arch/mips/lantiq/xway/gpio_ebu.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) 2010 John Crispin <blogic@openwrt.org>
   7  */
   8
   9 #include <linux/init.h>
  10 #include <linux/export.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/io.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
  28 /* we keep a shadow value of the last value written to the ebu */
  29 static int ltq_ebu_gpio_shadow = 0x0;
  30 static void __iomem *ltq_ebu_gpio_membase;
  31
  32 static void ltq_ebu_apply(void)
  33 {
  34         unsigned long flags;
  35
  36         spin_lock_irqsave(&ebu_lock, flags);
  37         ltq_ebu_w32(LTQ_EBU_BUSCON, LTQ_EBU_BUSCON1);
  38         *((__u16 *)ltq_ebu_gpio_membase) = ltq_ebu_gpio_shadow;
  39         ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
  40         spin_unlock_irqrestore(&ebu_lock, flags);
  41 }
  42
  43 static void ltq_ebu_set(struct gpio_chip *chip, unsigned offset, int value)
  44 {
  45         if (value)
  46                 ltq_ebu_gpio_shadow |= (1 << offset);
  47         else
  48                 ltq_ebu_gpio_shadow &= ~(1 << offset);
  49         ltq_ebu_apply();
  50 }
  51
  52 static int ltq_ebu_direction_output(struct gpio_chip *chip, unsigned offset,
  53         int value)
  54 {
  55         ltq_ebu_set(chip, offset, value);
  56
  57         return 0;
  58 }
  59
  60 static struct gpio_chip ltq_ebu_chip = {
  61         .label = "ltq_ebu",
  62         .direction_output = ltq_ebu_direction_output,
  63         .set = ltq_ebu_set,
  64         .base = 72,
  65         .ngpio = 16,
  66         .can_sleep = 1,
  67         .owner = THIS_MODULE,
  68 };
  69
  70 static int ltq_ebu_probe(struct platform_device *pdev)
  71 {
  72         int ret = 0;
  73         struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
  74
  75         if (!res) {
  76                 dev_err(&pdev->dev, "failed to get memory resource\n");
  77                 return -ENOENT;
  78         }
  79
  80         res = devm_request_mem_region(&pdev->dev, res->start,
  81                 resource_size(res), dev_name(&pdev->dev));
  82         if (!res) {
  83                 dev_err(&pdev->dev, "failed to request memory resource\n");
  84                 return -EBUSY;
  85         }
  86
  87         ltq_ebu_gpio_membase = devm_ioremap_nocache(&pdev->dev, res->start,
  88                 resource_size(res));
  89         if (!ltq_ebu_gpio_membase) {
  90                 dev_err(&pdev->dev, "Failed to ioremap mem region\n");
  91                 return -ENOMEM;
  92         }
  93
  94         /* grab the default shadow value passed form the platform code */
  95         ltq_ebu_gpio_shadow = (unsigned int) pdev->dev.platform_data;
  96
  97         /* tell the ebu controller which memory address we will be using */
  98         ltq_ebu_w32(pdev->resource->start | 0x1, LTQ_EBU_ADDRSEL1);
  99
 100         /* write protect the region */
 101         ltq_ebu_w32(LTQ_EBU_BUSCON | LTQ_EBU_WP, LTQ_EBU_BUSCON1);
 102
 103         ret = gpiochip_add(&ltq_ebu_chip);
 104         if (!ret)
 105                 ltq_ebu_apply();
 106         return ret;
 107 }
 108
 109 static struct platform_driver ltq_ebu_driver = {
 110         .probe = ltq_ebu_probe,
 111         .driver = {
 112                 .name = "ltq_ebu",
 113                 .owner = THIS_MODULE,
 114         },
 115 };
 116
 117 static int __init ltq_ebu_init(void)
 118 {
 119         int ret = platform_driver_register(&ltq_ebu_driver);
 120
 121         if (ret)
 122                 pr_info("ltq_ebu : Error registering platfom driver!");
 123         return ret;
 124 }
 125
 126 postcore_initcall(ltq_ebu_init);