[PATCH v3 00/11] gpio: implement the configfs testing module

[PATCH v3 00/11] gpio: implement the configfs testing module

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

This series adds a new GPIO testing module based on configfs committable items
and sysfs. The goal is to provide a testing driver that will be configurable
at runtime (won't need module reload) and easily extensible. The control over
the attributes is also much more fine-grained than in gpio-mockup.

This series also contains a respin of the patches I sent separately to the
configfs maintainers - these patches implement the concept of committable
items that was well defined for a long time but never actually completed.

Apart from the new driver itself, its selftests and the configfs patches, this
series contains some changes to the bitmap API - most importantly: it adds
devres managed variants of bitmap_alloc() and bitmap_zalloc().

v1 -> v2:
- add selftests for gpio-sim
- add helper programs for selftests
- update the configfs rename callback to work with the new API introduced in
  v5.11
- fix a missing quote in the documentation
- use !! whenever using bits operation that are required to return 0 or 1
- use provided bitmap API instead of reimplementing copy or fill operations
- fix a deadlock in gpio_sim_direction_output()
- add new read-only configfs attributes for mapping of configfs items to GPIO
  device names
- and address other minor issues pointed out in reviews of v1

v2 -> v3:
- use devm_bitmap_alloc() instead of the zalloc variant if we're initializing
  the bitmap with 1s
- drop the patch exporting device_is_bound()
- don't return -ENODEV from dev_nam and chip_name configfs attributes, return
  a string indicating that the device is not available yet ('n/a')
- fix indentation where it makes sense
- don't protect IDA functions which use their own locking and where it's not
  needed
- use kmemdup() instead of kzalloc() + memcpy()
- collected review tags
- minor coding style fixes

Bartosz Golaszewski (11):
  configfs: increase the item name length
  configfs: use (1UL << bit) for internal flags
  configfs: implement committable items
  samples: configfs: add a committable group
  lib: bitmap: remove the 'extern' keyword from function declarations
  lib: bitmap: order includes alphabetically
  lib: bitmap: provide devm_bitmap_alloc() and devm_bitmap_zalloc()
  gpio: sim: new testing module
  selftests: gpio: provide a helper for reading chip info
  selftests: gpio: add a helper for reading GPIO line names
  selftests: gpio: add test cases for gpio-sim

 Documentation/admin-guide/gpio/gpio-sim.rst   |  72 ++
 Documentation/filesystems/configfs.rst        |   6 +-
 drivers/gpio/Kconfig                          |   8 +
 drivers/gpio/Makefile                         |   1 +
 drivers/gpio/gpio-sim.c                       | 879 ++++++++++++++++++
 fs/configfs/configfs_internal.h               |  22 +-
 fs/configfs/dir.c                             | 245 ++++-
 include/linux/bitmap.h                        | 127 +--
 include/linux/configfs.h                      |   3 +-
 lib/bitmap.c                                  |  42 +-
 samples/configfs/configfs_sample.c            | 153 +++
 tools/testing/selftests/gpio/.gitignore       |   2 +
 tools/testing/selftests/gpio/Makefile         |   4 +-
 tools/testing/selftests/gpio/config           |   1 +
 tools/testing/selftests/gpio/gpio-chip-info.c |  57 ++
 tools/testing/selftests/gpio/gpio-line-name.c |  55 ++
 tools/testing/selftests/gpio/gpio-sim.sh      | 229 +++++
 17 files changed, 1820 insertions(+), 86 deletions(-)
 create mode 100644 Documentation/admin-guide/gpio/gpio-sim.rst
 create mode 100644 drivers/gpio/gpio-sim.c
 create mode 100644 tools/testing/selftests/gpio/gpio-chip-info.c
 create mode 100644 tools/testing/selftests/gpio/gpio-line-name.c
 create mode 100755 tools/testing/selftests/gpio/gpio-sim.sh

-- 
2.30.1

[PATCH v3 01/11] configfs: increase the item name length

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

20 characters limit for item name is relatively small. Let's increase it
to 32 to fit '04-committable-children' - a name we'll use in the sample
code for committable items.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
---
 include/linux/configfs.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index 2e8c69b43c64..4f76dcc08134 100644
--- a/include/linux/configfs.h
+++ b/include/linux/configfs.h
@@ -27,7 +27,7 @@
 #include <linux/kref.h>   /* struct kref */
 #include <linux/mutex.h>  /* struct mutex */
 
-#define CONFIGFS_ITEM_NAME_LEN	20
+#define CONFIGFS_ITEM_NAME_LEN	32
 
 struct module;
 
-- 
2.30.1

[PATCH v3 02/11] configfs: use (1UL << bit) for internal flags

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

For better readability and maintenance: use the (1UL << bit) for flag
definitions.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
---
 fs/configfs/configfs_internal.h | 20 ++++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h
index 9a3aed249692..b495c9f043d4 100644
--- a/fs/configfs/configfs_internal.h
+++ b/fs/configfs/configfs_internal.h
@@ -46,16 +46,16 @@ struct configfs_dirent {
 	struct configfs_fragment *s_frag;
 };
 
-#define CONFIGFS_ROOT		0x0001
-#define CONFIGFS_DIR		0x0002
-#define CONFIGFS_ITEM_ATTR	0x0004
-#define CONFIGFS_ITEM_BIN_ATTR	0x0008
-#define CONFIGFS_ITEM_LINK	0x0020
-#define CONFIGFS_USET_DIR	0x0040
-#define CONFIGFS_USET_DEFAULT	0x0080
-#define CONFIGFS_USET_DROPPING	0x0100
-#define CONFIGFS_USET_IN_MKDIR	0x0200
-#define CONFIGFS_USET_CREATING	0x0400
+#define CONFIGFS_ROOT			(1UL << 0)
+#define CONFIGFS_DIR			(1UL << 1)
+#define CONFIGFS_ITEM_ATTR		(1UL << 2)
+#define CONFIGFS_ITEM_BIN_ATTR		(1UL << 3)
+#define CONFIGFS_ITEM_LINK		(1UL << 5)
+#define CONFIGFS_USET_DIR		(1UL << 6)
+#define CONFIGFS_USET_DEFAULT		(1UL << 7)
+#define CONFIGFS_USET_DROPPING		(1UL << 8)
+#define CONFIGFS_USET_IN_MKDIR		(1UL << 9)
+#define CONFIGFS_USET_CREATING		(1UL << 10)
 #define CONFIGFS_NOT_PINNED	(CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)
 
 extern struct mutex configfs_symlink_mutex;
-- 
2.30.1

[PATCH v3 03/11] configfs: implement committable items

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

This implements configfs committable items. We mostly follow the
documentation except that we extend config_group_ops with uncommit_item()
callback for reverting the changes made by commit_item().

Each committable group has two sub-directories: pending and live. New
items can only be created in pending/. Attributes can only be modified
while the item is in pending/. Once it's ready to be committed, it must
be moved over to live/ using the rename() system call. This is when the
commit_item() function will be called.

Implementation-wise: we reuse the default group mechanism to elegantly
plug the new pseude-groups into configfs. The pending group inherits the
parent group's operations so that config_items can be seamlesly created
in it using the callbacks supplied by the user as part of the committable
group itself.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
---
 Documentation/filesystems/configfs.rst |   6 +-
 fs/configfs/configfs_internal.h        |   2 +
 fs/configfs/dir.c                      | 245 ++++++++++++++++++++++++-
 include/linux/configfs.h               |   1 +
 4 files changed, 245 insertions(+), 9 deletions(-)

diff --git a/Documentation/filesystems/configfs.rst b/Documentation/filesystems/configfs.rst
index 1d3d6f4a82a9..7e0e7c356450 100644
--- a/Documentation/filesystems/configfs.rst
+++ b/Documentation/filesystems/configfs.rst
@@ -290,6 +290,7 @@ config_item_type::
 		struct config_group *(*make_group)(struct config_group *group,
 						   const char *name);
 		int (*commit_item)(struct config_item *item);
+		int (*uncommit_item)(struct config_item *item);
 		void (*disconnect_notify)(struct config_group *group,
 					  struct config_item *item);
 		void (*drop_item)(struct config_group *group,
@@ -490,9 +491,6 @@ pass up an error.
 Committable Items
 =================
 
-Note:
-     Committable items are currently unimplemented.
-
 Some config_items cannot have a valid initial state.  That is, no
 default values can be specified for the item's attributes such that the
 item can do its work.  Userspace must configure one or more attributes,
@@ -532,4 +530,4 @@ method returns zero and the item is moved to the "live" directory.
 As rmdir(2) does not work in the "live" directory, an item must be
 shutdown, or "uncommitted".  Again, this is done via rename(2), this
 time from the "live" directory back to the "pending" one.  The subsystem
-is notified by the ct_group_ops->uncommit_object() method.
+is notified by the ct_group_ops->uncommit_item() method.
diff --git a/fs/configfs/configfs_internal.h b/fs/configfs/configfs_internal.h
index b495c9f043d4..41ac21c82bf5 100644
--- a/fs/configfs/configfs_internal.h
+++ b/fs/configfs/configfs_internal.h
@@ -56,6 +56,8 @@ struct configfs_dirent {
 #define CONFIGFS_USET_DROPPING		(1UL << 8)
 #define CONFIGFS_USET_IN_MKDIR		(1UL << 9)
 #define CONFIGFS_USET_CREATING		(1UL << 10)
+#define CONFIGFS_GROUP_PENDING		(1UL << 11)
+#define CONFIGFS_GROUP_LIVE		(1UL << 12)
 #define CONFIGFS_NOT_PINNED	(CONFIGFS_ITEM_ATTR | CONFIGFS_ITEM_BIN_ATTR)
 
 extern struct mutex configfs_symlink_mutex;
diff --git a/fs/configfs/dir.c b/fs/configfs/dir.c
index b6098e02e20b..f3c95c1d5278 100644
--- a/fs/configfs/dir.c
+++ b/fs/configfs/dir.c
@@ -656,6 +656,13 @@ static void detach_groups(struct config_group *group)
 
 		inode_unlock(d_inode(child));
 
+		/*
+		 * Free memory allocated for the pending and live directories
+		 * of committable groups.
+		 */
+		if (sd->s_type & (CONFIGFS_GROUP_PENDING | CONFIGFS_GROUP_LIVE))
+			kfree(sd->s_element);
+
 		d_delete(child);
 		dput(child);
 	}
@@ -860,6 +867,134 @@ static void configfs_detach_item(struct config_item *item)
 	configfs_remove_dir(item);
 }
 
+static bool is_committable_group(struct config_item *item)
+{
+	const struct config_item_type *type = item->ci_type;
+
+	if (type && type->ct_group_ops &&
+	    type->ct_group_ops->commit_item &&
+	    type->ct_group_ops->uncommit_item)
+		return true;
+
+	return false;
+}
+
+struct pending_group_data {
+	struct config_group group;
+	struct config_item_type type;
+	struct configfs_group_operations group_ops;
+};
+
+struct live_group_data {
+	struct config_group group;
+	struct config_item_type type;
+};
+
+static int create_pending_group(struct config_item *parent_item,
+				struct configfs_fragment *frag)
+{
+	const struct config_item_type *parent_type = parent_item->ci_type;
+	struct pending_group_data *pending;
+	struct configfs_dirent *sd;
+	int ret;
+
+	pending = kzalloc(sizeof(*pending), GFP_KERNEL);
+	if (!pending)
+		return -ENOMEM;
+
+	/*
+	 * Let's inherit the group_ops from the parent except for item
+	 * committing and uncommitting.
+	 */
+	memcpy(&pending->group_ops, parent_type->ct_group_ops,
+	       sizeof(struct configfs_group_operations));
+	pending->type.ct_group_ops = &pending->group_ops;
+	pending->type.ct_group_ops->commit_item = NULL;
+	pending->type.ct_group_ops->uncommit_item = NULL;
+
+	/* Let's directly reuse item_ops. */
+	pending->type.ct_item_ops = parent_type->ct_item_ops;
+	pending->type.ct_owner = parent_type->ct_owner;
+
+	config_group_init_type_name(&pending->group, "pending", &pending->type);
+
+	ret = create_default_group(to_config_group(parent_item),
+				   &pending->group, frag);
+	if (ret) {
+		kfree(pending);
+		return ret;
+	}
+
+	link_group(to_config_group(parent_item), &pending->group);
+
+	sd = pending->group.cg_item.ci_dentry->d_fsdata;
+	/* Allow creating config_items in 'pending' group. */
+	sd->s_type |= (CONFIGFS_GROUP_PENDING | CONFIGFS_USET_DIR);
+
+	return 0;
+}
+
+static int create_live_group(struct config_item *parent_item,
+			     struct configfs_fragment *frag)
+{
+	struct live_group_data *live;
+	struct configfs_dirent *sd;
+	int ret;
+
+	live = kzalloc(sizeof(*live), GFP_KERNEL);
+	if (!live)
+		return -ENOMEM;
+
+	live->type.ct_owner = parent_item->ci_type->ct_owner;
+
+	config_group_init_type_name(&live->group, "live", &live->type);
+
+	ret = create_default_group(to_config_group(parent_item),
+				   &live->group, frag);
+	if (ret) {
+		kfree(live);
+		return ret;
+	}
+
+	link_group(to_config_group(parent_item), &live->group);
+
+	sd = live->group.cg_item.ci_dentry->d_fsdata;
+	sd->s_type |= CONFIGFS_GROUP_LIVE;
+	sd->s_type &= ~CONFIGFS_USET_DIR;
+
+	return 0;
+}
+
+static int create_committable_groups(struct config_item *parent_item,
+				     struct configfs_fragment *frag)
+{
+	struct configfs_dirent *sd;
+	int ret;
+
+	ret = create_pending_group(parent_item, frag);
+	if (ret)
+		return ret;
+
+	ret = create_live_group(parent_item, frag);
+	if (ret) {
+		detach_groups(to_config_group(parent_item));
+		return ret;
+	}
+
+	/* Disallow creating items directly in the committable group. */
+	sd = parent_item->ci_dentry->d_fsdata;
+	sd->s_type &= ~CONFIGFS_USET_DIR;
+
+	return 0;
+}
+
+static void dentry_mark_dead(struct config_item *item, struct dentry *dentry)
+{
+	configfs_detach_item(item);
+	d_inode(dentry)->i_flags |= S_DEAD;
+	dont_mount(dentry);
+}
+
 static int configfs_attach_group(struct config_item *parent_item,
 				 struct config_item *item,
 				 struct dentry *dentry,
@@ -885,11 +1020,15 @@ static int configfs_attach_group(struct config_item *parent_item,
 		inode_lock_nested(d_inode(dentry), I_MUTEX_CHILD);
 		configfs_adjust_dir_dirent_depth_before_populate(sd);
 		ret = populate_groups(to_config_group(item), frag);
-		if (ret) {
-			configfs_detach_item(item);
-			d_inode(dentry)->i_flags |= S_DEAD;
-			dont_mount(dentry);
+		if (ret)
+			dentry_mark_dead(item, dentry);
+
+		if (is_committable_group(item)) {
+			ret = create_committable_groups(item, frag);
+			if (ret)
+				dentry_mark_dead(item, dentry);
 		}
+
 		configfs_adjust_dir_dirent_depth_after_populate(sd);
 		inode_unlock(d_inode(dentry));
 		if (ret)
@@ -966,6 +1105,8 @@ static void configfs_dump_one(struct configfs_dirent *sd, int level)
 	type_print(CONFIGFS_USET_DIR);
 	type_print(CONFIGFS_USET_DEFAULT);
 	type_print(CONFIGFS_USET_DROPPING);
+	type_print(CONFIGFS_GROUP_PENDING);
+	type_print(CONFIGFS_GROUP_LIVE);
 #undef type_print
 }
 
@@ -1457,7 +1598,7 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
 	struct config_item *parent_item;
 	struct config_item *item;
 	struct configfs_subsystem *subsys;
-	struct configfs_dirent *sd;
+	struct configfs_dirent *sd, *parent_sd;
 	struct configfs_fragment *frag;
 	struct module *subsys_owner = NULL, *dead_item_owner = NULL;
 	int ret;
@@ -1476,6 +1617,12 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
 		return -EINVAL;
 	}
 
+	parent_sd = dentry->d_parent->d_fsdata;
+	if (parent_sd->s_type & CONFIGFS_GROUP_LIVE) {
+		config_item_put(parent_item);
+		return -EPERM;
+	}
+
 	/* configfs_mkdir() shouldn't have allowed this */
 	BUG_ON(!subsys->su_group.cg_item.ci_type);
 	subsys_owner = subsys->su_group.cg_item.ci_type->ct_owner;
@@ -1562,9 +1709,97 @@ static int configfs_rmdir(struct inode *dir, struct dentry *dentry)
 	return 0;
 }
 
+static int configfs_rename(struct user_namespace *mnt_userns,
+			   struct inode *old_dir, struct dentry *old_dentry,
+			   struct inode *new_dir, struct dentry *new_dentry,
+			   unsigned int flags)
+{
+	struct configfs_dirent *sd, *old_parent_sd, *new_parent_sd;
+	struct dentry *old_parent_dentry, *new_parent_dentry;
+	struct dentry *committable_group_dentry;
+	struct config_item *committable_group_item, *item, *new_parent_item;
+	struct configfs_subsystem *committable_group_subsys;
+	struct configfs_group_operations *committable_group_ops;
+	int ret = 0;
+
+	if (flags)
+		return -EINVAL;
+
+	old_parent_dentry = old_dentry->d_parent;
+	new_parent_dentry = new_dentry->d_parent;
+
+	sd = old_dentry->d_fsdata;
+	old_parent_sd = old_dentry->d_parent->d_fsdata;
+	new_parent_sd = new_dentry->d_parent->d_fsdata;
+
+	if (!old_parent_sd || !new_parent_sd)
+		return -EPERM;
+
+	/*
+	 * Renaming must always be between a 'pending' and a 'live' group and
+	 * both need to have the same parent. Changing the directory name is
+	 * not allowed.
+	 */
+	if (!((old_parent_sd->s_type & CONFIGFS_GROUP_PENDING) &&
+	      (new_parent_sd->s_type & CONFIGFS_GROUP_LIVE)) &&
+	    !((old_parent_sd->s_type & CONFIGFS_GROUP_LIVE) &&
+	      (new_parent_sd->s_type & CONFIGFS_GROUP_PENDING)))
+		return -EPERM;
+
+	if (old_parent_dentry->d_parent != new_parent_dentry->d_parent)
+		return -EPERM;
+
+	if (strcmp(old_dentry->d_name.name, new_dentry->d_name.name))
+		return -EPERM;
+
+	committable_group_dentry = old_parent_dentry->d_parent;
+	/*
+	 * Grab a reference to the committable group for the duration of
+	 * this function.
+	 */
+	committable_group_item =
+		configfs_get_config_item(committable_group_dentry);
+	committable_group_subsys =
+		to_config_group(committable_group_item)->cg_subsys;
+	committable_group_ops = committable_group_item->ci_type->ct_group_ops;
+
+	item = sd->s_element;
+	new_parent_item = new_parent_sd->s_element;
+
+	if (WARN_ON(!is_committable_group(committable_group_item))) {
+		/* This would be a result of a programming error in configfs. */
+		config_item_put(committable_group_item);
+		return -EPERM;
+	}
+
+	mutex_lock(&committable_group_subsys->su_mutex);
+
+	if ((old_parent_sd->s_type & CONFIGFS_GROUP_PENDING) &&
+	    (new_parent_sd->s_type & CONFIGFS_GROUP_LIVE))
+		ret = committable_group_ops->commit_item(item);
+	else
+		ret = committable_group_ops->uncommit_item(item);
+	if (ret)
+		goto out;
+
+	spin_lock(&configfs_dirent_lock);
+	new_dentry->d_fsdata = sd;
+	list_move(&sd->s_sibling, &new_parent_sd->s_children);
+	item->ci_parent = new_parent_item;
+	d_move(old_dentry, new_dentry);
+	spin_unlock(&configfs_dirent_lock);
+
+out:
+	mutex_unlock(&committable_group_subsys->su_mutex);
+	config_item_put(committable_group_item);
+
+	return ret;
+}
+
 const struct inode_operations configfs_dir_inode_operations = {
 	.mkdir		= configfs_mkdir,
 	.rmdir		= configfs_rmdir,
+	.rename		= configfs_rename,
 	.symlink	= configfs_symlink,
 	.unlink		= configfs_unlink,
 	.lookup		= configfs_lookup,
diff --git a/include/linux/configfs.h b/include/linux/configfs.h
index 4f76dcc08134..ff6b0e408136 100644
--- a/include/linux/configfs.h
+++ b/include/linux/configfs.h
@@ -219,6 +219,7 @@ struct configfs_group_operations {
 	struct config_item *(*make_item)(struct config_group *group, const char *name);
 	struct config_group *(*make_group)(struct config_group *group, const char *name);
 	int (*commit_item)(struct config_item *item);
+	int (*uncommit_item)(struct config_item *item);
 	void (*disconnect_notify)(struct config_group *group, struct config_item *item);
 	void (*drop_item)(struct config_group *group, struct config_item *item);
 };
-- 
2.30.1

[PATCH v3 04/11] samples: configfs: add a committable group

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Add an example of using committable items to configfs samples. Each
config item has two attributes: read-write 'storeme' which works
similarly to other examples in this file and a read-only 'committed'
attribute which changes its value between false and true depending on
whether it's committed or not at the moment.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
---
 samples/configfs/configfs_sample.c | 153 +++++++++++++++++++++++++++++
 1 file changed, 153 insertions(+)

diff --git a/samples/configfs/configfs_sample.c b/samples/configfs/configfs_sample.c
index f9008be7a8a1..9bef74e4369d 100644
--- a/samples/configfs/configfs_sample.c
+++ b/samples/configfs/configfs_sample.c
@@ -315,6 +315,158 @@ static struct configfs_subsystem group_children_subsys = {
 
 /* ----------------------------------------------------------------- */
 
+/*
+ * 04-committable-children
+ *
+ * This is an example of a committable group.  It's similar to the simple
+ * children example but each config_item has an additional 'committed'
+ * attribute which is read-only and is only modified when the config_item
+ * is moved from the 'pending' to the 'live' directory.
+ */
+
+struct committable_child {
+	struct config_item item;
+	int storeme;
+	bool committed;
+};
+
+static inline struct committable_child *
+to_committable_child(struct config_item *item)
+{
+	return container_of(item, struct committable_child, item);
+}
+
+static ssize_t
+committable_child_storeme_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%d\n", to_committable_child(item)->storeme);
+}
+
+static ssize_t committable_child_storeme_store(struct config_item *item,
+					       const char *page, size_t count)
+{
+	struct committable_child *child = to_committable_child(item);
+	int ret;
+
+	if (child->committed)
+		return -EPERM;
+
+	ret = kstrtoint(page, 10, &child->storeme);
+	if (ret)
+		return ret;
+
+	return count;
+}
+
+CONFIGFS_ATTR(committable_child_, storeme);
+
+static ssize_t
+committable_child_committed_show(struct config_item *item, char *page)
+{
+	return sprintf(page, "%s\n",
+		to_committable_child(item)->committed ? "true" : "false");
+}
+
+CONFIGFS_ATTR_RO(committable_child_, committed);
+
+static struct configfs_attribute *committable_child_attrs[] = {
+	&committable_child_attr_storeme,
+	&committable_child_attr_committed,
+	NULL,
+};
+
+static void committable_child_release(struct config_item *item)
+{
+	kfree(to_committable_child(item));
+}
+
+static struct configfs_item_operations committable_child_item_ops = {
+	.release	= committable_child_release,
+};
+
+static const struct config_item_type committable_child_type = {
+	.ct_item_ops	= &committable_child_item_ops,
+	.ct_attrs	= committable_child_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+struct committable_children {
+	struct config_group group;
+};
+
+static struct config_item *
+committable_children_make_item(struct config_group *group, const char *name)
+{
+	struct committable_child *child;
+
+	child = kzalloc(sizeof(*child), GFP_KERNEL);
+	if (!child)
+		return ERR_PTR(-ENOMEM);
+
+	config_item_init_type_name(&child->item, name, &committable_child_type);
+
+	return &child->item;
+}
+
+static ssize_t
+committable_children_description_show(struct config_item *item, char *page)
+{
+	return sprintf(page,
+"[04-committable-children]\n"
+"\n"
+"This subsystem allows creation of committable config_items.  The subsystem\n"
+"has two subdirectories: pending and live.  New config_items can only be\n"
+"created in pending/ and they have one writable and readable attribute as\n"
+"well as a single read-only attribute.  The latter is only changed once the\n"
+"item is 'committed'.  This is done by moving the config_item (using\n"
+"rename()) to the live/ directory.  In this example, the storeme attribute\n"
+"becomes 'read-only' once committed.\n");
+}
+
+CONFIGFS_ATTR_RO(committable_children_, description);
+
+static struct configfs_attribute *committable_children_attrs[] = {
+	&committable_children_attr_description,
+	NULL,
+};
+
+static int committable_children_commit_item(struct config_item *item)
+{
+	to_committable_child(item)->committed = true;
+
+	return 0;
+}
+
+static int committable_children_uncommit_item(struct config_item *item)
+{
+	to_committable_child(item)->committed = false;
+
+	return 0;
+}
+
+static struct configfs_group_operations committable_children_group_ops = {
+	.make_item	= committable_children_make_item,
+	.commit_item	= committable_children_commit_item,
+	.uncommit_item	= committable_children_uncommit_item,
+};
+
+static const struct config_item_type committable_children_type = {
+	.ct_group_ops	= &committable_children_group_ops,
+	.ct_attrs	= committable_children_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct configfs_subsystem committable_children_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf = "04-committable-children",
+			.ci_type = &committable_children_type,
+		},
+	},
+};
+
+/* ----------------------------------------------------------------- */
+
 /*
  * We're now done with our subsystem definitions.
  * For convenience in this module, here's a list of them all.  It
@@ -326,6 +478,7 @@ static struct configfs_subsystem *example_subsys[] = {
 	&childless_subsys.subsys,
 	&simple_children_subsys,
 	&group_children_subsys,
+	&committable_children_subsys,
 	NULL,
 };
 
-- 
2.30.1

[PATCH v3 05/11] lib: bitmap: remove the 'extern' keyword from function declarations

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

The 'extern' keyword doesn't have any benefits in header files. Remove it.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/bitmap.h | 115 ++++++++++++++++++++---------------------
 1 file changed, 57 insertions(+), 58 deletions(-)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 70a932470b2d..6939a8983026 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -118,54 +118,53 @@
  * Allocation and deallocation of bitmap.
  * Provided in lib/bitmap.c to avoid circular dependency.
  */
-extern unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags);
-extern unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags);
-extern void bitmap_free(const unsigned long *bitmap);
+unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags);
+unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags);
+void bitmap_free(const unsigned long *bitmap);
 
 /*
  * lib/bitmap.c provides these functions:
  */
 
-extern int __bitmap_equal(const unsigned long *bitmap1,
-			  const unsigned long *bitmap2, unsigned int nbits);
-extern bool __pure __bitmap_or_equal(const unsigned long *src1,
-				     const unsigned long *src2,
-				     const unsigned long *src3,
-				     unsigned int nbits);
-extern void __bitmap_complement(unsigned long *dst, const unsigned long *src,
-			unsigned int nbits);
-extern void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
-				unsigned int shift, unsigned int nbits);
-extern void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
-				unsigned int shift, unsigned int nbits);
-extern void bitmap_cut(unsigned long *dst, const unsigned long *src,
-		       unsigned int first, unsigned int cut,
-		       unsigned int nbits);
-extern int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
+int __bitmap_equal(const unsigned long *bitmap1,
+		   const unsigned long *bitmap2, unsigned int nbits);
+bool __pure __bitmap_or_equal(const unsigned long *src1,
+			      const unsigned long *src2,
+			      const unsigned long *src3,
+			      unsigned int nbits);
+void __bitmap_complement(unsigned long *dst, const unsigned long *src,
+			 unsigned int nbits);
+void __bitmap_shift_right(unsigned long *dst, const unsigned long *src,
+			  unsigned int shift, unsigned int nbits);
+void __bitmap_shift_left(unsigned long *dst, const unsigned long *src,
+			 unsigned int shift, unsigned int nbits);
+void bitmap_cut(unsigned long *dst, const unsigned long *src,
+		unsigned int first, unsigned int cut, unsigned int nbits);
+int __bitmap_and(unsigned long *dst, const unsigned long *bitmap1,
+		 const unsigned long *bitmap2, unsigned int nbits);
+void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
+		 const unsigned long *bitmap2, unsigned int nbits);
+void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
+		  const unsigned long *bitmap2, unsigned int nbits);
+int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
+		    const unsigned long *bitmap2, unsigned int nbits);
+void __bitmap_replace(unsigned long *dst,
+		      const unsigned long *old, const unsigned long *new,
+		      const unsigned long *mask, unsigned int nbits);
+int __bitmap_intersects(const unsigned long *bitmap1,
 			const unsigned long *bitmap2, unsigned int nbits);
-extern void __bitmap_or(unsigned long *dst, const unsigned long *bitmap1,
-			const unsigned long *bitmap2, unsigned int nbits);
-extern void __bitmap_xor(unsigned long *dst, const unsigned long *bitmap1,
-			const unsigned long *bitmap2, unsigned int nbits);
-extern int __bitmap_andnot(unsigned long *dst, const unsigned long *bitmap1,
-			const unsigned long *bitmap2, unsigned int nbits);
-extern void __bitmap_replace(unsigned long *dst,
-			const unsigned long *old, const unsigned long *new,
-			const unsigned long *mask, unsigned int nbits);
-extern int __bitmap_intersects(const unsigned long *bitmap1,
-			const unsigned long *bitmap2, unsigned int nbits);
-extern int __bitmap_subset(const unsigned long *bitmap1,
-			const unsigned long *bitmap2, unsigned int nbits);
-extern int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits);
-extern void __bitmap_set(unsigned long *map, unsigned int start, int len);
-extern void __bitmap_clear(unsigned long *map, unsigned int start, int len);
-
-extern unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
-						    unsigned long size,
-						    unsigned long start,
-						    unsigned int nr,
-						    unsigned long align_mask,
-						    unsigned long align_offset);
+int __bitmap_subset(const unsigned long *bitmap1,
+		    const unsigned long *bitmap2, unsigned int nbits);
+int __bitmap_weight(const unsigned long *bitmap, unsigned int nbits);
+void __bitmap_set(unsigned long *map, unsigned int start, int len);
+void __bitmap_clear(unsigned long *map, unsigned int start, int len);
+
+unsigned long bitmap_find_next_zero_area_off(unsigned long *map,
+					     unsigned long size,
+					     unsigned long start,
+					     unsigned int nr,
+					     unsigned long align_mask,
+					     unsigned long align_offset);
 
 /**
  * bitmap_find_next_zero_area - find a contiguous aligned zero area
@@ -190,33 +189,33 @@ bitmap_find_next_zero_area(unsigned long *map,
 					      align_mask, 0);
 }
 
-extern int bitmap_parse(const char *buf, unsigned int buflen,
+int bitmap_parse(const char *buf, unsigned int buflen,
 			unsigned long *dst, int nbits);
-extern int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
+int bitmap_parse_user(const char __user *ubuf, unsigned int ulen,
 			unsigned long *dst, int nbits);
-extern int bitmap_parselist(const char *buf, unsigned long *maskp,
+int bitmap_parselist(const char *buf, unsigned long *maskp,
 			int nmaskbits);
-extern int bitmap_parselist_user(const char __user *ubuf, unsigned int ulen,
+int bitmap_parselist_user(const char __user *ubuf, unsigned int ulen,
 			unsigned long *dst, int nbits);
-extern void bitmap_remap(unsigned long *dst, const unsigned long *src,
+void bitmap_remap(unsigned long *dst, const unsigned long *src,
 		const unsigned long *old, const unsigned long *new, unsigned int nbits);
-extern int bitmap_bitremap(int oldbit,
+int bitmap_bitremap(int oldbit,
 		const unsigned long *old, const unsigned long *new, int bits);
-extern void bitmap_onto(unsigned long *dst, const unsigned long *orig,
+void bitmap_onto(unsigned long *dst, const unsigned long *orig,
 		const unsigned long *relmap, unsigned int bits);
-extern void bitmap_fold(unsigned long *dst, const unsigned long *orig,
+void bitmap_fold(unsigned long *dst, const unsigned long *orig,
 		unsigned int sz, unsigned int nbits);
-extern int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order);
-extern void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order);
-extern int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order);
+int bitmap_find_free_region(unsigned long *bitmap, unsigned int bits, int order);
+void bitmap_release_region(unsigned long *bitmap, unsigned int pos, int order);
+int bitmap_allocate_region(unsigned long *bitmap, unsigned int pos, int order);
 
 #ifdef __BIG_ENDIAN
-extern void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits);
+void bitmap_copy_le(unsigned long *dst, const unsigned long *src, unsigned int nbits);
 #else
 #define bitmap_copy_le bitmap_copy
 #endif
-extern unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int ord, unsigned int nbits);
-extern int bitmap_print_to_pagebuf(bool list, char *buf,
+unsigned int bitmap_ord_to_pos(const unsigned long *bitmap, unsigned int ord, unsigned int nbits);
+int bitmap_print_to_pagebuf(bool list, char *buf,
 				   const unsigned long *maskp, int nmaskbits);
 
 #define BITMAP_FIRST_WORD_MASK(start) (~0UL << ((start) & (BITS_PER_LONG - 1)))
@@ -265,9 +264,9 @@ static inline void bitmap_copy_clear_tail(unsigned long *dst,
  * therefore conversion is not needed when copying data from/to arrays of u32.
  */
 #if BITS_PER_LONG == 64
-extern void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
+void bitmap_from_arr32(unsigned long *bitmap, const u32 *buf,
 							unsigned int nbits);
-extern void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap,
+void bitmap_to_arr32(u32 *buf, const unsigned long *bitmap,
 							unsigned int nbits);
 #else
 #define bitmap_from_arr32(bitmap, buf, nbits)			\
-- 
2.30.1

[PATCH v3 06/11] lib: bitmap: order includes alphabetically

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

For better readability and maintenance: order the includes in bitmap
source files alphabetically.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/bitmap.h | 4 ++--
 lib/bitmap.c           | 9 +++++----
 2 files changed, 7 insertions(+), 6 deletions(-)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 6939a8983026..3282db97e06c 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -4,10 +4,10 @@
 
 #ifndef __ASSEMBLY__
 
-#include <linux/types.h>
 #include <linux/bitops.h>
-#include <linux/string.h>
 #include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/types.h>
 
 /*
  * bitmaps provide bit arrays that consume one or more unsigned
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 75006c4036e9..78f70d9007ad 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -3,17 +3,18 @@
  * lib/bitmap.c
  * Helper functions for bitmap.h.
  */
-#include <linux/export.h>
-#include <linux/thread_info.h>
-#include <linux/ctype.h>
-#include <linux/errno.h>
+
 #include <linux/bitmap.h>
 #include <linux/bitops.h>
 #include <linux/bug.h>
+#include <linux/ctype.h>
+#include <linux/errno.h>
+#include <linux/export.h>
 #include <linux/kernel.h>
 #include <linux/mm.h>
 #include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/thread_info.h>
 #include <linux/uaccess.h>
 
 #include <asm/page.h>
-- 
2.30.1

[PATCH v3 07/11] lib: bitmap: provide devm_bitmap_alloc() and devm_bitmap_zalloc()

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Provide managed variants of bitmap_alloc() and bitmap_zalloc().

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/bitmap.h |  8 ++++++++
 lib/bitmap.c           | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 41 insertions(+)

diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
index 3282db97e06c..73d039476fa4 100644
--- a/include/linux/bitmap.h
+++ b/include/linux/bitmap.h
@@ -9,6 +9,8 @@
 #include <linux/string.h>
 #include <linux/types.h>
 
+struct device;
+
 /*
  * bitmaps provide bit arrays that consume one or more unsigned
  * longs.  The bitmap interface and available operations are listed
@@ -122,6 +124,12 @@ unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags);
 unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags);
 void bitmap_free(const unsigned long *bitmap);
 
+/* Managed variants of the above. */
+unsigned long *devm_bitmap_alloc(struct device *dev,
+				 unsigned int nbits, gfp_t flags);
+unsigned long *devm_bitmap_zalloc(struct device *dev,
+				  unsigned int nbits, gfp_t flags);
+
 /*
  * lib/bitmap.c provides these functions:
  */
diff --git a/lib/bitmap.c b/lib/bitmap.c
index 78f70d9007ad..b4fd7fd084c6 100644
--- a/lib/bitmap.c
+++ b/lib/bitmap.c
@@ -8,6 +8,7 @@
 #include <linux/bitops.h>
 #include <linux/bug.h>
 #include <linux/ctype.h>
+#include <linux/device.h>
 #include <linux/errno.h>
 #include <linux/export.h>
 #include <linux/kernel.h>
@@ -1263,6 +1264,38 @@ void bitmap_free(const unsigned long *bitmap)
 }
 EXPORT_SYMBOL(bitmap_free);
 
+static void devm_bitmap_free(void *data)
+{
+	unsigned long *bitmap = data;
+
+	bitmap_free(bitmap);
+}
+
+unsigned long *devm_bitmap_alloc(struct device *dev,
+				 unsigned int nbits, gfp_t flags)
+{
+	unsigned long *bitmap;
+	int ret;
+
+	bitmap = bitmap_alloc(nbits, flags);
+	if (!bitmap)
+		return NULL;
+
+	ret = devm_add_action_or_reset(dev, devm_bitmap_free, bitmap);
+	if (ret)
+		return NULL;
+
+	return bitmap;
+}
+EXPORT_SYMBOL(devm_bitmap_alloc);
+
+unsigned long *devm_bitmap_zalloc(struct device *dev,
+				  unsigned int nbits, gfp_t flags)
+{
+	return devm_bitmap_alloc(dev, nbits, flags | __GFP_ZERO);
+}
+EXPORT_SYMBOL(devm_bitmap_zalloc);
+
 #if BITS_PER_LONG == 64
 /**
  * bitmap_from_arr32 - copy the contents of u32 array of bits to bitmap
-- 
2.30.1

[PATCH v3 08/11] gpio: sim: new testing module

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Implement a new, modern GPIO testing module controlled by configfs
attributes instead of module parameters. The goal of this driver is
to provide a replacement for gpio-mockup that will be easily extensible
with new features and doesn't require reloading the module to change
the setup.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 Documentation/admin-guide/gpio/gpio-sim.rst |  72 ++
 drivers/gpio/Kconfig                        |   8 +
 drivers/gpio/Makefile                       |   1 +
 drivers/gpio/gpio-sim.c                     | 879 ++++++++++++++++++++
 4 files changed, 960 insertions(+)
 create mode 100644 Documentation/admin-guide/gpio/gpio-sim.rst
 create mode 100644 drivers/gpio/gpio-sim.c

diff --git a/Documentation/admin-guide/gpio/gpio-sim.rst b/Documentation/admin-guide/gpio/gpio-sim.rst
new file mode 100644
index 000000000000..08eac487e35e
--- /dev/null
+++ b/Documentation/admin-guide/gpio/gpio-sim.rst
@@ -0,0 +1,72 @@
+.. SPDX-License-Identifier: GPL-2.0-or-later
+
+Configfs GPIO Simulator
+=======================
+
+The configfs GPIO Simulator (gpio-sim) provides a way to create simulated GPIO
+chips for testing purposes. The lines exposed by these chips can be accessed
+using the standard GPIO character device interface as well as manipulated
+using sysfs attributes.
+
+Creating simulated chips
+------------------------
+
+The gpio-sim module registers a configfs subsystem called 'gpio-sim'. It's a
+subsystem with committable items which means two subdirectories are created in
+the filesystem: pending and live. For more information on configfs and
+committable items, please refer to Documentation/filesystems/configfs.rst.
+
+In order to instantiate a new simulated chip, the user needs to mkdir() a new
+directory in pending/. Inside each new directory, there's a set of attributes
+that can be used to configure the new chip. Once the configuration is complete,
+the user needs to use rename() to move the chip to the live/ directory. This
+creates and registers the new device.
+
+In order to destroy a simulated chip, it has to be moved back to pending first
+and then removed using rmdir().
+
+Currently supported configuration attributes are:
+
+  num_lines - an unsigned integer value defining the number of GPIO lines to
+              export
+
+  label - a string defining the label for the GPIO chip
+
+  line_names - a list of GPIO line names in the form of quoted strings
+               separated by commas, e.g.: '"foo", "bar", "", "foobar"'. The
+               number of strings doesn't have to be equal to the value set in
+               the num_lines attribute. If it's lower than the number of lines,
+               the remaining lines are unnamed. If it's larger, the superfluous
+               lines are ignored. A name of the form: '""' means the line
+               should be unnamed.
+
+Additionally two read-only attributes named 'chip_name' and 'dev_name' are
+exposed in order to provide users with a mapping from configfs directories to
+the actual devices created in the kernel. The former returns the name of the
+GPIO device as assigned by gpiolib (i.e. "gpiochip0", "gpiochip1", etc.). The
+latter returns the parent device name as defined by the gpio-sim driver (i.e.
+"gpio-sim.0", "gpio-sim.1", etc.). This allows user-space to map the configfs
+items both to the correct character device file as well as the associated entry
+in sysfs.
+
+Simulated GPIO chips can also be defined in device-tree. The compatible string
+must be: "gpio-simulator". Supported properties are:
+
+  "gpio-sim,label" - chip label
+
+  "gpio-sim,nr-gpios" - number of lines
+
+Other standard GPIO properties (like "gpio-line-names" and gpio-hog) are also
+supported.
+
+Manipulating simulated lines
+----------------------------
+
+Each simulated GPIO chip creates a sysfs attribute group under its device
+directory called 'line-ctrl'. Inside each group, there's a separate attribute
+for each GPIO line. The name of the attribute is of the form 'gpioX' where X
+is the line's offset in the chip.
+
+Reading from a line attribute returns the current value. Writing to it (0 or 1)
+changes the configuration of the simulated pull-up/pull-down resistor
+(1 - pull-up, 0 - pull-down).
diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
index e3607ec4c2e8..b6b6150d0d04 100644
--- a/drivers/gpio/Kconfig
+++ b/drivers/gpio/Kconfig
@@ -1633,6 +1633,14 @@ config GPIO_MOCKUP
 	  tools/testing/selftests/gpio/gpio-mockup.sh. Reference the usage in
 	  it.
 
+config GPIO_SIM
+	tristate "GPIO Simulator Module"
+	select IRQ_SIM
+	select CONFIGFS_FS
+	help
+	  This enables the GPIO simulator - a configfs-based GPIO testing
+	  driver.
+
 endmenu
 
 endif
diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index c58a90a3c3b1..d717aa85f8e1 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -130,6 +130,7 @@ obj-$(CONFIG_GPIO_SAMA5D2_PIOBU)	+= gpio-sama5d2-piobu.o
 obj-$(CONFIG_GPIO_SCH311X)		+= gpio-sch311x.o
 obj-$(CONFIG_GPIO_SCH)			+= gpio-sch.o
 obj-$(CONFIG_GPIO_SIFIVE)		+= gpio-sifive.o
+obj-$(CONFIG_GPIO_SIM)			+= gpio-sim.o
 obj-$(CONFIG_GPIO_SIOX)			+= gpio-siox.o
 obj-$(CONFIG_GPIO_SL28CPLD)		+= gpio-sl28cpld.o
 obj-$(CONFIG_GPIO_SODAVILLE)		+= gpio-sodaville.o
diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
new file mode 100644
index 000000000000..253f5b4bd1f5
--- /dev/null
+++ b/drivers/gpio/gpio-sim.c
@@ -0,0 +1,879 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GPIO testing driver based on configfs.
+ *
+ * Copyright (C) 2021 Bartosz Golaszewski <bgolaszewski@baylibre.com>
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/bitmap.h>
+#include <linux/configfs.h>
+#include <linux/device.h>
+#include <linux/gpio/driver.h>
+#include <linux/idr.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irq_sim.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/platform_device.h>
+#include <linux/property.h>
+#include <linux/slab.h>
+#include <linux/string.h>
+#include <linux/string_helpers.h>
+#include <linux/sysfs.h>
+
+#include "gpiolib.h"
+
+/*
+ * This normally should correspond with the number of attributes exposed over
+ * configfs + sentinel.
+ */
+#define GPIO_SIM_MAX_PROP 4
+
+static DEFINE_IDA(gpio_sim_ida);
+
+struct gpio_sim_chip {
+	struct gpio_chip gc;
+	unsigned long *directions;
+	unsigned long *values;
+	unsigned long *pulls;
+	struct irq_domain *irq_sim;
+	struct mutex lock;
+	struct attribute_group attr_group;
+};
+
+struct gpio_sim_attribute {
+	struct device_attribute dev_attr;
+	unsigned int offset;
+};
+
+static struct gpio_sim_attribute *
+to_gpio_sim_attr(struct device_attribute *dev_attr)
+{
+	return container_of(dev_attr, struct gpio_sim_attribute, dev_attr);
+}
+
+static int gpio_sim_apply_pull(struct gpio_sim_chip *chip,
+			       unsigned int offset, int value)
+{
+	int curr_val, irq, irq_type, ret;
+	struct gpio_desc *desc;
+	struct gpio_chip *gc;
+
+	gc = &chip->gc;
+	desc = &gc->gpiodev->descs[offset];
+
+	mutex_lock(&chip->lock);
+
+	if (test_bit(FLAG_REQUESTED, &desc->flags) &&
+	    !test_bit(FLAG_IS_OUT, &desc->flags)) {
+		curr_val = !!test_bit(offset, chip->values);
+		if (curr_val == value)
+			goto set_pull;
+
+		/*
+		 * This is fine - it just means, nobody is listening
+		 * for interrupts on this line, otherwise
+		 * irq_create_mapping() would have been called from
+		 * the to_irq() callback.
+		 */
+		irq = irq_find_mapping(chip->irq_sim, offset);
+		if (!irq)
+			goto set_value;
+
+		irq_type = irq_get_trigger_type(irq);
+
+		if ((value && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
+		    (!value && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
+			ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
+						    true);
+			if (ret)
+				goto set_pull;
+		}
+	}
+
+set_value:
+	/* Change the value unless we're actively driving the line. */
+	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
+	    !test_bit(FLAG_IS_OUT, &desc->flags))
+		__assign_bit(offset, chip->values, value);
+
+set_pull:
+	__assign_bit(offset, chip->pulls, value);
+	mutex_unlock(&chip->lock);
+	return 0;
+}
+
+static int gpio_sim_get(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+	int ret;
+
+	mutex_lock(&chip->lock);
+	ret = !!test_bit(offset, chip->values);
+	mutex_unlock(&chip->lock);
+
+	return ret;
+}
+
+static void gpio_sim_set(struct gpio_chip *gc, unsigned int offset, int value)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	__assign_bit(offset, chip->values, value);
+	mutex_unlock(&chip->lock);
+}
+
+static int gpio_sim_get_multiple(struct gpio_chip *gc,
+				 unsigned long *mask, unsigned long *bits)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	bitmap_copy(bits, chip->values, gc->ngpio);
+	mutex_unlock(&chip->lock);
+
+	return 0;
+}
+
+static void gpio_sim_set_multiple(struct gpio_chip *gc,
+				  unsigned long *mask, unsigned long *bits)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	bitmap_copy(chip->values, bits, gc->ngpio);
+	mutex_unlock(&chip->lock);
+}
+
+static int gpio_sim_direction_output(struct gpio_chip *gc,
+				     unsigned int offset, int value)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	__clear_bit(offset, chip->directions);
+	__assign_bit(offset, chip->values, value);
+	mutex_unlock(&chip->lock);
+
+	return 0;
+}
+
+static int gpio_sim_direction_input(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	__set_bit(offset, chip->directions);
+	mutex_unlock(&chip->lock);
+
+	return 0;
+}
+
+static int gpio_sim_get_direction(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+	int direction;
+
+	mutex_lock(&chip->lock);
+	direction = !!test_bit(offset, chip->directions);
+	mutex_unlock(&chip->lock);
+
+	return direction ? GPIO_LINE_DIRECTION_IN : GPIO_LINE_DIRECTION_OUT;
+}
+
+static int gpio_sim_set_config(struct gpio_chip *gc,
+				  unsigned int offset, unsigned long config)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	switch (pinconf_to_config_param(config)) {
+	case PIN_CONFIG_BIAS_PULL_UP:
+		return gpio_sim_apply_pull(chip, offset, 1);
+	case PIN_CONFIG_BIAS_PULL_DOWN:
+		return gpio_sim_apply_pull(chip, offset, 0);
+	default:
+		break;
+	}
+
+	return -ENOTSUPP;
+}
+
+static int gpio_sim_to_irq(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	return irq_create_mapping(chip->irq_sim, offset);
+}
+
+static void gpio_sim_free(struct gpio_chip *gc, unsigned int offset)
+{
+	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
+
+	mutex_lock(&chip->lock);
+	__assign_bit(offset, chip->values, !!test_bit(offset, chip->pulls));
+	mutex_unlock(&chip->lock);
+}
+
+static ssize_t gpio_sim_sysfs_line_show(struct device *dev,
+					struct device_attribute *attr,
+					char *buf)
+{
+	struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
+	struct gpio_sim_chip *chip = dev_get_drvdata(dev);
+	int ret;
+
+	mutex_lock(&chip->lock);
+	ret = sprintf(buf, "%u\n", !!test_bit(line_attr->offset, chip->values));
+	mutex_unlock(&chip->lock);
+
+	return ret;
+}
+
+static ssize_t gpio_sim_sysfs_line_store(struct device *dev,
+					 struct device_attribute *attr,
+					 const char *buf, size_t len)
+{
+	struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
+	struct gpio_sim_chip *chip = dev_get_drvdata(dev);
+	int ret, val;
+
+	if (len > 2 || (buf[0] != '0' && buf[0] != '1'))
+		return -EINVAL;
+
+	val = buf[0] == '0' ? 0 : 1;
+
+	ret = gpio_sim_apply_pull(chip, line_attr->offset, val);
+	if (ret)
+		return ret;
+
+	return len;
+}
+
+static void gpio_sim_mutex_destroy(void *data)
+{
+	struct mutex *lock = data;
+
+	mutex_destroy(lock);
+}
+
+static void gpio_sim_sysfs_remove(void *data)
+{
+	struct gpio_sim_chip *chip = data;
+
+	sysfs_remove_group(&chip->gc.parent->kobj, &chip->attr_group);
+}
+
+static int gpio_sim_setup_sysfs(struct gpio_sim_chip *chip)
+{
+	unsigned int i, num_lines = chip->gc.ngpio;
+	struct device *dev = chip->gc.parent;
+	struct gpio_sim_attribute *line_attr;
+	struct device_attribute *dev_attr;
+	struct attribute **attrs;
+	int ret;
+
+	attrs = devm_kcalloc(dev, sizeof(*attrs), num_lines + 1, GFP_KERNEL);
+	if (!attrs)
+		return -ENOMEM;
+
+	for (i = 0; i < num_lines; i++) {
+		line_attr = devm_kzalloc(dev, sizeof(*line_attr), GFP_KERNEL);
+		if (!line_attr)
+			return -ENOMEM;
+
+		line_attr->offset = i;
+
+		dev_attr = &line_attr->dev_attr;
+
+		dev_attr->attr.name = devm_kasprintf(dev, GFP_KERNEL,
+						     "gpio%u", i);
+		if (!dev_attr->attr.name)
+			return -ENOMEM;
+
+		dev_attr->attr.mode = 0644;
+
+		dev_attr->show = gpio_sim_sysfs_line_show;
+		dev_attr->store = gpio_sim_sysfs_line_store;
+
+		attrs[i] = &dev_attr->attr;
+	}
+
+	chip->attr_group.name = "line-ctrl";
+	chip->attr_group.attrs = attrs;
+
+	ret = sysfs_create_group(&dev->kobj, &chip->attr_group);
+	if (ret)
+		return ret;
+
+	return devm_add_action_or_reset(dev, gpio_sim_sysfs_remove, chip);
+}
+
+static int gpio_sim_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gpio_sim_chip *chip;
+	struct gpio_chip *gc;
+	const char *label;
+	u32 num_lines;
+	int ret;
+
+	ret = device_property_read_u32(dev, "gpio-sim,nr-gpios", &num_lines);
+	if (ret)
+		return ret;
+
+	ret = device_property_read_string(dev, "gpio-sim,label", &label);
+	if (ret)
+		label = dev_name(dev);
+
+	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
+	if (!chip)
+		return -ENOMEM;
+
+	chip->directions = devm_bitmap_alloc(dev, num_lines, GFP_KERNEL);
+	if (!chip->directions)
+		return -ENOMEM;
+
+	/* Default to input mode. */
+	bitmap_fill(chip->directions, num_lines);
+
+	chip->values = devm_bitmap_zalloc(dev, num_lines, GFP_KERNEL);
+	if (!chip->values)
+		return -ENOMEM;
+
+	chip->pulls = devm_bitmap_zalloc(dev, num_lines, GFP_KERNEL);
+	if (!chip->pulls)
+		return -ENOMEM;
+
+	chip->irq_sim = devm_irq_domain_create_sim(dev, NULL, num_lines);
+	if (IS_ERR(chip->irq_sim))
+		return PTR_ERR(chip->irq_sim);
+
+	mutex_init(&chip->lock);
+	ret = devm_add_action_or_reset(dev, gpio_sim_mutex_destroy,
+				       &chip->lock);
+	if (ret)
+		return ret;
+
+	gc = &chip->gc;
+	gc->base = -1;
+	gc->ngpio = num_lines;
+	gc->label = label;
+	gc->owner = THIS_MODULE;
+	gc->parent = dev;
+	gc->get = gpio_sim_get;
+	gc->set = gpio_sim_set;
+	gc->get_multiple = gpio_sim_get_multiple;
+	gc->set_multiple = gpio_sim_set_multiple;
+	gc->direction_output = gpio_sim_direction_output;
+	gc->direction_input = gpio_sim_direction_input;
+	gc->get_direction = gpio_sim_get_direction;
+	gc->set_config = gpio_sim_set_config;
+	gc->to_irq = gpio_sim_to_irq;
+	gc->free = gpio_sim_free;
+
+	ret = devm_gpiochip_add_data(dev, gc, chip);
+	if (ret)
+		return ret;
+
+	/* Used by sysfs and configfs callbacks. */
+	dev_set_drvdata(dev, chip);
+
+	ret = gpio_sim_setup_sysfs(chip);
+	if (ret)
+		return ret;
+
+	return 0;
+}
+
+static const struct of_device_id gpio_sim_of_match[] = {
+	{ .compatible = "gpio-simulator" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, gpio_sim_of_match);
+
+static struct platform_driver gpio_sim_driver = {
+	.driver = {
+		.name = "gpio-sim",
+	},
+	.probe = gpio_sim_probe,
+};
+
+struct gpio_sim_chip_config {
+	struct config_item item;
+
+	/*
+	 * If pdev is NULL, the item is 'pending' (waiting for configuration).
+	 * Once the pointer is assigned, the device has been created and the
+	 * item is 'live'.
+	 */
+	struct platform_device *pdev;
+
+	/*
+	 * Each configfs filesystem operation is protected with the subsystem
+	 * mutex. Each separate attribute is protected with the buffer mutex.
+	 * This structure however can be modified by callbacks of different
+	 * attributes so we need another lock.
+	 */
+	struct mutex lock;
+
+	char label[32];
+	unsigned int num_lines;
+	char **line_names;
+	unsigned int num_line_names;
+};
+
+static struct gpio_sim_chip_config *
+to_gpio_sim_chip_config(struct config_item *item)
+{
+	return container_of(item, struct gpio_sim_chip_config, item);
+}
+
+static ssize_t gpio_sim_config_dev_name_show(struct config_item *item,
+					     char *page)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+	struct platform_device *pdev;
+	int ret;
+
+	mutex_lock(&config->lock);
+	pdev = config->pdev;
+	if (pdev)
+		ret = sprintf(page, "%s\n", dev_name(&pdev->dev));
+	else
+		ret = sprintf(page, "n/a\n");
+	mutex_unlock(&config->lock);
+
+	return ret;
+}
+
+CONFIGFS_ATTR_RO(gpio_sim_config_, dev_name);
+
+static ssize_t gpio_sim_config_chip_name_show(struct config_item *item,
+					      char *page)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+	struct gpio_sim_chip *chip = NULL;
+	struct platform_device *pdev;
+	int ret;
+
+	mutex_lock(&config->lock);
+	pdev = config->pdev;
+	if (pdev)
+		chip = dev_get_drvdata(&pdev->dev);
+
+	if (chip)
+		ret = sprintf(page, "%s\n", dev_name(&chip->gc.gpiodev->dev));
+	else
+		ret = sprintf(page, "n/a\n");
+	mutex_unlock(&config->lock);
+
+	return ret;
+}
+
+CONFIGFS_ATTR_RO(gpio_sim_config_, chip_name);
+
+static ssize_t gpio_sim_config_label_show(struct config_item *item, char *page)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+	int ret;
+
+	mutex_lock(&config->lock);
+	ret = sprintf(page, "%s\n", config->label);
+	mutex_unlock(&config->lock);
+
+	return ret;
+}
+
+static ssize_t gpio_sim_config_label_store(struct config_item *item,
+					   const char *page, size_t count)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+	char *dup, *trimmed;
+	int ret;
+
+	mutex_lock(&config->lock);
+
+	if (config->pdev) {
+		mutex_unlock(&config->lock);
+		return -EBUSY;
+	}
+
+	dup = kstrndup(page, count, GFP_KERNEL);
+	if (!dup) {
+		mutex_unlock(&config->lock);
+		return -ENOMEM;
+	}
+
+	trimmed = strstrip(dup);
+	ret = snprintf(config->label, sizeof(config->label), "%s", trimmed);
+	kfree(dup);
+	if (ret < 0) {
+		mutex_unlock(&config->lock);
+		return ret;
+	}
+
+	mutex_unlock(&config->lock);
+	return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_config_, label);
+
+static ssize_t gpio_sim_config_num_lines_show(struct config_item *item,
+					      char *page)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+	int ret;
+
+	mutex_lock(&config->lock);
+	ret = sprintf(page, "%u\n", config->num_lines);
+	mutex_unlock(&config->lock);
+
+	return ret;
+}
+
+static ssize_t gpio_sim_config_num_lines_store(struct config_item *item,
+					       const char *page, size_t count)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+	unsigned int num_lines;
+	int ret;
+
+	mutex_lock(&config->lock);
+
+	if (config->pdev) {
+		mutex_unlock(&config->lock);
+		return -EBUSY;
+	}
+
+	ret = kstrtouint(page, 10, &num_lines);
+	if (ret) {
+		mutex_unlock(&config->lock);
+		return ret;
+	}
+
+	if (num_lines == 0) {
+		mutex_unlock(&config->lock);
+		return -EINVAL;
+	}
+
+	config->num_lines = num_lines;
+
+	mutex_unlock(&config->lock);
+	return count;
+}
+
+CONFIGFS_ATTR(gpio_sim_config_, num_lines);
+
+static ssize_t gpio_sim_config_line_names_show(struct config_item *item,
+					       char *page)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+	int ret, i, written = 0;
+
+	mutex_lock(&config->lock);
+
+	if (!config->line_names) {
+		mutex_unlock(&config->lock);
+		return sprintf(page, "\n");
+	}
+
+	for (i = 0; i < config->num_line_names; i++) {
+		ret = sprintf(page + written,
+			i < config->num_line_names - 1 ? "\"%s\", " : "\"%s\"\n",
+			config->line_names[i] ?: "");
+		if (ret < 0) {
+			mutex_unlock(&config->lock);
+			return ret;
+		}
+
+		written += ret;
+	}
+
+	mutex_unlock(&config->lock);
+	return written;
+}
+
+static ssize_t gpio_sim_config_line_names_store(struct config_item *item,
+						const char *page, size_t count)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+	unsigned int num_new_names = 1, num_old_names, name_idx = 0;
+	bool in_quote = false, got_comma = true;
+	char **new_names, **old_names, *name, c;
+	const char *start = page;
+	size_t pos, name_len;
+	int err = -EINVAL;
+
+	mutex_lock(&config->lock);
+
+	if (config->pdev) {
+		mutex_unlock(&config->lock);
+		return -EBUSY;
+	}
+
+	/*
+	 * Line names are stored in a pointer array so that we can easily
+	 * pass them down to the GPIO subsystem in a "gpio-line-names"
+	 * property.
+	 *
+	 * Line names must be passed as a list of quoted names separated by
+	 * commas, for example: '"foo", "bar", "foobar"'.
+	 */
+
+	for (pos = 0; pos < count; pos++) {
+		/*
+		 * Just count the commas and assume the number if strings
+		 * equals the number of commas + 1. If the format is wrong
+		 * we'll bail out anyway.
+		 */
+		if (page[pos] == ',')
+			num_new_names++;
+	}
+
+	new_names = kcalloc(num_new_names, sizeof(char *), GFP_KERNEL);
+	if (!new_names) {
+		mutex_unlock(&config->lock);
+		return -ENOMEM;
+	}
+
+	/*
+	 * REVISIT There are more users in the kernel that want to split
+	 * comma-separated strings into tokens. We should generalize it and
+	 * put it into lib/.
+	 */
+	for (pos = 0; pos < count; pos++) {
+		c = page[pos];
+
+		if (in_quote) {
+			if (c == '"') {
+				/* This is the end of the name. */
+				in_quote = got_comma = false;
+				name_len = (page + pos) - start;
+				if (name_len == 0) {
+					/* Name is empty (passed as ""). */
+					name_idx++;
+					continue;
+				}
+
+				name = kmemdup(start, name_len + 1, GFP_KERNEL);
+				if (!name) {
+					err = -ENOMEM;
+					goto err_out;
+				}
+
+				name[name_len] = '\0';
+				new_names[name_idx++] = name;
+			}
+		} else {
+			if (c == '"') {
+				/* Enforce separating names with commas. */
+				if (!got_comma)
+					goto err_out;
+
+				start = page + pos + 1;
+				in_quote = true;
+			} else if (c == ',') {
+				if (!got_comma)
+					got_comma = true;
+				else
+					/* Double commas are not allowed. */
+					goto err_out;
+			} else if (!isspace(c)) {
+				goto err_out;
+			}
+		}
+	}
+
+	/*
+	 * End of input sanity checks, must not have a comma at the end and
+	 * must have finished scanning the last name.
+	 */
+	if (in_quote || got_comma)
+		goto err_out;
+
+	old_names = config->line_names;
+	num_old_names = config->num_line_names;
+	config->line_names = new_names;
+	config->num_line_names = num_new_names;
+
+	mutex_unlock(&config->lock);
+	kfree_strarray(old_names, num_old_names);
+	return count;
+
+err_out:
+	mutex_unlock(&config->lock);
+	kfree_strarray(new_names, name_idx);
+	return err;
+}
+
+CONFIGFS_ATTR(gpio_sim_config_, line_names);
+
+static struct configfs_attribute *gpio_sim_config_attrs[] = {
+	&gpio_sim_config_attr_dev_name,
+	&gpio_sim_config_attr_chip_name,
+	&gpio_sim_config_attr_label,
+	&gpio_sim_config_attr_num_lines,
+	&gpio_sim_config_attr_line_names,
+	NULL
+};
+
+static void gpio_sim_chip_config_release(struct config_item *item)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+
+	mutex_destroy(&config->lock);
+	kfree_strarray(config->line_names, config->num_line_names);
+	kfree(config);
+}
+
+static struct configfs_item_operations gpio_sim_config_item_ops = {
+	.release	= gpio_sim_chip_config_release,
+};
+
+static const struct config_item_type gpio_sim_chip_config_type = {
+	.ct_item_ops	= &gpio_sim_config_item_ops,
+	.ct_attrs	= gpio_sim_config_attrs,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct config_item *
+gpio_sim_config_make_item(struct config_group *group, const char *name)
+{
+	struct gpio_sim_chip_config *config;
+
+	config = kzalloc(sizeof(*config), GFP_KERNEL);
+	if (!config)
+		return ERR_PTR(-ENOMEM);
+
+	config_item_init_type_name(&config->item, name,
+				   &gpio_sim_chip_config_type);
+	config->num_lines = 1;
+	mutex_init(&config->lock);
+
+	return &config->item;
+}
+
+static int gpio_sim_config_commit_item(struct config_item *item)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+	struct property_entry properties[GPIO_SIM_MAX_PROP];
+	struct platform_device_info pdevinfo;
+	struct platform_device *pdev;
+	unsigned int prop_idx = 0;
+
+	memset(&pdevinfo, 0, sizeof(pdevinfo));
+	memset(properties, 0, sizeof(properties));
+
+	mutex_lock(&config->lock);
+
+	properties[prop_idx++] = PROPERTY_ENTRY_U32("gpio-sim,nr-gpios",
+						    config->num_lines);
+
+	if (config->label[0] != '\0')
+		properties[prop_idx++] = PROPERTY_ENTRY_STRING("gpio-sim,label",
+							       config->label);
+
+	if (config->line_names)
+		properties[prop_idx++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
+						"gpio-line-names",
+						config->line_names,
+						config->num_line_names);
+
+	pdevinfo.id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
+	if (pdevinfo.id < 0) {
+		mutex_unlock(&config->lock);
+		return pdevinfo.id;
+	}
+
+	pdevinfo.name = "gpio-sim";
+	pdevinfo.properties = properties;
+
+	pdev = platform_device_register_full(&pdevinfo);
+	if (IS_ERR(pdev)) {
+		ida_free(&gpio_sim_ida, pdevinfo.id);
+		mutex_unlock(&config->lock);
+		return PTR_ERR(pdev);
+	}
+
+	config->pdev = pdev;
+	mutex_unlock(&config->lock);
+
+	return 0;
+}
+
+static int gpio_sim_config_uncommit_item(struct config_item *item)
+{
+	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
+	int id;
+
+	mutex_lock(&config->lock);
+	id = config->pdev->id;
+	platform_device_unregister(config->pdev);
+	config->pdev = NULL;
+	mutex_unlock(&config->lock);
+
+	ida_free(&gpio_sim_ida, id);
+	return 0;
+}
+
+static struct configfs_group_operations gpio_sim_config_group_ops = {
+	.make_item	= gpio_sim_config_make_item,
+	.commit_item	= gpio_sim_config_commit_item,
+	.uncommit_item	= gpio_sim_config_uncommit_item,
+};
+
+static const struct config_item_type gpio_sim_config_type = {
+	.ct_group_ops	= &gpio_sim_config_group_ops,
+	.ct_owner	= THIS_MODULE,
+};
+
+static struct configfs_subsystem gpio_sim_config_subsys = {
+	.su_group = {
+		.cg_item = {
+			.ci_namebuf	= "gpio-sim",
+			.ci_type	= &gpio_sim_config_type,
+		},
+	},
+};
+
+static int __init gpio_sim_init(void)
+{
+	int ret;
+
+	ret = platform_driver_register(&gpio_sim_driver);
+	if (ret) {
+		pr_err("Error %d while registering the platform driver\n", ret);
+		return ret;
+	}
+
+	config_group_init(&gpio_sim_config_subsys.su_group);
+	mutex_init(&gpio_sim_config_subsys.su_mutex);
+	ret = configfs_register_subsystem(&gpio_sim_config_subsys);
+	if (ret) {
+		pr_err("Error %d while registering the configfs subsystem %s\n",
+		       ret, gpio_sim_config_subsys.su_group.cg_item.ci_namebuf);
+		mutex_destroy(&gpio_sim_config_subsys.su_mutex);
+		platform_driver_unregister(&gpio_sim_driver);
+		return ret;
+	}
+
+	return 0;
+}
+module_init(gpio_sim_init);
+
+static void __exit gpio_sim_exit(void)
+{
+	configfs_unregister_subsystem(&gpio_sim_config_subsys);
+	mutex_destroy(&gpio_sim_config_subsys.su_mutex);
+	platform_driver_unregister(&gpio_sim_driver);
+}
+module_exit(gpio_sim_exit);
+
+MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
+MODULE_DESCRIPTION("GPIO Simulator Module");
+MODULE_LICENSE("GPL");
-- 
2.30.1

[PATCH v3 09/11] selftests: gpio: provide a helper for reading chip info

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Add a simple program that allows to retrieve chip properties from the
GPIO character device. This will be used in gpio-sim selftests.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 tools/testing/selftests/gpio/.gitignore       |  1 +
 tools/testing/selftests/gpio/Makefile         |  2 +-
 tools/testing/selftests/gpio/gpio-chip-info.c | 57 +++++++++++++++++++
 3 files changed, 59 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/gpio/gpio-chip-info.c

diff --git a/tools/testing/selftests/gpio/.gitignore b/tools/testing/selftests/gpio/.gitignore
index a4969f7ee020..4ea4f58dab1a 100644
--- a/tools/testing/selftests/gpio/.gitignore
+++ b/tools/testing/selftests/gpio/.gitignore
@@ -1,2 +1,3 @@
 # SPDX-License-Identifier: GPL-2.0-only
 gpio-mockup-cdev
+gpio-chip-info
diff --git a/tools/testing/selftests/gpio/Makefile b/tools/testing/selftests/gpio/Makefile
index 39f2bbe8dd3d..84b48547f94c 100644
--- a/tools/testing/selftests/gpio/Makefile
+++ b/tools/testing/selftests/gpio/Makefile
@@ -2,6 +2,6 @@
 
 TEST_PROGS := gpio-mockup.sh
 TEST_FILES := gpio-mockup-sysfs.sh
-TEST_GEN_PROGS_EXTENDED := gpio-mockup-cdev
+TEST_GEN_PROGS_EXTENDED := gpio-mockup-cdev gpio-chip-info
 
 include ../lib.mk
diff --git a/tools/testing/selftests/gpio/gpio-chip-info.c b/tools/testing/selftests/gpio/gpio-chip-info.c
new file mode 100644
index 000000000000..4d26fa7c254a
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-chip-info.c
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GPIO character device helper for reading chip information.
+ *
+ * Copyright (C) 2021 Bartosz Golaszewski <bgolaszewski@baylibre.com>
+ */
+
+#include <fcntl.h>
+#include <linux/gpio.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+
+static void print_usage(void)
+{
+	printf("usage:\n");
+	printf("  gpio-chip-info <chip path> [name|label|num-lines]\n");
+}
+
+int main(int argc, char **argv)
+{
+	struct gpiochip_info info;
+	int fd, ret;
+
+	if (argc !=3) {
+		print_usage();
+		return EXIT_FAILURE;
+	}
+
+	fd = open(argv[1], O_RDWR);
+	if (fd < 0) {
+		perror("unable to open the GPIO chip");
+		return EXIT_FAILURE;
+	}
+
+	memset(&info, 0, sizeof(info));
+	ret = ioctl(fd, GPIO_GET_CHIPINFO_IOCTL, &info);
+	if (ret) {
+		perror("chip info ioctl failed");
+		return EXIT_FAILURE;
+	}
+
+	if (strcmp(argv[2], "name") == 0) {
+		printf("%s\n", info.name);
+	} else if (strcmp(argv[2], "label") == 0) {
+		printf("%s\n", info.label);
+	} else if (strcmp(argv[2], "num-lines") == 0) {
+		printf("%u\n", info.lines);
+	} else {
+		fprintf(stderr, "unknown command: %s\n", argv[2]);
+		return EXIT_FAILURE;
+	}
+
+	return EXIT_SUCCESS;
+}
-- 
2.30.1

[PATCH v3 10/11] selftests: gpio: add a helper for reading GPIO line names

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Add a simple program that allows to read GPIO line names from the
character device. This will be used in gpio-sim selftests.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 tools/testing/selftests/gpio/.gitignore       |  1 +
 tools/testing/selftests/gpio/Makefile         |  2 +-
 tools/testing/selftests/gpio/gpio-line-name.c | 55 +++++++++++++++++++
 3 files changed, 57 insertions(+), 1 deletion(-)
 create mode 100644 tools/testing/selftests/gpio/gpio-line-name.c

diff --git a/tools/testing/selftests/gpio/.gitignore b/tools/testing/selftests/gpio/.gitignore
index 4ea4f58dab1a..ededb077a3a6 100644
--- a/tools/testing/selftests/gpio/.gitignore
+++ b/tools/testing/selftests/gpio/.gitignore
@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0-only
 gpio-mockup-cdev
 gpio-chip-info
+gpio-line-name
diff --git a/tools/testing/selftests/gpio/Makefile b/tools/testing/selftests/gpio/Makefile
index 84b48547f94c..d7d8f1985d99 100644
--- a/tools/testing/selftests/gpio/Makefile
+++ b/tools/testing/selftests/gpio/Makefile
@@ -2,6 +2,6 @@
 
 TEST_PROGS := gpio-mockup.sh
 TEST_FILES := gpio-mockup-sysfs.sh
-TEST_GEN_PROGS_EXTENDED := gpio-mockup-cdev gpio-chip-info
+TEST_GEN_PROGS_EXTENDED := gpio-mockup-cdev gpio-chip-info gpio-line-name
 
 include ../lib.mk
diff --git a/tools/testing/selftests/gpio/gpio-line-name.c b/tools/testing/selftests/gpio/gpio-line-name.c
new file mode 100644
index 000000000000..a52e75bc37ba
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-line-name.c
@@ -0,0 +1,55 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GPIO character device helper for reading line names.
+ *
+ * Copyright (C) 2021 Bartosz Golaszewski <bgolaszewski@baylibre.com>
+ */
+
+#include <fcntl.h>
+#include <linux/gpio.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/types.h>
+
+static void print_usage(void)
+{
+	printf("usage:\n");
+	printf("  gpio-line-name <chip path> <line offset>\n");
+}
+
+int main(int argc, char **argv)
+{
+	struct gpio_v2_line_info info;
+	int fd, ret;
+	char *endp;
+
+	if (argc != 3) {
+		print_usage();
+		return EXIT_FAILURE;
+	}
+
+	fd = open(argv[1], O_RDWR);
+	if (fd < 0) {
+		perror("unable to open the GPIO chip");
+		return EXIT_FAILURE;
+	}
+
+	memset(&info, 0, sizeof(info));
+	info.offset = strtoul(argv[2], &endp, 10);
+	if (*endp != '\0') {
+		print_usage();
+		return EXIT_FAILURE;
+	}
+
+	ret = ioctl(fd, GPIO_V2_GET_LINEINFO_IOCTL, &info);
+	if (ret) {
+		perror("line info ioctl failed");
+		return EXIT_FAILURE;
+	}
+
+	printf("%s\n", info.name);
+
+	return EXIT_SUCCESS;
+}
-- 
2.30.1

[PATCH v3 11/11] selftests: gpio: add test cases for gpio-sim

[Bartosz Golaszewski]

From: Bartosz Golaszewski <bgolaszewski@baylibre.com>

Add a set of tests for the new gpio-sim module. This is a pure shell
test-suite and uses the helper programs available in the gpio selftests
directory. These test-cases only test the functionalities exposed by the
gpio-sim driver, not those handled by core gpiolib code.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
---
 tools/testing/selftests/gpio/Makefile    |   2 +-
 tools/testing/selftests/gpio/config      |   1 +
 tools/testing/selftests/gpio/gpio-sim.sh | 229 +++++++++++++++++++++++
 3 files changed, 231 insertions(+), 1 deletion(-)
 create mode 100755 tools/testing/selftests/gpio/gpio-sim.sh

diff --git a/tools/testing/selftests/gpio/Makefile b/tools/testing/selftests/gpio/Makefile
index d7d8f1985d99..4c6df61c76a8 100644
--- a/tools/testing/selftests/gpio/Makefile
+++ b/tools/testing/selftests/gpio/Makefile
@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0
 
-TEST_PROGS := gpio-mockup.sh
+TEST_PROGS := gpio-mockup.sh gpio-sim.sh
 TEST_FILES := gpio-mockup-sysfs.sh
 TEST_GEN_PROGS_EXTENDED := gpio-mockup-cdev gpio-chip-info gpio-line-name
 
diff --git a/tools/testing/selftests/gpio/config b/tools/testing/selftests/gpio/config
index ce100342c20b..409a8532facc 100644
--- a/tools/testing/selftests/gpio/config
+++ b/tools/testing/selftests/gpio/config
@@ -1,3 +1,4 @@
 CONFIG_GPIOLIB=y
 CONFIG_GPIO_CDEV=y
 CONFIG_GPIO_MOCKUP=m
+CONFIG_GPIO_SIM=m
diff --git a/tools/testing/selftests/gpio/gpio-sim.sh b/tools/testing/selftests/gpio/gpio-sim.sh
new file mode 100755
index 000000000000..c8c6e4a7aebe
--- /dev/null
+++ b/tools/testing/selftests/gpio/gpio-sim.sh
@@ -0,0 +1,229 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# Copyright (C) 2021 Bartosz Golaszewski <bgolaszewski@baylibre.com>
+
+BASE_DIR=`dirname $0`
+CONFIGFS_DIR="/sys/kernel/config/gpio-sim"
+PENDING_DIR=$CONFIGFS_DIR/pending
+LIVE_DIR=$CONFIGFS_DIR/live
+MODULE="gpio-sim"
+
+fail() {
+	echo "$*" >&2
+	echo "GPIO $MODULE test FAIL"
+	exit 1
+}
+
+skip() {
+	echo "$*" >&2
+	echo "GPIO $MODULE test SKIP"
+	exit 4
+}
+
+configfs_cleanup() {
+	for DIR in `ls $LIVE_DIR`; do
+		mv $LIVE_DIR/$DIR $PENDING_DIR
+	done
+
+	for DIR in `ls $PENDING_DIR`; do
+		rmdir $PENDING_DIR/$DIR
+	done
+}
+
+create_pending_chip() {
+	local NAME="$1"
+	local LABEL="$2"
+	local NUM_LINES="$3"
+	local LINE_NAMES="$4"
+	local CHIP_DIR="$PENDING_DIR/$NAME"
+
+	mkdir $CHIP_DIR
+	test -n "$LABEL" && echo $LABEL > $CHIP_DIR/label
+	test -n "$NUM_LINES" && echo $NUM_LINES > $CHIP_DIR/num_lines
+	if [ -n "$LINE_NAMES" ]; then
+		echo $LINE_NAMES 2> /dev/null > $CHIP_DIR/line_names
+		# This one can fail
+		if [ "$?" -ne "0" ]; then
+			return 1
+		fi
+	fi
+}
+
+create_live_chip() {
+	local CHIP_DIR="$PENDING_DIR/$1"
+
+	create_pending_chip "$@" || fail "unable to create the chip configfs item"
+	mv $CHIP_DIR $LIVE_DIR || fail "unable to commit the chip configfs item"
+}
+
+remove_pending_chip() {
+	local NAME="$1"
+
+	rmdir $PENDING_DIR/$NAME || fail "unable to remove the chip configfs item"
+}
+
+remove_live_chip() {
+	local NAME="$1"
+
+	mv $LIVE_DIR/$NAME $PENDING_DIR || fail "unable to uncommit the chip configfs item"
+	remove_pending_chip "$@"
+}
+
+configfs_chip_name() {
+	local CHIP="$1"
+
+	cat $LIVE_DIR/$CHIP/chip_name 2> /dev/null || return 1
+}
+
+configfs_dev_name() {
+	local CHIP="$1"
+
+	cat $LIVE_DIR/$CHIP/dev_name 2> /dev/null || return 1
+}
+
+get_chip_num_lines() {
+	local CHIP="$1"
+
+	$BASE_DIR/gpio-chip-info /dev/`configfs_chip_name $CHIP` num-lines
+}
+
+get_chip_label() {
+	local CHIP="$1"
+
+	$BASE_DIR/gpio-chip-info /dev/`configfs_chip_name $CHIP` label
+}
+
+get_line_name() {
+	local CHIP="$1"
+	local OFFSET="$2"
+
+	$BASE_DIR/gpio-line-name /dev/`configfs_chip_name $CHIP` $OFFSET
+}
+
+sysfs_set_pull() {
+	local CHIP="$1"
+	local OFFSET="$2"
+	local PULL="$3"
+	local SYSFSPATH="/sys/devices/platform/`configfs_dev_name $CHIP`/line-ctrl/gpio$OFFSET"
+
+	echo $PULL > $SYSFSPATH
+}
+
+# Load the gpio-sim module. This will pull in configfs if needed too.
+modprobe gpio-sim || skip "unable to load the gpio-sim module"
+# Make sure configfs is mounted at /sys/kernel/config. Wait a bit if needed.
+for IDX in `seq 5`; do
+	if [ "$IDX" -eq "5" ]; then
+		skip "configfs not mounted at /sys/kernel/config"
+	fi
+
+	mountpoint -q /sys/kernel/config && break
+	sleep 0.1
+done
+# If the module was already loaded: remove all previous chips
+configfs_cleanup
+
+trap "exit 1" SIGTERM SIGINT
+trap configfs_cleanup EXIT
+
+echo "1. chip_name and dev_name attributes"
+
+echo "1.1. Chip name is communicated to user"
+create_live_chip chip
+test -n `cat $LIVE_DIR/chip/chip_name` || fail "chip_name doesn't work"
+remove_live_chip chip
+
+echo "1.2. chip_name returns 'n/a' if the chip is still pending"
+create_pending_chip chip
+test "`cat $PENDING_DIR/chip/chip_name`" = "n/a" || fail "chip_name doesn't return 'n/a' for a pending chip"
+remove_pending_chip chip
+
+echo "1.3. Device name is communicated to user"
+create_live_chip chip
+test -n `cat $LIVE_DIR/chip/dev_name` || fail "dev_name doesn't work"
+remove_live_chip chip
+
+echo "1.4. dev_name returns 'n/a' if chip is still pending"
+create_pending_chip chip
+test "`cat $PENDING_DIR/chip/dev_name`" = "n/a" || fail "dev_name doesn't return 'n/a' for a pending chip"
+remove_pending_chip chip
+
+echo "2. Creating simulated chips"
+
+echo "2.1. Default number of lines is 1"
+create_live_chip chip
+test "`get_chip_num_lines chip`" = "1" || fail "default number of lines is not 1"
+remove_live_chip chip
+
+echo "2.2. Number of lines can be specified"
+create_live_chip chip test-label 16
+test "`get_chip_num_lines chip`" = "16" || fail "number of lines is not 16"
+remove_live_chip chip
+
+echo "2.3. Label can be set"
+create_live_chip chip foobar
+test "`get_chip_label chip`" = "foobar" || fail "label is incorrect"
+remove_live_chip chip
+
+echo "2.4. Label can be left empty"
+create_live_chip chip
+test -z "`cat $LIVE_DIR/chip/label`" || fail "label is not empty"
+remove_live_chip chip
+
+echo "2.5. Line names can be configured"
+create_live_chip chip test-label 16 '"foo", "", "bar"'
+test "`get_line_name chip 0`" = "foo" || fail "line name is incorrect"
+test "`get_line_name chip 2`" = "bar" || fail "line name is incorrect"
+remove_live_chip chip
+
+echo "2.6. Errors in line names are detected"
+create_pending_chip chip test-label 8 '"foo", bar' && fail "incorrect line name accepted"
+remove_pending_chip chip
+create_pending_chip chip test-label 8 '"foo" "bar"' && fail "incorrect line name accepted"
+remove_pending_chip chip
+
+echo "2.7. Multiple chips can be created"
+create_live_chip chip0
+create_live_chip chip1
+create_live_chip chip2
+remove_live_chip chip0
+remove_live_chip chip1
+remove_live_chip chip2
+
+echo "3. Controlling simulated chips"
+
+echo "3.3. Pull can be set over sysfs"
+create_live_chip chip test-label 8
+sysfs_set_pull chip 0 1
+$BASE_DIR/gpio-mockup-cdev /dev/`configfs_chip_name chip` 0
+test "$?" = "1" || fail "pull set incorrectly"
+sysfs_set_pull chip 0 0
+$BASE_DIR/gpio-mockup-cdev /dev/`configfs_chip_name chip` 1
+test "$?" = "0" || fail "pull set incorrectly"
+remove_live_chip chip
+
+echo "3.4. Incorrect input in sysfs is rejected"
+create_live_chip chip test-label 8
+SYSFS_PATH="/sys/devices/platform/`configfs_dev_name chip`/line-ctrl/gpio0"
+echo 2 > $SYSFS_PATH 2> /dev/null && fail "invalid input not detectec"
+remove_live_chip chip
+
+echo "4. Simulated GPIO chips are functional"
+
+echo "4.1. Values can be read from sysfs"
+create_live_chip chip test-label 8
+SYSFS_PATH="/sys/devices/platform/`configfs_dev_name chip`/line-ctrl/gpio0"
+test `cat $SYSFS_PATH` = "0" || fail "incorrect value read from sysfs"
+$BASE_DIR/gpio-mockup-cdev -s 1 /dev/`configfs_chip_name chip` 0 &
+sleep 0.1 # FIXME Any better way?
+test `cat $SYSFS_PATH` = "1" || fail "incorrect value read from sysfs"
+kill $!
+remove_live_chip chip
+
+echo "4.2. Bias settings work correctly"
+create_live_chip chip test-label 8
+$BASE_DIR/gpio-mockup-cdev -b pull-up /dev/`configfs_chip_name chip` 0
+test `cat $SYSFS_PATH` = "1" || fail "bias setting does not work"
+remove_live_chip chip
+
+echo "GPIO $MODULE test PASS"
-- 
2.30.1

Re: [PATCH v3 07/11] lib: bitmap: provide devm_bitmap_alloc() and devm_bitmap_zalloc()

[Greg Kroah-Hartman]

On Tue, Mar 09, 2021 at 09:59:17PM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> Provide managed variants of bitmap_alloc() and bitmap_zalloc().
> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  include/linux/bitmap.h |  8 ++++++++
>  lib/bitmap.c           | 33 +++++++++++++++++++++++++++++++++
>  2 files changed, 41 insertions(+)
> 
> diff --git a/include/linux/bitmap.h b/include/linux/bitmap.h
> index 3282db97e06c..73d039476fa4 100644
> --- a/include/linux/bitmap.h
> +++ b/include/linux/bitmap.h
> @@ -9,6 +9,8 @@
>  #include <linux/string.h>
>  #include <linux/types.h>
>  
> +struct device;
> +
>  /*
>   * bitmaps provide bit arrays that consume one or more unsigned
>   * longs.  The bitmap interface and available operations are listed
> @@ -122,6 +124,12 @@ unsigned long *bitmap_alloc(unsigned int nbits, gfp_t flags);
>  unsigned long *bitmap_zalloc(unsigned int nbits, gfp_t flags);
>  void bitmap_free(const unsigned long *bitmap);
>  
> +/* Managed variants of the above. */
> +unsigned long *devm_bitmap_alloc(struct device *dev,
> +				 unsigned int nbits, gfp_t flags);
> +unsigned long *devm_bitmap_zalloc(struct device *dev,
> +				  unsigned int nbits, gfp_t flags);
> +
>  /*
>   * lib/bitmap.c provides these functions:
>   */
> diff --git a/lib/bitmap.c b/lib/bitmap.c
> index 78f70d9007ad..b4fd7fd084c6 100644
> --- a/lib/bitmap.c
> +++ b/lib/bitmap.c
> @@ -8,6 +8,7 @@
>  #include <linux/bitops.h>
>  #include <linux/bug.h>
>  #include <linux/ctype.h>
> +#include <linux/device.h>
>  #include <linux/errno.h>
>  #include <linux/export.h>
>  #include <linux/kernel.h>
> @@ -1263,6 +1264,38 @@ void bitmap_free(const unsigned long *bitmap)
>  }
>  EXPORT_SYMBOL(bitmap_free);
>  
> +static void devm_bitmap_free(void *data)
> +{
> +	unsigned long *bitmap = data;
> +
> +	bitmap_free(bitmap);
> +}
> +
> +unsigned long *devm_bitmap_alloc(struct device *dev,
> +				 unsigned int nbits, gfp_t flags)
> +{
> +	unsigned long *bitmap;
> +	int ret;
> +
> +	bitmap = bitmap_alloc(nbits, flags);
> +	if (!bitmap)
> +		return NULL;
> +
> +	ret = devm_add_action_or_reset(dev, devm_bitmap_free, bitmap);
> +	if (ret)
> +		return NULL;
> +
> +	return bitmap;
> +}
> +EXPORT_SYMBOL(devm_bitmap_alloc);
> +
> +unsigned long *devm_bitmap_zalloc(struct device *dev,
> +				  unsigned int nbits, gfp_t flags)
> +{
> +	return devm_bitmap_alloc(dev, nbits, flags | __GFP_ZERO);
> +}
> +EXPORT_SYMBOL(devm_bitmap_zalloc);

devm_* functions have been traditionally exported with
EXPORT_SYMBOL_GPL() due to the use of a struct device *.  Perhaps do
that here as well?

thanks,

greg k-h

Re: [PATCH v3 00/11] gpio: implement the configfs testing module

[Greg Kroah-Hartman]

On Tue, Mar 09, 2021 at 09:59:10PM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> This series adds a new GPIO testing module based on configfs committable items
> and sysfs. The goal is to provide a testing driver that will be configurable
> at runtime (won't need module reload) and easily extensible. The control over
> the attributes is also much more fine-grained than in gpio-mockup.
> 
> This series also contains a respin of the patches I sent separately to the
> configfs maintainers - these patches implement the concept of committable
> items that was well defined for a long time but never actually completed.
> 
> Apart from the new driver itself, its selftests and the configfs patches, this
> series contains some changes to the bitmap API - most importantly: it adds
> devres managed variants of bitmap_alloc() and bitmap_zalloc().
> 
> v1 -> v2:
> - add selftests for gpio-sim
> - add helper programs for selftests
> - update the configfs rename callback to work with the new API introduced in
>   v5.11
> - fix a missing quote in the documentation
> - use !! whenever using bits operation that are required to return 0 or 1
> - use provided bitmap API instead of reimplementing copy or fill operations
> - fix a deadlock in gpio_sim_direction_output()
> - add new read-only configfs attributes for mapping of configfs items to GPIO
>   device names
> - and address other minor issues pointed out in reviews of v1
> 
> v2 -> v3:
> - use devm_bitmap_alloc() instead of the zalloc variant if we're initializing
>   the bitmap with 1s
> - drop the patch exporting device_is_bound()
> - don't return -ENODEV from dev_nam and chip_name configfs attributes, return
>   a string indicating that the device is not available yet ('n/a')
> - fix indentation where it makes sense
> - don't protect IDA functions which use their own locking and where it's not
>   needed
> - use kmemdup() instead of kzalloc() + memcpy()
> - collected review tags
> - minor coding style fixes

Thanks for dropping the device_is_bound() stuff, looks sane to me.

greg k-h

Re: [PATCH v3 08/11] gpio: sim: new testing module

[Andy Shevchenko]

On Tue, Mar 09, 2021 at 09:59:18PM +0100, Bartosz Golaszewski wrote:
> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> 
> Implement a new, modern GPIO testing module controlled by configfs
> attributes instead of module parameters. The goal of this driver is
> to provide a replacement for gpio-mockup that will be easily extensible
> with new features and doesn't require reloading the module to change
> the setup.

Thanks for an update!
Looks much better now, although few minor comments below.
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>

> 
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
> ---
>  Documentation/admin-guide/gpio/gpio-sim.rst |  72 ++
>  drivers/gpio/Kconfig                        |   8 +
>  drivers/gpio/Makefile                       |   1 +
>  drivers/gpio/gpio-sim.c                     | 879 ++++++++++++++++++++
>  4 files changed, 960 insertions(+)
>  create mode 100644 Documentation/admin-guide/gpio/gpio-sim.rst
>  create mode 100644 drivers/gpio/gpio-sim.c
> 
> diff --git a/Documentation/admin-guide/gpio/gpio-sim.rst b/Documentation/admin-guide/gpio/gpio-sim.rst
> new file mode 100644
> index 000000000000..08eac487e35e
> --- /dev/null
> +++ b/Documentation/admin-guide/gpio/gpio-sim.rst
> @@ -0,0 +1,72 @@
> +.. SPDX-License-Identifier: GPL-2.0-or-later
> +
> +Configfs GPIO Simulator
> +=======================
> +
> +The configfs GPIO Simulator (gpio-sim) provides a way to create simulated GPIO
> +chips for testing purposes. The lines exposed by these chips can be accessed
> +using the standard GPIO character device interface as well as manipulated
> +using sysfs attributes.
> +
> +Creating simulated chips
> +------------------------
> +
> +The gpio-sim module registers a configfs subsystem called 'gpio-sim'. It's a
> +subsystem with committable items which means two subdirectories are created in
> +the filesystem: pending and live. For more information on configfs and
> +committable items, please refer to Documentation/filesystems/configfs.rst.
> +
> +In order to instantiate a new simulated chip, the user needs to mkdir() a new
> +directory in pending/. Inside each new directory, there's a set of attributes
> +that can be used to configure the new chip. Once the configuration is complete,
> +the user needs to use rename() to move the chip to the live/ directory. This
> +creates and registers the new device.
> +
> +In order to destroy a simulated chip, it has to be moved back to pending first
> +and then removed using rmdir().
> +
> +Currently supported configuration attributes are:
> +
> +  num_lines - an unsigned integer value defining the number of GPIO lines to
> +              export
> +
> +  label - a string defining the label for the GPIO chip
> +
> +  line_names - a list of GPIO line names in the form of quoted strings
> +               separated by commas, e.g.: '"foo", "bar", "", "foobar"'. The
> +               number of strings doesn't have to be equal to the value set in
> +               the num_lines attribute. If it's lower than the number of lines,
> +               the remaining lines are unnamed. If it's larger, the superfluous
> +               lines are ignored. A name of the form: '""' means the line
> +               should be unnamed.
> +
> +Additionally two read-only attributes named 'chip_name' and 'dev_name' are
> +exposed in order to provide users with a mapping from configfs directories to
> +the actual devices created in the kernel. The former returns the name of the
> +GPIO device as assigned by gpiolib (i.e. "gpiochip0", "gpiochip1", etc.). The
> +latter returns the parent device name as defined by the gpio-sim driver (i.e.
> +"gpio-sim.0", "gpio-sim.1", etc.). This allows user-space to map the configfs
> +items both to the correct character device file as well as the associated entry
> +in sysfs.
> +
> +Simulated GPIO chips can also be defined in device-tree. The compatible string
> +must be: "gpio-simulator". Supported properties are:
> +
> +  "gpio-sim,label" - chip label
> +
> +  "gpio-sim,nr-gpios" - number of lines
> +
> +Other standard GPIO properties (like "gpio-line-names" and gpio-hog) are also
> +supported.
> +
> +Manipulating simulated lines
> +----------------------------
> +
> +Each simulated GPIO chip creates a sysfs attribute group under its device
> +directory called 'line-ctrl'. Inside each group, there's a separate attribute
> +for each GPIO line. The name of the attribute is of the form 'gpioX' where X
> +is the line's offset in the chip.
> +
> +Reading from a line attribute returns the current value. Writing to it (0 or 1)
> +changes the configuration of the simulated pull-up/pull-down resistor
> +(1 - pull-up, 0 - pull-down).
> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
> index e3607ec4c2e8..b6b6150d0d04 100644
> --- a/drivers/gpio/Kconfig
> +++ b/drivers/gpio/Kconfig
> @@ -1633,6 +1633,14 @@ config GPIO_MOCKUP
>  	  tools/testing/selftests/gpio/gpio-mockup.sh. Reference the usage in
>  	  it.
>  
> +config GPIO_SIM
> +	tristate "GPIO Simulator Module"
> +	select IRQ_SIM
> +	select CONFIGFS_FS
> +	help
> +	  This enables the GPIO simulator - a configfs-based GPIO testing
> +	  driver.
> +
>  endmenu
>  
>  endif
> diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
> index c58a90a3c3b1..d717aa85f8e1 100644
> --- a/drivers/gpio/Makefile
> +++ b/drivers/gpio/Makefile
> @@ -130,6 +130,7 @@ obj-$(CONFIG_GPIO_SAMA5D2_PIOBU)	+= gpio-sama5d2-piobu.o
>  obj-$(CONFIG_GPIO_SCH311X)		+= gpio-sch311x.o
>  obj-$(CONFIG_GPIO_SCH)			+= gpio-sch.o
>  obj-$(CONFIG_GPIO_SIFIVE)		+= gpio-sifive.o
> +obj-$(CONFIG_GPIO_SIM)			+= gpio-sim.o
>  obj-$(CONFIG_GPIO_SIOX)			+= gpio-siox.o
>  obj-$(CONFIG_GPIO_SL28CPLD)		+= gpio-sl28cpld.o
>  obj-$(CONFIG_GPIO_SODAVILLE)		+= gpio-sodaville.o
> diff --git a/drivers/gpio/gpio-sim.c b/drivers/gpio/gpio-sim.c
> new file mode 100644
> index 000000000000..253f5b4bd1f5
> --- /dev/null
> +++ b/drivers/gpio/gpio-sim.c
> @@ -0,0 +1,879 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + * GPIO testing driver based on configfs.
> + *
> + * Copyright (C) 2021 Bartosz Golaszewski <bgolaszewski@baylibre.com>
> + */
> +
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/bitmap.h>
> +#include <linux/configfs.h>
> +#include <linux/device.h>
> +#include <linux/gpio/driver.h>
> +#include <linux/idr.h>
> +#include <linux/interrupt.h>
> +#include <linux/irq.h>
> +#include <linux/irq_sim.h>
> +#include <linux/mod_devicetable.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/platform_device.h>
> +#include <linux/property.h>
> +#include <linux/slab.h>
> +#include <linux/string.h>
> +#include <linux/string_helpers.h>
> +#include <linux/sysfs.h>
> +
> +#include "gpiolib.h"
> +
> +/*
> + * This normally should correspond with the number of attributes exposed over
> + * configfs + sentinel.
> + */
> +#define GPIO_SIM_MAX_PROP 4
> +
> +static DEFINE_IDA(gpio_sim_ida);
> +
> +struct gpio_sim_chip {
> +	struct gpio_chip gc;
> +	unsigned long *directions;
> +	unsigned long *values;
> +	unsigned long *pulls;
> +	struct irq_domain *irq_sim;
> +	struct mutex lock;
> +	struct attribute_group attr_group;
> +};
> +
> +struct gpio_sim_attribute {
> +	struct device_attribute dev_attr;
> +	unsigned int offset;
> +};
> +
> +static struct gpio_sim_attribute *
> +to_gpio_sim_attr(struct device_attribute *dev_attr)
> +{
> +	return container_of(dev_attr, struct gpio_sim_attribute, dev_attr);
> +}
> +
> +static int gpio_sim_apply_pull(struct gpio_sim_chip *chip,
> +			       unsigned int offset, int value)
> +{
> +	int curr_val, irq, irq_type, ret;
> +	struct gpio_desc *desc;
> +	struct gpio_chip *gc;
> +
> +	gc = &chip->gc;
> +	desc = &gc->gpiodev->descs[offset];
> +
> +	mutex_lock(&chip->lock);
> +
> +	if (test_bit(FLAG_REQUESTED, &desc->flags) &&
> +	    !test_bit(FLAG_IS_OUT, &desc->flags)) {
> +		curr_val = !!test_bit(offset, chip->values);
> +		if (curr_val == value)
> +			goto set_pull;
> +
> +		/*
> +		 * This is fine - it just means, nobody is listening
> +		 * for interrupts on this line, otherwise
> +		 * irq_create_mapping() would have been called from
> +		 * the to_irq() callback.
> +		 */
> +		irq = irq_find_mapping(chip->irq_sim, offset);
> +		if (!irq)
> +			goto set_value;
> +
> +		irq_type = irq_get_trigger_type(irq);
> +
> +		if ((value && (irq_type & IRQ_TYPE_EDGE_RISING)) ||
> +		    (!value && (irq_type & IRQ_TYPE_EDGE_FALLING))) {
> +			ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING,
> +						    true);
> +			if (ret)
> +				goto set_pull;
> +		}
> +	}
> +
> +set_value:
> +	/* Change the value unless we're actively driving the line. */
> +	if (!test_bit(FLAG_REQUESTED, &desc->flags) ||
> +	    !test_bit(FLAG_IS_OUT, &desc->flags))
> +		__assign_bit(offset, chip->values, value);
> +
> +set_pull:
> +	__assign_bit(offset, chip->pulls, value);
> +	mutex_unlock(&chip->lock);
> +	return 0;
> +}
> +
> +static int gpio_sim_get(struct gpio_chip *gc, unsigned int offset)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +	int ret;
> +
> +	mutex_lock(&chip->lock);
> +	ret = !!test_bit(offset, chip->values);
> +	mutex_unlock(&chip->lock);
> +
> +	return ret;
> +}
> +
> +static void gpio_sim_set(struct gpio_chip *gc, unsigned int offset, int value)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +
> +	mutex_lock(&chip->lock);
> +	__assign_bit(offset, chip->values, value);
> +	mutex_unlock(&chip->lock);
> +}
> +
> +static int gpio_sim_get_multiple(struct gpio_chip *gc,
> +				 unsigned long *mask, unsigned long *bits)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +
> +	mutex_lock(&chip->lock);
> +	bitmap_copy(bits, chip->values, gc->ngpio);
> +	mutex_unlock(&chip->lock);
> +
> +	return 0;
> +}
> +
> +static void gpio_sim_set_multiple(struct gpio_chip *gc,
> +				  unsigned long *mask, unsigned long *bits)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +
> +	mutex_lock(&chip->lock);
> +	bitmap_copy(chip->values, bits, gc->ngpio);
> +	mutex_unlock(&chip->lock);
> +}
> +
> +static int gpio_sim_direction_output(struct gpio_chip *gc,
> +				     unsigned int offset, int value)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +
> +	mutex_lock(&chip->lock);
> +	__clear_bit(offset, chip->directions);
> +	__assign_bit(offset, chip->values, value);
> +	mutex_unlock(&chip->lock);
> +
> +	return 0;
> +}
> +
> +static int gpio_sim_direction_input(struct gpio_chip *gc, unsigned int offset)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +
> +	mutex_lock(&chip->lock);
> +	__set_bit(offset, chip->directions);
> +	mutex_unlock(&chip->lock);
> +
> +	return 0;
> +}
> +
> +static int gpio_sim_get_direction(struct gpio_chip *gc, unsigned int offset)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +	int direction;
> +
> +	mutex_lock(&chip->lock);
> +	direction = !!test_bit(offset, chip->directions);
> +	mutex_unlock(&chip->lock);
> +
> +	return direction ? GPIO_LINE_DIRECTION_IN : GPIO_LINE_DIRECTION_OUT;
> +}
> +
> +static int gpio_sim_set_config(struct gpio_chip *gc,
> +				  unsigned int offset, unsigned long config)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +
> +	switch (pinconf_to_config_param(config)) {
> +	case PIN_CONFIG_BIAS_PULL_UP:
> +		return gpio_sim_apply_pull(chip, offset, 1);
> +	case PIN_CONFIG_BIAS_PULL_DOWN:
> +		return gpio_sim_apply_pull(chip, offset, 0);
> +	default:
> +		break;
> +	}
> +
> +	return -ENOTSUPP;
> +}
> +
> +static int gpio_sim_to_irq(struct gpio_chip *gc, unsigned int offset)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +
> +	return irq_create_mapping(chip->irq_sim, offset);
> +}
> +
> +static void gpio_sim_free(struct gpio_chip *gc, unsigned int offset)
> +{
> +	struct gpio_sim_chip *chip = gpiochip_get_data(gc);
> +
> +	mutex_lock(&chip->lock);
> +	__assign_bit(offset, chip->values, !!test_bit(offset, chip->pulls));
> +	mutex_unlock(&chip->lock);
> +}
> +
> +static ssize_t gpio_sim_sysfs_line_show(struct device *dev,
> +					struct device_attribute *attr,
> +					char *buf)
> +{
> +	struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
> +	struct gpio_sim_chip *chip = dev_get_drvdata(dev);
> +	int ret;
> +
> +	mutex_lock(&chip->lock);
> +	ret = sprintf(buf, "%u\n", !!test_bit(line_attr->offset, chip->values));

Shouldn't we use sysfs_emit() in a new code?

> +	mutex_unlock(&chip->lock);
> +
> +	return ret;
> +}
> +
> +static ssize_t gpio_sim_sysfs_line_store(struct device *dev,
> +					 struct device_attribute *attr,
> +					 const char *buf, size_t len)
> +{
> +	struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
> +	struct gpio_sim_chip *chip = dev_get_drvdata(dev);
> +	int ret, val;
> +
> +	if (len > 2 || (buf[0] != '0' && buf[0] != '1'))
> +		return -EINVAL;
> +
> +	val = buf[0] == '0' ? 0 : 1;
> +
> +	ret = gpio_sim_apply_pull(chip, line_attr->offset, val);
> +	if (ret)
> +		return ret;
> +
> +	return len;
> +}
> +
> +static void gpio_sim_mutex_destroy(void *data)
> +{
> +	struct mutex *lock = data;
> +
> +	mutex_destroy(lock);
> +}
> +
> +static void gpio_sim_sysfs_remove(void *data)
> +{
> +	struct gpio_sim_chip *chip = data;
> +
> +	sysfs_remove_group(&chip->gc.parent->kobj, &chip->attr_group);
> +}
> +
> +static int gpio_sim_setup_sysfs(struct gpio_sim_chip *chip)
> +{
> +	unsigned int i, num_lines = chip->gc.ngpio;
> +	struct device *dev = chip->gc.parent;
> +	struct gpio_sim_attribute *line_attr;
> +	struct device_attribute *dev_attr;
> +	struct attribute **attrs;
> +	int ret;
> +
> +	attrs = devm_kcalloc(dev, sizeof(*attrs), num_lines + 1, GFP_KERNEL);
> +	if (!attrs)
> +		return -ENOMEM;
> +
> +	for (i = 0; i < num_lines; i++) {
> +		line_attr = devm_kzalloc(dev, sizeof(*line_attr), GFP_KERNEL);
> +		if (!line_attr)
> +			return -ENOMEM;
> +
> +		line_attr->offset = i;
> +
> +		dev_attr = &line_attr->dev_attr;
> +
> +		dev_attr->attr.name = devm_kasprintf(dev, GFP_KERNEL,
> +						     "gpio%u", i);
> +		if (!dev_attr->attr.name)
> +			return -ENOMEM;
> +
> +		dev_attr->attr.mode = 0644;
> +
> +		dev_attr->show = gpio_sim_sysfs_line_show;
> +		dev_attr->store = gpio_sim_sysfs_line_store;
> +
> +		attrs[i] = &dev_attr->attr;
> +	}
> +
> +	chip->attr_group.name = "line-ctrl";
> +	chip->attr_group.attrs = attrs;
> +
> +	ret = sysfs_create_group(&dev->kobj, &chip->attr_group);
> +	if (ret)
> +		return ret;
> +
> +	return devm_add_action_or_reset(dev, gpio_sim_sysfs_remove, chip);
> +}
> +
> +static int gpio_sim_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct gpio_sim_chip *chip;
> +	struct gpio_chip *gc;
> +	const char *label;
> +	u32 num_lines;
> +	int ret;
> +
> +	ret = device_property_read_u32(dev, "gpio-sim,nr-gpios", &num_lines);
> +	if (ret)
> +		return ret;
> +
> +	ret = device_property_read_string(dev, "gpio-sim,label", &label);
> +	if (ret)
> +		label = dev_name(dev);
> +
> +	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);
> +	if (!chip)
> +		return -ENOMEM;
> +
> +	chip->directions = devm_bitmap_alloc(dev, num_lines, GFP_KERNEL);
> +	if (!chip->directions)
> +		return -ENOMEM;
> +
> +	/* Default to input mode. */
> +	bitmap_fill(chip->directions, num_lines);
> +
> +	chip->values = devm_bitmap_zalloc(dev, num_lines, GFP_KERNEL);
> +	if (!chip->values)
> +		return -ENOMEM;
> +
> +	chip->pulls = devm_bitmap_zalloc(dev, num_lines, GFP_KERNEL);
> +	if (!chip->pulls)
> +		return -ENOMEM;
> +
> +	chip->irq_sim = devm_irq_domain_create_sim(dev, NULL, num_lines);
> +	if (IS_ERR(chip->irq_sim))
> +		return PTR_ERR(chip->irq_sim);
> +
> +	mutex_init(&chip->lock);
> +	ret = devm_add_action_or_reset(dev, gpio_sim_mutex_destroy,
> +				       &chip->lock);
> +	if (ret)
> +		return ret;
> +
> +	gc = &chip->gc;
> +	gc->base = -1;
> +	gc->ngpio = num_lines;
> +	gc->label = label;
> +	gc->owner = THIS_MODULE;
> +	gc->parent = dev;
> +	gc->get = gpio_sim_get;
> +	gc->set = gpio_sim_set;
> +	gc->get_multiple = gpio_sim_get_multiple;
> +	gc->set_multiple = gpio_sim_set_multiple;
> +	gc->direction_output = gpio_sim_direction_output;
> +	gc->direction_input = gpio_sim_direction_input;
> +	gc->get_direction = gpio_sim_get_direction;
> +	gc->set_config = gpio_sim_set_config;
> +	gc->to_irq = gpio_sim_to_irq;
> +	gc->free = gpio_sim_free;
> +
> +	ret = devm_gpiochip_add_data(dev, gc, chip);
> +	if (ret)
> +		return ret;
> +
> +	/* Used by sysfs and configfs callbacks. */
> +	dev_set_drvdata(dev, chip);
> +
> +	ret = gpio_sim_setup_sysfs(chip);
> +	if (ret)
> +		return ret;
> +
> +	return 0;
> +}
> +
> +static const struct of_device_id gpio_sim_of_match[] = {
> +	{ .compatible = "gpio-simulator" },
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, gpio_sim_of_match);
> +
> +static struct platform_driver gpio_sim_driver = {
> +	.driver = {
> +		.name = "gpio-sim",
> +	},
> +	.probe = gpio_sim_probe,
> +};
> +
> +struct gpio_sim_chip_config {
> +	struct config_item item;
> +
> +	/*
> +	 * If pdev is NULL, the item is 'pending' (waiting for configuration).
> +	 * Once the pointer is assigned, the device has been created and the
> +	 * item is 'live'.
> +	 */
> +	struct platform_device *pdev;
> +
> +	/*
> +	 * Each configfs filesystem operation is protected with the subsystem
> +	 * mutex. Each separate attribute is protected with the buffer mutex.
> +	 * This structure however can be modified by callbacks of different
> +	 * attributes so we need another lock.
> +	 */
> +	struct mutex lock;
> +
> +	char label[32];
> +	unsigned int num_lines;
> +	char **line_names;
> +	unsigned int num_line_names;
> +};
> +
> +static struct gpio_sim_chip_config *
> +to_gpio_sim_chip_config(struct config_item *item)
> +{
> +	return container_of(item, struct gpio_sim_chip_config, item);
> +}
> +
> +static ssize_t gpio_sim_config_dev_name_show(struct config_item *item,
> +					     char *page)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +	struct platform_device *pdev;
> +	int ret;
> +
> +	mutex_lock(&config->lock);
> +	pdev = config->pdev;
> +	if (pdev)
> +		ret = sprintf(page, "%s\n", dev_name(&pdev->dev));
> +	else
> +		ret = sprintf(page, "n/a\n");

I dunno '/' (slash) is a good character to be handled in a shell.
I would prefer 'none' or 'not available' (I think space is easier,
because the rules to escape much simpler: need just to take it into
quotes, while / needs to be escaped separately).

> +	mutex_unlock(&config->lock);
> +
> +	return ret;
> +}
> +
> +CONFIGFS_ATTR_RO(gpio_sim_config_, dev_name);
> +
> +static ssize_t gpio_sim_config_chip_name_show(struct config_item *item,
> +					      char *page)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +	struct gpio_sim_chip *chip = NULL;
> +	struct platform_device *pdev;
> +	int ret;
> +
> +	mutex_lock(&config->lock);
> +	pdev = config->pdev;
> +	if (pdev)
> +		chip = dev_get_drvdata(&pdev->dev);
> +
> +	if (chip)
> +		ret = sprintf(page, "%s\n", dev_name(&chip->gc.gpiodev->dev));
> +	else

> +		ret = sprintf(page, "n/a\n");

Ditto.

Also don't know what the rules about using s*printf() in the configfs.
Maybe we have sysfs_emit() analogue or it doesn't applicable here at all.
Greg?

> +	mutex_unlock(&config->lock);
> +
> +	return ret;
> +}
> +
> +CONFIGFS_ATTR_RO(gpio_sim_config_, chip_name);
> +
> +static ssize_t gpio_sim_config_label_show(struct config_item *item, char *page)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +	int ret;
> +
> +	mutex_lock(&config->lock);
> +	ret = sprintf(page, "%s\n", config->label);
> +	mutex_unlock(&config->lock);
> +
> +	return ret;
> +}
> +
> +static ssize_t gpio_sim_config_label_store(struct config_item *item,
> +					   const char *page, size_t count)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +	char *dup, *trimmed;
> +	int ret;
> +
> +	mutex_lock(&config->lock);
> +
> +	if (config->pdev) {
> +		mutex_unlock(&config->lock);
> +		return -EBUSY;
> +	}
> +
> +	dup = kstrndup(page, count, GFP_KERNEL);
> +	if (!dup) {
> +		mutex_unlock(&config->lock);
> +		return -ENOMEM;
> +	}
> +
> +	trimmed = strstrip(dup);
> +	ret = snprintf(config->label, sizeof(config->label), "%s", trimmed);
> +	kfree(dup);
> +	if (ret < 0) {
> +		mutex_unlock(&config->lock);
> +		return ret;
> +	}
> +
> +	mutex_unlock(&config->lock);
> +	return count;
> +}
> +
> +CONFIGFS_ATTR(gpio_sim_config_, label);
> +
> +static ssize_t gpio_sim_config_num_lines_show(struct config_item *item,
> +					      char *page)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +	int ret;
> +
> +	mutex_lock(&config->lock);
> +	ret = sprintf(page, "%u\n", config->num_lines);
> +	mutex_unlock(&config->lock);
> +
> +	return ret;
> +}
> +
> +static ssize_t gpio_sim_config_num_lines_store(struct config_item *item,
> +					       const char *page, size_t count)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +	unsigned int num_lines;
> +	int ret;
> +
> +	mutex_lock(&config->lock);
> +
> +	if (config->pdev) {
> +		mutex_unlock(&config->lock);
> +		return -EBUSY;
> +	}
> +
> +	ret = kstrtouint(page, 10, &num_lines);
> +	if (ret) {
> +		mutex_unlock(&config->lock);
> +		return ret;
> +	}
> +
> +	if (num_lines == 0) {
> +		mutex_unlock(&config->lock);
> +		return -EINVAL;
> +	}
> +
> +	config->num_lines = num_lines;
> +
> +	mutex_unlock(&config->lock);
> +	return count;
> +}
> +
> +CONFIGFS_ATTR(gpio_sim_config_, num_lines);
> +
> +static ssize_t gpio_sim_config_line_names_show(struct config_item *item,
> +					       char *page)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +	int ret, i, written = 0;
> +
> +	mutex_lock(&config->lock);
> +
> +	if (!config->line_names) {
> +		mutex_unlock(&config->lock);
> +		return sprintf(page, "\n");
> +	}
> +
> +	for (i = 0; i < config->num_line_names; i++) {
> +		ret = sprintf(page + written,
> +			i < config->num_line_names - 1 ? "\"%s\", " : "\"%s\"\n",
> +			config->line_names[i] ?: "");
> +		if (ret < 0) {
> +			mutex_unlock(&config->lock);
> +			return ret;
> +		}
> +
> +		written += ret;
> +	}
> +
> +	mutex_unlock(&config->lock);
> +	return written;
> +}
> +
> +static ssize_t gpio_sim_config_line_names_store(struct config_item *item,
> +						const char *page, size_t count)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +	unsigned int num_new_names = 1, num_old_names, name_idx = 0;
> +	bool in_quote = false, got_comma = true;
> +	char **new_names, **old_names, *name, c;
> +	const char *start = page;
> +	size_t pos, name_len;
> +	int err = -EINVAL;
> +
> +	mutex_lock(&config->lock);
> +
> +	if (config->pdev) {
> +		mutex_unlock(&config->lock);
> +		return -EBUSY;
> +	}
> +
> +	/*
> +	 * Line names are stored in a pointer array so that we can easily
> +	 * pass them down to the GPIO subsystem in a "gpio-line-names"
> +	 * property.
> +	 *
> +	 * Line names must be passed as a list of quoted names separated by
> +	 * commas, for example: '"foo", "bar", "foobar"'.
> +	 */
> +
> +	for (pos = 0; pos < count; pos++) {
> +		/*
> +		 * Just count the commas and assume the number if strings
> +		 * equals the number of commas + 1. If the format is wrong
> +		 * we'll bail out anyway.
> +		 */
> +		if (page[pos] == ',')
> +			num_new_names++;
> +	}
> +
> +	new_names = kcalloc(num_new_names, sizeof(char *), GFP_KERNEL);
> +	if (!new_names) {
> +		mutex_unlock(&config->lock);
> +		return -ENOMEM;
> +	}
> +
> +	/*
> +	 * REVISIT There are more users in the kernel that want to split
> +	 * comma-separated strings into tokens. We should generalize it and
> +	 * put it into lib/.
> +	 */

Thanks!

> +	for (pos = 0; pos < count; pos++) {
> +		c = page[pos];
> +
> +		if (in_quote) {
> +			if (c == '"') {
> +				/* This is the end of the name. */
> +				in_quote = got_comma = false;
> +				name_len = (page + pos) - start;
> +				if (name_len == 0) {
> +					/* Name is empty (passed as ""). */
> +					name_idx++;
> +					continue;
> +				}
> +
> +				name = kmemdup(start, name_len + 1, GFP_KERNEL);
> +				if (!name) {
> +					err = -ENOMEM;
> +					goto err_out;
> +				}
> +
> +				name[name_len] = '\0';
> +				new_names[name_idx++] = name;
> +			}
> +		} else {
> +			if (c == '"') {
> +				/* Enforce separating names with commas. */
> +				if (!got_comma)
> +					goto err_out;
> +
> +				start = page + pos + 1;
> +				in_quote = true;
> +			} else if (c == ',') {
> +				if (!got_comma)
> +					got_comma = true;
> +				else
> +					/* Double commas are not allowed. */
> +					goto err_out;
> +			} else if (!isspace(c)) {
> +				goto err_out;
> +			}
> +		}
> +	}
> +
> +	/*
> +	 * End of input sanity checks, must not have a comma at the end and
> +	 * must have finished scanning the last name.
> +	 */
> +	if (in_quote || got_comma)
> +		goto err_out;
> +
> +	old_names = config->line_names;
> +	num_old_names = config->num_line_names;
> +	config->line_names = new_names;
> +	config->num_line_names = num_new_names;
> +
> +	mutex_unlock(&config->lock);
> +	kfree_strarray(old_names, num_old_names);
> +	return count;
> +
> +err_out:
> +	mutex_unlock(&config->lock);
> +	kfree_strarray(new_names, name_idx);
> +	return err;
> +}
> +
> +CONFIGFS_ATTR(gpio_sim_config_, line_names);
> +
> +static struct configfs_attribute *gpio_sim_config_attrs[] = {
> +	&gpio_sim_config_attr_dev_name,
> +	&gpio_sim_config_attr_chip_name,
> +	&gpio_sim_config_attr_label,
> +	&gpio_sim_config_attr_num_lines,
> +	&gpio_sim_config_attr_line_names,
> +	NULL
> +};
> +
> +static void gpio_sim_chip_config_release(struct config_item *item)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +
> +	mutex_destroy(&config->lock);
> +	kfree_strarray(config->line_names, config->num_line_names);
> +	kfree(config);
> +}
> +
> +static struct configfs_item_operations gpio_sim_config_item_ops = {
> +	.release	= gpio_sim_chip_config_release,
> +};
> +
> +static const struct config_item_type gpio_sim_chip_config_type = {
> +	.ct_item_ops	= &gpio_sim_config_item_ops,
> +	.ct_attrs	= gpio_sim_config_attrs,
> +	.ct_owner	= THIS_MODULE,
> +};
> +
> +static struct config_item *
> +gpio_sim_config_make_item(struct config_group *group, const char *name)
> +{
> +	struct gpio_sim_chip_config *config;
> +
> +	config = kzalloc(sizeof(*config), GFP_KERNEL);
> +	if (!config)
> +		return ERR_PTR(-ENOMEM);
> +
> +	config_item_init_type_name(&config->item, name,
> +				   &gpio_sim_chip_config_type);
> +	config->num_lines = 1;
> +	mutex_init(&config->lock);
> +
> +	return &config->item;
> +}
> +
> +static int gpio_sim_config_commit_item(struct config_item *item)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +	struct property_entry properties[GPIO_SIM_MAX_PROP];
> +	struct platform_device_info pdevinfo;
> +	struct platform_device *pdev;
> +	unsigned int prop_idx = 0;
> +
> +	memset(&pdevinfo, 0, sizeof(pdevinfo));
> +	memset(properties, 0, sizeof(properties));
> +
> +	mutex_lock(&config->lock);
> +
> +	properties[prop_idx++] = PROPERTY_ENTRY_U32("gpio-sim,nr-gpios",
> +						    config->num_lines);

> +	if (config->label[0] != '\0')

I'm wondering if we need this check. Isn't core taking care of it?

> +		properties[prop_idx++] = PROPERTY_ENTRY_STRING("gpio-sim,label",
> +							       config->label);

> +	if (config->line_names)

Ditto.

> +		properties[prop_idx++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
> +						"gpio-line-names",
> +						config->line_names,
> +						config->num_line_names);
> +
> +	pdevinfo.id = ida_alloc(&gpio_sim_ida, GFP_KERNEL);
> +	if (pdevinfo.id < 0) {
> +		mutex_unlock(&config->lock);
> +		return pdevinfo.id;
> +	}
> +
> +	pdevinfo.name = "gpio-sim";
> +	pdevinfo.properties = properties;
> +
> +	pdev = platform_device_register_full(&pdevinfo);
> +	if (IS_ERR(pdev)) {
> +		ida_free(&gpio_sim_ida, pdevinfo.id);
> +		mutex_unlock(&config->lock);
> +		return PTR_ERR(pdev);
> +	}
> +
> +	config->pdev = pdev;
> +	mutex_unlock(&config->lock);
> +
> +	return 0;
> +}
> +
> +static int gpio_sim_config_uncommit_item(struct config_item *item)
> +{
> +	struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> +	int id;
> +
> +	mutex_lock(&config->lock);
> +	id = config->pdev->id;
> +	platform_device_unregister(config->pdev);
> +	config->pdev = NULL;
> +	mutex_unlock(&config->lock);
> +
> +	ida_free(&gpio_sim_ida, id);
> +	return 0;
> +}
> +
> +static struct configfs_group_operations gpio_sim_config_group_ops = {
> +	.make_item	= gpio_sim_config_make_item,
> +	.commit_item	= gpio_sim_config_commit_item,
> +	.uncommit_item	= gpio_sim_config_uncommit_item,
> +};
> +
> +static const struct config_item_type gpio_sim_config_type = {
> +	.ct_group_ops	= &gpio_sim_config_group_ops,
> +	.ct_owner	= THIS_MODULE,
> +};
> +
> +static struct configfs_subsystem gpio_sim_config_subsys = {
> +	.su_group = {
> +		.cg_item = {
> +			.ci_namebuf	= "gpio-sim",
> +			.ci_type	= &gpio_sim_config_type,
> +		},
> +	},
> +};
> +
> +static int __init gpio_sim_init(void)
> +{
> +	int ret;
> +
> +	ret = platform_driver_register(&gpio_sim_driver);
> +	if (ret) {
> +		pr_err("Error %d while registering the platform driver\n", ret);
> +		return ret;
> +	}
> +
> +	config_group_init(&gpio_sim_config_subsys.su_group);
> +	mutex_init(&gpio_sim_config_subsys.su_mutex);
> +	ret = configfs_register_subsystem(&gpio_sim_config_subsys);
> +	if (ret) {
> +		pr_err("Error %d while registering the configfs subsystem %s\n",
> +		       ret, gpio_sim_config_subsys.su_group.cg_item.ci_namebuf);
> +		mutex_destroy(&gpio_sim_config_subsys.su_mutex);
> +		platform_driver_unregister(&gpio_sim_driver);
> +		return ret;
> +	}
> +
> +	return 0;
> +}
> +module_init(gpio_sim_init);
> +
> +static void __exit gpio_sim_exit(void)
> +{
> +	configfs_unregister_subsystem(&gpio_sim_config_subsys);
> +	mutex_destroy(&gpio_sim_config_subsys.su_mutex);
> +	platform_driver_unregister(&gpio_sim_driver);
> +}
> +module_exit(gpio_sim_exit);
> +
> +MODULE_AUTHOR("Bartosz Golaszewski <bgolaszewski@baylibre.com>");
> +MODULE_DESCRIPTION("GPIO Simulator Module");
> +MODULE_LICENSE("GPL");
> -- 
> 2.30.1
> 

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH v3 08/11] gpio: sim: new testing module

[Linus Walleij]

On Tue, Mar 9, 2021 at 9:59 PM Bartosz Golaszewski <brgl@bgdev.pl> wrote:

> From: Bartosz Golaszewski <bgolaszewski@baylibre.com>
>
> Implement a new, modern GPIO testing module controlled by configfs
> attributes instead of module parameters. The goal of this driver is
> to provide a replacement for gpio-mockup that will be easily extensible
> with new features and doesn't require reloading the module to change
> the setup.
>
> Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

This looks really useful and helpful and clean to me!
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>

Yours,
Linus Walleij

Re: [PATCH v3 08/11] gpio: sim: new testing module

[Bartosz Golaszewski]

On Wed, Mar 10, 2021 at 1:28 PM Andy Shevchenko
<andriy.shevchenko@linux.intel.com> wrote:
>

[snip]

> > +
> > +static ssize_t gpio_sim_sysfs_line_show(struct device *dev,
> > +                                     struct device_attribute *attr,
> > +                                     char *buf)
> > +{
> > +     struct gpio_sim_attribute *line_attr = to_gpio_sim_attr(attr);
> > +     struct gpio_sim_chip *chip = dev_get_drvdata(dev);
> > +     int ret;
> > +
> > +     mutex_lock(&chip->lock);
> > +     ret = sprintf(buf, "%u\n", !!test_bit(line_attr->offset, chip->values));
>
> Shouldn't we use sysfs_emit() in a new code?
>

TIL it exists. :) I'll use it.

[snip]

> > +
> > +static ssize_t gpio_sim_config_dev_name_show(struct config_item *item,
> > +                                          char *page)
> > +{
> > +     struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> > +     struct platform_device *pdev;
> > +     int ret;
> > +
> > +     mutex_lock(&config->lock);
> > +     pdev = config->pdev;
> > +     if (pdev)
> > +             ret = sprintf(page, "%s\n", dev_name(&pdev->dev));
> > +     else
> > +             ret = sprintf(page, "n/a\n");
>
> I dunno '/' (slash) is a good character to be handled in a shell.
> I would prefer 'none' or 'not available' (I think space is easier,
> because the rules to escape much simpler: need just to take it into
> quotes, while / needs to be escaped separately).
>

My test cases work fine with 'n/a' but I can change it to 'none' if
it's less controversial.

[snip]

>
> Also don't know what the rules about using s*printf() in the configfs.
> Maybe we have sysfs_emit() analogue or it doesn't applicable here at all.
> Greg?
>

There's no configfs_emit() or anything similar. Output for simple
attributes must simply not exceed 4096 bytes. It used to be PAGE_SIZE,
now it's defined in fs/configfs/file.c as SIMPLE_ATTR_SIZE. There's no
need to check the length of the string here though as we're only
showing what we received from the user-space anyway and configfs makes
sure we don't get more than SIMPLE_ATTR_SIZE in the store callback.

[snip]

> > +
> > +static int gpio_sim_config_commit_item(struct config_item *item)
> > +{
> > +     struct gpio_sim_chip_config *config = to_gpio_sim_chip_config(item);
> > +     struct property_entry properties[GPIO_SIM_MAX_PROP];
> > +     struct platform_device_info pdevinfo;
> > +     struct platform_device *pdev;
> > +     unsigned int prop_idx = 0;
> > +
> > +     memset(&pdevinfo, 0, sizeof(pdevinfo));
> > +     memset(properties, 0, sizeof(properties));
> > +
> > +     mutex_lock(&config->lock);
> > +
> > +     properties[prop_idx++] = PROPERTY_ENTRY_U32("gpio-sim,nr-gpios",
> > +                                                 config->num_lines);
>
> > +     if (config->label[0] != '\0')
>
> I'm wondering if we need this check. Isn't core taking care of it?
>
> > +             properties[prop_idx++] = PROPERTY_ENTRY_STRING("gpio-sim,label",
> > +                                                            config->label);
>
> > +     if (config->line_names)
>
> Ditto.
>
> > +             properties[prop_idx++] = PROPERTY_ENTRY_STRING_ARRAY_LEN(
> > +                                             "gpio-line-names",
> > +                                             config->line_names,
> > +                                             config->num_line_names);
> > +

But I would be creating empty properties for nothing. Better to just
not have them at all.

[snip]

Bartosz

Re: [PATCH v3 08/11] gpio: sim: new testing module

[Andy Shevchenko]

On Fri, Mar 12, 2021 at 09:54:58AM +0100, Bartosz Golaszewski wrote:
> On Wed, Mar 10, 2021 at 1:28 PM Andy Shevchenko
> <andriy.shevchenko@linux.intel.com> wrote:

...

> > > +             ret = sprintf(page, "n/a\n");
> >
> > I dunno '/' (slash) is a good character to be handled in a shell.
> > I would prefer 'none' or 'not available' (I think space is easier,
> > because the rules to escape much simpler: need just to take it into
> > quotes, while / needs to be escaped separately).
> >
> 
> My test cases work fine with 'n/a' but I can change it to 'none' if
> it's less controversial.


% git grep -n -w '"none"' -- drivers/ arch/ | wc -l
371

% git grep -n -w '"n/a"' -- drivers/ arch/ | wc -l
15

% git grep -n -w '"not available"' -- drivers/ arch/ | wc -l
5

...

> But I would be creating empty properties for nothing. Better to just
> not have them at all.

Up to you.

-- 
With Best Regards,
Andy Shevchenko