[RFC,v3,1/3] drivers/accel: define kconfig and register a new major
Commit Message
Add a new Kconfig for the accel subsystem. The Kconfig currently
contains only the basic CONFIG_DRM_ACCEL option that will be used to
decide whether to compile the accel registration code. Therefore, the
kconfig option is defined as bool.
The accel code will be compiled as part of drm.ko and will be called
directly from the DRM core code. The reason we compile it as part of
drm.ko and not as a separate module is because of cyclic dependency
between drm.ko and the separate module (if it would have existed).
This is due to the fact that DRM core code calls accel functions and
vice-versa.
The accelerator devices will be exposed to the user space with a new,
dedicated major number - 261.
The accel init function registers the new major number as a char device
and create corresponding sysfs and debugfs root entries, similar to
what is done in DRM init function.
I added a new header called drm_accel.h to include/drm/, that will hold
the prototypes of the drm_accel.c functions. In case CONFIG_DRM_ACCEL
is set to 'N', that header will contain empty inline implementations of
those functions, to allow DRM core code to compile successfully
without dependency on CONFIG_DRM_ACCEL.
I Updated the MAINTAINERS file accordingly with the newly added folder
and I have taken the liberty to appropriate the dri-devel mailing list
and the dri-devel IRC channel for the accel subsystem.
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
---
Changes in v3:
- Remove accel kernel module and build the code as part of drm.ko.
- Rename CONFIG_ACCEL to CONFIG_DRM_ACCEL as the code is built as part of
drm.ko.
- Rename accel_drv.c to drm_accel.c
- Change kconfig option to be bool instead of tristate
- Add . at end of help text in kconfig
Documentation/admin-guide/devices.txt | 5 ++
MAINTAINERS | 8 +++
drivers/Kconfig | 2 +
drivers/accel/Kconfig | 24 ++++++++
drivers/accel/drm_accel.c | 82 +++++++++++++++++++++++++++
drivers/gpu/drm/Makefile | 1 +
include/drm/drm_accel.h | 31 ++++++++++
7 files changed, 153 insertions(+)
create mode 100644 drivers/accel/Kconfig
create mode 100644 drivers/accel/drm_accel.c
create mode 100644 include/drm/drm_accel.h
--
2.25.1
Comments
On 11/6/2022 2:02 PM, Oded Gabbay wrote:
> +int __init accel_core_init(void)
> +{
> + int ret;
> +
> + ret = accel_sysfs_init();
> + if (ret < 0) {
> + DRM_ERROR("Cannot create ACCEL class: %d\n", ret);
> + goto error;
> + }
> +
> + accel_debugfs_root = debugfs_create_dir("accel", NULL);
> +
> + ret = register_chrdev(ACCEL_MAJOR, "accel", &accel_stub_fops);
> + if (ret < 0)
> + goto error;
We are not jumping over anything here. Seems like this whole if block
could just be removed.
> +
> +error:
> + /* Any cleanup will be done in drm_core_exit() that will call
> + * to accel_core_exit()
> + */
This doesn't look like the standard multi-line comment style. Are we
going to say that the accel subsystem follows net and differs from the
kernel standard?
> + return ret;
> +}
On Mon, Nov 7, 2022 at 6:12 PM Jeffrey Hugo <quic_jhugo@quicinc.com> wrote:
>
> On 11/6/2022 2:02 PM, Oded Gabbay wrote:
> > +int __init accel_core_init(void)
> > +{
> > + int ret;
> > +
> > + ret = accel_sysfs_init();
> > + if (ret < 0) {
> > + DRM_ERROR("Cannot create ACCEL class: %d\n", ret);
> > + goto error;
> > + }
> > +
> > + accel_debugfs_root = debugfs_create_dir("accel", NULL);
> > +
> > + ret = register_chrdev(ACCEL_MAJOR, "accel", &accel_stub_fops);
> > + if (ret < 0)
> > + goto error;
>
> We are not jumping over anything here. Seems like this whole if block
> could just be removed.
correct, will be fixed.
>
> > +
> > +error:
> > + /* Any cleanup will be done in drm_core_exit() that will call
> > + * to accel_core_exit()
> > + */
>
> This doesn't look like the standard multi-line comment style. Are we
> going to say that the accel subsystem follows net and differs from the
> kernel standard?
I'll change it to the kernel standard.
Thx,
Oded
>
> > + return ret;
> > +}
On Sun, Nov 06, 2022 at 11:02:23PM +0200, Oded Gabbay wrote:
> Add a new Kconfig for the accel subsystem. The Kconfig currently
> contains only the basic CONFIG_DRM_ACCEL option that will be used to
> decide whether to compile the accel registration code. Therefore, the
> kconfig option is defined as bool.
>
> The accel code will be compiled as part of drm.ko and will be called
> directly from the DRM core code. The reason we compile it as part of
> drm.ko and not as a separate module is because of cyclic dependency
> between drm.ko and the separate module (if it would have existed).
> This is due to the fact that DRM core code calls accel functions and
> vice-versa.
>
> The accelerator devices will be exposed to the user space with a new,
> dedicated major number - 261.
>
> The accel init function registers the new major number as a char device
> and create corresponding sysfs and debugfs root entries, similar to
> what is done in DRM init function.
>
> I added a new header called drm_accel.h to include/drm/, that will hold
> the prototypes of the drm_accel.c functions. In case CONFIG_DRM_ACCEL
> is set to 'N', that header will contain empty inline implementations of
> those functions, to allow DRM core code to compile successfully
> without dependency on CONFIG_DRM_ACCEL.
>
> I Updated the MAINTAINERS file accordingly with the newly added folder
> and I have taken the liberty to appropriate the dri-devel mailing list
> and the dri-devel IRC channel for the accel subsystem.
>
> Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
Tested-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
I tested those patches with intel_vpu driver. After initial troubles,
I got things worked with our driver and user mode components.
Regards
Stanislaw
On Tue, Nov 8, 2022 at 2:46 PM Stanislaw Gruszka
<stanislaw.gruszka@linux.intel.com> wrote:
>
> On Sun, Nov 06, 2022 at 11:02:23PM +0200, Oded Gabbay wrote:
> > Add a new Kconfig for the accel subsystem. The Kconfig currently
> > contains only the basic CONFIG_DRM_ACCEL option that will be used to
> > decide whether to compile the accel registration code. Therefore, the
> > kconfig option is defined as bool.
> >
> > The accel code will be compiled as part of drm.ko and will be called
> > directly from the DRM core code. The reason we compile it as part of
> > drm.ko and not as a separate module is because of cyclic dependency
> > between drm.ko and the separate module (if it would have existed).
> > This is due to the fact that DRM core code calls accel functions and
> > vice-versa.
> >
> > The accelerator devices will be exposed to the user space with a new,
> > dedicated major number - 261.
> >
> > The accel init function registers the new major number as a char device
> > and create corresponding sysfs and debugfs root entries, similar to
> > what is done in DRM init function.
> >
> > I added a new header called drm_accel.h to include/drm/, that will hold
> > the prototypes of the drm_accel.c functions. In case CONFIG_DRM_ACCEL
> > is set to 'N', that header will contain empty inline implementations of
> > those functions, to allow DRM core code to compile successfully
> > without dependency on CONFIG_DRM_ACCEL.
> >
> > I Updated the MAINTAINERS file accordingly with the newly added folder
> > and I have taken the liberty to appropriate the dri-devel mailing list
> > and the dri-devel IRC channel for the accel subsystem.
> >
> > Signed-off-by: Oded Gabbay <ogabbay@kernel.org>
>
> Tested-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
>
> I tested those patches with intel_vpu driver. After initial troubles,
> I got things worked with our driver and user mode components.
>
> Regards
> Stanislaw
Thanks!
Great to hear that.
Oded
@@ -3080,6 +3080,11 @@
...
255 = /dev/osd255 256th OSD Device
+ 261 char Compute Acceleration Devices
+ 0 = /dev/accel/accel0 First acceleration device
+ 1 = /dev/accel/accel1 Second acceleration device
+ ...
+
384-511 char RESERVED FOR DYNAMIC ASSIGNMENT
Character devices that request a dynamic allocation of major
number will take numbers starting from 511 and downward,
@@ -6825,6 +6825,14 @@ F: include/drm/drm*
F: include/linux/vga*
F: include/uapi/drm/drm*
+DRM COMPUTE ACCELERATORS DRIVERS AND FRAMEWORK
+M: Oded Gabbay <ogabbay@kernel.org>
+L: dri-devel@lists.freedesktop.org
+S: Maintained
+C: irc://irc.oftc.net/dri-devel
+T: git https://git.kernel.org/pub/scm/linux/kernel/git/ogabbay/accel.git
+F: drivers/accel/
+
DRM DRIVERS FOR ALLWINNER A10
M: Maxime Ripard <mripard@kernel.org>
M: Chen-Yu Tsai <wens@csie.org>
@@ -99,6 +99,8 @@ source "drivers/media/Kconfig"
source "drivers/video/Kconfig"
+source "drivers/accel/Kconfig"
+
source "sound/Kconfig"
source "drivers/hid/Kconfig"
new file mode 100644
@@ -0,0 +1,24 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# Compute Acceleration device configuration
+#
+# This framework provides support for compute acceleration devices, such
+# as, but not limited to, Machine-Learning and Deep-Learning acceleration
+# devices
+#
+menuconfig DRM_ACCEL
+ bool "Compute Acceleration Framework"
+ depends on DRM
+ help
+ Framework for device drivers of compute acceleration devices, such
+ as, but not limited to, Machine-Learning and Deep-Learning
+ acceleration devices.
+ If you say Y here, you need to select the module that's right for
+ your acceleration device from the list below.
+ This framework is integrated with the DRM subsystem as compute
+ accelerators and GPUs share a lot in common and can use almost the
+ same infrastructure code.
+ Having said that, acceleration devices will have a different
+ major number than GPUs, and will be exposed to user-space using
+ different device files, called accel/accel* (in /dev, sysfs
+ and debugfs).
new file mode 100644
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
+
+/*
+ * Copyright 2022 HabanaLabs, Ltd.
+ * All Rights Reserved.
+ *
+ */
+
+#include <linux/debugfs.h>
+#include <linux/device.h>
+
+#include <drm/drm_accel.h>
+#include <drm/drm_ioctl.h>
+#include <drm/drm_print.h>
+
+static struct dentry *accel_debugfs_root;
+static struct class *accel_class;
+
+static char *accel_devnode(struct device *dev, umode_t *mode)
+{
+ return kasprintf(GFP_KERNEL, "accel/%s", dev_name(dev));
+}
+
+static int accel_sysfs_init(void)
+{
+ accel_class = class_create(THIS_MODULE, "accel");
+ if (IS_ERR(accel_class))
+ return PTR_ERR(accel_class);
+
+ accel_class->devnode = accel_devnode;
+
+ return 0;
+}
+
+static void accel_sysfs_destroy(void)
+{
+ if (IS_ERR_OR_NULL(accel_class))
+ return;
+ class_destroy(accel_class);
+ accel_class = NULL;
+}
+
+static int accel_stub_open(struct inode *inode, struct file *filp)
+{
+ return -EOPNOTSUPP;
+}
+
+static const struct file_operations accel_stub_fops = {
+ .owner = THIS_MODULE,
+ .open = accel_stub_open,
+ .llseek = noop_llseek,
+};
+
+void accel_core_exit(void)
+{
+ unregister_chrdev(ACCEL_MAJOR, "accel");
+ debugfs_remove(accel_debugfs_root);
+ accel_sysfs_destroy();
+}
+
+int __init accel_core_init(void)
+{
+ int ret;
+
+ ret = accel_sysfs_init();
+ if (ret < 0) {
+ DRM_ERROR("Cannot create ACCEL class: %d\n", ret);
+ goto error;
+ }
+
+ accel_debugfs_root = debugfs_create_dir("accel", NULL);
+
+ ret = register_chrdev(ACCEL_MAJOR, "accel", &accel_stub_fops);
+ if (ret < 0)
+ goto error;
+
+error:
+ /* Any cleanup will be done in drm_core_exit() that will call
+ * to accel_core_exit()
+ */
+ return ret;
+}
@@ -70,6 +70,7 @@ drm-$(CONFIG_DRM_LOAD_EDID_FIRMWARE) += drm_edid_load.o
drm-$(CONFIG_DRM_PRIVACY_SCREEN) += \
drm_privacy_screen.o \
drm_privacy_screen_x86.o
+drm-$(CONFIG_DRM_ACCEL) += ../../accel/drm_accel.o
obj-$(CONFIG_DRM) += drm.o
obj-$(CONFIG_DRM_NOMODESET) += drm_nomodeset.o
new file mode 100644
@@ -0,0 +1,31 @@
+/* SPDX-License-Identifier: GPL-2.0
+ *
+ * Copyright 2022 HabanaLabs, Ltd.
+ * All Rights Reserved.
+ *
+ */
+
+#ifndef DRM_ACCEL_H_
+#define DRM_ACCEL_H_
+
+#define ACCEL_MAJOR 261
+
+#if IS_ENABLED(CONFIG_DRM_ACCEL)
+
+void accel_core_exit(void);
+int accel_core_init(void);
+
+#else
+
+static inline void accel_core_exit(void)
+{
+}
+
+static inline int __init accel_core_init(void)
+{
+ return 0;
+}
+
+#endif /* IS_ENABLED(CONFIG_DRM_ACCEL) */
+
+#endif /* DRM_ACCEL_H_ */