Add an fbdev emulation for SHMEM-based memory managers. The code is similar to fbdev-generic, but does not require an addition shadow buffer for mmap(). Fbdev-shmem operates directly on the buffer object's SHMEM pages. Fbdev's deferred-I/O mechanism updates the hardware state on write operations. Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx> --- drivers/gpu/drm/Makefile | 1 + drivers/gpu/drm/drm_fbdev_shmem.c | 316 ++++++++++++++++++++++++++++++ include/drm/drm_fbdev_shmem.h | 15 ++ 3 files changed, 332 insertions(+) create mode 100644 drivers/gpu/drm/drm_fbdev_shmem.c create mode 100644 include/drm/drm_fbdev_shmem.h diff --git a/drivers/gpu/drm/Makefile b/drivers/gpu/drm/Makefile index a73c04d2d7a39..50a2f0cffdac2 100644 --- a/drivers/gpu/drm/Makefile +++ b/drivers/gpu/drm/Makefile @@ -107,6 +107,7 @@ drm_dma_helper-$(CONFIG_DRM_KMS_HELPER) += drm_fb_dma_helper.o obj-$(CONFIG_DRM_GEM_DMA_HELPER) += drm_dma_helper.o drm_shmem_helper-y := drm_gem_shmem_helper.o +drm_shmem_helper-$(CONFIG_DRM_FBDEV_EMULATION) += drm_fbdev_shmem.o obj-$(CONFIG_DRM_GEM_SHMEM_HELPER) += drm_shmem_helper.o drm_suballoc_helper-y := drm_suballoc.o diff --git a/drivers/gpu/drm/drm_fbdev_shmem.c b/drivers/gpu/drm/drm_fbdev_shmem.c new file mode 100644 index 0000000000000..f568efcb198d6 --- /dev/null +++ b/drivers/gpu/drm/drm_fbdev_shmem.c @@ -0,0 +1,316 @@ +// SPDX-License-Identifier: MIT + +#include <linux/fb.h> + +#include <drm/drm_crtc_helper.h> +#include <drm/drm_drv.h> +#include <drm/drm_fb_helper.h> +#include <drm/drm_framebuffer.h> +#include <drm/drm_gem_framebuffer_helper.h> +#include <drm/drm_gem_shmem_helper.h> + +#include <drm/drm_fbdev_shmem.h> + +/* + * struct fb_ops + */ + +static int drm_fbdev_shmem_fb_open(struct fb_info *info, int user) +{ + struct drm_fb_helper *fb_helper = info->par; + + /* No need to take a ref for fbcon because it unbinds on unregister */ + if (user && !try_module_get(fb_helper->dev->driver->fops->owner)) + return -ENODEV; + + return 0; +} + +static int drm_fbdev_shmem_fb_release(struct fb_info *info, int user) +{ + struct drm_fb_helper *fb_helper = info->par; + + if (user) + module_put(fb_helper->dev->driver->fops->owner); + + return 0; +} + +FB_GEN_DEFAULT_DEFERRED_SYSMEM_OPS(drm_fbdev_shmem, + drm_fb_helper_damage_range, + drm_fb_helper_damage_area); + +static int drm_fbdev_shmem_fb_mmap(struct fb_info *info, struct vm_area_struct *vma) +{ + struct drm_fb_helper *fb_helper = info->par; + struct drm_framebuffer *fb = fb_helper->fb; + struct drm_gem_object *obj = drm_gem_fb_get_obj(fb, 0); + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj); + + if (shmem->map_wc) + vma->vm_page_prot = pgprot_writecombine(vma->vm_page_prot); + + return fb_deferred_io_mmap(info, vma); +} + +static void drm_fbdev_shmem_fb_destroy(struct fb_info *info) +{ + struct drm_fb_helper *fb_helper = info->par; + + if (!fb_helper->dev) + return; + + drm_fb_helper_fini(fb_helper); + + drm_client_buffer_vunmap(fb_helper->buffer); + drm_client_framebuffer_delete(fb_helper->buffer); + drm_client_release(&fb_helper->client); + drm_fb_helper_unprepare(fb_helper); + kfree(fb_helper); +} + +static const struct fb_ops drm_fbdev_shmem_fb_ops = { + .owner = THIS_MODULE, + .fb_open = drm_fbdev_shmem_fb_open, + .fb_release = drm_fbdev_shmem_fb_release, + __FB_DEFAULT_DEFERRED_OPS_RDWR(drm_fbdev_shmem), + DRM_FB_HELPER_DEFAULT_OPS, + __FB_DEFAULT_DEFERRED_OPS_DRAW(drm_fbdev_shmem), + .fb_mmap = drm_fbdev_shmem_fb_mmap, + .fb_destroy = drm_fbdev_shmem_fb_destroy, +}; + +static struct page *drm_fbdev_shmem_get_page(struct fb_info *info, unsigned long offset) +{ + struct drm_fb_helper *fb_helper = info->par; + struct drm_framebuffer *fb = fb_helper->fb; + struct drm_gem_object *obj = drm_gem_fb_get_obj(fb, 0); + struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj); + unsigned int i = offset >> PAGE_SHIFT; + struct page *page; + + if (fb_WARN_ON_ONCE(info, offset > obj->size)) + return NULL; + + page = shmem->pages[i]; // protected by active vmap + if (page) + get_page(page); + fb_WARN_ON_ONCE(info, !page); + + return page; +} + +/* + * struct drm_fb_helper + */ + +static int drm_fbdev_shmem_helper_fb_probe(struct drm_fb_helper *fb_helper, + struct drm_fb_helper_surface_size *sizes) +{ + struct drm_client_dev *client = &fb_helper->client; + struct drm_device *dev = fb_helper->dev; + struct drm_client_buffer *buffer; + struct drm_gem_shmem_object *shmem; + struct drm_framebuffer *fb; + struct fb_info *info; + u32 format; + struct iosys_map map; + int ret; + + drm_dbg_kms(dev, "surface width(%d), height(%d) and bpp(%d)\n", + sizes->surface_width, sizes->surface_height, + sizes->surface_bpp); + + format = drm_mode_legacy_fb_format(sizes->surface_bpp, sizes->surface_depth); + buffer = drm_client_framebuffer_create(client, sizes->surface_width, + sizes->surface_height, format); + if (IS_ERR(buffer)) + return PTR_ERR(buffer); + shmem = to_drm_gem_shmem_obj(buffer->gem); + + fb = buffer->fb; + + ret = drm_client_buffer_vmap(buffer, &map); + if (ret) { + goto err_drm_client_buffer_delete; + } else if (drm_WARN_ON(dev, map.is_iomem)) { + ret = -ENODEV; /* I/O memory not supported; use generic emulation */ + goto err_drm_client_buffer_delete; + } + + fb_helper->buffer = buffer; + fb_helper->fb = fb; + + info = drm_fb_helper_alloc_info(fb_helper); + if (IS_ERR(info)) { + ret = PTR_ERR(info); + goto err_drm_client_buffer_vunmap; + } + + drm_fb_helper_fill_info(info, fb_helper, sizes); + + info->fbops = &drm_fbdev_shmem_fb_ops; + + /* screen */ + info->flags |= FBINFO_VIRTFB; /* system memory */ + if (!shmem->map_wc) + info->flags |= FBINFO_READS_FAST; /* signal caching */ + info->screen_size = sizes->surface_height * fb->pitches[0]; + info->screen_buffer = map.vaddr; + info->fix.smem_len = info->screen_size; + + /* deferred I/O */ + fb_helper->fbdefio.delay = HZ / 20; + fb_helper->fbdefio.get_page = drm_fbdev_shmem_get_page; + fb_helper->fbdefio.deferred_io = drm_fb_helper_deferred_io; + + info->fbdefio = &fb_helper->fbdefio; + ret = fb_deferred_io_init(info); + if (ret) + goto err_drm_fb_helper_release_info; + + return 0; + +err_drm_fb_helper_release_info: + drm_fb_helper_release_info(fb_helper); +err_drm_client_buffer_vunmap: + fb_helper->fb = NULL; + fb_helper->buffer = NULL; + drm_client_buffer_vunmap(buffer); +err_drm_client_buffer_delete: + drm_client_framebuffer_delete(buffer); + return ret; +} + +static int drm_fbdev_shmem_helper_fb_dirty(struct drm_fb_helper *helper, + struct drm_clip_rect *clip) +{ + struct drm_device *dev = helper->dev; + int ret; + + /* Call damage handlers only if necessary */ + if (!(clip->x1 < clip->x2 && clip->y1 < clip->y2)) + return 0; + + if (helper->fb->funcs->dirty) { + ret = helper->fb->funcs->dirty(helper->fb, NULL, 0, 0, clip, 1); + if (drm_WARN_ONCE(dev, ret, "Dirty helper failed: ret=%d\n", ret)) + return ret; + } + + return 0; +} + +static const struct drm_fb_helper_funcs drm_fbdev_shmem_helper_funcs = { + .fb_probe = drm_fbdev_shmem_helper_fb_probe, + .fb_dirty = drm_fbdev_shmem_helper_fb_dirty, +}; + +/* + * struct drm_client_funcs + */ + +static void drm_fbdev_shmem_client_unregister(struct drm_client_dev *client) +{ + struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client); + + if (fb_helper->info) { + drm_fb_helper_unregister_info(fb_helper); + } else { + drm_client_release(&fb_helper->client); + drm_fb_helper_unprepare(fb_helper); + kfree(fb_helper); + } +} + +static int drm_fbdev_shmem_client_restore(struct drm_client_dev *client) +{ + drm_fb_helper_lastclose(client->dev); + + return 0; +} + +static int drm_fbdev_shmem_client_hotplug(struct drm_client_dev *client) +{ + struct drm_fb_helper *fb_helper = drm_fb_helper_from_client(client); + struct drm_device *dev = client->dev; + int ret; + + if (dev->fb_helper) + return drm_fb_helper_hotplug_event(dev->fb_helper); + + ret = drm_fb_helper_init(dev, fb_helper); + if (ret) + goto err_drm_err; + + if (!drm_drv_uses_atomic_modeset(dev)) + drm_helper_disable_unused_functions(dev); + + ret = drm_fb_helper_initial_config(fb_helper); + if (ret) + goto err_drm_fb_helper_fini; + + return 0; + +err_drm_fb_helper_fini: + drm_fb_helper_fini(fb_helper); +err_drm_err: + drm_err(dev, "fbdev-shmem: Failed to setup emulation (ret=%d)\n", ret); + return ret; +} + +static const struct drm_client_funcs drm_fbdev_shmem_client_funcs = { + .owner = THIS_MODULE, + .unregister = drm_fbdev_shmem_client_unregister, + .restore = drm_fbdev_shmem_client_restore, + .hotplug = drm_fbdev_shmem_client_hotplug, +}; + +/** + * drm_fbdev_shmem_setup() - Setup fbdev emulation for GEM SHMEM helpers + * @dev: DRM device + * @preferred_bpp: Preferred bits per pixel for the device. + * 32 is used if this is zero. + * + * This function sets up fbdev emulation for GEM DMA drivers that support + * dumb buffers with a virtual address and that can be mmap'ed. + * drm_fbdev_shmem_setup() shall be called after the DRM driver registered + * the new DRM device with drm_dev_register(). + * + * Restore, hotplug events and teardown are all taken care of. Drivers that do + * suspend/resume need to call drm_fb_helper_set_suspend_unlocked() themselves. + * Simple drivers might use drm_mode_config_helper_suspend(). + * + * This function is safe to call even when there are no connectors present. + * Setup will be retried on the next hotplug event. + * + * The fbdev is destroyed by drm_dev_unregister(). + */ +void drm_fbdev_shmem_setup(struct drm_device *dev, unsigned int preferred_bpp) +{ + struct drm_fb_helper *fb_helper; + int ret; + + drm_WARN(dev, !dev->registered, "Device has not been registered.\n"); + drm_WARN(dev, dev->fb_helper, "fb_helper is already set!\n"); + + fb_helper = kzalloc(sizeof(*fb_helper), GFP_KERNEL); + if (!fb_helper) + return; + drm_fb_helper_prepare(dev, fb_helper, preferred_bpp, &drm_fbdev_shmem_helper_funcs); + + ret = drm_client_init(dev, &fb_helper->client, "fbdev", &drm_fbdev_shmem_client_funcs); + if (ret) { + drm_err(dev, "Failed to register client: %d\n", ret); + goto err_drm_client_init; + } + + drm_client_register(&fb_helper->client); + + return; + +err_drm_client_init: + drm_fb_helper_unprepare(fb_helper); + kfree(fb_helper); +} +EXPORT_SYMBOL(drm_fbdev_shmem_setup); diff --git a/include/drm/drm_fbdev_shmem.h b/include/drm/drm_fbdev_shmem.h new file mode 100644 index 0000000000000..fb43cadd1950c --- /dev/null +++ b/include/drm/drm_fbdev_shmem.h @@ -0,0 +1,15 @@ +/* SPDX-License-Identifier: MIT */ + +#ifndef DRM_FBDEV_SHMEM_H +#define DRM_FBDEV_SHMEM_H + +struct drm_device; + +#ifdef CONFIG_DRM_FBDEV_EMULATION +void drm_fbdev_shmem_setup(struct drm_device *dev, unsigned int preferred_bpp); +#else +static inline void drm_fbdev_shmem_setup(struct drm_device *dev, unsigned int preferred_bpp) +{ } +#endif + +#endif -- 2.44.0