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Subject[PATCH 6/9] drm/xen-front: Introduce DRM/KMS virtual display driver
Date
From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>

Implement essential initialization of the display driver:
- introduce required data structures
- handle DRM/KMS driver registration
- perform basic DRM driver initialization
- register driver on backend connection
- remove driver on backend disconnect
- introduce essential callbacks required by DRM/KMS core
- introduce essential callbacks required for frontend operations

Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
---
drivers/gpu/drm/xen/Makefile | 1 +
drivers/gpu/drm/xen/xen_drm_front.c | 169 ++++++++++++++++++++++++-
drivers/gpu/drm/xen/xen_drm_front.h | 24 ++++
drivers/gpu/drm/xen/xen_drm_front_drv.c | 211 ++++++++++++++++++++++++++++++++
drivers/gpu/drm/xen/xen_drm_front_drv.h | 60 +++++++++
5 files changed, 462 insertions(+), 3 deletions(-)
create mode 100644 drivers/gpu/drm/xen/xen_drm_front_drv.c
create mode 100644 drivers/gpu/drm/xen/xen_drm_front_drv.h

diff --git a/drivers/gpu/drm/xen/Makefile b/drivers/gpu/drm/xen/Makefile
index f1823cb596c5..d3068202590f 100644
--- a/drivers/gpu/drm/xen/Makefile
+++ b/drivers/gpu/drm/xen/Makefile
@@ -1,6 +1,7 @@
# SPDX-License-Identifier: GPL-2.0

drm_xen_front-objs := xen_drm_front.o \
+ xen_drm_front_drv.o \
xen_drm_front_evtchnl.o \
xen_drm_front_shbuf.o \
xen_drm_front_cfg.o
diff --git a/drivers/gpu/drm/xen/xen_drm_front.c b/drivers/gpu/drm/xen/xen_drm_front.c
index 0d94ff272da3..8de88e359d5e 100644
--- a/drivers/gpu/drm/xen/xen_drm_front.c
+++ b/drivers/gpu/drm/xen/xen_drm_front.c
@@ -18,6 +18,8 @@

#include <drm/drmP.h>

+#include <linux/of_device.h>
+
#include <xen/platform_pci.h>
#include <xen/xen.h>
#include <xen/xenbus.h>
@@ -25,15 +27,161 @@
#include <xen/interface/io/displif.h>

#include "xen_drm_front.h"
+#include "xen_drm_front_drv.h"
#include "xen_drm_front_evtchnl.h"
#include "xen_drm_front_shbuf.h"

+static int be_mode_set(struct xen_drm_front_drm_pipeline *pipeline, uint32_t x,
+ uint32_t y, uint32_t width, uint32_t height, uint32_t bpp,
+ uint64_t fb_cookie)
+
+{
+ return 0;
+}
+
+static int be_dbuf_create_int(struct xen_drm_front_info *front_info,
+ uint64_t dbuf_cookie, uint32_t width, uint32_t height,
+ uint32_t bpp, uint64_t size, struct page **pages,
+ struct sg_table *sgt)
+{
+ return 0;
+}
+
+static int be_dbuf_create_from_sgt(struct xen_drm_front_info *front_info,
+ uint64_t dbuf_cookie, uint32_t width, uint32_t height,
+ uint32_t bpp, uint64_t size, struct sg_table *sgt)
+{
+ return be_dbuf_create_int(front_info, dbuf_cookie, width, height,
+ bpp, size, NULL, sgt);
+}
+
+static int be_dbuf_create_from_pages(struct xen_drm_front_info *front_info,
+ uint64_t dbuf_cookie, uint32_t width, uint32_t height,
+ uint32_t bpp, uint64_t size, struct page **pages)
+{
+ return be_dbuf_create_int(front_info, dbuf_cookie, width, height,
+ bpp, size, pages, NULL);
+}
+
+static int be_dbuf_destroy(struct xen_drm_front_info *front_info,
+ uint64_t dbuf_cookie)
+{
+ return 0;
+}
+
+static int be_fb_attach(struct xen_drm_front_info *front_info,
+ uint64_t dbuf_cookie, uint64_t fb_cookie, uint32_t width,
+ uint32_t height, uint32_t pixel_format)
+{
+ return 0;
+}
+
+static int be_fb_detach(struct xen_drm_front_info *front_info,
+ uint64_t fb_cookie)
+{
+ return 0;
+}
+
+static int be_page_flip(struct xen_drm_front_info *front_info, int conn_idx,
+ uint64_t fb_cookie)
+{
+ return 0;
+}
+
+static void xen_drm_drv_unload(struct xen_drm_front_info *front_info)
+{
+ if (front_info->xb_dev->state != XenbusStateReconfiguring)
+ return;
+
+ DRM_DEBUG("Can try removing driver now\n");
+ xenbus_switch_state(front_info->xb_dev, XenbusStateInitialising);
+}
+
static struct xen_drm_front_ops front_ops = {
- /* placeholder for now */
+ .mode_set = be_mode_set,
+ .dbuf_create_from_pages = be_dbuf_create_from_pages,
+ .dbuf_create_from_sgt = be_dbuf_create_from_sgt,
+ .dbuf_destroy = be_dbuf_destroy,
+ .fb_attach = be_fb_attach,
+ .fb_detach = be_fb_detach,
+ .page_flip = be_page_flip,
+ .drm_last_close = xen_drm_drv_unload,
+};
+
+static int xen_drm_drv_probe(struct platform_device *pdev)
+{
+ /*
+ * The device is not spawn from a device tree, so arch_setup_dma_ops
+ * is not called, thus leaving the device with dummy DMA ops.
+ * This makes the device return error on PRIME buffer import, which
+ * is not correct: to fix this call of_dma_configure() with a NULL
+ * node to set default DMA ops.
+ */
+ of_dma_configure(&pdev->dev, NULL);
+ return xen_drm_front_drv_probe(pdev, &front_ops);
+}
+
+static int xen_drm_drv_remove(struct platform_device *pdev)
+{
+ return xen_drm_front_drv_remove(pdev);
+}
+
+struct platform_device_info xen_drm_front_platform_info = {
+ .name = XENDISPL_DRIVER_NAME,
+ .id = 0,
+ .num_res = 0,
+ .dma_mask = DMA_BIT_MASK(32),
};

+static struct platform_driver xen_drm_front_front_info = {
+ .probe = xen_drm_drv_probe,
+ .remove = xen_drm_drv_remove,
+ .driver = {
+ .name = XENDISPL_DRIVER_NAME,
+ },
+};
+
+static void xen_drm_drv_deinit(struct xen_drm_front_info *front_info)
+{
+ if (!front_info->drm_pdrv_registered)
+ return;
+
+ if (front_info->drm_pdev)
+ platform_device_unregister(front_info->drm_pdev);
+
+ platform_driver_unregister(&xen_drm_front_front_info);
+ front_info->drm_pdrv_registered = false;
+ front_info->drm_pdev = NULL;
+}
+
+static int xen_drm_drv_init(struct xen_drm_front_info *front_info)
+{
+ int ret;
+
+ ret = platform_driver_register(&xen_drm_front_front_info);
+ if (ret < 0)
+ return ret;
+
+ front_info->drm_pdrv_registered = true;
+ /* pass card configuration via platform data */
+ xen_drm_front_platform_info.data = &front_info->cfg;
+ xen_drm_front_platform_info.size_data = sizeof(front_info->cfg);
+
+ front_info->drm_pdev = platform_device_register_full(
+ &xen_drm_front_platform_info);
+ if (IS_ERR_OR_NULL(front_info->drm_pdev)) {
+ DRM_ERROR("Failed to register " XENDISPL_DRIVER_NAME " PV DRM driver\n");
+ front_info->drm_pdev = NULL;
+ xen_drm_drv_deinit(front_info);
+ return -ENODEV;
+ }
+
+ return 0;
+}
+
static void xen_drv_remove_internal(struct xen_drm_front_info *front_info)
{
+ xen_drm_drv_deinit(front_info);
xen_drm_front_evtchnl_free_all(front_info);
}

@@ -59,13 +207,27 @@ static int backend_on_initwait(struct xen_drm_front_info *front_info)
static int backend_on_connected(struct xen_drm_front_info *front_info)
{
xen_drm_front_evtchnl_set_state(front_info, EVTCHNL_STATE_CONNECTED);
- return 0;
+ return xen_drm_drv_init(front_info);
}

static void backend_on_disconnected(struct xen_drm_front_info *front_info)
{
+ bool removed = true;
+
+ if (front_info->drm_pdev) {
+ if (xen_drm_front_drv_is_used(front_info->drm_pdev)) {
+ DRM_WARN("DRM driver still in use, deferring removal\n");
+ removed = false;
+ } else
+ xen_drv_remove_internal(front_info);
+ }
+
xen_drm_front_evtchnl_set_state(front_info, EVTCHNL_STATE_DISCONNECTED);
- xenbus_switch_state(front_info->xb_dev, XenbusStateInitialising);
+
+ if (removed)
+ xenbus_switch_state(front_info->xb_dev, XenbusStateInitialising);
+ else
+ xenbus_switch_state(front_info->xb_dev, XenbusStateReconfiguring);
}

static void backend_on_changed(struct xenbus_device *xb_dev,
@@ -148,6 +310,7 @@ static int xen_drv_probe(struct xenbus_device *xb_dev,

front_info->xb_dev = xb_dev;
spin_lock_init(&front_info->io_lock);
+ front_info->drm_pdrv_registered = false;
dev_set_drvdata(&xb_dev->dev, front_info);
return xenbus_switch_state(xb_dev, XenbusStateInitialising);
}
diff --git a/drivers/gpu/drm/xen/xen_drm_front.h b/drivers/gpu/drm/xen/xen_drm_front.h
index 13f22736ae02..9ed5bfb248d0 100644
--- a/drivers/gpu/drm/xen/xen_drm_front.h
+++ b/drivers/gpu/drm/xen/xen_drm_front.h
@@ -19,6 +19,8 @@
#ifndef __XEN_DRM_FRONT_H_
#define __XEN_DRM_FRONT_H_

+#include <linux/scatterlist.h>
+
#include "xen_drm_front_cfg.h"

#ifndef GRANT_INVALID_REF
@@ -30,16 +32,38 @@
#define GRANT_INVALID_REF 0
#endif

+struct xen_drm_front_drm_pipeline;
+
struct xen_drm_front_ops {
+ int (*mode_set)(struct xen_drm_front_drm_pipeline *pipeline,
+ uint32_t x, uint32_t y, uint32_t width, uint32_t height,
+ uint32_t bpp, uint64_t fb_cookie);
+ int (*dbuf_create_from_pages)(struct xen_drm_front_info *front_info,
+ uint64_t dbuf_cookie, uint32_t width, uint32_t height,
+ uint32_t bpp, uint64_t size, struct page **pages);
+ int (*dbuf_create_from_sgt)(struct xen_drm_front_info *front_info,
+ uint64_t dbuf_cookie, uint32_t width, uint32_t height,
+ uint32_t bpp, uint64_t size, struct sg_table *sgt);
+ int (*dbuf_destroy)(struct xen_drm_front_info *front_info,
+ uint64_t dbuf_cookie);
+ int (*fb_attach)(struct xen_drm_front_info *front_info,
+ uint64_t dbuf_cookie, uint64_t fb_cookie,
+ uint32_t width, uint32_t height, uint32_t pixel_format);
+ int (*fb_detach)(struct xen_drm_front_info *front_info,
+ uint64_t fb_cookie);
+ int (*page_flip)(struct xen_drm_front_info *front_info,
+ int conn_idx, uint64_t fb_cookie);
/* CAUTION! this is called with a spin_lock held! */
void (*on_frame_done)(struct platform_device *pdev,
int conn_idx, uint64_t fb_cookie);
+ void (*drm_last_close)(struct xen_drm_front_info *front_info);
};

struct xen_drm_front_info {
struct xenbus_device *xb_dev;
/* to protect data between backend IO code and interrupt handler */
spinlock_t io_lock;
+ bool drm_pdrv_registered;
/* virtual DRM platform device */
struct platform_device *drm_pdev;

diff --git a/drivers/gpu/drm/xen/xen_drm_front_drv.c b/drivers/gpu/drm/xen/xen_drm_front_drv.c
new file mode 100644
index 000000000000..b3764d5ed0f6
--- /dev/null
+++ b/drivers/gpu/drm/xen/xen_drm_front_drv.c
@@ -0,0 +1,211 @@
+/*
+ * Xen para-virtual DRM device
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * Copyright (C) 2016-2018 EPAM Systems Inc.
+ *
+ * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
+ */
+
+#include <drm/drmP.h>
+#include <drm/drm_gem.h>
+#include <drm/drm_atomic_helper.h>
+
+#include "xen_drm_front.h"
+#include "xen_drm_front_cfg.h"
+#include "xen_drm_front_drv.h"
+
+static int dumb_create(struct drm_file *filp,
+ struct drm_device *dev, struct drm_mode_create_dumb *args)
+{
+ return -EINVAL;
+}
+
+static void free_object(struct drm_gem_object *obj)
+{
+ struct xen_drm_front_drm_info *drm_info = obj->dev->dev_private;
+
+ drm_info->front_ops->dbuf_destroy(drm_info->front_info,
+ xen_drm_front_dbuf_to_cookie(obj));
+}
+
+static void on_frame_done(struct platform_device *pdev,
+ int conn_idx, uint64_t fb_cookie)
+{
+}
+
+static void lastclose(struct drm_device *dev)
+{
+ struct xen_drm_front_drm_info *drm_info = dev->dev_private;
+
+ drm_info->front_ops->drm_last_close(drm_info->front_info);
+}
+
+static int gem_mmap(struct file *filp, struct vm_area_struct *vma)
+{
+ return -EINVAL;
+}
+
+static struct sg_table *prime_get_sg_table(struct drm_gem_object *obj)
+{
+ return NULL;
+}
+
+static struct drm_gem_object *prime_import_sg_table(struct drm_device *dev,
+ struct dma_buf_attachment *attach, struct sg_table *sgt)
+{
+ return NULL;
+}
+
+static void *prime_vmap(struct drm_gem_object *obj)
+{
+ return NULL;
+}
+
+static void prime_vunmap(struct drm_gem_object *obj, void *vaddr)
+{
+}
+
+static int prime_mmap(struct drm_gem_object *obj, struct vm_area_struct *vma)
+{
+ return -EINVAL;
+}
+
+static const struct file_operations xendrm_fops = {
+ .owner = THIS_MODULE,
+ .open = drm_open,
+ .release = drm_release,
+ .unlocked_ioctl = drm_ioctl,
+#ifdef CONFIG_COMPAT
+ .compat_ioctl = drm_compat_ioctl,
+#endif
+ .poll = drm_poll,
+ .read = drm_read,
+ .llseek = no_llseek,
+ .mmap = gem_mmap,
+};
+
+static const struct vm_operations_struct xen_drm_vm_ops = {
+ .open = drm_gem_vm_open,
+ .close = drm_gem_vm_close,
+};
+
+struct drm_driver xen_drm_driver = {
+ .driver_features = DRIVER_GEM | DRIVER_MODESET |
+ DRIVER_PRIME | DRIVER_ATOMIC,
+ .lastclose = lastclose,
+ .gem_free_object_unlocked = free_object,
+ .gem_vm_ops = &xen_drm_vm_ops,
+ .prime_handle_to_fd = drm_gem_prime_handle_to_fd,
+ .prime_fd_to_handle = drm_gem_prime_fd_to_handle,
+ .gem_prime_import = drm_gem_prime_import,
+ .gem_prime_export = drm_gem_prime_export,
+ .gem_prime_get_sg_table = prime_get_sg_table,
+ .gem_prime_import_sg_table = prime_import_sg_table,
+ .gem_prime_vmap = prime_vmap,
+ .gem_prime_vunmap = prime_vunmap,
+ .gem_prime_mmap = prime_mmap,
+ .dumb_create = dumb_create,
+ .fops = &xendrm_fops,
+ .name = "xendrm-du",
+ .desc = "Xen PV DRM Display Unit",
+ .date = "20161109",
+ .major = 1,
+ .minor = 0,
+};
+
+int xen_drm_front_drv_probe(struct platform_device *pdev,
+ struct xen_drm_front_ops *front_ops)
+{
+ struct xen_drm_front_cfg *cfg = dev_get_platdata(&pdev->dev);
+ struct xen_drm_front_drm_info *drm_info;
+ struct drm_device *dev;
+ int ret;
+
+ DRM_INFO("Creating %s\n", xen_drm_driver.desc);
+
+ drm_info = devm_kzalloc(&pdev->dev, sizeof(*drm_info), GFP_KERNEL);
+ if (!drm_info)
+ return -ENOMEM;
+
+ drm_info->front_ops = front_ops;
+ drm_info->front_ops->on_frame_done = on_frame_done;
+ drm_info->front_info = cfg->front_info;
+
+ dev = drm_dev_alloc(&xen_drm_driver, &pdev->dev);
+ if (!dev)
+ return -ENOMEM;
+
+ drm_info->drm_dev = dev;
+
+ drm_info->cfg = cfg;
+ dev->dev_private = drm_info;
+ platform_set_drvdata(pdev, drm_info);
+
+ ret = drm_vblank_init(dev, cfg->num_connectors);
+ if (ret) {
+ DRM_ERROR("Failed to initialize vblank, ret %d\n", ret);
+ return ret;
+ }
+
+ dev->irq_enabled = 1;
+
+ ret = drm_dev_register(dev, 0);
+ if (ret)
+ goto fail_register;
+
+ DRM_INFO("Initialized %s %d.%d.%d %s on minor %d\n",
+ xen_drm_driver.name, xen_drm_driver.major,
+ xen_drm_driver.minor, xen_drm_driver.patchlevel,
+ xen_drm_driver.date, dev->primary->index);
+
+ return 0;
+
+fail_register:
+ drm_dev_unregister(dev);
+ drm_mode_config_cleanup(dev);
+ return ret;
+}
+
+int xen_drm_front_drv_remove(struct platform_device *pdev)
+{
+ struct xen_drm_front_drm_info *drm_info = platform_get_drvdata(pdev);
+ struct drm_device *dev = drm_info->drm_dev;
+
+ if (dev) {
+ drm_dev_unregister(dev);
+ drm_atomic_helper_shutdown(dev);
+ drm_mode_config_cleanup(dev);
+ drm_dev_unref(dev);
+ }
+ return 0;
+}
+
+bool xen_drm_front_drv_is_used(struct platform_device *pdev)
+{
+ struct xen_drm_front_drm_info *drm_info = platform_get_drvdata(pdev);
+ struct drm_device *dev;
+
+ if (!drm_info)
+ return false;
+
+ dev = drm_info->drm_dev;
+ if (!dev)
+ return false;
+
+ /*
+ * FIXME: the code below must be protected by drm_global_mutex,
+ * but it is not accessible to us. Anyways there is a race condition,
+ * but we will re-try.
+ */
+ return dev->open_count != 0;
+}
diff --git a/drivers/gpu/drm/xen/xen_drm_front_drv.h b/drivers/gpu/drm/xen/xen_drm_front_drv.h
new file mode 100644
index 000000000000..aaa476535c13
--- /dev/null
+++ b/drivers/gpu/drm/xen/xen_drm_front_drv.h
@@ -0,0 +1,60 @@
+/*
+ * Xen para-virtual DRM device
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * Copyright (C) 2016-2018 EPAM Systems Inc.
+ *
+ * Author: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
+ */
+
+#ifndef __XEN_DRM_FRONT_DRV_H_
+#define __XEN_DRM_FRONT_DRV_H_
+
+#include <drm/drmP.h>
+
+#include "xen_drm_front.h"
+#include "xen_drm_front_cfg.h"
+
+struct xen_drm_front_drm_pipeline {
+ struct xen_drm_front_drm_info *drm_info;
+
+ int index;
+};
+
+struct xen_drm_front_drm_info {
+ struct xen_drm_front_info *front_info;
+ struct xen_drm_front_ops *front_ops;
+ struct drm_device *drm_dev;
+ struct xen_drm_front_cfg *cfg;
+};
+
+static inline uint64_t xen_drm_front_fb_to_cookie(
+ struct drm_framebuffer *fb)
+{
+ return (uint64_t)fb;
+}
+
+static inline uint64_t xen_drm_front_dbuf_to_cookie(
+ struct drm_gem_object *gem_obj)
+{
+ return (uint64_t)gem_obj;
+}
+
+int xen_drm_front_drv_probe(struct platform_device *pdev,
+ struct xen_drm_front_ops *front_ops);
+
+int xen_drm_front_drv_remove(struct platform_device *pdev);
+
+bool xen_drm_front_drv_is_used(struct platform_device *pdev);
+
+#endif /* __XEN_DRM_FRONT_DRV_H_ */
+
--
2.7.4
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