[PATCH 2/2] drm: simpledrm: add fbdev fallback support

[Noralf TrÃnnes]

Create a simple fbdev device during SimpleDRM setup so legacy user-space
and fbcon can use it.

Original work by David Herrmann.

Cc: dh.herrmann@xxxxxxxxx
Signed-off-by: Noralf TrÃnnes <noralf@xxxxxxxxxxx>
---

Changes from previous version:
- Remove the DRM_SIMPLEDRM_FBDEV kconfig option and use DRM_FBDEV_EMULATION
- Suspend fbcon/fbdev when the pipeline is enabled, resume in lastclose
- Add FBINFO_CAN_FORCE_OUTPUT flag so we get oops'es on the console

 drivers/gpu/drm/simpledrm/Kconfig           |   3 +
 drivers/gpu/drm/simpledrm/Makefile          |   1 +
 drivers/gpu/drm/simpledrm/simpledrm.h       |  24 +++++
 drivers/gpu/drm/simpledrm/simpledrm_drv.c   |   3 +
 drivers/gpu/drm/simpledrm/simpledrm_fbdev.c | 160 ++++++++++++++++++++++++++++
 drivers/gpu/drm/simpledrm/simpledrm_kms.c   |  12 +++
 6 files changed, 203 insertions(+)
 create mode 100644 drivers/gpu/drm/simpledrm/simpledrm_fbdev.c

diff --git a/drivers/gpu/drm/simpledrm/Kconfig b/drivers/gpu/drm/simpledrm/Kconfig
index f45b25d..9454536 100644
--- a/drivers/gpu/drm/simpledrm/Kconfig
+++ b/drivers/gpu/drm/simpledrm/Kconfig
@@ -13,6 +13,9 @@ config DRM_SIMPLEDRM
 	  SimpleDRM supports "simple-framebuffer" DeviceTree objects and
 	  compatible platform framebuffers.

+	  If fbdev support is enabled, this driver will also provide an fbdev
+	  compatibility layer.
+
 	  If unsure, say Y.

 	  To compile this driver as a module, choose M here: the
diff --git a/drivers/gpu/drm/simpledrm/Makefile b/drivers/gpu/drm/simpledrm/Makefile
index f6a62dc..7087245 100644
--- a/drivers/gpu/drm/simpledrm/Makefile
+++ b/drivers/gpu/drm/simpledrm/Makefile
@@ -1,4 +1,5 @@
 simpledrm-y :=	simpledrm_drv.o simpledrm_kms.o simpledrm_gem.o \
 		simpledrm_damage.o
+simpledrm-$(CONFIG_DRM_FBDEV_EMULATION) += simpledrm_fbdev.o

 obj-$(CONFIG_DRM_SIMPLEDRM) := simpledrm.o
diff --git a/drivers/gpu/drm/simpledrm/simpledrm.h b/drivers/gpu/drm/simpledrm/simpledrm.h
index e841655..a1ed251 100644
--- a/drivers/gpu/drm/simpledrm/simpledrm.h
+++ b/drivers/gpu/drm/simpledrm/simpledrm.h
@@ -30,6 +30,7 @@ struct sdrm_device {
 	struct drm_device *ddev;
 	struct drm_simple_display_pipe pipe;
 	struct drm_connector conn;
+	struct fb_info *fbdev;

 	/* framebuffer information */
 	const struct simplefb_format *fb_sformat;
@@ -43,6 +44,7 @@ struct sdrm_device {
 	void *fb_map;
 };

+void sdrm_lastclose(struct drm_device *ddev);
 int sdrm_drm_modeset_init(struct sdrm_device *sdrm);
 int sdrm_drm_mmap(struct file *filp, struct vm_area_struct *vma);

@@ -84,4 +86,26 @@ struct sdrm_framebuffer {

 #define to_sdrm_fb(x) container_of(x, struct sdrm_framebuffer, base)

+#ifdef CONFIG_DRM_FBDEV_EMULATION
+
+void sdrm_fbdev_init(struct sdrm_device *sdrm);
+void sdrm_fbdev_cleanup(struct sdrm_device *sdrm);
+void sdrm_fbdev_set_suspend(struct sdrm_device *sdrm, int state);
+
+#else
+
+static inline void sdrm_fbdev_init(struct sdrm_device *sdrm)
+{
+}
+
+static inline void sdrm_fbdev_cleanup(struct sdrm_device *sdrm)
+{
+}
+
+static inline void sdrm_fbdev_set_suspend(struct sdrm_device *sdrm, int state)
+{
+}
+
+#endif
+
 #endif /* SDRM_DRV_H */
diff --git a/drivers/gpu/drm/simpledrm/simpledrm_drv.c b/drivers/gpu/drm/simpledrm/simpledrm_drv.c
index 26b4ca9..5574fec 100644
--- a/drivers/gpu/drm/simpledrm/simpledrm_drv.c
+++ b/drivers/gpu/drm/simpledrm/simpledrm_drv.c
@@ -36,6 +36,7 @@ static struct drm_driver sdrm_drm_driver = {
 	.driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_PRIME |
 			   DRIVER_ATOMIC,
 	.fops = &sdrm_drm_fops,
+	.lastclose = sdrm_lastclose,

 	.gem_free_object = sdrm_gem_free_object,
 	.prime_fd_to_handle = drm_gem_prime_fd_to_handle,
@@ -223,6 +224,7 @@ static int sdrm_simplefb_probe(struct platform_device *pdev)
 	if (ret)
 		goto err_cleanup;

+	sdrm_fbdev_init(ddev->dev_private);
 	platform_set_drvdata(pdev, ddev);

 	DRM_INFO("Initialized %s on minor %d\n", ddev->driver->name,
@@ -246,6 +248,7 @@ static int sdrm_simplefb_remove(struct platform_device *pdev)
 	struct drm_device *ddev = platform_get_drvdata(pdev);
 	struct sdrm_device *sdrm = ddev->dev_private;

+	sdrm_fbdev_cleanup(sdrm);
 	drm_dev_unregister(ddev);
 	drm_mode_config_cleanup(ddev);

diff --git a/drivers/gpu/drm/simpledrm/simpledrm_fbdev.c b/drivers/gpu/drm/simpledrm/simpledrm_fbdev.c
new file mode 100644
index 0000000..b83646b
--- /dev/null
+++ b/drivers/gpu/drm/simpledrm/simpledrm_fbdev.c
@@ -0,0 +1,160 @@
+/*
+ * SimpleDRM firmware framebuffer driver
+ * Copyright (c) 2012-2014 David Herrmann <dh.herrmann@xxxxxxxxx>
+ *
+ * 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.
+ */
+
+/*
+ * fbdev compatibility layer
+ * We provide a basic fbdev device for the same framebuffer that is used for
+ * the pseudo CRTC.
+ */
+
+#include <linux/console.h>
+#include <linux/errno.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/fb.h>
+#include "simpledrm.h"
+
+struct sdrm_fbdev {
+	u32 palette[16];
+};
+
+static int sdrm_fbdev_setcolreg(u_int regno, u_int red, u_int green,
+				u_int blue, u_int transp, struct fb_info *info)
+{
+	u32 *pal = info->pseudo_palette;
+	u32 cr = red >> (16 - info->var.red.length);
+	u32 cg = green >> (16 - info->var.green.length);
+	u32 cb = blue >> (16 - info->var.blue.length);
+	u32 value;
+
+	if (regno >= 16)
+		return -EINVAL;
+
+	value = (cr << info->var.red.offset) |
+		(cg << info->var.green.offset) |
+		(cb << info->var.blue.offset);
+
+	if (info->var.transp.length > 0) {
+		u32 mask = (1 << info->var.transp.length) - 1;
+
+		mask <<= info->var.transp.offset;
+		value |= mask;
+	}
+
+	pal[regno] = value;
+
+	return 0;
+}
+
+static struct fb_ops sdrm_fbdev_ops = {
+	.owner		= THIS_MODULE,
+	.fb_setcolreg	= sdrm_fbdev_setcolreg,
+	.fb_fillrect	= cfb_fillrect,
+	.fb_copyarea	= cfb_copyarea,
+	.fb_imageblit	= cfb_imageblit,
+};
+
+void sdrm_fbdev_init(struct sdrm_device *sdrm)
+{
+	struct sdrm_fbdev *fb;
+	struct fb_info *info;
+	int ret;
+
+	if (fb_get_options("simpledrmfb", NULL))
+		return;
+
+	info = framebuffer_alloc(sizeof(struct sdrm_fbdev), sdrm->ddev->dev);
+	if (!info)
+		goto err_out;
+
+	fb = info->par;
+	info->flags = FBINFO_DEFAULT | FBINFO_MISC_FIRMWARE |
+		      FBINFO_CAN_FORCE_OUTPUT;
+	info->pseudo_palette = fb->palette;
+	info->fbops = &sdrm_fbdev_ops;
+	info->screen_base = sdrm->fb_map;
+
+	strncpy(info->fix.id, "simpledrmfb", 15);
+	info->fix.type = FB_TYPE_PACKED_PIXELS;
+	info->fix.visual = FB_VISUAL_TRUECOLOR;
+	info->fix.accel = FB_ACCEL_NONE;
+	info->fix.smem_start = (unsigned long)sdrm->fb_base;
+	info->fix.smem_len = sdrm->fb_size;
+	info->fix.line_length = sdrm->fb_stride;
+
+	info->var.activate = FB_ACTIVATE_NOW;
+	info->var.vmode = FB_VMODE_NONINTERLACED;
+	info->var.bits_per_pixel = sdrm->fb_bpp;
+	info->var.height = -1;
+	info->var.width = -1;
+	info->var.xres = sdrm->fb_width;
+	info->var.yres = sdrm->fb_height;
+	info->var.xres_virtual = info->var.xres;
+	info->var.yres_virtual = info->var.yres;
+	info->var.red = sdrm->fb_sformat->red;
+	info->var.green = sdrm->fb_sformat->green;
+	info->var.blue = sdrm->fb_sformat->blue;
+	info->var.transp = sdrm->fb_sformat->transp;
+
+	/* some dummy values for timing to make fbset happy */
+	info->var.pixclock = 10000000 / info->var.xres * 1000 / info->var.yres;
+	info->var.left_margin = (info->var.xres / 8) & 0xf8;
+	info->var.right_margin = 32;
+	info->var.upper_margin = 16;
+	info->var.lower_margin = 4;
+	info->var.hsync_len = (info->var.xres / 8) & 0xf8;
+	info->var.vsync_len = 4;
+
+	ret = register_framebuffer(info);
+	if (ret < 0)
+		goto err_free;
+
+	sdrm->fbdev = info;
+	dev_info(sdrm->ddev->dev, "fbdev frontend %s as fb%d\n",
+		 info->fix.id, info->node);
+
+	return;
+
+err_free:
+	framebuffer_release(info);
+err_out:
+	dev_warn(sdrm->ddev->dev, "cannot create fbdev frontend\n");
+}
+
+void sdrm_fbdev_cleanup(struct sdrm_device *sdrm)
+{
+	struct fb_info *info;
+
+	if (!sdrm->fbdev)
+		return;
+
+	info = sdrm->fbdev;
+	sdrm->fbdev = NULL;
+
+	dev_info(sdrm->ddev->dev, "remove fbdev frontend %s (fb%d)\n",
+		 info->fix.id, info->node);
+
+	if (unregister_framebuffer(info))
+		dev_err(sdrm->ddev->dev, "unregister_framebuffer() failed, leaking fw-fb\n");
+	else
+		framebuffer_release(info);
+}
+
+void sdrm_fbdev_set_suspend(struct sdrm_device *sdrm, int state)
+{
+	if (!sdrm->fbdev)
+		return;
+
+	console_lock();
+	fb_set_suspend(sdrm->fbdev, state);
+	console_unlock();
+}
diff --git a/drivers/gpu/drm/simpledrm/simpledrm_kms.c b/drivers/gpu/drm/simpledrm/simpledrm_kms.c
index 6295a9f..dd176f2 100644
--- a/drivers/gpu/drm/simpledrm/simpledrm_kms.c
+++ b/drivers/gpu/drm/simpledrm/simpledrm_kms.c
@@ -25,6 +25,14 @@ static const uint32_t sdrm_formats[] = {
 	DRM_FORMAT_XRGB8888,
 };

+void sdrm_lastclose(struct drm_device *ddev)
+{
+	struct sdrm_device *sdrm = ddev->dev_private;
+
+	/* resume fbcon/fbdev */
+	sdrm_fbdev_set_suspend(sdrm, 0);
+}
+
 static int sdrm_conn_get_modes(struct drm_connector *conn)
 {
 	struct sdrm_device *sdrm = conn->dev->dev_private;
@@ -118,7 +126,11 @@ static void sdrm_crtc_send_vblank_event(struct drm_crtc *crtc)
 static void sdrm_display_pipe_enable(struct drm_simple_display_pipe *pipe,
 				     struct drm_crtc_state *crtc_state)
 {
+	struct sdrm_device *sdrm = pipe_to_sdrm(pipe);
+
 	sdrm_crtc_send_vblank_event(&pipe->crtc);
+	/* suspend fbcon/fbdev */
+	sdrm_fbdev_set_suspend(sdrm, 1);
 }

 static void sdrm_display_pipe_disable(struct drm_simple_display_pipe *pipe)
--
2.8.2