LXR linux/drivers/gpio/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/of_gpio.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
  29struct 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 dont 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->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 */
  60static 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 */
  79static 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 */
  90static 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
 101static 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
 124static 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
 133static const struct of_device_id ltq_mm_match[] = {
 134        { .compatible = "lantiq,gpio-mm" },
 135        {},
 136};
 137MODULE_DEVICE_TABLE(of, ltq_mm_match);
 138
 139static 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
 148static int __init ltq_mm_init(void)
 149{
 150        return platform_driver_register(&ltq_mm_driver);
 151}
 152
 153subsys_initcall(ltq_mm_init);
 154
 155static void __exit ltq_mm_exit(void)
 156{
 157        platform_driver_unregister(&ltq_mm_driver);
 158}
 159module_exit(ltq_mm_exit);
 160