Root/drivers/gpio/gpio-mm-lantiq.c

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 resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
108    struct ltq_mm *chip;
109    const __be32 *shadow;
110    int ret = 0;
111
112    if (!res) {
113        dev_err(&pdev->dev, "failed to get memory resource\n");
114        return -ENOENT;
115    }
116
117    chip = kzalloc(sizeof(*chip), GFP_KERNEL);
118    if (!chip)
119        return -ENOMEM;
120
121    chip->mmchip.gc.ngpio = 16;
122    chip->mmchip.gc.label = "gpio-mm-ltq";
123    chip->mmchip.gc.direction_output = ltq_mm_dir_out;
124    chip->mmchip.gc.set = ltq_mm_set;
125    chip->mmchip.save_regs = ltq_mm_save_regs;
126
127    /* store the shadow value if one was passed by the devicetree */
128    shadow = of_get_property(pdev->dev.of_node, "lantiq,shadow", NULL);
129    if (shadow)
130        chip->shadow = be32_to_cpu(*shadow);
131
132    ret = of_mm_gpiochip_add(pdev->dev.of_node, &chip->mmchip);
133    if (ret)
134        kfree(chip);
135    return ret;
136}
137
138static const struct of_device_id ltq_mm_match[] = {
139    { .compatible = "lantiq,gpio-mm" },
140    {},
141};
142MODULE_DEVICE_TABLE(of, ltq_mm_match);
143
144static struct platform_driver ltq_mm_driver = {
145    .probe = ltq_mm_probe,
146    .driver = {
147        .name = "gpio-mm-ltq",
148        .owner = THIS_MODULE,
149        .of_match_table = ltq_mm_match,
150    },
151};
152
153static int __init ltq_mm_init(void)
154{
155    return platform_driver_register(&ltq_mm_driver);
156}
157
158subsys_initcall(ltq_mm_init);
159

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