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
  31 struct 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  */
  43 static 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  */
  62 static 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  */
  83 static 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  */
  94 static 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
 105 static int ltq_mm_probe(struct platform_device *pdev)
 106 {
 107         struct ltq_mm *chip;
 108         u32 shadow;
 109
 110         chip = devm_kzalloc(&pdev->dev, sizeof(*chip), GFP_KERNEL);
 111         if (!chip)
 112                 return -ENOMEM;
 113
 114         platform_set_drvdata(pdev, chip);
 115
 116         chip->mmchip.gc.ngpio = 16;
 117         chip->mmchip.gc.direction_output = ltq_mm_dir_out;
 118         chip->mmchip.gc.set = ltq_mm_set;
 119         chip->mmchip.save_regs = ltq_mm_save_regs;
 120
 121         /* store the shadow value if one was passed by the devicetree */
 122         if (!of_property_read_u32(pdev->dev.of_node, "lantiq,shadow", &shadow))
 123                 chip->shadow = shadow;
 124
 125         return of_mm_gpiochip_add(pdev->dev.of_node, &chip->mmchip);
 126 }
 127
 128 static int ltq_mm_remove(struct platform_device *pdev)
 129 {
 130         struct ltq_mm *chip = platform_get_drvdata(pdev);
 131
 132         of_mm_gpiochip_remove(&chip->mmchip);
 133
 134         return 0;
 135 }
 136
 137 static const struct of_device_id ltq_mm_match[] = {
 138         { .compatible = "lantiq,gpio-mm" },
 139         {},
 140 };
 141 MODULE_DEVICE_TABLE(of, ltq_mm_match);
 142
 143 static struct platform_driver ltq_mm_driver = {
 144         .probe = ltq_mm_probe,
 145         .remove = ltq_mm_remove,
 146         .driver = {
 147                 .name = "gpio-mm-ltq",
 148                 .of_match_table = ltq_mm_match,
 149         },
 150 };
 151
 152 static int __init ltq_mm_init(void)
 153 {
 154         return platform_driver_register(&ltq_mm_driver);
 155 }
 156
 157 subsys_initcall(ltq_mm_init);
 158
 159 static void __exit ltq_mm_exit(void)
 160 {
 161         platform_driver_unregister(&ltq_mm_driver);
 162 }
 163 module_exit(ltq_mm_exit);