target/linux/brcm2708/patches-4.9/950-0090-OF-DT-Overlay-configfs-interface.patch

   1 From ef4a8376af32bb6722e1ea933a9e1a83ebc8f175 Mon Sep 17 00:00:00 2001
   2 From: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
   3 Date: Wed, 3 Dec 2014 13:23:28 +0200
   4 Subject: [PATCH] OF: DT-Overlay configfs interface
   5
   6 This is a port of Pantelis Antoniou's v3 port that makes use of the
   7 new upstreamed configfs support for binary attributes.
   8
   9 Original commit message:
  10
  11 Add a runtime interface to using configfs for generic device tree overlay
  12 usage. With it its possible to use device tree overlays without having
  13 to use a per-platform overlay manager.
  14
  15 Please see Documentation/devicetree/configfs-overlays.txt for more info.
  16
  17 Changes since v2:
  18 - Removed ifdef CONFIG_OF_OVERLAY (since for now it's required)
  19 - Created a documentation entry
  20 - Slight rewording in Kconfig
  21
  22 Changes since v1:
  23 - of_resolve() -> of_resolve_phandles().
  24
  25 Originally-signed-off-by: Pantelis Antoniou <pantelis.antoniou@konsulko.com>
  26 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  27
  28 DT configfs: Fix build errors on other platforms
  29
  30 Signed-off-by: Phil Elwell <phil@raspberrypi.org>
  31
  32 DT configfs: fix build error
  33
  34 There is an error when compiling rpi-4.6.y branch:
  35   CC      drivers/of/configfs.o
  36 drivers/of/configfs.c:291:21: error: initialization from incompatible pointer type [-Werror=incompatible-pointer-types]
  37    .default_groups = of_cfs_def_groups,
  38                      ^
  39 drivers/of/configfs.c:291:21: note: (near initialization for 'of_cfs_subsys.su_group.default_groups.next')
  40
  41 The .default_groups is linked list since commit
  42 1ae1602de028acaa42a0f6ff18d19756f8e825c6.
  43 This commit uses configfs_add_default_group to fix this problem.
  44
  45 Signed-off-by: Slawomir Stepien <sst@poczta.fm>
  46 ---
  47  Documentation/devicetree/configfs-overlays.txt |  31 +++
  48  drivers/of/Kconfig                             |   7 +
  49  drivers/of/Makefile                            |   1 +
  50  drivers/of/configfs.c                          | 311 +++++++++++++++++++++++++
  51  4 files changed, 350 insertions(+)
  52  create mode 100644 Documentation/devicetree/configfs-overlays.txt
  53  create mode 100644 drivers/of/configfs.c
  54
  55 --- /dev/null
  56 +++ b/Documentation/devicetree/configfs-overlays.txt
  57 @@ -0,0 +1,31 @@
  58 +Howto use the configfs overlay interface.
  59 +
  60 +A device-tree configfs entry is created in /config/device-tree/overlays
  61 +and and it is manipulated using standard file system I/O.
  62 +Note that this is a debug level interface, for use by developers and
  63 +not necessarily something accessed by normal users due to the
  64 +security implications of having direct access to the kernel's device tree.
  65 +
  66 +* To create an overlay you mkdir the directory:
  67 +
  68 +       # mkdir /config/device-tree/overlays/foo
  69 +
  70 +* Either you echo the overlay firmware file to the path property file.
  71 +
  72 +       # echo foo.dtbo >/config/device-tree/overlays/foo/path
  73 +
  74 +* Or you cat the contents of the overlay to the dtbo file
  75 +
  76 +       # cat foo.dtbo >/config/device-tree/overlays/foo/dtbo
  77 +
  78 +The overlay file will be applied, and devices will be created/destroyed
  79 +as required.
  80 +
  81 +To remove it simply rmdir the directory.
  82 +
  83 +       # rmdir /config/device-tree/overlays/foo
  84 +
  85 +The rationalle of the dual interface (firmware & direct copy) is that each is
  86 +better suited to different use patterns. The firmware interface is what's
  87 +intended to be used by hardware managers in the kernel, while the copy interface
  88 +make sense for developers (since it avoids problems with namespaces).
  89 --- a/drivers/of/Kconfig
  90 +++ b/drivers/of/Kconfig
  91 @@ -112,4 +112,11 @@ config OF_OVERLAY
  92  config OF_NUMA
  93         bool
  94
  95 +config OF_CONFIGFS
  96 +       bool "Device Tree Overlay ConfigFS interface"
  97 +       select CONFIGFS_FS
  98 +       select OF_OVERLAY
  99 +       help
 100 +         Enable a simple user-space driven DT overlay interface.
 101 +
 102  endif # OF
 103 --- a/drivers/of/Makefile
 104 +++ b/drivers/of/Makefile
 105 @@ -1,4 +1,5 @@
 106  obj-y = base.o device.o platform.o
 107 +obj-$(CONFIG_OF_CONFIGFS) += configfs.o
 108  obj-$(CONFIG_OF_DYNAMIC) += dynamic.o
 109  obj-$(CONFIG_OF_FLATTREE) += fdt.o
 110  obj-$(CONFIG_OF_EARLY_FLATTREE) += fdt_address.o
 111 --- /dev/null
 112 +++ b/drivers/of/configfs.c
 113 @@ -0,0 +1,311 @@
 114 +/*
 115 + * Configfs entries for device-tree
 116 + *
 117 + * Copyright (C) 2013 - Pantelis Antoniou <panto@antoniou-consulting.com>
 118 + *
 119 + * This program is free software; you can redistribute it and/or
 120 + * modify it under the terms of the GNU General Public License
 121 + * as published by the Free Software Foundation; either version
 122 + * 2 of the License, or (at your option) any later version.
 123 + */
 124 +#include <linux/ctype.h>
 125 +#include <linux/cpu.h>
 126 +#include <linux/module.h>
 127 +#include <linux/of.h>
 128 +#include <linux/of_fdt.h>
 129 +#include <linux/spinlock.h>
 130 +#include <linux/slab.h>
 131 +#include <linux/proc_fs.h>
 132 +#include <linux/configfs.h>
 133 +#include <linux/types.h>
 134 +#include <linux/stat.h>
 135 +#include <linux/limits.h>
 136 +#include <linux/file.h>
 137 +#include <linux/vmalloc.h>
 138 +#include <linux/firmware.h>
 139 +#include <linux/sizes.h>
 140 +
 141 +#include "of_private.h"
 142 +
 143 +struct cfs_overlay_item {
 144 +       struct config_item      item;
 145 +
 146 +       char                    path[PATH_MAX];
 147 +
 148 +       const struct firmware   *fw;
 149 +       struct device_node      *overlay;
 150 +       int                     ov_id;
 151 +
 152 +       void                    *dtbo;
 153 +       int                     dtbo_size;
 154 +};
 155 +
 156 +static int create_overlay(struct cfs_overlay_item *overlay, void *blob)
 157 +{
 158 +       int err;
 159 +
 160 +       /* unflatten the tree */
 161 +       of_fdt_unflatten_tree(blob, NULL, &overlay->overlay);
 162 +       if (overlay->overlay == NULL) {
 163 +               pr_err("%s: failed to unflatten tree\n", __func__);
 164 +               err = -EINVAL;
 165 +               goto out_err;
 166 +       }
 167 +       pr_debug("%s: unflattened OK\n", __func__);
 168 +
 169 +       /* mark it as detached */
 170 +       of_node_set_flag(overlay->overlay, OF_DETACHED);
 171 +
 172 +       /* perform resolution */
 173 +       err = of_resolve_phandles(overlay->overlay);
 174 +       if (err != 0) {
 175 +               pr_err("%s: Failed to resolve tree\n", __func__);
 176 +               goto out_err;
 177 +       }
 178 +       pr_debug("%s: resolved OK\n", __func__);
 179 +
 180 +       err = of_overlay_create(overlay->overlay);
 181 +       if (err < 0) {
 182 +               pr_err("%s: Failed to create overlay (err=%d)\n",
 183 +                               __func__, err);
 184 +               goto out_err;
 185 +       }
 186 +       overlay->ov_id = err;
 187 +
 188 +out_err:
 189 +       return err;
 190 +}
 191 +
 192 +static inline struct cfs_overlay_item *to_cfs_overlay_item(
 193 +               struct config_item *item)
 194 +{
 195 +       return item ? container_of(item, struct cfs_overlay_item, item) : NULL;
 196 +}
 197 +
 198 +static ssize_t cfs_overlay_item_path_show(struct config_item *item,
 199 +               char *page)
 200 +{
 201 +       struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
 202 +       return sprintf(page, "%s\n", overlay->path);
 203 +}
 204 +
 205 +static ssize_t cfs_overlay_item_path_store(struct config_item *item,
 206 +               const char *page, size_t count)
 207 +{
 208 +       struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
 209 +       const char *p = page;
 210 +       char *s;
 211 +       int err;
 212 +
 213 +       /* if it's set do not allow changes */
 214 +       if (overlay->path[0] != '\0' || overlay->dtbo_size > 0)
 215 +               return -EPERM;
 216 +
 217 +       /* copy to path buffer (and make sure it's always zero terminated */
 218 +       count = snprintf(overlay->path, sizeof(overlay->path) - 1, "%s", p);
 219 +       overlay->path[sizeof(overlay->path) - 1] = '\0';
 220 +
 221 +       /* strip trailing newlines */
 222 +       s = overlay->path + strlen(overlay->path);
 223 +       while (s > overlay->path && *--s == '\n')
 224 +               *s = '\0';
 225 +
 226 +       pr_debug("%s: path is '%s'\n", __func__, overlay->path);
 227 +
 228 +       err = request_firmware(&overlay->fw, overlay->path, NULL);
 229 +       if (err != 0)
 230 +               goto out_err;
 231 +
 232 +       err = create_overlay(overlay, (void *)overlay->fw->data);
 233 +       if (err != 0)
 234 +               goto out_err;
 235 +
 236 +       return count;
 237 +
 238 +out_err:
 239 +
 240 +       release_firmware(overlay->fw);
 241 +       overlay->fw = NULL;
 242 +
 243 +       overlay->path[0] = '\0';
 244 +       return err;
 245 +}
 246 +
 247 +static ssize_t cfs_overlay_item_status_show(struct config_item *item,
 248 +               char *page)
 249 +{
 250 +       struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
 251 +
 252 +       return sprintf(page, "%s\n",
 253 +                       overlay->ov_id >= 0 ? "applied" : "unapplied");
 254 +}
 255 +
 256 +CONFIGFS_ATTR(cfs_overlay_item_, path);
 257 +CONFIGFS_ATTR_RO(cfs_overlay_item_, status);
 258 +
 259 +static struct configfs_attribute *cfs_overlay_attrs[] = {
 260 +       &cfs_overlay_item_attr_path,
 261 +       &cfs_overlay_item_attr_status,
 262 +       NULL,
 263 +};
 264 +
 265 +ssize_t cfs_overlay_item_dtbo_read(struct config_item *item,
 266 +               void *buf, size_t max_count)
 267 +{
 268 +       struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
 269 +
 270 +       pr_debug("%s: buf=%p max_count=%zu\n", __func__,
 271 +                       buf, max_count);
 272 +
 273 +       if (overlay->dtbo == NULL)
 274 +               return 0;
 275 +
 276 +       /* copy if buffer provided */
 277 +       if (buf != NULL) {
 278 +               /* the buffer must be large enough */
 279 +               if (overlay->dtbo_size > max_count)
 280 +                       return -ENOSPC;
 281 +
 282 +               memcpy(buf, overlay->dtbo, overlay->dtbo_size);
 283 +       }
 284 +
 285 +       return overlay->dtbo_size;
 286 +}
 287 +
 288 +ssize_t cfs_overlay_item_dtbo_write(struct config_item *item,
 289 +               const void *buf, size_t count)
 290 +{
 291 +       struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
 292 +       int err;
 293 +
 294 +       /* if it's set do not allow changes */
 295 +       if (overlay->path[0] != '\0' || overlay->dtbo_size > 0)
 296 +               return -EPERM;
 297 +
 298 +       /* copy the contents */
 299 +       overlay->dtbo = kmemdup(buf, count, GFP_KERNEL);
 300 +       if (overlay->dtbo == NULL)
 301 +               return -ENOMEM;
 302 +
 303 +       overlay->dtbo_size = count;
 304 +
 305 +       err = create_overlay(overlay, overlay->dtbo);
 306 +       if (err != 0)
 307 +               goto out_err;
 308 +
 309 +       return count;
 310 +
 311 +out_err:
 312 +       kfree(overlay->dtbo);
 313 +       overlay->dtbo = NULL;
 314 +       overlay->dtbo_size = 0;
 315 +
 316 +       return err;
 317 +}
 318 +
 319 +CONFIGFS_BIN_ATTR(cfs_overlay_item_, dtbo, NULL, SZ_1M);
 320 +
 321 +static struct configfs_bin_attribute *cfs_overlay_bin_attrs[] = {
 322 +       &cfs_overlay_item_attr_dtbo,
 323 +       NULL,
 324 +};
 325 +
 326 +static void cfs_overlay_release(struct config_item *item)
 327 +{
 328 +       struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
 329 +
 330 +       if (overlay->ov_id >= 0)
 331 +               of_overlay_destroy(overlay->ov_id);
 332 +       if (overlay->fw)
 333 +               release_firmware(overlay->fw);
 334 +       /* kfree with NULL is safe */
 335 +       kfree(overlay->dtbo);
 336 +       kfree(overlay);
 337 +}
 338 +
 339 +static struct configfs_item_operations cfs_overlay_item_ops = {
 340 +       .release        = cfs_overlay_release,
 341 +};
 342 +
 343 +static struct config_item_type cfs_overlay_type = {
 344 +       .ct_item_ops    = &cfs_overlay_item_ops,
 345 +       .ct_attrs       = cfs_overlay_attrs,
 346 +       .ct_bin_attrs   = cfs_overlay_bin_attrs,
 347 +       .ct_owner       = THIS_MODULE,
 348 +};
 349 +
 350 +static struct config_item *cfs_overlay_group_make_item(
 351 +               struct config_group *group, const char *name)
 352 +{
 353 +       struct cfs_overlay_item *overlay;
 354 +
 355 +       overlay = kzalloc(sizeof(*overlay), GFP_KERNEL);
 356 +       if (!overlay)
 357 +               return ERR_PTR(-ENOMEM);
 358 +       overlay->ov_id = -1;
 359 +
 360 +       config_item_init_type_name(&overlay->item, name, &cfs_overlay_type);
 361 +       return &overlay->item;
 362 +}
 363 +
 364 +static void cfs_overlay_group_drop_item(struct config_group *group,
 365 +               struct config_item *item)
 366 +{
 367 +       struct cfs_overlay_item *overlay = to_cfs_overlay_item(item);
 368 +
 369 +       config_item_put(&overlay->item);
 370 +}
 371 +
 372 +static struct configfs_group_operations overlays_ops = {
 373 +       .make_item      = cfs_overlay_group_make_item,
 374 +       .drop_item      = cfs_overlay_group_drop_item,
 375 +};
 376 +
 377 +static struct config_item_type overlays_type = {
 378 +       .ct_group_ops   = &overlays_ops,
 379 +       .ct_owner       = THIS_MODULE,
 380 +};
 381 +
 382 +static struct configfs_group_operations of_cfs_ops = {
 383 +       /* empty - we don't allow anything to be created */
 384 +};
 385 +
 386 +static struct config_item_type of_cfs_type = {
 387 +       .ct_group_ops   = &of_cfs_ops,
 388 +       .ct_owner       = THIS_MODULE,
 389 +};
 390 +
 391 +struct config_group of_cfs_overlay_group;
 392 +
 393 +static struct configfs_subsystem of_cfs_subsys = {
 394 +       .su_group = {
 395 +               .cg_item = {
 396 +                       .ci_namebuf = "device-tree",
 397 +                       .ci_type = &of_cfs_type,
 398 +               },
 399 +       },
 400 +       .su_mutex = __MUTEX_INITIALIZER(of_cfs_subsys.su_mutex),
 401 +};
 402 +
 403 +static int __init of_cfs_init(void)
 404 +{
 405 +       int ret;
 406 +
 407 +       pr_info("%s\n", __func__);
 408 +
 409 +       config_group_init(&of_cfs_subsys.su_group);
 410 +       config_group_init_type_name(&of_cfs_overlay_group, "overlays",
 411 +                       &overlays_type);
 412 +       configfs_add_default_group(&of_cfs_overlay_group,
 413 +                       &of_cfs_subsys.su_group);
 414 +
 415 +       ret = configfs_register_subsystem(&of_cfs_subsys);
 416 +       if (ret != 0) {
 417 +               pr_err("%s: failed to register subsys\n", __func__);
 418 +               goto out;
 419 +       }
 420 +       pr_info("%s: OK\n", __func__);
 421 +out:
 422 +       return ret;
 423 +}
 424 +late_initcall(of_cfs_init);