xref: /openbmc/linux/drivers/gpio/gpio-mm-lantiq.c (revision 2ffd04ca)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *
4  *  Copyright (C) 2012 John Crispin <john@phrozen.org>
5  */
6 
7 #include <linux/init.h>
8 #include <linux/module.h>
9 #include <linux/types.h>
10 #include <linux/platform_device.h>
11 #include <linux/mutex.h>
12 #include <linux/gpio/driver.h>
13 #include <linux/gpio/legacy-of-mm-gpiochip.h>
14 #include <linux/of.h>
15 #include <linux/io.h>
16 #include <linux/slab.h>
17 
18 #include <lantiq_soc.h>
19 
20 /*
21  * By attaching hardware latches to the EBU it is possible to create output
22  * only gpios. This driver configures a special memory address, which when
23  * written to outputs 16 bit to the latches.
24  */
25 
26 #define LTQ_EBU_BUSCON	0x1e7ff		/* 16 bit access, slowest timing */
27 #define LTQ_EBU_WP	0x80000000	/* write protect bit */
28 
29 struct ltq_mm {
30 	struct of_mm_gpio_chip mmchip;
31 	u16 shadow;	/* shadow the latches state */
32 };
33 
34 /**
35  * ltq_mm_apply() - write the shadow value to the ebu address.
36  * @chip:     Pointer to our private data structure.
37  *
38  * Write the shadow value to the EBU to set the gpios. We need to set the
39  * global EBU lock to make sure that PCI/MTD don't break.
40  */
ltq_mm_apply(struct ltq_mm * chip)41 static void ltq_mm_apply(struct ltq_mm *chip)
42 {
43 	unsigned long flags;
44 
45 	spin_lock_irqsave(&ebu_lock, flags);
46 	ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1);
47 	__raw_writew(chip->shadow, chip->mmchip.regs);
48 	ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
49 	spin_unlock_irqrestore(&ebu_lock, flags);
50 }
51 
52 /**
53  * ltq_mm_set() - gpio_chip->set - set gpios.
54  * @gc:     Pointer to gpio_chip device structure.
55  * @gpio:   GPIO signal number.
56  * @val:    Value to be written to specified signal.
57  *
58  * Set the shadow value and call ltq_mm_apply.
59  */
ltq_mm_set(struct gpio_chip * gc,unsigned offset,int value)60 static void ltq_mm_set(struct gpio_chip *gc, unsigned offset, int value)
61 {
62 	struct ltq_mm *chip = gpiochip_get_data(gc);
63 
64 	if (value)
65 		chip->shadow |= (1 << offset);
66 	else
67 		chip->shadow &= ~(1 << offset);
68 	ltq_mm_apply(chip);
69 }
70 
71 /**
72  * ltq_mm_dir_out() - gpio_chip->dir_out - set gpio direction.
73  * @gc:     Pointer to gpio_chip device structure.
74  * @gpio:   GPIO signal number.
75  * @val:    Value to be written to specified signal.
76  *
77  * Same as ltq_mm_set, always returns 0.
78  */
ltq_mm_dir_out(struct gpio_chip * gc,unsigned offset,int value)79 static int ltq_mm_dir_out(struct gpio_chip *gc, unsigned offset, int value)
80 {
81 	ltq_mm_set(gc, offset, value);
82 
83 	return 0;
84 }
85 
86 /**
87  * ltq_mm_save_regs() - Set initial values of GPIO pins
88  * @mm_gc: pointer to memory mapped GPIO chip structure
89  */
ltq_mm_save_regs(struct of_mm_gpio_chip * mm_gc)90 static void ltq_mm_save_regs(struct of_mm_gpio_chip *mm_gc)
91 {
92 	struct ltq_mm *chip =
93 		container_of(mm_gc, struct ltq_mm, mmchip);
94 
95 	/* tell the ebu controller which memory address we will be using */
96 	ltq_ebu_w32(CPHYSADDR(chip->mmchip.regs) | 0x1, LTQ_EBU_ADDRSEL1);
97 
98 	ltq_mm_apply(chip);
99 }
100 
ltq_mm_probe(struct platform_device * pdev)101 static int ltq_mm_probe(struct platform_device *pdev)
102 {
103 	struct ltq_mm *chip;
104 	u32 shadow;
105 
106 	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
107 	if (!chip)
108 		return -ENOMEM;
109 
110 	platform_set_drvdata(pdev, chip);
111 
112 	chip->mmchip.gc.ngpio = 16;
113 	chip->mmchip.gc.direction_output = ltq_mm_dir_out;
114 	chip->mmchip.gc.set = ltq_mm_set;
115 	chip->mmchip.save_regs = ltq_mm_save_regs;
116 
117 	/* store the shadow value if one was passed by the devicetree */
118 	if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow))
119 		chip->shadow = shadow;
120 
121 	return of_mm_gpiochip_add_data(pdev->dev.of_node, &chip->mmchip, chip);
122 }
123 
ltq_mm_remove(struct platform_device * pdev)124 static int ltq_mm_remove(struct platform_device *pdev)
125 {
126 	struct ltq_mm *chip = platform_get_drvdata(pdev);
127 
128 	of_mm_gpiochip_remove(&chip->mmchip);
129 
130 	return 0;
131 }
132 
133 static const struct of_device_id ltq_mm_match[] = {
134 	{ .compatible = "lantiq,gpio-mm" },
135 	{},
136 };
137 MODULE_DEVICE_TABLE(of, ltq_mm_match);
138 
139 static struct platform_driver ltq_mm_driver = {
140 	.probe = ltq_mm_probe,
141 	.remove = ltq_mm_remove,
142 	.driver = {
143 		.name = "gpio-mm-ltq",
144 		.of_match_table = ltq_mm_match,
145 	},
146 };
147 
ltq_mm_init(void)148 static int __init ltq_mm_init(void)
149 {
150 	return platform_driver_register(&ltq_mm_driver);
151 }
152 
153 subsys_initcall(ltq_mm_init);
154 
ltq_mm_exit(void)155 static void __exit ltq_mm_exit(void)
156 {
157 	platform_driver_unregister(&ltq_mm_driver);
158 }
159 module_exit(ltq_mm_exit);
160