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 ltq_mm *chip = gpiochip_get_data(gc);
 65
 66	if (value)
 67		chip->shadow |= (1 << offset);
 68	else
 69		chip->shadow &= ~(1 << offset);
 70	ltq_mm_apply(chip);
 71}
 72
 73/**
 74 * ltq_mm_dir_out() - gpio_chip->dir_out - set gpio direction.
 75 * @gc:     Pointer to gpio_chip device structure.
 76 * @gpio:   GPIO signal number.
 77 * @val:    Value to be written to specified signal.
 78 *
 79 * Same as ltq_mm_set, always returns 0.
 80 */
 81static int ltq_mm_dir_out(struct gpio_chip *gc, unsigned offset, int value)
 82{
 83	ltq_mm_set(gc, offset, value);
 84
 85	return 0;
 86}
 87
 88/**
 89 * ltq_mm_save_regs() - Set initial values of GPIO pins
 90 * @mm_gc: pointer to memory mapped GPIO chip structure
 91 */
 92static void ltq_mm_save_regs(struct of_mm_gpio_chip *mm_gc)
 93{
 94	struct ltq_mm *chip =
 95		container_of(mm_gc, struct ltq_mm, mmchip);
 96
 97	/* tell the ebu controller which memory address we will be using */
 98	ltq_ebu_w32(CPHYSADDR(chip->mmchip.regs) | 0x1, LTQ_EBU_ADDRSEL1);
 99
100	ltq_mm_apply(chip);
101}
102
103static int ltq_mm_probe(struct platform_device *pdev)
104{
105	struct ltq_mm *chip;
106	u32 shadow;
107
108	chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
109	if (!chip)
110		return -ENOMEM;
111
112	platform_set_drvdata(pdev, chip);
113
114	chip->mmchip.gc.ngpio = 16;
115	chip->mmchip.gc.direction_output = ltq_mm_dir_out;
116	chip->mmchip.gc.set = ltq_mm_set;
117	chip->mmchip.save_regs = ltq_mm_save_regs;
118
119	/* store the shadow value if one was passed by the devicetree */
120	if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow))
121		chip->shadow = shadow;
122
123	return of_mm_gpiochip_add_data(pdev->dev.of_node, &chip->mmchip, chip);
124}
125
126static int ltq_mm_remove(struct platform_device *pdev)
127{
128	struct ltq_mm *chip = platform_get_drvdata(pdev);
129
130	of_mm_gpiochip_remove(&chip->mmchip);
131
132	return 0;
133}
134
135static const struct of_device_id ltq_mm_match[] = {
136	{ .compatible = "lantiq,gpio-mm" },
137	{},
138};
139MODULE_DEVICE_TABLE(of, ltq_mm_match);
140
141static struct platform_driver ltq_mm_driver = {
142	.probe = ltq_mm_probe,
143	.remove = ltq_mm_remove,
144	.driver = {
145		.name = "gpio-mm-ltq",
146		.of_match_table = ltq_mm_match,
147	},
148};
149
150static int __init ltq_mm_init(void)
151{
152	return platform_driver_register(&ltq_mm_driver);
153}
154
155subsys_initcall(ltq_mm_init);
156
157static void __exit ltq_mm_exit(void)
158{
159	platform_driver_unregister(&ltq_mm_driver);
160}
161module_exit(ltq_mm_exit);