drm: document drm_ioctl.[hc]
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).
v4: Add missing space in comment (Neil).
Cc: Sergi Granell <xerpi.g.12@gmail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170404095304.17599-4-daniel.vetter@ffwll.ch
diff --git a/drivers/gpu/drm/drm_ioc32.c b/drivers/gpu/drm/drm_ioc32.c
index b134482..ae38678 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
*
- * \param file_priv DRM file private.
- * \param cmd command.
- * \param arg user argument.
- * \return zero on success or negative number on failure.
+ * 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.
+ *
+ * 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 7d6deaa..9f4241f 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.