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Subject[PATCH v2 4/6] drm/tiny: Add TinyDRM for DSI/DBI panels
Date
The new API function mipi_dsi_maybe_register_tiny_driver() is supposed
to be called by DSI/DBI panel drivers at the end of their probe.

If it is detected that the panel is not connected to any controller,
because it has no port #0 node in Device Tree that points back to it,
then a TinyDRM driver is registered with it.

This TinyDRM driver expects that a DCS-compliant protocol is used by the
DSI/DBI panel and can only be used with these.

v2: No change

Signed-off-by: Paul Cercueil <paul@crapouillou.net>
---
drivers/gpu/drm/tiny/Kconfig | 8 +
drivers/gpu/drm/tiny/Makefile | 1 +
drivers/gpu/drm/tiny/tiny-dsi.c | 266 ++++++++++++++++++++++++++++++++
include/drm/drm_mipi_dsi.h | 19 +++
4 files changed, 294 insertions(+)
create mode 100644 drivers/gpu/drm/tiny/tiny-dsi.c

diff --git a/drivers/gpu/drm/tiny/Kconfig b/drivers/gpu/drm/tiny/Kconfig
index 2b6414f0fa75..b62427b88dfe 100644
--- a/drivers/gpu/drm/tiny/Kconfig
+++ b/drivers/gpu/drm/tiny/Kconfig
@@ -28,6 +28,14 @@ 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 TINYDRM_DSI
+ tristate "DRM support for generic DBI/DSI display panels"
+ depends on DRM && DRM_MIPI_DSI
+ select DRM_MIPI_DBI
+ select DRM_KMS_CMA_HELPER
+ help
+ DRM driver for generic DBI/DSI display panels
+
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..2bfee13347a5 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-$(CONFIG_TINYDRM_DSI) += tiny-dsi.o
obj-$(CONFIG_TINYDRM_HX8357D) += hx8357d.o
obj-$(CONFIG_TINYDRM_ILI9225) += ili9225.o
obj-$(CONFIG_TINYDRM_ILI9341) += ili9341.o
diff --git a/drivers/gpu/drm/tiny/tiny-dsi.c b/drivers/gpu/drm/tiny/tiny-dsi.c
new file mode 100644
index 000000000000..b24d49836125
--- /dev/null
+++ b/drivers/gpu/drm/tiny/tiny-dsi.c
@@ -0,0 +1,266 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * TinyDRM driver for standard DSI/DBI panels
+ *
+ * Copyright 2020 Paul Cercueil <paul@crapouillou.net>
+ */
+
+#include <linux/dma-mapping.h>
+#include <linux/module.h>
+
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_damage_helper.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_mipi_dbi.h>
+#include <drm/drm_mipi_dsi.h>
+#include <drm/drm_modeset_helper.h>
+#include <drm/drm_panel.h>
+#include <drm/drm_probe_helper.h>
+
+#include <video/mipi_display.h>
+
+struct tiny_dsi {
+ struct drm_device drm;
+ struct drm_connector connector;
+ struct drm_simple_display_pipe pipe;
+
+ struct mipi_dsi_device *dsi;
+ struct drm_panel *panel;
+};
+
+#define mipi_dcs_command(dsi, cmd, seq...) \
+({ \
+ u8 d[] = { seq }; \
+ mipi_dsi_dcs_write(dsi, cmd, d, ARRAY_SIZE(d)); \
+})
+
+static inline struct tiny_dsi *drm_to_tiny_dsi(struct drm_device *drm)
+{
+ return container_of(drm, struct tiny_dsi, drm);
+}
+
+static void tiny_dsi_fb_dirty(struct drm_framebuffer *fb, struct drm_rect *rect)
+{
+ struct drm_gem_object *gem = drm_gem_fb_get_obj(fb, 0);
+ struct drm_gem_cma_object *cma_obj = to_drm_gem_cma_obj(gem);
+ struct tiny_dsi *priv = drm_to_tiny_dsi(fb->dev);
+ unsigned int height = rect->y2 - rect->y1;
+ unsigned int width = rect->x2 - rect->x1;
+ bool fb_convert;
+ int idx, ret;
+ void *tr;
+
+ if (!drm_dev_enter(fb->dev, &idx))
+ return;
+
+ DRM_DEBUG_KMS("Flushing [FB:%d] " DRM_RECT_FMT "\n", fb->base.id, DRM_RECT_ARG(rect));
+
+ fb_convert = width != fb->width || height != fb->height
+ || fb->format->format == DRM_FORMAT_XRGB8888;
+ if (fb_convert) {
+ tr = kzalloc(width * height * 2, GFP_KERNEL);
+
+ /* TODO: swap pixels if needed */
+ ret = mipi_dbi_buf_copy(tr, fb, rect, false);
+ if (ret)
+ goto err_msg;
+ } else {
+ tr = cma_obj->vaddr;
+ }
+
+ mipi_dcs_command(priv->dsi, MIPI_DCS_SET_COLUMN_ADDRESS,
+ (rect->x1 >> 8) & 0xff, rect->x1 & 0xff,
+ (rect->x2 >> 8) & 0xff, rect->x2 & 0xff);
+ mipi_dcs_command(priv->dsi, MIPI_DCS_SET_PAGE_ADDRESS,
+ (rect->y1 >> 8) & 0xff, rect->y1 & 0xff,
+ (rect->y2 >> 8) & 0xff, rect->y2 & 0xff);
+
+ ret = mipi_dsi_dcs_write(priv->dsi, MIPI_DCS_WRITE_MEMORY_START,
+ tr, width * height * 2);
+err_msg:
+ if (ret)
+ dev_err_once(fb->dev->dev, "Failed to update display %d\n", ret);
+
+ if (fb_convert)
+ kfree(tr);
+ drm_dev_exit(idx);
+}
+
+static void tiny_dsi_enable(struct drm_simple_display_pipe *pipe,
+ struct drm_crtc_state *crtc_state,
+ struct drm_plane_state *plane_state)
+{
+ struct tiny_dsi *priv = drm_to_tiny_dsi(pipe->crtc.dev);
+
+ drm_panel_enable(priv->panel);
+}
+
+static void tiny_dsi_disable(struct drm_simple_display_pipe *pipe)
+{
+ struct tiny_dsi *priv = drm_to_tiny_dsi(pipe->crtc.dev);
+
+ drm_panel_disable(priv->panel);
+}
+
+static void tiny_dsi_update(struct drm_simple_display_pipe *pipe,
+ struct drm_plane_state *old_state)
+{
+ struct drm_plane_state *state = pipe->plane.state;
+ struct drm_rect rect;
+
+ if (drm_atomic_helper_damage_merged(old_state, state, &rect))
+ tiny_dsi_fb_dirty(state->fb, &rect);
+}
+
+static const struct drm_simple_display_pipe_funcs tiny_dsi_pipe_funcs = {
+ .enable = tiny_dsi_enable,
+ .disable = tiny_dsi_disable,
+ .update = tiny_dsi_update,
+ .prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
+};
+
+static int tiny_dsi_connector_get_modes(struct drm_connector *connector)
+{
+ struct tiny_dsi *priv = drm_to_tiny_dsi(connector->dev);
+
+ return drm_panel_get_modes(priv->panel, connector);
+}
+
+static const struct drm_connector_helper_funcs tiny_dsi_connector_hfuncs = {
+ .get_modes = tiny_dsi_connector_get_modes,
+};
+
+static const struct drm_connector_funcs tiny_dsi_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 const uint32_t tiny_dsi_formats[] = {
+ DRM_FORMAT_RGB565,
+ DRM_FORMAT_XRGB8888,
+};
+
+static const struct drm_mode_config_funcs tiny_dsi_mode_config_funcs = {
+ .fb_create = drm_gem_fb_create_with_dirty,
+ .atomic_check = drm_atomic_helper_check,
+ .atomic_commit = drm_atomic_helper_commit,
+};
+
+DEFINE_DRM_GEM_CMA_FOPS(tiny_dsi_fops);
+
+static struct drm_driver tiny_dsi_driver = {
+ .driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
+ .name = "tiny-dsi",
+ .desc = "Tiny DSI",
+ .date = "20200605",
+ .major = 1,
+ .minor = 0,
+
+ .fops = &tiny_dsi_fops,
+ DRM_GEM_CMA_DRIVER_OPS,
+};
+
+static void tiny_dsi_remove(void *drm)
+{
+ drm_dev_unplug(drm);
+ drm_atomic_helper_shutdown(drm);
+}
+
+int mipi_dsi_register_tiny_driver(struct mipi_dsi_device *dsi)
+{
+ struct device *dev = &dsi->dev;
+ struct drm_device *drm;
+ struct tiny_dsi *priv;
+ static const uint64_t modifiers[] = {
+ DRM_FORMAT_MOD_LINEAR,
+ DRM_FORMAT_MOD_INVALID
+ };
+ int ret;
+
+ /*
+ * Even though it's not the SPI device that does DMA (the master does),
+ * the dma mask is necessary for the dma_alloc_wc() in
+ * drm_gem_cma_create(). The dma_addr returned will be a physical
+ * address which might be different from the bus address, but this is
+ * not a problem since the address will not be used.
+ * The virtual address is used in the transfer and the SPI core
+ * re-maps it on the SPI master device using the DMA streaming API
+ * (spi_map_buf()).
+ */
+ if (!dev->coherent_dma_mask) {
+ ret = dma_coerce_mask_and_coherent(dev, DMA_BIT_MASK(32));
+ if (ret) {
+ dev_warn(dev, "Failed to set dma mask %d\n", ret);
+ return ret;
+ }
+ }
+
+ priv = devm_drm_dev_alloc(dev, &tiny_dsi_driver, struct tiny_dsi, drm);
+ if (!priv)
+ return ret;
+
+ priv->dsi = dsi;
+ drm = &priv->drm;
+
+ priv->panel = of_drm_find_panel(dev->of_node);
+ if (IS_ERR(priv->panel)) {
+ dev_err(dev, "Unable to find panel\n");
+ return PTR_ERR(priv->panel);
+ }
+
+ drm_mode_config_init(drm);
+
+ drm->mode_config.preferred_depth = 16;
+
+ drm->mode_config.funcs = &tiny_dsi_mode_config_funcs;
+ drm->mode_config.min_width = 0;
+ drm->mode_config.min_height = 0;
+ drm->mode_config.max_width = 4096;
+ drm->mode_config.max_height = 4096;
+
+ drm_connector_helper_add(&priv->connector, &tiny_dsi_connector_hfuncs);
+ ret = drm_connector_init(drm, &priv->connector, &tiny_dsi_connector_funcs,
+ DRM_MODE_CONNECTOR_DSI);
+ if (ret) {
+ dev_err(dev, "Unable to init connector\n");
+ return ret;
+ }
+
+ ret = drm_simple_display_pipe_init(drm, &priv->pipe, &tiny_dsi_pipe_funcs,
+ tiny_dsi_formats, ARRAY_SIZE(tiny_dsi_formats),
+ modifiers, &priv->connector);
+ if (ret) {
+ dev_err(dev, "Unable to init display pipe\n");
+ return ret;
+ }
+
+ drm_plane_enable_fb_damage_clips(&priv->pipe.plane);
+
+ drm_mode_config_reset(drm);
+
+ ret = drm_dev_register(drm, 0);
+ if (ret) {
+ dev_err(dev, "Failed to register DRM driver\n");
+ return ret;
+ }
+
+ ret = devm_add_action_or_reset(dev, tiny_dsi_remove, drm);
+ if (ret)
+ return ret;
+
+ drm_fbdev_generic_setup(drm, 0);
+
+ return 0;
+}
+EXPORT_SYMBOL_GPL(mipi_dsi_register_tiny_driver);
+
+MODULE_DESCRIPTION("DSI/DBI TinyDRM driver");
+MODULE_AUTHOR("Paul Cercueil <paul@crapouillou.net>");
+MODULE_LICENSE("GPL");
diff --git a/include/drm/drm_mipi_dsi.h b/include/drm/drm_mipi_dsi.h
index 802644c4c0c4..ee9538633943 100644
--- a/include/drm/drm_mipi_dsi.h
+++ b/include/drm/drm_mipi_dsi.h
@@ -10,6 +10,7 @@
#define __DRM_MIPI_DSI_H__

#include <linux/device.h>
+#include <linux/of_graph.h>

struct mipi_dsi_host;
struct mipi_dsi_device;
@@ -350,4 +351,22 @@ void mipi_dsi_driver_unregister(struct mipi_dsi_driver *driver);
module_driver(__mipi_dsi_driver, mipi_dsi_driver_register, \
mipi_dsi_driver_unregister)

+#if IS_ENABLED(CONFIG_TINYDRM_DSI)
+int mipi_dsi_register_tiny_driver(struct mipi_dsi_device *dsi);
+#else
+static inline int mipi_dsi_register_tiny_driver(struct mipi_dsi_device *dsi)
+{
+ return 0;
+}
+#endif
+
+static inline int mipi_dsi_maybe_register_tiny_driver(struct mipi_dsi_device *dsi)
+{
+ /* Register the TinyDRM DSI/DBI driver if the panel has no controller */
+ if (!of_graph_get_port_by_id(dsi->dev.of_node, 0))
+ return mipi_dsi_register_tiny_driver(dsi);
+
+ return 0;
+}
+
#endif /* __DRM_MIPI_DSI__ */
--
2.28.0
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