[PATCH v8 0/3] Enable PPI sysfs interface for TPM 2.0

[PATCH v8 0/3] Enable PPI sysfs interface for TPM 2.0

[Jarkko Sakkinen]

v8:
* Renamed sysfs_link_entry_to_kobj() to
  __compat_only_sysfs_link_entry_to_kobj()

v7:
* Fixed compile error when CONFIG_SYSFS is not enabled.

v6:
* Updated documentation.

v5:
* Removed dangling export of kernfs_remove_by_name_ns() from the sysfs
  patch.

v4:
* Use sysfs_remove_link()

v3:
* Fixed to_tpm_chip() macro.
* Split into two patches.
* Renamed sysfs_link_group_to_kobj to sysfs_link_entry_to_kobj
* Only create the "backwards compatibility" symlink for TPM 1.x devices.

Jarkko Sakkinen (3):
  sysfs: added sysfs_link_entry_to_kobj()
  tpm: move the PPI attributes to character device directory.
  tpm: update PPI documentation to address the location change.

 Documentation/ABI/testing/sysfs-driver-ppi | 19 ++++++++-----
 drivers/char/tpm/tpm-chip.c                | 24 ++++++++++------
 drivers/char/tpm/tpm.h                     | 17 ++++--------
 drivers/char/tpm/tpm_ppi.c                 | 34 ++++++++---------------
 fs/sysfs/group.c                           | 44 ++++++++++++++++++++++++++++++
 include/linux/sysfs.h                      | 10 +++++++
 6 files changed, 99 insertions(+), 49 deletions(-)

-- 
2.1.4

[PATCH v8 0/3] Enable PPI sysfs interface for TPM 2.0

[Jarkko Sakkinen]

v8:
* Renamed sysfs_link_entry_to_kobj() to
  __compat_only_sysfs_link_entry_to_kobj()

v7:
* Fixed compile error when CONFIG_SYSFS is not enabled.

v6:
* Updated documentation.

v5:
* Removed dangling export of kernfs_remove_by_name_ns() from the sysfs
  patch.

v4:
* Use sysfs_remove_link()

v3:
* Fixed to_tpm_chip() macro.
* Split into two patches.
* Renamed sysfs_link_group_to_kobj to sysfs_link_entry_to_kobj
* Only create the "backwards compatibility" symlink for TPM 1.x devices.

Jarkko Sakkinen (3):
  sysfs: added sysfs_link_entry_to_kobj()
  tpm: move the PPI attributes to character device directory.
  tpm: update PPI documentation to address the location change.

 Documentation/ABI/testing/sysfs-driver-ppi | 19 ++++++++-----
 drivers/char/tpm/tpm-chip.c                | 24 ++++++++++------
 drivers/char/tpm/tpm.h                     | 17 ++++--------
 drivers/char/tpm/tpm_ppi.c                 | 34 ++++++++---------------
 fs/sysfs/group.c                           | 44 ++++++++++++++++++++++++++++++
 include/linux/sysfs.h                      | 10 +++++++
 6 files changed, 99 insertions(+), 49 deletions(-)

-- 
2.1.4

[PATCH v8 1/3] sysfs: added sysfs_link_entry_to_kobj()

[Jarkko Sakkinen]

Added a new function sysfs_link_group_to_kobj() that adds a symlink
from attribute or group to a kobject. Exported kernfs_remove_by_name_ns
in order to provide a way to remove such symlinks.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 fs/sysfs/group.c      | 44 ++++++++++++++++++++++++++++++++++++++++++++
 include/linux/sysfs.h | 10 ++++++++++
 2 files changed, 54 insertions(+)

diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
index b400c04..0fb4b6e 100644
--- a/fs/sysfs/group.c
+++ b/fs/sysfs/group.c
@@ -352,3 +352,47 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 	}
 }
 EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
+
+/**
+ * __compat_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing
+ * to a group or an attribute
+ * @kobj:		The kobject containing the group.
+ * @target_kobj:	The target kobject.
+ * @target_name:	The name of the target group or attribute.
+ */
+int __compat_sysfs_link_entry_to_kobj(struct kobject *kobj,
+				      struct kobject *target_kobj,
+				      const char *target_name)
+{
+	struct kernfs_node *target;
+	struct kernfs_node *entry;
+	struct kernfs_node *link;
+
+	/*
+	 * We don't own @target_kobj and it may be removed at any time.
+	 * Synchronize using sysfs_symlink_target_lock. See sysfs_remove_dir()
+	 * for details.
+	 */
+	spin_lock(&sysfs_symlink_target_lock);
+	target = target_kobj->sd;
+	if (target)
+		kernfs_get(target);
+	spin_unlock(&sysfs_symlink_target_lock);
+	if (!target)
+		return -ENOENT;
+
+	entry = kernfs_find_and_get(target_kobj->sd, target_name);
+	if (!entry) {
+		kernfs_put(target);
+		return -ENOENT;
+	}
+
+	link = kernfs_create_link(kobj->sd, target_name, entry);
+	if (IS_ERR(link) && PTR_ERR(link) == -EEXIST)
+		sysfs_warn_dup(kobj->sd, target_name);
+
+	kernfs_put(entry);
+	kernfs_put(target);
+	return IS_ERR(link) ? PTR_ERR(link) : 0;
+}
+EXPORT_SYMBOL_GPL(__compat_sysfs_link_entry_to_kobj);
diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
index 99382c0..f30b663 100644
--- a/include/linux/sysfs.h
+++ b/include/linux/sysfs.h
@@ -264,6 +264,9 @@ int sysfs_add_link_to_group(struct kobject *kobj, const char *group_name,
 			    struct kobject *target, const char *link_name);
 void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
 				  const char *link_name);
+int __compat_sysfs_link_entry_to_kobj(struct kobject *kobj,
+				      struct kobject *target_kobj,
+				      const char *target_name);
 
 void sysfs_notify(struct kobject *kobj, const char *dir, const char *attr);
 
@@ -436,6 +439,13 @@ static inline void sysfs_remove_link_from_group(struct kobject *kobj,
 {
 }
 
+static inline int __compat_sysfs_link_entry_to_kobj(struct kobject *kobj,
+						    struct kobject *target_kobj,
+						    const char *target_name)
+{
+	return 0;
+}
+
 static inline void sysfs_notify(struct kobject *kobj, const char *dir,
 				const char *attr)
 {
-- 
2.1.4

Re: [PATCH v8 1/3] sysfs: added sysfs_link_entry_to_kobj()

[Greg Kroah-Hartman]

On Fri, Jul 03, 2015 at 05:27:18PM +0300, Jarkko Sakkinen wrote:
> Added a new function sysfs_link_group_to_kobj() that adds a symlink
> from attribute or group to a kobject. Exported kernfs_remove_by_name_ns
> in order to provide a way to remove such symlinks.

This text doesn't match the function name you exported :(

> 
> Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> ---
>  fs/sysfs/group.c      | 44 ++++++++++++++++++++++++++++++++++++++++++++
>  include/linux/sysfs.h | 10 ++++++++++
>  2 files changed, 54 insertions(+)
> 
> diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> index b400c04..0fb4b6e 100644
> --- a/fs/sysfs/group.c
> +++ b/fs/sysfs/group.c
> @@ -352,3 +352,47 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
>  	}
>  }
>  EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
> +
> +/**
> + * __compat_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing

Why __compat?

Re: [PATCH v8 1/3] sysfs: added sysfs_link_entry_to_kobj()

[Jarkko Sakkinen]

On Wed, Aug 05, 2015 at 01:11:23PM -0700, Greg Kroah-Hartman wrote:
> On Fri, Jul 03, 2015 at 05:27:18PM +0300, Jarkko Sakkinen wrote:
> > Added a new function sysfs_link_group_to_kobj() that adds a symlink
> > from attribute or group to a kobject. Exported kernfs_remove_by_name_ns
> > in order to provide a way to remove such symlinks.
> 
> This text doesn't match the function name you exported :(

D'oh.

> > 
> > Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
> > ---
> >  fs/sysfs/group.c      | 44 ++++++++++++++++++++++++++++++++++++++++++++
> >  include/linux/sysfs.h | 10 ++++++++++
> >  2 files changed, 54 insertions(+)
> > 
> > diff --git a/fs/sysfs/group.c b/fs/sysfs/group.c
> > index b400c04..0fb4b6e 100644
> > --- a/fs/sysfs/group.c
> > +++ b/fs/sysfs/group.c
> > @@ -352,3 +352,47 @@ void sysfs_remove_link_from_group(struct kobject *kobj, const char *group_name,
> >  	}
> >  }
> >  EXPORT_SYMBOL_GPL(sysfs_remove_link_from_group);
> > +
> > +/**
> > + * __compat_sysfs_link_entry_to_kobj - add a symlink to a kobject pointing
> 
> Why __compat?

https://lkml.org/lkml/2015/7/2/455

Although, should have been '__compat_only'.

/Jarkko

[PATCH v8 2/3] tpm: move the PPI attributes to character device directory.

[Jarkko Sakkinen]

Moved PPI attributes to the character device directory. This aligns with
the sysfs guidelines and makes them race free because they are created
atomically with the character device as part of device_register().The
character device and the sysfs attributes appear at the same time to the
user space.

As part of this change we enable PPI attributes also for TPM 2.0
devices. In order to retain backwards compatibility with TPM 1.x
devices, a symlink is created to the platform device directory.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
Reviewed-by: Jason Gunthorpe <jason.gunthorpe@obsidianresearch.com>
---
 drivers/char/tpm/tpm-chip.c | 24 ++++++++++++++++--------
 drivers/char/tpm/tpm.h      | 17 ++++++-----------
 drivers/char/tpm/tpm_ppi.c  | 34 +++++++++++-----------------------
 3 files changed, 33 insertions(+), 42 deletions(-)

diff --git a/drivers/char/tpm/tpm-chip.c b/drivers/char/tpm/tpm-chip.c
index 283f00a..bdfaf86 100644
--- a/drivers/char/tpm/tpm-chip.c
+++ b/drivers/char/tpm/tpm-chip.c
@@ -119,6 +119,9 @@ struct tpm_chip *tpmm_chip_alloc(struct device *dev,
 	chip->dev.class = tpm_class;
 	chip->dev.release = tpm_dev_release;
 	chip->dev.parent = chip->pdev;
+#ifdef CONFIG_ACPI
+	chip->dev.groups = chip->groups;
+#endif
 
 	if (chip->dev_num == 0)
 		chip->dev.devt = MKDEV(MISC_MAJOR, TPM_MINOR);
@@ -181,12 +184,6 @@ static int tpm1_chip_register(struct tpm_chip *chip)
 	if (rc)
 		return rc;
 
-	rc = tpm_add_ppi(chip);
-	if (rc) {
-		tpm_sysfs_del_device(chip);
-		return rc;
-	}
-
 	chip->bios_dir = tpm_bios_log_setup(chip->devname);
 
 	return 0;
@@ -200,8 +197,6 @@ static void tpm1_chip_unregister(struct tpm_chip *chip)
 	if (chip->bios_dir)
 		tpm_bios_log_teardown(chip->bios_dir);
 
-	tpm_remove_ppi(chip);
-
 	tpm_sysfs_del_device(chip);
 }
 
@@ -224,10 +219,20 @@ int tpm_chip_register(struct tpm_chip *chip)
 	if (rc)
 		return rc;
 
+	tpm_add_ppi(chip);
+
 	rc = tpm_dev_add_device(chip);
 	if (rc)
 		goto out_err;
 
+	if (!(chip->flags & TPM_CHIP_FLAG_TPM2)) {
+		rc = __compat_sysfs_link_entry_to_kobj(&chip->pdev->kobj,
+						       &chip->dev.kobj,
+						       "ppi");
+		if (rc)
+			goto out_err;
+	}
+
 	/* Make the chip available. */
 	spin_lock(&driver_lock);
 	list_add_rcu(&chip->list, &tpm_chip_list);
@@ -262,6 +267,9 @@ void tpm_chip_unregister(struct tpm_chip *chip)
 	spin_unlock(&driver_lock);
 	synchronize_rcu();
 
+	if (!(chip->flags & TPM_CHIP_FLAG_TPM2))
+		sysfs_remove_link(&chip->pdev->kobj, "ppi");
+
 	tpm1_chip_unregister(chip);
 	tpm_dev_del_device(chip);
 }
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index f8319a0..5e7231a 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -151,8 +151,7 @@ struct tpm_vendor_specific {
 
 enum tpm_chip_flags {
 	TPM_CHIP_FLAG_REGISTERED	= BIT(0),
-	TPM_CHIP_FLAG_PPI		= BIT(1),
-	TPM_CHIP_FLAG_TPM2		= BIT(2),
+	TPM_CHIP_FLAG_TPM2		= BIT(1),
 };
 
 struct tpm_chip {
@@ -175,6 +174,8 @@ struct tpm_chip {
 	struct dentry **bios_dir;
 
 #ifdef CONFIG_ACPI
+	const struct attribute_group *groups[2];
+	unsigned int groups_cnt;
 	acpi_handle acpi_dev_handle;
 	char ppi_version[TPM_PPI_VERSION_LEN + 1];
 #endif /* CONFIG_ACPI */
@@ -182,7 +183,7 @@ struct tpm_chip {
 	struct list_head list;
 };
 
-#define to_tpm_chip(n) container_of(n, struct tpm_chip, vendor)
+#define to_tpm_chip(d) container_of(d, struct tpm_chip, dev)
 
 static inline void tpm_chip_put(struct tpm_chip *chip)
 {
@@ -412,15 +413,9 @@ void tpm_sysfs_del_device(struct tpm_chip *chip);
 int tpm_pcr_read_dev(struct tpm_chip *chip, int pcr_idx, u8 *res_buf);
 
 #ifdef CONFIG_ACPI
-extern int tpm_add_ppi(struct tpm_chip *chip);
-extern void tpm_remove_ppi(struct tpm_chip *chip);
+extern void tpm_add_ppi(struct tpm_chip *chip);
 #else
-static inline int tpm_add_ppi(struct tpm_chip *chip)
-{
-	return 0;
-}
-
-static inline void tpm_remove_ppi(struct tpm_chip *chip)
+static inline void tpm_add_ppi(struct tpm_chip *chip)
 {
 }
 #endif
diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
index 6ca9b5d..692a2c6 100644
--- a/drivers/char/tpm/tpm_ppi.c
+++ b/drivers/char/tpm/tpm_ppi.c
@@ -53,7 +53,7 @@ tpm_eval_dsm(acpi_handle ppi_handle, int func, acpi_object_type type,
 static ssize_t tpm_show_ppi_version(struct device *dev,
 				    struct device_attribute *attr, char *buf)
 {
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	return scnprintf(buf, PAGE_SIZE, "%s\n", chip->ppi_version);
 }
@@ -63,7 +63,7 @@ static ssize_t tpm_show_ppi_request(struct device *dev,
 {
 	ssize_t size = -EINVAL;
 	union acpi_object *obj;
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETREQ,
 			   ACPI_TYPE_PACKAGE, NULL);
@@ -100,7 +100,7 @@ static ssize_t tpm_store_ppi_request(struct device *dev,
 	int func = TPM_PPI_FN_SUBREQ;
 	union acpi_object *obj, tmp;
 	union acpi_object argv4 = ACPI_INIT_DSM_ARGV4(1, &tmp);
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	/*
 	 * the function to submit TPM operation request to pre-os environment
@@ -156,7 +156,7 @@ static ssize_t tpm_show_ppi_transition_action(struct device *dev,
 		.buffer.length = 0,
 		.buffer.pointer = NULL
 	};
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	static char *info[] = {
 		"None",
@@ -197,7 +197,7 @@ static ssize_t tpm_show_ppi_response(struct device *dev,
 	acpi_status status = -EINVAL;
 	union acpi_object *obj, *ret_obj;
 	u64 req, res;
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	obj = tpm_eval_dsm(chip->acpi_dev_handle, TPM_PPI_FN_GETRSP,
 			   ACPI_TYPE_PACKAGE, NULL);
@@ -296,7 +296,7 @@ static ssize_t tpm_show_ppi_tcg_operations(struct device *dev,
 					   struct device_attribute *attr,
 					   char *buf)
 {
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	return show_ppi_operations(chip->acpi_dev_handle, buf, 0,
 				   PPI_TPM_REQ_MAX);
@@ -306,7 +306,7 @@ static ssize_t tpm_show_ppi_vs_operations(struct device *dev,
 					  struct device_attribute *attr,
 					  char *buf)
 {
-	struct tpm_chip *chip = dev_get_drvdata(dev);
+	struct tpm_chip *chip = to_tpm_chip(dev);
 
 	return show_ppi_operations(chip->acpi_dev_handle, buf, PPI_VS_REQ_START,
 				   PPI_VS_REQ_END);
@@ -334,17 +334,16 @@ static struct attribute_group ppi_attr_grp = {
 	.attrs = ppi_attrs
 };
 
-int tpm_add_ppi(struct tpm_chip *chip)
+void tpm_add_ppi(struct tpm_chip *chip)
 {
 	union acpi_object *obj;
-	int rc;
 
 	if (!chip->acpi_dev_handle)
-		return 0;
+		return;
 
 	if (!acpi_check_dsm(chip->acpi_dev_handle, tpm_ppi_uuid,
 			    TPM_PPI_REVISION_ID, 1 << TPM_PPI_FN_VERSION))
-		return 0;
+		return;
 
 	/* Cache PPI version string. */
 	obj = acpi_evaluate_dsm_typed(chip->acpi_dev_handle, tpm_ppi_uuid,
@@ -356,16 +355,5 @@ int tpm_add_ppi(struct tpm_chip *chip)
 		ACPI_FREE(obj);
 	}
 
-	rc = sysfs_create_group(&chip->pdev->kobj, &ppi_attr_grp);
-
-	if (!rc)
-		chip->flags |= TPM_CHIP_FLAG_PPI;
-
-	return rc;
-}
-
-void tpm_remove_ppi(struct tpm_chip *chip)
-{
-	if (chip->flags & TPM_CHIP_FLAG_PPI)
-		sysfs_remove_group(&chip->pdev->kobj, &ppi_attr_grp);
+	chip->groups[chip->groups_cnt++] = &ppi_attr_grp;
 }
-- 
2.1.4

[PATCH v8 3/3] tpm: update PPI documentation to address the location change.

[Jarkko Sakkinen]

Updated Documentation/ABI/testing/sysfs-driver-ppi in order to explain
where PPI attributes are located and how backwards compatiblity is
addressed.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen-VuQAYsv1563Yd54FQh9/CA@public.gmane.org>
---
 Documentation/ABI/testing/sysfs-driver-ppi | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-driver-ppi b/Documentation/ABI/testing/sysfs-driver-ppi
index 7d1435b..9921ef2 100644
--- a/Documentation/ABI/testing/sysfs-driver-ppi
+++ b/Documentation/ABI/testing/sysfs-driver-ppi
@@ -1,4 +1,4 @@
-What:		/sys/devices/pnp0/<bus-num>/ppi/
+What:		/sys/class/tpm/tpmX/ppi/
 Date:		August 2012
 Kernel Version:	3.6
 Contact:	xiaoyan.zhang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org
@@ -8,9 +8,14 @@ Description:
 		folder makes sense. The folder path can be got by command
 		'find /sys/ -name 'pcrs''. For the detail information of PPI,
 		please refer to the PPI specification from
+
 		http://www.trustedcomputinggroup.org/
 
-What:		/sys/devices/pnp0/<bus-num>/ppi/version
+		In Linux 4.2 ppi was moved to the character device directory.
+		A symlink from tpmX/device/ppi to tpmX/ppi to provide backwards
+		compatibility.
+
+What:		/sys/class/tpm/tpmX/ppi/version
 Date:		August 2012
 Contact:	xiaoyan.zhang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org
 Description:
@@ -18,7 +23,7 @@ Description:
 		platform.
 		This file is readonly.
 
-What:		/sys/devices/pnp0/<bus-num>/ppi/request
+What:		/sys/class/tpm/tpmX/ppi/request
 Date:		August 2012
 Contact:	xiaoyan.zhang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org
 Description:
@@ -28,7 +33,7 @@ Description:
 		integer value range from 1 to 160, and 0 means no request.
 		This file can be read and written.
 
-What:		/sys/devices/pnp0/00:<bus-num>/ppi/response
+What:		/sys/class/tpm/tpmX/ppi/response
 Date:		August 2012
 Contact:	xiaoyan.zhang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org
 Description:
@@ -37,7 +42,7 @@ Description:
 		: <response description>".
 		This file is readonly.
 
-What:		/sys/devices/pnp0/<bus-num>/ppi/transition_action
+What:		/sys/class/tpm/tpmX/ppi/transition_action
 Date:		August 2012
 Contact:	xiaoyan.zhang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org
 Description:
@@ -47,7 +52,7 @@ Description:
 		description>".
 		This file is readonly.
 
-What:		/sys/devices/pnp0/<bus-num>/ppi/tcg_operations
+What:		/sys/class/tpm/tpmX/ppi/tcg_operations
 Date:		August 2012
 Contact:	xiaoyan.zhang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org
 Description:
@@ -58,7 +63,7 @@ Description:
 		This attribute is only supported by PPI version 1.2+.
 		This file is readonly.
 
-What:		/sys/devices/pnp0/<bus-num>/ppi/vs_operations
+What:		/sys/class/tpm/tpmX/ppi/vs_operations
 Date:		August 2012
 Contact:	xiaoyan.zhang-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org
 Description:
-- 
2.1.4

[PATCH v8 3/3] tpm: update PPI documentation to address the location change.

[Jarkko Sakkinen]

Updated Documentation/ABI/testing/sysfs-driver-ppi in order to explain
where PPI attributes are located and how backwards compatiblity is
addressed.

Signed-off-by: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
---
 Documentation/ABI/testing/sysfs-driver-ppi | 19 ++++++++++++-------
 1 file changed, 12 insertions(+), 7 deletions(-)

diff --git a/Documentation/ABI/testing/sysfs-driver-ppi b/Documentation/ABI/testing/sysfs-driver-ppi
index 7d1435b..9921ef2 100644
--- a/Documentation/ABI/testing/sysfs-driver-ppi
+++ b/Documentation/ABI/testing/sysfs-driver-ppi
@@ -1,4 +1,4 @@
-What:		/sys/devices/pnp0/<bus-num>/ppi/
+What:		/sys/class/tpm/tpmX/ppi/
 Date:		August 2012
 Kernel Version:	3.6
 Contact:	xiaoyan.zhang@intel.com
@@ -8,9 +8,14 @@ Description:
 		folder makes sense. The folder path can be got by command
 		'find /sys/ -name 'pcrs''. For the detail information of PPI,
 		please refer to the PPI specification from
+
 		http://www.trustedcomputinggroup.org/
 
-What:		/sys/devices/pnp0/<bus-num>/ppi/version
+		In Linux 4.2 ppi was moved to the character device directory.
+		A symlink from tpmX/device/ppi to tpmX/ppi to provide backwards
+		compatibility.
+
+What:		/sys/class/tpm/tpmX/ppi/version
 Date:		August 2012
 Contact:	xiaoyan.zhang@intel.com
 Description:
@@ -18,7 +23,7 @@ Description:
 		platform.
 		This file is readonly.
 
-What:		/sys/devices/pnp0/<bus-num>/ppi/request
+What:		/sys/class/tpm/tpmX/ppi/request
 Date:		August 2012
 Contact:	xiaoyan.zhang@intel.com
 Description:
@@ -28,7 +33,7 @@ Description:
 		integer value range from 1 to 160, and 0 means no request.
 		This file can be read and written.
 
-What:		/sys/devices/pnp0/00:<bus-num>/ppi/response
+What:		/sys/class/tpm/tpmX/ppi/response
 Date:		August 2012
 Contact:	xiaoyan.zhang@intel.com
 Description:
@@ -37,7 +42,7 @@ Description:
 		: <response description>".
 		This file is readonly.
 
-What:		/sys/devices/pnp0/<bus-num>/ppi/transition_action
+What:		/sys/class/tpm/tpmX/ppi/transition_action
 Date:		August 2012
 Contact:	xiaoyan.zhang@intel.com
 Description:
@@ -47,7 +52,7 @@ Description:
 		description>".
 		This file is readonly.
 
-What:		/sys/devices/pnp0/<bus-num>/ppi/tcg_operations
+What:		/sys/class/tpm/tpmX/ppi/tcg_operations
 Date:		August 2012
 Contact:	xiaoyan.zhang@intel.com
 Description:
@@ -58,7 +63,7 @@ Description:
 		This attribute is only supported by PPI version 1.2+.
 		This file is readonly.
 
-What:		/sys/devices/pnp0/<bus-num>/ppi/vs_operations
+What:		/sys/class/tpm/tpmX/ppi/vs_operations
 Date:		August 2012
 Contact:	xiaoyan.zhang@intel.com
 Description:
-- 
2.1.4