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