1/*
2 *  This program is free software; you can redistribute it and/or modify it
3 *  under the terms of the GNU General Public License version 2 as published
4 *  by the Free Software Foundation.
5 *
6 *  Copyright (C) 2012 John Crispin <blogic@openwrt.org>
7 */
8
9#include <linux/init.h>
10#include <linux/module.h>
11#include <linux/types.h>
12#include <linux/platform_device.h>
13#include <linux/mutex.h>
14#include <linux/gpio.h>
15#include <linux/of.h>
16#include <linux/of_gpio.h>
17#include <linux/io.h>
18#include <linux/slab.h>
19
20#include <lantiq_soc.h>
21
22/*
23 * By attaching hardware latches to the EBU it is possible to create output
24 * only gpios. This driver configures a special memory address, which when
25 * written to outputs 16 bit to the latches.
26 */
27
28#define LTQ_EBU_BUSCON	0x1e7ff		/* 16 bit access, slowest timing */
29#define LTQ_EBU_WP	0x80000000	/* write protect bit */
30
31struct ltq_mm {
32	struct of_mm_gpio_chip mmchip;
33	u16 shadow;	/* shadow the latches state */
34};
35
36/**
37 * ltq_mm_apply() - write the shadow value to the ebu address.
38 * @chip:     Pointer to our private data structure.
39 *
40 * Write the shadow value to the EBU to set the gpios. We need to set the
41 * global EBU lock to make sure that PCI/MTD dont break.
42 */
43static void ltq_mm_apply(struct ltq_mm *chip)
44{
45	unsigned long flags;
46
47	spin_lock_irqsave(&ebu_lock, flags);
48	ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1);
49	__raw_writew(chip->shadow, chip->mmchip.regs);
50	ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
51	spin_unlock_irqrestore(&ebu_lock, flags);
52}
53
54/**
55 * ltq_mm_set() - gpio_chip->set - set gpios.
56 * @gc:     Pointer to gpio_chip device structure.
57 * @gpio:   GPIO signal number.
58 * @val:    Value to be written to specified signal.
59 *
60 * Set the shadow value and call ltq_mm_apply.
61 */
62static void ltq_mm_set(struct gpio_chip *gc, unsigned offset, int value)
63{
64	struct of_mm_gpio_chip *mm_gc = to_of_mm_gpio_chip(gc);
65	struct ltq_mm *chip =
66		container_of(mm_gc, struct ltq_mm, mmchip);
67
68	if (value)
69		chip->shadow |= (1 << offset);
70	else
71		chip->shadow &= ~(1 << offset);
72	ltq_mm_apply(chip);
73}
74
75/**
76 * ltq_mm_dir_out() - gpio_chip->dir_out - set gpio direction.
77 * @gc:     Pointer to gpio_chip device structure.
78 * @gpio:   GPIO signal number.
79 * @val:    Value to be written to specified signal.
80 *
81 * Same as ltq_mm_set, always returns 0.
82 */
83static int ltq_mm_dir_out(struct gpio_chip *gc, unsigned offset, int value)
84{
85	ltq_mm_set(gc, offset, value);
86
87	return 0;
88}
89
90/**
91 * ltq_mm_save_regs() - Set initial values of GPIO pins
92 * @mm_gc: pointer to memory mapped GPIO chip structure
93 */
94static void ltq_mm_save_regs(struct of_mm_gpio_chip *mm_gc)
95{
96	struct ltq_mm *chip =
97		container_of(mm_gc, struct ltq_mm, mmchip);
98
99	/* tell the ebu controller which memory address we will be using */
100	ltq_ebu_w32(CPHYSADDR(chip->mmchip.regs) | 0x1, LTQ_EBU_ADDRSEL1);
101
102	ltq_mm_apply(chip);
103}
104
105static int ltq_mm_probe(struct platform_device *pdev)
106{
107	struct ltq_mm *chip;
108	u32 shadow;
109
110	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
111	if (!chip)
112		return -ENOMEM;
113
114	platform_set_drvdata(pdev, chip);
115
116	chip->mmchip.gc.ngpio = 16;
117	chip->mmchip.gc.direction_output = ltq_mm_dir_out;
118	chip->mmchip.gc.set = ltq_mm_set;
119	chip->mmchip.save_regs = ltq_mm_save_regs;
120
121	/* store the shadow value if one was passed by the devicetree */
122	if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow))
123		chip->shadow = shadow;
124
125	return of_mm_gpiochip_add(pdev->dev.of_node, &chip->mmchip);
126}
127
128static int ltq_mm_remove(struct platform_device *pdev)
129{
130	struct ltq_mm *chip = platform_get_drvdata(pdev);
131
132	of_mm_gpiochip_remove(&chip->mmchip);
133
134	return 0;
135}
136
137static const struct of_device_id ltq_mm_match[] = {
138	{ .compatible = "lantiq,gpio-mm" },
139	{},
140};
141MODULE_DEVICE_TABLE(of, ltq_mm_match);
142
143static struct platform_driver ltq_mm_driver = {
144	.probe = ltq_mm_probe,
145	.remove = ltq_mm_remove,
146	.driver = {
147		.name = "gpio-mm-ltq",
148		.of_match_table = ltq_mm_match,
149	},
150};
151
152static int __init ltq_mm_init(void)
153{
154	return platform_driver_register(&ltq_mm_driver);
155}
156
157subsys_initcall(ltq_mm_init);
158
159static void __exit ltq_mm_exit(void)
160{
161	platform_driver_unregister(&ltq_mm_driver);
162}
163module_exit(ltq_mm_exit);
164