drivers/gpio/gpio-bcm-virt.c

   1 /*
   2  *  brcmvirt GPIO driver
   3  *
   4  *  Copyright (C) 2012,2013 Dom Cobley <popcornmix@gmail.com>
   5  *  Based on gpio-clps711x.c by Alexander Shiyan <shc_work@mail.ru>
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  */
  12
  13 #include <linux/err.h>
  14 #include <linux/gpio.h>
  15 #include <linux/module.h>
  16 #include <linux/platform_device.h>
  17 #include <linux/dma-mapping.h>
  18 #include <soc/bcm2835/raspberrypi-firmware.h>
  19
  20 #define MODULE_NAME "brcmvirt-gpio"
  21 #define NUM_GPIO 2
  22
  23 struct brcmvirt_gpio {
  24         struct gpio_chip        gc;
  25         u32 __iomem             *ts_base;
  26         /* two packed 16-bit counts of enabled and disables
  27            Allows host to detect a brief enable that was missed */
  28         u32                     enables_disables[NUM_GPIO];
  29         dma_addr_t              bus_addr;
  30 };
  31
  32 static int brcmvirt_gpio_dir_in(struct gpio_chip *gc, unsigned off)
  33 {
  34         struct brcmvirt_gpio *gpio;
  35         gpio = container_of(gc, struct brcmvirt_gpio, gc);
  36         return -EINVAL;
  37 }
  38
  39 static int brcmvirt_gpio_dir_out(struct gpio_chip *gc, unsigned off, int val)
  40 {
  41         struct brcmvirt_gpio *gpio;
  42         gpio = container_of(gc, struct brcmvirt_gpio, gc);
  43         return 0;
  44 }
  45
  46 static int brcmvirt_gpio_get(struct gpio_chip *gc, unsigned off)
  47 {
  48         struct brcmvirt_gpio *gpio;
  49         unsigned v;
  50         gpio = container_of(gc, struct brcmvirt_gpio, gc);
  51         v = readl(gpio->ts_base + off);
  52         return (v >> off) & 1;
  53 }
  54
  55 static void brcmvirt_gpio_set(struct gpio_chip *gc, unsigned off, int val)
  56 {
  57         struct brcmvirt_gpio *gpio;
  58         u16 enables, disables;
  59         s16 diff;
  60         bool lit;
  61         gpio = container_of(gc, struct brcmvirt_gpio, gc);
  62         enables  = gpio->enables_disables[off] >> 16;
  63         disables = gpio->enables_disables[off] >>  0;
  64         diff = (s16)(enables - disables);
  65         lit = diff > 0;
  66         if ((val && lit) || (!val && !lit))
  67                 return;
  68         if (val)
  69                 enables++;
  70         else
  71                 disables++;
  72         diff = (s16)(enables - disables);
  73         BUG_ON(diff != 0 && diff != 1);
  74         gpio->enables_disables[off] = (enables << 16) | (disables << 0);
  75         writel(gpio->enables_disables[off], gpio->ts_base + off);
  76 }
  77
  78 static int brcmvirt_gpio_probe(struct platform_device *pdev)
  79 {
  80         int err = 0;
  81         struct device *dev = &pdev->dev;
  82         struct device_node *np = dev->of_node;
  83         struct device_node *fw_node;
  84         struct rpi_firmware *fw;
  85         struct brcmvirt_gpio *ucb;
  86         u32 gpiovirtbuf;
  87
  88         fw_node = of_parse_phandle(np, "firmware", 0);
  89         if (!fw_node) {
  90                 dev_err(dev, "Missing firmware node\n");
  91                 return -ENOENT;
  92         }
  93
  94         fw = rpi_firmware_get(fw_node);
  95         if (!fw)
  96                 return -EPROBE_DEFER;
  97
  98         ucb = devm_kzalloc(dev, sizeof *ucb, GFP_KERNEL);
  99         if (!ucb) {
 100                 err = -EINVAL;
 101                 goto out;
 102         }
 103
 104         ucb->ts_base = dma_zalloc_coherent(dev, PAGE_SIZE, &ucb->bus_addr, GFP_KERNEL);
 105         if (!ucb->ts_base) {
 106                 pr_err("[%s]: failed to dma_alloc_coherent(%ld)\n",
 107                                 __func__, PAGE_SIZE);
 108                 err = -ENOMEM;
 109                 goto out;
 110         }
 111
 112         gpiovirtbuf = (u32)ucb->bus_addr;
 113         err = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_SET_GPIOVIRTBUF,
 114                                     &gpiovirtbuf, sizeof(gpiovirtbuf));
 115
 116         if (err || gpiovirtbuf != 0) {
 117                 dev_warn(dev, "Failed to set gpiovirtbuf, trying to get err:%x\n", err);
 118                 dma_free_coherent(dev, PAGE_SIZE, ucb->ts_base, ucb->bus_addr);
 119                 ucb->ts_base = 0;
 120                 ucb->bus_addr = 0;
 121         }
 122
 123         if (!ucb->ts_base) {
 124                 err = rpi_firmware_property(fw, RPI_FIRMWARE_FRAMEBUFFER_GET_GPIOVIRTBUF,
 125                                             &gpiovirtbuf, sizeof(gpiovirtbuf));
 126
 127                 if (err) {
 128                         dev_err(dev, "Failed to get gpiovirtbuf\n");
 129                         goto out;
 130                 }
 131
 132                 if (!gpiovirtbuf) {
 133                         dev_err(dev, "No virtgpio buffer\n");
 134                         err = -ENOENT;
 135                         goto out;
 136                 }
 137
 138                 // mmap the physical memory
 139                 gpiovirtbuf &= ~0xc0000000;
 140                 ucb->ts_base = ioremap(gpiovirtbuf, 4096);
 141                 if (ucb->ts_base == NULL) {
 142                         dev_err(dev, "Failed to map physical address\n");
 143                         err = -ENOENT;
 144                         goto out;
 145                 }
 146                 ucb->bus_addr = 0;
 147         }
 148         ucb->gc.label = MODULE_NAME;
 149         ucb->gc.owner = THIS_MODULE;
 150         //ucb->gc.dev = dev;
 151         ucb->gc.of_node = np;
 152         ucb->gc.base = 100;
 153         ucb->gc.ngpio = NUM_GPIO;
 154
 155         ucb->gc.direction_input = brcmvirt_gpio_dir_in;
 156         ucb->gc.direction_output = brcmvirt_gpio_dir_out;
 157         ucb->gc.get = brcmvirt_gpio_get;
 158         ucb->gc.set = brcmvirt_gpio_set;
 159         ucb->gc.can_sleep = true;
 160
 161         err = gpiochip_add(&ucb->gc);
 162         if (err)
 163                 goto out;
 164
 165         platform_set_drvdata(pdev, ucb);
 166
 167         return 0;
 168 out:
 169         if (ucb->bus_addr) {
 170                 dma_free_coherent(dev, PAGE_SIZE, ucb->ts_base, ucb->bus_addr);
 171                 ucb->bus_addr = 0;
 172                 ucb->ts_base = NULL;
 173         } else if (ucb->ts_base) {
 174                 iounmap(ucb->ts_base);
 175                 ucb->ts_base = NULL;
 176         }
 177         return err;
 178 }
 179
 180 static int brcmvirt_gpio_remove(struct platform_device *pdev)
 181 {
 182         struct device *dev = &pdev->dev;
 183         int err = 0;
 184         struct brcmvirt_gpio *ucb = platform_get_drvdata(pdev);
 185
 186         gpiochip_remove(&ucb->gc);
 187         if (ucb->bus_addr)
 188                 dma_free_coherent(dev, PAGE_SIZE, ucb->ts_base, ucb->bus_addr);
 189         else if (ucb->ts_base)
 190                 iounmap(ucb->ts_base);
 191         return err;
 192 }
 193
 194 static const struct of_device_id __maybe_unused brcmvirt_gpio_ids[] = {
 195         { .compatible = "brcm,bcm2835-virtgpio" },
 196         { }
 197 };
 198 MODULE_DEVICE_TABLE(of, brcmvirt_gpio_ids);
 199
 200 static struct platform_driver brcmvirt_gpio_driver = {
 201         .driver = {
 202                 .name           = MODULE_NAME,
 203                 .owner          = THIS_MODULE,
 204                 .of_match_table = of_match_ptr(brcmvirt_gpio_ids),
 205         },
 206         .probe  = brcmvirt_gpio_probe,
 207         .remove = brcmvirt_gpio_remove,
 208 };
 209 module_platform_driver(brcmvirt_gpio_driver);
 210
 211 MODULE_LICENSE("GPL");
 212 MODULE_AUTHOR("Dom Cobley <popcornmix@gmail.com>");
 213 MODULE_DESCRIPTION("brcmvirt GPIO driver");
 214 MODULE_ALIAS("platform:brcmvirt-gpio");