gpio-mm-lantiq.c

  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/of.h>
 14#include <linux/io.h>
 15#include <linux/slab.h>
 16
 17#include <lantiq_soc.h>
 18
 19/*
 20 * By attaching hardware latches to the EBU it is possible to create output
 21 * only gpios. This driver configures a special memory address, which when
 22 * written to outputs 16 bit to the latches.
 23 */
 24
 25#define LTQ_EBU_BUSCON	0x1e7ff		/* 16 bit access, slowest timing */
 26#define LTQ_EBU_WP	0x80000000	/* write protect bit */
 27
 28struct ltq_mm {
 29	struct gpio_chip gc;
 30	void __iomem *regs;
 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 */
 41static 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->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 * @offset: GPIO signal number.
 56 * @value:  Value to be written to specified signal.
 57 *
 58 * Set the shadow value and call ltq_mm_apply. Always returns 0.
 59 */
 60static int ltq_mm_set(struct gpio_chip *gc, unsigned int 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	return 0;
 71}
 72
 73/**
 74 * ltq_mm_dir_out() - gpio_chip->dir_out - set gpio direction.
 75 * @gc:     Pointer to gpio_chip device structure.
 76 * @offset: GPIO signal number.
 77 * @value:  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	return ltq_mm_set(gc, offset, value);
 84}
 85
 86/**
 87 * ltq_mm_save_regs() - Set initial values of GPIO pins
 88 * @chip: Pointer to our private data structure.
 89 */
 90static void ltq_mm_save_regs(struct ltq_mm *chip)
 91{
 92	/* tell the ebu controller which memory address we will be using */
 93	ltq_ebu_w32(CPHYSADDR((__force void *)chip->regs) | 0x1, LTQ_EBU_ADDRSEL1);
 94
 95	ltq_mm_apply(chip);
 96}
 97
 98static int ltq_mm_probe(struct platform_device *pdev)
 99{
100	struct device *dev = &pdev->dev;
101	struct device_node *np = dev->of_node;
102	struct gpio_chip *gc;
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	gc = &chip->gc;
111
112	gc->base = -1;
113	gc->ngpio = 16;
114	gc->direction_output = ltq_mm_dir_out;
115	gc->set = ltq_mm_set;
116	gc->parent = dev;
117	gc->owner = THIS_MODULE;
118	gc->label = devm_kasprintf(dev, GFP_KERNEL, "%pOF", np);
119	if (!gc->label)
120		return -ENOMEM;
121
122	chip->regs = devm_of_iomap(dev, np, 0, NULL);
123	if (IS_ERR(chip->regs))
124		return PTR_ERR(chip->regs);
125
126	ltq_mm_save_regs(chip);
127
128	/* store the shadow value if one was passed by the devicetree */
129	if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow))
130		chip->shadow = shadow;
131
132	return devm_gpiochip_add_data(dev, gc, chip);
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	.driver = {
144		.name = "gpio-mm-ltq",
145		.of_match_table = ltq_mm_match,
146	},
147};
148
149static int __init ltq_mm_init(void)
150{
151	return platform_driver_register(&ltq_mm_driver);
152}
153
154subsys_initcall(ltq_mm_init);
155
156static void __exit ltq_mm_exit(void)
157{
158	platform_driver_unregister(&ltq_mm_driver);
159}
160module_exit(ltq_mm_exit);