1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Driver for the ps-mode pin configuration.
4 *
5 * Copyright (c) 2021 Xilinx, Inc.
6 */
7
8 #include <linux/delay.h>
9 #include <linux/err.h>
10 #include <linux/gpio/driver.h>
11 #include <linux/io.h>
12 #include <linux/kernel.h>
13 #include <linux/module.h>
14 #include <linux/platform_device.h>
15 #include <linux/slab.h>
16 #include <linux/firmware/xlnx-zynqmp.h>
17
18 /* 4-bit boot mode pins */
19 #define MODE_PINS 4
20
21 /**
22 * modepin_gpio_get_value - Get the state of the specified pin of GPIO device
23 * @chip: gpio_chip instance to be worked on
24 * @pin: gpio pin number within the device
25 *
26 * This function reads the state of the specified pin of the GPIO device.
27 *
28 * Return: 0 if the pin is low, 1 if pin is high, -EINVAL wrong pin configured
29 * or error value.
30 */
modepin_gpio_get_value(struct gpio_chip * chip,unsigned int pin)31 static int modepin_gpio_get_value(struct gpio_chip *chip, unsigned int pin)
32 {
33 u32 regval = 0;
34 int ret;
35
36 ret = zynqmp_pm_bootmode_read(®val);
37 if (ret)
38 return ret;
39
40 /* When [0:3] corresponding bit is set, then read output bit [8:11],
41 * if the bit is clear then read input bit [4:7] for status or value.
42 */
43 if (regval & BIT(pin))
44 return !!(regval & BIT(pin + 8));
45 else
46 return !!(regval & BIT(pin + 4));
47 }
48
49 /**
50 * modepin_gpio_set_value - Modify the state of the pin with specified value
51 * @chip: gpio_chip instance to be worked on
52 * @pin: gpio pin number within the device
53 * @state: value used to modify the state of the specified pin
54 *
55 * This function reads the state of the specified pin of the GPIO device, mask
56 * with the capture state of GPIO pin, and update pin of GPIO device.
57 *
58 * Return: None.
59 */
modepin_gpio_set_value(struct gpio_chip * chip,unsigned int pin,int state)60 static void modepin_gpio_set_value(struct gpio_chip *chip, unsigned int pin,
61 int state)
62 {
63 u32 bootpin_val = 0;
64 int ret;
65
66 zynqmp_pm_bootmode_read(&bootpin_val);
67
68 /* Configure pin as an output by set bit [0:3] */
69 bootpin_val |= BIT(pin);
70
71 if (state)
72 bootpin_val |= BIT(pin + 8);
73 else
74 bootpin_val &= ~BIT(pin + 8);
75
76 /* Configure bootpin value */
77 ret = zynqmp_pm_bootmode_write(bootpin_val);
78 if (ret)
79 pr_err("modepin: set value error %d for pin %d\n", ret, pin);
80 }
81
82 /**
83 * modepin_gpio_dir_in - Set the direction of the specified GPIO pin as input
84 * @chip: gpio_chip instance to be worked on
85 * @pin: gpio pin number within the device
86 *
87 * Return: 0 always
88 */
modepin_gpio_dir_in(struct gpio_chip * chip,unsigned int pin)89 static int modepin_gpio_dir_in(struct gpio_chip *chip, unsigned int pin)
90 {
91 return 0;
92 }
93
94 /**
95 * modepin_gpio_dir_out - Set the direction of the specified GPIO pin as output
96 * @chip: gpio_chip instance to be worked on
97 * @pin: gpio pin number within the device
98 * @state: value to be written to specified pin
99 *
100 * Return: 0 always
101 */
modepin_gpio_dir_out(struct gpio_chip * chip,unsigned int pin,int state)102 static int modepin_gpio_dir_out(struct gpio_chip *chip, unsigned int pin,
103 int state)
104 {
105 return 0;
106 }
107
108 /**
109 * modepin_gpio_probe - Initialization method for modepin_gpio
110 * @pdev: platform device instance
111 *
112 * Return: 0 on success, negative error otherwise.
113 */
modepin_gpio_probe(struct platform_device * pdev)114 static int modepin_gpio_probe(struct platform_device *pdev)
115 {
116 struct gpio_chip *chip;
117 int status;
118
119 chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
120 if (!chip)
121 return -ENOMEM;
122
123 platform_set_drvdata(pdev, chip);
124
125 /* configure the gpio chip */
126 chip->base = -1;
127 chip->ngpio = MODE_PINS;
128 chip->owner = THIS_MODULE;
129 chip->parent = &pdev->dev;
130 chip->get = modepin_gpio_get_value;
131 chip->set = modepin_gpio_set_value;
132 chip->direction_input = modepin_gpio_dir_in;
133 chip->direction_output = modepin_gpio_dir_out;
134 chip->label = dev_name(&pdev->dev);
135
136 /* modepin gpio registration */
137 status = devm_gpiochip_add_data(&pdev->dev, chip, chip);
138 if (status)
139 return dev_err_probe(&pdev->dev, status,
140 "Failed to add GPIO chip\n");
141
142 return status;
143 }
144
145 static const struct of_device_id modepin_platform_id[] = {
146 { .compatible = "xlnx,zynqmp-gpio-modepin", },
147 { }
148 };
149
150 static struct platform_driver modepin_platform_driver = {
151 .driver = {
152 .name = "modepin-gpio",
153 .of_match_table = modepin_platform_id,
154 },
155 .probe = modepin_gpio_probe,
156 };
157
158 module_platform_driver(modepin_platform_driver);
159
160 MODULE_AUTHOR("Piyush Mehta <piyush.mehta@xilinx.com>");
161 MODULE_DESCRIPTION("ZynqMP Boot PS_MODE Configuration");
162 MODULE_LICENSE("GPL v2");
163