio_lock);
64}
65
66static int loongson_gpio_direction_input(struct gpio_chip *chip, unsigned gpio)
67{
68 u32 temp;
69
70 spin_lock(lock: &gpio_lock);
71 temp = LOONGSON_GPIOIE;
72 temp |= BIT(gpio);
73 LOONGSON_GPIOIE = temp;
74 spin_unlock(lock: &gpio_lock);
75
76 return 0;
77}
78
79static int loongson_gpio_direction_output(struct gpio_chip *chip,
80 unsigned gpio, int level)
81{
82 u32 temp;
83
84 loongson_gpio_set_value(chip, gpio, value: level);
85 spin_lock(lock: &gpio_lock);
86 temp = LOONGSON_GPIOIE;
87 temp &= ~BIT(gpio);
88 LOONGSON_GPIOIE = temp;
89 spin_unlock(lock: &gpio_lock);
90
91 return 0;
92}
93
94static int loongson_gpio_probe(struct platform_device *pdev)
95{
96 struct gpio_chip *gc;
97 struct device *dev = &pdev->dev;
98
99 gc = devm_kzalloc(dev, size: sizeof(*gc), GFP_KERNEL);
100 if (!gc)
101 return -ENOMEM;
102
103 gc->label = "loongson-gpio-chip";
104 gc->base = 0;
105 gc->ngpio = LOONGSON_N_GPIO;
106 gc->get = loongson_gpio_get_value;
107 gc->set = loongson_gpio_set_value;
108 gc->direction_input = loongson_gpio_direction_input;
109 gc->direction_output = loongson_gpio_direction_output;
110
111 return gpiochip_add_data(gc, NULL);
112}
113
114static struct platform_driver loongson_gpio_driver = {
115 .driver = {
116 .name = "loongson-gpio",
117 },
118 .probe = loongson_gpio_probe,
119};
120
121static int __init loongson_gpio_setup(void)
122{
123 struct platform_device *pdev;
124 int ret;
125
126 ret = platform_driver_register(&loongson_gpio_driver);
127 if (ret) {
128 pr_err("error registering loongson GPIO driver\n");
129 return ret;
130 }
131
132 pdev = platform_device_register_simple(name: "loongson-gpio", id: -1, NULL, num: 0);
133 return PTR_ERR_OR_ZERO(ptr: pdev);
134}
135postcore_initcall(loongson_gpio_setup);
136

source code of linux/drivers/gpio/gpio-loongson.c