target/linux/brcm2708/patches-4.1/0168-Add-dev-gpiomem-device-for-rootless-user-GPIO-access.patch

   1 From ba24fdcd3a1f7282dfba9e5137beaa9d0f999969 Mon Sep 17 00:00:00 2001
   2 From: Luke Wren <luke@raspberrypi.org>
   3 Date: Fri, 21 Aug 2015 23:14:48 +0100
   4 Subject: [PATCH 168/171] Add /dev/gpiomem device for rootless user GPIO access
   5
   6 Signed-off-by: Luke Wren <luke@raspberrypi.org>
   7 ---
   8  arch/arm/boot/dts/bcm2708.dtsi          |   6 +
   9  arch/arm/boot/dts/bcm2709.dtsi          |   6 +
  10  drivers/char/broadcom/Kconfig           |   9 ++
  11  drivers/char/broadcom/Makefile          |   3 +
  12  drivers/char/broadcom/bcm2835-gpiomem.c | 265 ++++++++++++++++++++++++++++++++
  13  5 files changed, 289 insertions(+)
  14  create mode 100644 drivers/char/broadcom/bcm2835-gpiomem.c
  15
  16 --- a/arch/arm/boot/dts/bcm2708.dtsi
  17 +++ b/arch/arm/boot/dts/bcm2708.dtsi
  18 @@ -15,5 +15,11 @@
  19                 arm-pmu {
  20                         compatible = "arm,arm1176-pmu";
  21                 };
  22 +
  23 +               gpiomem {
  24 +                       compatible = "brcm,bcm2835-gpiomem";
  25 +                       reg = <0x7e200000 0x1000>;
  26 +                       status = "okay";
  27 +               };
  28         };
  29  };
  30 --- a/arch/arm/boot/dts/bcm2709.dtsi
  31 +++ b/arch/arm/boot/dts/bcm2709.dtsi
  32 @@ -16,6 +16,12 @@
  33                         compatible = "arm,cortex-a7-pmu";
  34                         interrupts = <3 9>;
  35                 };
  36 +
  37 +               gpiomem {
  38 +                       compatible = "brcm,bcm2835-gpiomem";
  39 +                       reg = <0x7e200000 0x1000>;
  40 +                       status = "okay";
  41 +               };
  42         };
  43
  44         timer {
  45 --- a/drivers/char/broadcom/Kconfig
  46 +++ b/drivers/char/broadcom/Kconfig
  47 @@ -38,3 +38,12 @@ config BCM_VC_SM
  48         help
  49         Support for the VC shared memory on the Broadcom reference
  50         design. Uses the VCHIQ stack.
  51 +
  52 +config BCM2835_DEVGPIOMEM
  53 +       tristate "/dev/gpiomem rootless GPIO access via mmap() on the BCM2835"
  54 +       default m
  55 +       help
  56 +               Provides users with root-free access to the GPIO registers
  57 +               on the 2835. Calling mmap(/dev/gpiomem) will map the GPIO
  58 +               register page to the user's pointer.
  59 +
  60 --- a/drivers/char/broadcom/Makefile
  61 +++ b/drivers/char/broadcom/Makefile
  62 @@ -2,3 +2,6 @@ obj-$(CONFIG_BCM_VC_CMA)        += vc_cma/
  63  obj-$(CONFIG_BCM2708_VCMEM)    += vc_mem.o
  64  obj-$(CONFIG_BCM_VCIO)         += vcio.o
  65  obj-$(CONFIG_BCM_VC_SM)         += vc_sm/
  66 +
  67 +obj-$(CONFIG_BCM2835_DEVGPIOMEM)+= bcm2835-gpiomem.o
  68 +
  69 --- /dev/null
  70 +++ b/drivers/char/broadcom/bcm2835-gpiomem.c
  71 @@ -0,0 +1,265 @@
  72 +/**
  73 + * GPIO memory device driver
  74 + *
  75 + * Creates a chardev /dev/gpiomem which will provide user access to
  76 + * the BCM2835's GPIO registers when it is mmap()'d.
  77 + * No longer need root for user GPIO access, but without relaxing permissions
  78 + * on /dev/mem.
  79 + *
  80 + * Written by Luke Wren <luke@raspberrypi.org>
  81 + * Copyright (c) 2015, Raspberry Pi (Trading) Ltd.
  82 + *
  83 + * Redistribution and use in source and binary forms, with or without
  84 + * modification, are permitted provided that the following conditions
  85 + * are met:
  86 + * 1. Redistributions of source code must retain the above copyright
  87 + *    notice, this list of conditions, and the following disclaimer,
  88 + *    without modification.
  89 + * 2. Redistributions in binary form must reproduce the above copyright
  90 + *    notice, this list of conditions and the following disclaimer in the
  91 + *    documentation and/or other materials provided with the distribution.
  92 + * 3. The names of the above-listed copyright holders may not be used
  93 + *    to endorse or promote products derived from this software without
  94 + *    specific prior written permission.
  95 + *
  96 + * ALTERNATIVELY, this software may be distributed under the terms of the
  97 + * GNU General Public License ("GPL") version 2, as published by the Free
  98 + * Software Foundation.
  99 + *
 100 + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 101 + * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 102 + * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 103 + * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 104 + * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 105 + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 106 + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 107 + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 108 + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 109 + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 110 + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 111 + */
 112 +
 113 +#include <linux/kernel.h>
 114 +#include <linux/module.h>
 115 +#include <linux/of.h>
 116 +#include <linux/platform_device.h>
 117 +#include <linux/mm.h>
 118 +#include <linux/slab.h>
 119 +#include <linux/cdev.h>
 120 +#include <linux/pagemap.h>
 121 +#include <linux/io.h>
 122 +
 123 +#define DEVICE_NAME "bcm2835-gpiomem"
 124 +#define DRIVER_NAME "gpiomem-bcm2835"
 125 +#define DEVICE_MINOR 0
 126 +
 127 +struct bcm2835_gpiomem_instance {
 128 +       unsigned long gpio_regs_phys;
 129 +       struct device *dev;
 130 +};
 131 +
 132 +static struct cdev bcm2835_gpiomem_cdev;
 133 +static dev_t bcm2835_gpiomem_devid;
 134 +static struct class *bcm2835_gpiomem_class;
 135 +static struct device *bcm2835_gpiomem_dev;
 136 +static struct bcm2835_gpiomem_instance *inst;
 137 +
 138 +
 139 +/****************************************************************************
 140 +*
 141 +*   GPIO mem chardev file ops
 142 +*
 143 +***************************************************************************/
 144 +
 145 +static int bcm2835_gpiomem_open(struct inode *inode, struct file *file)
 146 +{
 147 +       int dev = iminor(inode);
 148 +       int ret = 0;
 149 +
 150 +       dev_info(inst->dev, "gpiomem device opened.");
 151 +
 152 +       if (dev != DEVICE_MINOR) {
 153 +               dev_err(inst->dev, "Unknown minor device: %d", dev);
 154 +               ret = -ENXIO;
 155 +       }
 156 +       return ret;
 157 +}
 158 +
 159 +static int bcm2835_gpiomem_release(struct inode *inode, struct file *file)
 160 +{
 161 +       int dev = iminor(inode);
 162 +       int ret = 0;
 163 +
 164 +       if (dev != DEVICE_MINOR) {
 165 +               dev_err(inst->dev, "Unknown minor device %d", dev);
 166 +               ret = -ENXIO;
 167 +       }
 168 +       return ret;
 169 +}
 170 +
 171 +static const struct vm_operations_struct bcm2835_gpiomem_vm_ops = {
 172 +#ifdef CONFIG_HAVE_IOREMAP_PROT
 173 +       .access = generic_access_phys
 174 +#endif
 175 +};
 176 +
 177 +static int bcm2835_gpiomem_mmap(struct file *file, struct vm_area_struct *vma)
 178 +{
 179 +       /* Ignore what the user says - they're getting the GPIO regs
 180 +          whether they like it or not! */
 181 +       unsigned long gpio_page = inst->gpio_regs_phys >> PAGE_SHIFT;
 182 +
 183 +       vma->vm_page_prot = phys_mem_access_prot(file, gpio_page,
 184 +                                                PAGE_SIZE,
 185 +                                                vma->vm_page_prot);
 186 +       vma->vm_ops = &bcm2835_gpiomem_vm_ops;
 187 +       if (remap_pfn_range(vma, vma->vm_start,
 188 +                       gpio_page,
 189 +                       PAGE_SIZE,
 190 +                       vma->vm_page_prot)) {
 191 +               return -EAGAIN;
 192 +       }
 193 +       return 0;
 194 +}
 195 +
 196 +static const struct file_operations
 197 +bcm2835_gpiomem_fops = {
 198 +       .owner = THIS_MODULE,
 199 +       .open = bcm2835_gpiomem_open,
 200 +       .release = bcm2835_gpiomem_release,
 201 +       .mmap = bcm2835_gpiomem_mmap,
 202 +};
 203 +
 204 +
 205 + /****************************************************************************
 206 +*
 207 +*   Probe and remove functions
 208 +*
 209 +***************************************************************************/
 210 +
 211 +
 212 +static int bcm2835_gpiomem_probe(struct platform_device *pdev)
 213 +{
 214 +       int err;
 215 +       void *ptr_err;
 216 +       struct device *dev = &pdev->dev;
 217 +       struct device_node *node = dev->of_node;
 218 +       struct resource *ioresource;
 219 +
 220 +       /* Allocate buffers and instance data */
 221 +
 222 +       inst = kzalloc(sizeof(struct bcm2835_gpiomem_instance), GFP_KERNEL);
 223 +
 224 +       if (!inst) {
 225 +               err = -ENOMEM;
 226 +               goto failed_inst_alloc;
 227 +       }
 228 +
 229 +       inst->dev = dev;
 230 +
 231 +       /* Create character device entries */
 232 +
 233 +       err = alloc_chrdev_region(&bcm2835_gpiomem_devid,
 234 +                                 DEVICE_MINOR, 1, DEVICE_NAME);
 235 +       if (err != 0) {
 236 +               dev_err(inst->dev, "unable to allocate device number");
 237 +               goto failed_alloc_chrdev;
 238 +       }
 239 +       cdev_init(&bcm2835_gpiomem_cdev, &bcm2835_gpiomem_fops);
 240 +       bcm2835_gpiomem_cdev.owner = THIS_MODULE;
 241 +       err = cdev_add(&bcm2835_gpiomem_cdev, bcm2835_gpiomem_devid, 1);
 242 +       if (err != 0) {
 243 +               dev_err(inst->dev, "unable to register device");
 244 +               goto failed_cdev_add;
 245 +       }
 246 +
 247 +       /* Create sysfs entries */
 248 +
 249 +       bcm2835_gpiomem_class = class_create(THIS_MODULE, DEVICE_NAME);
 250 +       ptr_err = bcm2835_gpiomem_class;
 251 +       if (IS_ERR(ptr_err))
 252 +               goto failed_class_create;
 253 +
 254 +       bcm2835_gpiomem_dev = device_create(bcm2835_gpiomem_class, NULL,
 255 +                                       bcm2835_gpiomem_devid, NULL,
 256 +                                       "gpiomem");
 257 +       ptr_err = bcm2835_gpiomem_dev;
 258 +       if (IS_ERR(ptr_err))
 259 +               goto failed_device_create;
 260 +
 261 +       /* Get address from device tree if available (*_resource() correctly
 262 +          converts the bus address in device tree to a physical address),
 263 +          or use hardcoded offset + BCM2708_PERI_BASE if not.
 264 +          (In spite of its name 2708 actually seems to have the correct
 265 +          mach-dependent value on 2709 etc, as it is defined in
 266 +          mach-bcm270x/platform.h) */
 267 +
 268 +       if (node) {
 269 +               ioresource = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 270 +               inst->gpio_regs_phys = ioresource->start;
 271 +       } else {
 272 +               inst->gpio_regs_phys = GPIO_BASE;
 273 +       }
 274 +
 275 +       dev_info(inst->dev, "Initialised: Registers at 0x%08lx",
 276 +               inst->gpio_regs_phys);
 277 +
 278 +       return 0;
 279 +
 280 +failed_device_create:
 281 +       class_destroy(bcm2835_gpiomem_class);
 282 +failed_class_create:
 283 +       cdev_del(&bcm2835_gpiomem_cdev);
 284 +       err = PTR_ERR(ptr_err);
 285 +failed_cdev_add:
 286 +       unregister_chrdev_region(bcm2835_gpiomem_devid, 1);
 287 +failed_alloc_chrdev:
 288 +       kfree(inst);
 289 +failed_inst_alloc:
 290 +       dev_err(inst->dev, "could not load bcm2835_gpiomem");
 291 +       return err;
 292 +}
 293 +
 294 +static int bcm2835_gpiomem_remove(struct platform_device *pdev)
 295 +{
 296 +       struct device *dev = inst->dev;
 297 +
 298 +       kfree(inst);
 299 +       device_destroy(bcm2835_gpiomem_class, bcm2835_gpiomem_devid);
 300 +       class_destroy(bcm2835_gpiomem_class);
 301 +       cdev_del(&bcm2835_gpiomem_cdev);
 302 +       unregister_chrdev_region(bcm2835_gpiomem_devid, 1);
 303 +
 304 +       dev_info(dev, "GPIO mem driver removed - OK");
 305 +       return 0;
 306 +}
 307 +
 308 + /****************************************************************************
 309 +*
 310 +*   Register the driver with device tree
 311 +*
 312 +***************************************************************************/
 313 +
 314 +static const struct of_device_id bcm2835_gpiomem_of_match[] = {
 315 +       {.compatible = "brcm,bcm2835-gpiomem",},
 316 +       { /* sentinel */ },
 317 +};
 318 +
 319 +MODULE_DEVICE_TABLE(of, bcm2835_gpiomem_of_match);
 320 +
 321 +static struct platform_driver bcm2835_gpiomem_driver = {
 322 +       .probe = bcm2835_gpiomem_probe,
 323 +       .remove = bcm2835_gpiomem_remove,
 324 +       .driver = {
 325 +                  .name = DRIVER_NAME,
 326 +                  .owner = THIS_MODULE,
 327 +                  .of_match_table = bcm2835_gpiomem_of_match,
 328 +                  },
 329 +};
 330 +
 331 +module_platform_driver(bcm2835_gpiomem_driver);
 332 +
 333 +MODULE_ALIAS("platform:gpiomem-bcm2835");
 334 +MODULE_LICENSE("GPL");
 335 +MODULE_DESCRIPTION("gpiomem driver for accessing GPIO from userspace");
 336 +MODULE_AUTHOR("Luke Wren <luke@raspberrypi.org>");