[Intel-gfx] [PATCH 04/11] drm: document drm_ioctl.[hc]
Daniel Vetter
daniel.vetter at ffwll.ch
Tue Apr 4 09:52:57 UTC 2017
Also unify/merge with the existing stuff.
I was a bit torn where to put this, but in the end I decided to put
all the ioctl/sysfs/debugfs stuff into drm-uapi.rst. That means we
have a bit a split with the other uapi related stuff used internally,
like drm_file.[hc], but I think overall this makes more sense.
If it's too confusing we can always add more cross-links to make it
more discoverable. But the auto-sprinkling of links kernel-doc already
does seems sufficient.
Also for prettier docs and more cross-links, switch the internal
defines over to an enum, as usual.
v2: Update kerneldoc fro drm_compat_ioctl too (caught by 0day), plus a
bit more drive-by polish.
v3: Fix typo, spotted by xerpi on irc (Sergi).
Cc: Sergi Granell <xerpi.g.12 at gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter at intel.com>
---
Documentation/gpu/drm-internals.rst | 50 ----------------
Documentation/gpu/drm-uapi.rst | 14 +++++
drivers/gpu/drm/drm_ioc32.c | 76 ++++++++++++-----------
drivers/gpu/drm/drm_ioctl.c | 50 +++++++++++++++-
include/drm/drm_ioctl.h | 116 +++++++++++++++++++++++++++++++-----
5 files changed, 203 insertions(+), 103 deletions(-)
diff --git a/Documentation/gpu/drm-internals.rst b/Documentation/gpu/drm-internals.rst
index a09c721f9e89..babfb6143bd9 100644
--- a/Documentation/gpu/drm-internals.rst
+++ b/Documentation/gpu/drm-internals.rst
@@ -255,56 +255,6 @@ File Operations
.. kernel-doc:: drivers/gpu/drm/drm_file.c
:export:
-IOCTLs
-------
-
-struct drm_ioctl_desc \*ioctls; int num_ioctls;
- Driver-specific ioctls descriptors table.
-
-Driver-specific ioctls numbers start at DRM_COMMAND_BASE. The ioctls
-descriptors table is indexed by the ioctl number offset from the base
-value. Drivers can use the DRM_IOCTL_DEF_DRV() macro to initialize
-the table entries.
-
-::
-
- DRM_IOCTL_DEF_DRV(ioctl, func, flags)
-
-``ioctl`` is the ioctl name. Drivers must define the DRM_##ioctl and
-DRM_IOCTL_##ioctl macros to the ioctl number offset from
-DRM_COMMAND_BASE and the ioctl number respectively. The first macro is
-private to the device while the second must be exposed to userspace in a
-public header.
-
-``func`` is a pointer to the ioctl handler function compatible with the
-``drm_ioctl_t`` type.
-
-::
-
- typedef int drm_ioctl_t(struct drm_device *dev, void *data,
- struct drm_file *file_priv);
-
-``flags`` is a bitmask combination of the following values. It restricts
-how the ioctl is allowed to be called.
-
-- DRM_AUTH - Only authenticated callers allowed
-
-- DRM_MASTER - The ioctl can only be called on the master file handle
-
-- DRM_ROOT_ONLY - Only callers with the SYSADMIN capability allowed
-
-- DRM_CONTROL_ALLOW - The ioctl can only be called on a control
- device
-
-- DRM_UNLOCKED - The ioctl handler will be called without locking the
- DRM global mutex. This is the enforced default for kms drivers (i.e.
- using the DRIVER_MODESET flag) and hence shouldn't be used any more
- for new drivers.
-
-.. kernel-doc:: drivers/gpu/drm/drm_ioctl.c
- :export:
-
-
Misc Utilities
==============
diff --git a/Documentation/gpu/drm-uapi.rst b/Documentation/gpu/drm-uapi.rst
index 8b0f0e403f0c..858457567d3d 100644
--- a/Documentation/gpu/drm-uapi.rst
+++ b/Documentation/gpu/drm-uapi.rst
@@ -160,6 +160,20 @@ other hand, a driver requires shared state between clients which is
visible to user-space and accessible beyond open-file boundaries, they
cannot support render nodes.
+IOCTL Support on Device Nodes
+=============================
+
+.. kernel-doc:: drivers/gpu/drm/drm_ioctl.c
+ :doc: driver specific ioctls
+
+.. kernel-doc:: include/drm/drm_ioctl.h
+ :internal:
+
+.. kernel-doc:: drivers/gpu/drm/drm_ioctl.c
+ :export:
+
+.. kernel-doc:: drivers/gpu/drm/drm_ioc32.c
+ :export:
Testing and validation
======================
diff --git a/drivers/gpu/drm/drm_ioc32.c b/drivers/gpu/drm/drm_ioc32.c
index b134482f4022..0fa7827cb0fd 100644
--- a/drivers/gpu/drm/drm_ioc32.c
+++ b/drivers/gpu/drm/drm_ioc32.c
@@ -1,4 +1,4 @@
-/**
+/*
* \file drm_ioc32.c
*
* 32-bit ioctl compatibility routines for the DRM.
@@ -72,15 +72,15 @@
#define DRM_IOCTL_MODE_ADDFB232 DRM_IOWR(0xb8, drm_mode_fb_cmd232_t)
typedef struct drm_version_32 {
- int version_major; /**< Major version */
- int version_minor; /**< Minor version */
- int version_patchlevel; /**< Patch level */
- u32 name_len; /**< Length of name buffer */
- u32 name; /**< Name of driver */
- u32 date_len; /**< Length of date buffer */
- u32 date; /**< User-space buffer to hold date */
- u32 desc_len; /**< Length of desc buffer */
- u32 desc; /**< User-space buffer to hold desc */
+ int version_major; /* Major version */
+ int version_minor; /* Minor version */
+ int version_patchlevel; /* Patch level */
+ u32 name_len; /* Length of name buffer */
+ u32 name; /* Name of driver */
+ u32 date_len; /* Length of date buffer */
+ u32 date; /* User-space buffer to hold date */
+ u32 desc_len; /* Length of desc buffer */
+ u32 desc; /* User-space buffer to hold desc */
} drm_version32_t;
static int compat_drm_version(struct file *file, unsigned int cmd,
@@ -126,8 +126,8 @@ static int compat_drm_version(struct file *file, unsigned int cmd,
}
typedef struct drm_unique32 {
- u32 unique_len; /**< Length of unique */
- u32 unique; /**< Unique name for driver instantiation */
+ u32 unique_len; /* Length of unique */
+ u32 unique; /* Unique name for driver instantiation */
} drm_unique32_t;
static int compat_drm_getunique(struct file *file, unsigned int cmd,
@@ -180,12 +180,12 @@ static int compat_drm_setunique(struct file *file, unsigned int cmd,
}
typedef struct drm_map32 {
- u32 offset; /**< Requested physical address (0 for SAREA)*/
- u32 size; /**< Requested physical size (bytes) */
- enum drm_map_type type; /**< Type of memory to map */
- enum drm_map_flags flags; /**< Flags */
- u32 handle; /**< User-space: "Handle" to pass to mmap() */
- int mtrr; /**< MTRR slot used */
+ u32 offset; /* Requested physical address (0 for SAREA)*/
+ u32 size; /* Requested physical size (bytes) */
+ enum drm_map_type type; /* Type of memory to map */
+ enum drm_map_flags flags; /* Flags */
+ u32 handle; /* User-space: "Handle" to pass to mmap() */
+ int mtrr; /* MTRR slot used */
} drm_map32_t;
static int compat_drm_getmap(struct file *file, unsigned int cmd,
@@ -286,12 +286,12 @@ static int compat_drm_rmmap(struct file *file, unsigned int cmd,
}
typedef struct drm_client32 {
- int idx; /**< Which client desired? */
- int auth; /**< Is client authenticated? */
- u32 pid; /**< Process ID */
- u32 uid; /**< User ID */
- u32 magic; /**< Magic */
- u32 iocs; /**< Ioctl count */
+ int idx; /* Which client desired? */
+ int auth; /* Is client authenticated? */
+ u32 pid; /* Process ID */
+ u32 uid; /* User ID */
+ u32 magic; /* Magic */
+ u32 iocs; /* Ioctl count */
} drm_client32_t;
static int compat_drm_getclient(struct file *file, unsigned int cmd,
@@ -366,12 +366,12 @@ static int compat_drm_getstats(struct file *file, unsigned int cmd,
}
typedef struct drm_buf_desc32 {
- int count; /**< Number of buffers of this size */
- int size; /**< Size in bytes */
- int low_mark; /**< Low water mark */
- int high_mark; /**< High water mark */
+ int count; /* Number of buffers of this size */
+ int size; /* Size in bytes */
+ int low_mark; /* Low water mark */
+ int high_mark; /* High water mark */
int flags;
- u32 agp_start; /**< Start address in the AGP aperture */
+ u32 agp_start; /* Start address in the AGP aperture */
} drm_buf_desc32_t;
static int compat_drm_addbufs(struct file *file, unsigned int cmd,
@@ -1111,13 +1111,18 @@ static drm_ioctl_compat_t *drm_compat_ioctls[] = {
};
/**
- * Called whenever a 32-bit process running under a 64-bit kernel
- * performs an ioctl on /dev/drm.
+ * drm_compat_ioctl - 32bit IOCTL compatibility handler for DRM drivers
+ * @filp: file this ioctl is called on
+ * @cmd: ioctl cmd number
+ * @arg: user argument
+ *
+ * Compatibility handler for 32 bit userspace running on 64 kernels. All actual
+ * IOCTL handling is forwarded to drm_ioctl(), while marshalling structures as
+ * appropriate. Note that this only handles DRM core IOCTLs, if the driver has
+ * botched IOCTL itself, it must handle those by wrapping this function.
*
- * \param file_priv DRM file private.
- * \param cmd command.
- * \param arg user argument.
- * \return zero on success or negative number on failure.
+ * Returns:
+ * Zero on success, negative error code on failure.
*/
long drm_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
{
@@ -1141,5 +1146,4 @@ long drm_compat_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
return ret;
}
-
EXPORT_SYMBOL(drm_compat_ioctl);
diff --git a/drivers/gpu/drm/drm_ioctl.c b/drivers/gpu/drm/drm_ioctl.c
index 7f4f4f48e390..f908ea94b784 100644
--- a/drivers/gpu/drm/drm_ioctl.c
+++ b/drivers/gpu/drm/drm_ioctl.c
@@ -647,13 +647,59 @@ static const struct drm_ioctl_desc drm_ioctls[] = {
#define DRM_CORE_IOCTL_COUNT ARRAY_SIZE( drm_ioctls )
/**
+ * DOC: driver specific ioctls
+ *
+ * First things first, driver private IOCTLs should only be needed for drivers
+ * supporting rendering. Kernel modesetting is all standardized, and extended
+ * through properties. There are a few exceptions in some existing drivers,
+ * which define IOCTL for use by the display DRM master, but they all predate
+ * properties.
+ *
+ * Now if you do have a render driver you always have to support it through
+ * driver private properties. There's a few steps needed to wire all the things
+ * up.
+ *
+ * First you need to define the structure for your IOCTL in your driver private
+ * UAPI header in ``include/uapi/drm/my_driver_drm.h``::
+ *
+ * struct my_driver_operation {
+ * u32 some_thing;
+ * u32 another_thing;
+ * };
+ *
+ * Please make sure that you follow all the best practices from
+ * ``Documentation/ioctl/botching-up-ioctls.txt``. Note that drm_ioctl()
+ * automatically zero-extends structures, hence make sure you can add more stuff
+ * at the end, i.e. don't put a variable sized array there.
+ *
+ * Then you need to define your IOCTL number, using one of DRM_IO(), DRM_IOR(),
+ * DRM_IOW() or DRM_IOWR(). It must start with the DRM_IOCTL\_ prefix::
+ *
+ * ##define DRM_IOCTL_MY_DRIVER_OPERATION \
+ * DRM_IOW(DRM_COMMAND_BASE, struct my_driver_operation)
+ *
+ * DRM driver private IOCTL must be in the range from DRM_COMMAND_BASE to
+ * DRM_COMMAND_END. Finally you need an array of &struct drm_ioctl_desc to wire
+ * up the handlers and set the access rights:
+ *
+ * static const struct drm_ioctl_desc my_driver_ioctls[] = {
+ * DRM_IOCTL_DEF_DRV(MY_DRIVER_OPERATION, my_driver_operation,
+ * DRM_AUTH|DRM_RENDER_ALLOW),
+ * };
+ *
+ * And then assign this to the &drm_driver.ioctls field in your driver
+ * structure.
+ */
+
+/**
* drm_ioctl - ioctl callback implementation for DRM drivers
* @filp: file this ioctl is called on
* @cmd: ioctl cmd number
* @arg: user argument
*
- * Looks up the ioctl function in the ::ioctls table, checking for root
- * previleges if so required, and dispatches to the respective function.
+ * Looks up the ioctl function in the DRM core and the driver dispatch table,
+ * stored in &drm_driver.ioctls. It checks for necessary permission by calling
+ * drm_ioctl_permit(), and dispatches to the respective function.
*
* Returns:
* Zero on success, negative error code on failure.
diff --git a/include/drm/drm_ioctl.h b/include/drm/drm_ioctl.h
index f17ee077f649..ee03b3c44b3b 100644
--- a/include/drm/drm_ioctl.h
+++ b/include/drm/drm_ioctl.h
@@ -33,6 +33,7 @@
#define _DRM_IOCTL_H_
#include <linux/types.h>
+#include <linux/bitops.h>
#include <asm/ioctl.h>
@@ -41,41 +42,126 @@ struct drm_file;
struct file;
/**
- * Ioctl function type.
+ * drm_ioctl_t - DRM ioctl function type.
+ * @dev: DRM device inode
+ * @data: private pointer of the ioctl call
+ * @file_priv: DRM file this ioctl was made on
*
- * \param inode device inode.
- * \param file_priv DRM file private pointer.
- * \param cmd command.
- * \param arg argument.
+ * This is the DRM ioctl typedef. Note that drm_ioctl() has alrady copied @data
+ * into kernel-space, and will also copy it back, depending upon the read/write
+ * settings in the ioctl command code.
*/
typedef int drm_ioctl_t(struct drm_device *dev, void *data,
struct drm_file *file_priv);
+/**
+ * drm_ioctl_compat_t - compatibility DRM ioctl function type.
+ * @filp: file pointer
+ * @cmd: ioctl command code
+ * @arg: DRM file this ioctl was made on
+ *
+ * Just a typedef to make declaring an array of compatibility handlers easier.
+ * New drivers shouldn't screw up the structure layout for their ioctl
+ * structures and hence never need this.
+ */
typedef int drm_ioctl_compat_t(struct file *filp, unsigned int cmd,
unsigned long arg);
#define DRM_IOCTL_NR(n) _IOC_NR(n)
#define DRM_MAJOR 226
-#define DRM_AUTH 0x1
-#define DRM_MASTER 0x2
-#define DRM_ROOT_ONLY 0x4
-#define DRM_CONTROL_ALLOW 0x8
-#define DRM_UNLOCKED 0x10
-#define DRM_RENDER_ALLOW 0x20
+/**
+ * enum drm_ioctl_flags - DRM ioctl flags
+ *
+ * Various flags that can be set in &drm_ioctl_desc.flags to control how
+ * userspace can use a given ioctl.
+ */
+enum drm_ioctl_flags {
+ /**
+ * @DRM_AUTH:
+ *
+ * This is for ioctl which are used for rendering, and require that the
+ * file descriptor is either for a render node, or if it's a
+ * legacy/primary node, then it must be authenticated.
+ */
+ DRM_AUTH = BIT(0),
+ /**
+ * @DRM_MASTER:
+ *
+ * This must be set for any ioctl which can change the modeset or
+ * display state. Userspace must call the ioctl through a primary node,
+ * while it is the active master.
+ *
+ * Note that read-only modeset ioctl can also be called by
+ * unauthenticated clients, or when a master is not the currently active
+ * one.
+ */
+ DRM_MASTER = BIT(1),
+ /**
+ * @DRM_ROOT_ONLY:
+ *
+ * Anything that could potentially wreak a master file descriptor needs
+ * to have this flag set. Current that's only for the SETMASTER and
+ * DROPMASTER ioctl, which e.g. logind can call to force a non-behaving
+ * master (display compositor) into compliance.
+ *
+ * This is equivalent to callers with the SYSADMIN capability.
+ */
+ DRM_ROOT_ONLY = BIT(2),
+ /**
+ * @DRM_CONTROL_ALLOW:
+ *
+ * Deprecated, do not use. Control nodes are in the process of getting
+ * removed.
+ */
+ DRM_CONTROL_ALLOW = BIT(3),
+ /**
+ * @DRM_UNLOCKED:
+ *
+ * Whether &drm_ioctl_desc.func should be called with the DRM BKL held
+ * or not. Enforced as the default for all modern drivers, hence there
+ * should never be a need to set this flag.
+ */
+ DRM_UNLOCKED = BIT(4),
+ /**
+ * @DRM_RENDER_ALLOW:
+ *
+ * This is used for all ioctl needed for rendering only, for drivers
+ * which support render nodes. This should be all new render drivers,
+ * and hence it should be always set for any ioctl with DRM_AUTH set.
+ * Note though that read-only query ioctl might have this set, but have
+ * not set DRM_AUTH because they do not require authentication.
+ */
+ DRM_RENDER_ALLOW = BIT(5),
+};
+/**
+ * struct drm_ioctl_desc - DRM driver ioctl entry
+ * @cmd: ioctl command number, without flags
+ * @flags: a bitmask of &enum drm_ioctl_flags
+ * @func: handler for this ioctl
+ * @name: user-readable name for debug output
+ *
+ * For convenience it's easier to create these using the DRM_IOCTL_DEF_DRV()
+ * macro.
+ */
struct drm_ioctl_desc {
unsigned int cmd;
- int flags;
+ enum drm_ioctl_flags flags;
drm_ioctl_t *func;
const char *name;
};
/**
- * Creates a driver or general drm_ioctl_desc array entry for the given
- * ioctl, for use by drm_ioctl().
+ * DRM_IOCTL_DEF_DRV() - helper macro to fill out a &struct drm_ioctl_desc
+ * @ioctl: ioctl command suffix
+ * @_func: handler for the ioctl
+ * @_flags: a bitmask of &enum drm_ioctl_flags
+ *
+ * Small helper macro to create a &struct drm_ioctl_desc entry. The ioctl
+ * command number is constructed by prepending ``DRM_IOCTL\_`` and passing that
+ * to DRM_IOCTL_NR().
*/
-
#define DRM_IOCTL_DEF_DRV(ioctl, _func, _flags) \
[DRM_IOCTL_NR(DRM_IOCTL_##ioctl) - DRM_COMMAND_BASE] = { \
.cmd = DRM_IOCTL_##ioctl, \
--
2.11.0
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