The simplekms driver is a DRM driver for simplefb framebuffers as
provided by the kernel's boot code. This driver enables basic
graphical output on many different graphics devices that are provided
by the platform (e.g., EFI, VESA, embedded framebuffers).
With the kernel's simplefb infrastructure, the kernel receives a
pre-configured framebuffer from the system (i.e., firmware, boot
loader). It creates a platform device to which simplekms attaches.
The system's framebuffer consists of a memory range, size and format.
Based on these values, simplekms creates a DRM devices. No actual
modesetting is possible.
Signed-off-by: Thomas Zimmermann <tzimmermann@xxxxxxx>
---
MAINTAINERS | 6 +
drivers/gpu/drm/tiny/Kconfig | 16 +
drivers/gpu/drm/tiny/Makefile | 1 +
drivers/gpu/drm/tiny/simplekms.c | 495 +++++++++++++++++++++++++++++++
4 files changed, 518 insertions(+)
create mode 100644 drivers/gpu/drm/tiny/simplekms.c
diff --git a/MAINTAINERS b/MAINTAINERS
index f17d99164a77..ac517dc8d05d 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5505,6 +5505,12 @@ S: Orphan / Obsolete
F: drivers/gpu/drm/savage/
F: include/uapi/drm/savage_drm.h
+DRM DRIVER FOR SIMPLE FRAMEBUFFERS
+M: Thomas Zimmermann <tzimmermann@xxxxxxx>
+S: Maintained
+T: git git://anongit.freedesktop.org/drm/drm-misc
+F: drivers/gpu/drm/tiny/simplekms.c
+
DRM DRIVER FOR SIS VIDEO CARDS
S: Orphan / Obsolete
F: drivers/gpu/drm/sis/
diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
index 2b6414f0fa75..50dbde8bdcb2 100644
--- a/drivers/gpu/drm/tiny/Kconfig
+++ b/drivers/gpu/drm/tiny/Kconfig
@@ -28,6 +28,22 @@ config DRM_GM12U320
This is a KMS driver for projectors which use the GM12U320 chipset
for video transfer over USB2/3, such as the Acer C120 mini projector.
+config DRM_SIMPLEKMS
+ tristate "Simple framebuffer driver"
+ depends on DRM
+ select DRM_GEM_SHMEM_HELPER
+ select DRM_KMS_HELPER
+ help
+ DRM driver for simple platform-provided framebuffers.
+
+ This driver assumes that the display hardware has been initialized
+ by the firmware or bootloader before the kernel boots. Scanout
+ buffer, size, and display format must be provided via device tree,
+ UEFI, VESA, etc.
+
+ On x86 and compatible, you should also select CONFIG_X86_SYSFB to
+ use UEFI and VESA framebuffers.
+
config TINYDRM_HX8357D
tristate "DRM support for HX8357D display panels"
depends on DRM && SPI
diff --git a/drivers/gpu/drm/tiny/Makefile b/drivers/gpu/drm/tiny/Makefile
index 6ae4e9e5a35f..e83fbbfa7344 100644
--- a/drivers/gpu/drm/tiny/Makefile
+++ b/drivers/gpu/drm/tiny/Makefile
@@ -2,6 +2,7 @@
obj-$(CONFIG_DRM_CIRRUS_QEMU) += cirrus.o
obj-$(CONFIG_DRM_GM12U320) += gm12u320.o
+obj-$(CONFIG_DRM_SIMPLEKMS) += simplekms.o
obj-$(CONFIG_TINYDRM_HX8357D) += hx8357d.o
obj-$(CONFIG_TINYDRM_ILI9225) += ili9225.o
obj-$(CONFIG_TINYDRM_ILI9341) += ili9341.o
diff --git a/drivers/gpu/drm/tiny/simplekms.c b/drivers/gpu/drm/tiny/simplekms.c
new file mode 100644
index 000000000000..dc7cf3983945
--- /dev/null
+++ b/drivers/gpu/drm/tiny/simplekms.c
@@ -0,0 +1,495 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+#include <linux/platform_data/simplefb.h>
+#include <linux/platform_device.h>
+
+#include <drm/drm_atomic_state_helper.h>
+#include <drm/drm_connector.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_device.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_format_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_gem_shmem_helper.h>
+#include <drm/drm_managed.h>
+#include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_probe_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+
+#define DRIVER_NAME "simplekms"
+#define DRIVER_DESC "DRM driver for simple-framebuffer platform devices"
+#define DRIVER_DATE "20200625"
+#define DRIVER_MAJOR 1
+#define DRIVER_MINOR 0
+
+/*
+ * Assume a monitor resolution of 96 dpi to
+ * get a somewhat reasonable screen size.
+ */
+#define RES_MM(d) \
+ (((d) * 254ul) / (96ul * 10ul))
+
+#define SIMPLEKMS_MODE(hd, vd) \
+ DRM_SIMPLE_MODE(hd, vd, RES_MM(hd), RES_MM(vd))
+
+/*
+ * Helpers for simplefb
+ */
+
+static int
+simplefb_get_validated_int(struct drm_device *dev, const char *name,
+ uint32_t value)
+{
+ if (value > INT_MAX) {
+ drm_err(dev, "simplefb: invalid framebuffer %s of %u\n",
+ name, value);
+ return -EINVAL;
+ }
+ return (int)value;
+}
+
+static int
+simplefb_get_validated_int0(struct drm_device *dev, const char *name,
+ uint32_t value)
+{
+ if (!value) {
+ drm_err(dev, "simplefb: invalid framebuffer %s of %u\n",
+ name, value);
+ return -EINVAL;
+ }
+ return simplefb_get_validated_int(dev, name, value);
+}
+
+static const struct drm_format_info *
+simplefb_get_validated_format(struct drm_device *dev, const char *format_name)
+{
+ static const struct simplefb_format formats[] = SIMPLEFB_FORMATS;
+ const struct simplefb_format *fmt = formats;
+ const struct simplefb_format *end = fmt + ARRAY_SIZE(formats);
+
+ if (!format_name) {
+ drm_err(dev, "simplefb: missing framebuffer format\n");
+ return ERR_PTR(-EINVAL);
+ }
+
+ while (fmt < end) {
+ if (!strcmp(format_name, fmt->name))
+ return drm_format_info(fmt->fourcc);
+ ++fmt;
+ }
+
+ drm_err(dev, "simplefb: unknown framebuffer format %s\n",
+ format_name);
+
+ return ERR_PTR(-EINVAL);
+}
+
+static int
+simplefb_get_width_pd(struct drm_device *dev,
+ const struct simplefb_platform_data *pd)
+{
+ return simplefb_get_validated_int0(dev, "width", pd->width);
+}
+
+static int
+simplefb_get_height_pd(struct drm_device *dev,
+ const struct simplefb_platform_data *pd)
+{
+ return simplefb_get_validated_int0(dev, "height", pd->height);
+}
+
+static int
+simplefb_get_stride_pd(struct drm_device *dev,
+ const struct simplefb_platform_data *pd)
+{
+ return simplefb_get_validated_int(dev, "stride", pd->stride);
+}
+
+static const struct drm_format_info *
+simplefb_get_format_pd(struct drm_device *dev,
+ const struct simplefb_platform_data *pd)
+{
+ return simplefb_get_validated_format(dev, pd->format);
+}
+
+/*
+ * Simple Framebuffer device
+ */
+
+struct simplekms_device {
+ struct drm_device dev;
+ struct platform_device *pdev;
+
+ /* simplefb settings */
+ struct drm_display_mode mode;
+ const struct drm_format_info *format;
+ unsigned int pitch;
+
+ /* memory management */
+ struct resource *mem;
+ void __iomem *screen_base;
+
+ /* modesetting */
+ struct drm_connector connector;
+ struct drm_simple_display_pipe pipe;
+};
+
+static struct simplekms_device *simplekms_device_of_dev(struct drm_device *dev)
+{
+ return container_of(dev, struct simplekms_device, dev);
+}
+
+/*
+ * Simplefb settings
+ */
+
+static struct drm_display_mode simplekms_mode(unsigned int width,
+ unsigned int height)
+{
+ struct drm_display_mode mode = { SIMPLEKMS_MODE(width, height) };
+
+ mode.clock = 60 /* Hz */ * mode.hdisplay * mode.vdisplay;
+ drm_mode_set_name(&mode);
+
+ return mode;
+}
+
+static int simplekms_device_init_fb(struct simplekms_device *sdev)
+{
+ int width, height, stride;
+ const struct drm_format_info *format;
+ struct drm_format_name_buf buf;
+ struct drm_device *dev = &sdev->dev;
+ struct platform_device *pdev = sdev->pdev;
+ const struct simplefb_platform_data *pd = dev_get_platdata(&pdev->dev);
+
+ if (pd) {
+ width = simplefb_get_width_pd(dev, pd);
+ if (width < 0)
+ return width;
+ height = simplefb_get_height_pd(dev, pd);
+ if (height < 0)
+ return height;
+ stride = simplefb_get_stride_pd(dev, pd);
+ if (stride < 0)
+ return stride;
+ format = simplefb_get_format_pd(dev, pd);
+ if (IS_ERR(format))
+ return PTR_ERR(format);
+ } else {
+ drm_err(dev, "no simplefb configuration found\n");
+ return -ENODEV;
+ }
+
+ sdev->mode = simplekms_mode(width, height);
+ sdev->format = format;
+ sdev->pitch = stride;
+
+ drm_dbg_kms(dev, "display mode={" DRM_MODE_FMT "}\n",
+ DRM_MODE_ARG(&sdev->mode));
+ drm_dbg_kms(dev,
+ "framebuffer format=\"%s\", size=%dx%d, stride=%d byte\n",
+ drm_get_format_name(format->format, &buf), width,
+ height, stride);
+
+ return 0;
+}
+
+/*
+ * Memory management
+ */
+
+static int simplekms_device_init_mm(struct simplekms_device *sdev)
+{
+ struct platform_device *pdev = sdev->pdev;
+ struct resource *mem;
+ void __iomem *screen_base;
+
+ mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (!mem)
+ return -EINVAL;
+
+ screen_base = devm_ioremap_wc(&pdev->dev, mem->start,
+ resource_size(mem));
+ if (!screen_base)
+ return -ENOMEM;
+
+ sdev->mem = mem;
+ sdev->screen_base = screen_base;
+
+ return 0;
+}
+
+/*
+ * Modesetting
+ */
+
+/*
+ * Support all formats of simplefb and maybe more; in order
+ * of preference. The display's update function will do any
+ * conversion necessary.
+ *
+ * TODO: Add blit helpers for remaining formats and uncomment
+ * constants.
+ */
+static const uint32_t simplekms_formats[] = {
+ DRM_FORMAT_XRGB8888,
+ DRM_FORMAT_ARGB8888,
+ DRM_FORMAT_RGB565,
+ //DRM_FORMAT_XRGB1555,
+ //DRM_FORMAT_ARGB1555,
+ DRM_FORMAT_RGB888,
+ //DRM_FORMAT_XRGB2101010,
+ //DRM_FORMAT_ARGB2101010,
+};
+
+static const uint64_t simplekms_format_modifiers[] = {
+ DRM_FORMAT_MOD_LINEAR,
+ DRM_FORMAT_MOD_INVALID
+};
+
+static int simplekms_connector_get_modes(struct drm_connector *connector)
+{
+ struct simplekms_device *sdev = simplekms_device_of_dev(connector->dev);
+ struct drm_display_mode *mode;
+
+ mode = drm_mode_duplicate(connector->dev, &sdev->mode);
+ if (!mode)
+ return 0;
+
+ if (mode->name[0] == '\0')
+ drm_mode_set_name(mode);
+
+ mode->type |= DRM_MODE_TYPE_PREFERRED;
+ drm_mode_probed_add(connector, mode);
+
+ if (mode->width_mm)
+ connector->display_info.width_mm = mode->width_mm;
+ if (mode->height_mm)
+ connector->display_info.height_mm = mode->height_mm;
+
+ return 1;
+}
+
+static const struct drm_connector_helper_funcs simplekms_connector_helper_funcs = {
+ .get_modes = simplekms_connector_get_modes,
+};
+
+static const struct drm_connector_funcs simplekms_connector_funcs = {
+ .reset = drm_atomic_helper_connector_reset,
+ .fill_modes = drm_helper_probe_single_connector_modes,
+ .destroy = drm_connector_cleanup,
+ .atomic_duplicate_state = drm_atomic_helper_connector_duplicate_state,
+ .atomic_destroy_state = drm_atomic_helper_connector_destroy_state,
+};
+
+static int
+simplekms_simple_display_pipe_mode_valid(struct drm_simple_display_pipe *pipe,
+ const struct drm_display_mode *mode)
+{
+ struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
+
+ if (mode->hdisplay != sdev->mode.hdisplay &&
+ mode->vdisplay != sdev->mode.vdisplay)
+ return MODE_ONE_SIZE;
+ else if (mode->hdisplay != sdev->mode.hdisplay)
+ return MODE_ONE_WIDTH;
+ else if (mode->vdisplay != sdev->mode.vdisplay)
+ return MODE_ONE_HEIGHT;
+
+ return MODE_OK;
+}
+
+static void
+simplekms_simple_display_pipe_enable(struct drm_simple_display_pipe *pipe,
+ struct drm_crtc_state *crtc_state,
+ struct drm_plane_state *plane_state)
+{
+ struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
+ struct drm_plane_state *state = pipe->plane.state;
+ struct drm_framebuffer *fb = state->fb;
+ void *vmap;
+
+ vmap = drm_gem_shmem_vmap(fb->obj[0]);
+ if (!vmap)
+ return;
+
+ drm_fb_blit_dstclip(sdev->screen_base, sdev->pitch,
+ sdev->format->format, vmap, fb);
+
+ drm_gem_shmem_vunmap(fb->obj[0], vmap);
+}
+
+static void
+simplekms_simple_display_pipe_update(struct drm_simple_display_pipe *pipe,
+ struct drm_plane_state *old_plane_state)
+{
+ struct simplekms_device *sdev = simplekms_device_of_dev(pipe->connector->dev);
+ struct drm_plane_state *state = pipe->plane.state;
+ struct drm_framebuffer *fb = state->fb;
+ struct drm_rect clip;
+ void *vmap;
+
+ if (!drm_atomic_helper_damage_merged(old_plane_state, state, &clip))
+ return;
+
+ vmap = drm_gem_shmem_vmap(fb->obj[0]);
+ if (!vmap)
+ return;
+
+ drm_fb_blit_rect_dstclip(sdev->screen_base, sdev->pitch,
+ sdev->format->format, vmap, fb, &clip);
+
+ drm_gem_shmem_vunmap(fb->obj[0], vmap);
+}
+
+static const struct drm_simple_display_pipe_funcs
+simplekms_simple_display_pipe_funcs = {
+ .mode_valid = simplekms_simple_display_pipe_mode_valid,
+ .enable = simplekms_simple_display_pipe_enable,
+ .update = simplekms_simple_display_pipe_update,
+ .prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
+};
+
+static const struct drm_mode_config_funcs simplekms_mode_config_funcs = {
+ .fb_create = drm_gem_fb_create_with_dirty,
+ .atomic_check = drm_atomic_helper_check,
+ .atomic_commit = drm_atomic_helper_commit,
+};
+
+static int simplekms_device_init_modeset(struct simplekms_device *sdev)
+{
+ struct drm_device *dev = &sdev->dev;
+ struct drm_display_mode *mode = &sdev->mode;
+ struct drm_connector *connector = &sdev->connector;
+ struct drm_simple_display_pipe *pipe = &sdev->pipe;
+ int ret;
+
+ ret = drmm_mode_config_init(dev);
+ if (ret)
+ return ret;
+
+ dev->mode_config.min_width = mode->hdisplay;
+ dev->mode_config.max_width = mode->hdisplay;
+ dev->mode_config.min_height = mode->vdisplay;
+ dev->mode_config.max_height = mode->vdisplay;
+ dev->mode_config.prefer_shadow = true;
+ dev->mode_config.preferred_depth = sdev->format->cpp[0] * 8;
+ dev->mode_config.funcs = &simplekms_mode_config_funcs;
+
+ drm_connector_helper_add(connector, &simplekms_connector_helper_funcs);
+ ret = drm_connector_init(dev, connector, &simplekms_connector_funcs,
+ DRM_MODE_CONNECTOR_Unknown);
+ if (ret)
+ return ret;
+
+ ret = drm_simple_display_pipe_init(dev, pipe,
+ &simplekms_simple_display_pipe_funcs,
+ simplekms_formats,
+ ARRAY_SIZE(simplekms_formats),
+ simplekms_format_modifiers,
+ connector);
+ if (ret)
+ return ret;
+
+ drm_mode_config_reset(dev);
+
+ return 0;
+}
+
+/*
+ * Init / Cleanup
+ */
+
+static void simplekms_device_cleanup(struct simplekms_device* sdev)
+{
+ struct drm_device *dev = &sdev->dev;
+
+ drm_dev_unregister(dev);
+}
+
+static struct simplekms_device *
+simplekms_device_create(struct drm_driver *drv, struct platform_device *pdev)
+{
+ struct simplekms_device *sdev;
+ int ret;
+
+ sdev = devm_drm_dev_alloc(&pdev->dev, drv, struct simplekms_device,
+ dev);
+ if (IS_ERR(sdev))
+ return ERR_CAST(sdev);
+ sdev->pdev = pdev;
+
+ ret = simplekms_device_init_fb(sdev);
+ if (ret)
+ return ERR_PTR(ret);
+ ret = simplekms_device_init_mm(sdev);
+ if (ret)
+ return ERR_PTR(ret);
+ ret = simplekms_device_init_modeset(sdev);
+ if (ret)
+ return ERR_PTR(ret);
+
+ return sdev;
+}
+
+/*
+ * DRM driver
+ */
+
+DEFINE_DRM_GEM_FOPS(simplekms_fops);
+
+static struct drm_driver simplekms_driver = {
+ DRM_GEM_SHMEM_DRIVER_OPS,
+ .name = DRIVER_NAME,
+ .desc = DRIVER_DESC,
+ .date = DRIVER_DATE,
+ .major = DRIVER_MAJOR,
+ .minor = DRIVER_MINOR,
+ .driver_features = DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
+ .fops = &simplekms_fops,
+};
+
+/*
+ * Platform driver
+ */
+
+static int simplekms_probe(struct platform_device *pdev)
+{
+ struct simplekms_device *sdev;
+ struct drm_device *dev;
+ int ret;
+
+ sdev = simplekms_device_create(&simplekms_driver, pdev);
+ if (IS_ERR(sdev))
+ return PTR_ERR(sdev);
+ dev = &sdev->dev;
+
+ ret = drm_dev_register(dev, 0);
+ if (ret)
+ return ret;
+
+ return 0;
+}
+
+static int simplekms_remove(struct platform_device *pdev)
+{
+ struct simplekms_device *sdev = platform_get_drvdata(pdev);
+
+ simplekms_device_cleanup(sdev);
+
+ return 0;
+}
+
+static struct platform_driver simplekms_platform_driver = {
+ .driver = {
+ .name = "simple-framebuffer", /* connect to sysfb */
+ },
+ .probe = simplekms_probe,
+ .remove = simplekms_remove,
+};
+
+module_platform_driver(simplekms_platform_driver);
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_LICENSE("GPL v2");
--
2.27.0
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