LXR linux/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 <john@phrozen.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/driver.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);
 162