This is a DRM based driver for the Atmel LCDC IP.
There exist today a framebuffer based driver and
this is a re-implmentation of the same on top of DRM.

The rewrite was based on the original fbdev driver
but the driver has also seen inspiration from
the atmel-hlcdc_dc driver and others.

The driver is not a full replacement:
- STN displays are not supported
        Binding support is missing but most of the
        STN specific functionality is otherwise ported
        from the fbdev driver.
- gamma support is missing
        The driver utilises drm_simple_kms_helper and
        this helper lacks support for settting up gamma
- modesetting is not checked (see TODO in file)
- support for extra modes as applicable (and lcd-wiring-mode)
- support for AVR32 (is it relevant?)

Signed-off-by: Sam Ravnborg <s...@ravnborg.org>
Cc: Nicolas Ferre <nicolas.fe...@atmel.com>
Cc: Boris Brezillon <boris.brezil...@free-electrons.com>
Cc: Alexandre Belloni <alexandre.bell...@bootlin.com>
---
 MAINTAINERS                           |    7 +
 drivers/gpu/drm/atmel/Kconfig         |   12 +
 drivers/gpu/drm/atmel/Makefile        |    2 +
 drivers/gpu/drm/atmel/atmel_lcdc-dc.c | 1094 +++++++++++++++++++++++++++++++++
 4 files changed, 1115 insertions(+)
 create mode 100644 drivers/gpu/drm/atmel/atmel_lcdc-dc.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 09ce76a9a1dc..0a594d02a7c0 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4685,6 +4685,13 @@ F:       drivers/gpu/drm/atmel/atmel-hlcdc*
 F:     Documentation/devicetree/bindings/display/atmel/
 T:     git git://anongit.freedesktop.org/drm/drm-misc
 
+DRM DRIVERS FOR ATMEL LCDC
+M:     Sam Ravnborg <s...@ravnborg.org>
+L:     dri-devel@lists.freedesktop.org
+S:     Maintained
+F:     drivers/gpu/drm/atmel/atmel-lcdc*
+F:     Documentation/devicetree/bindings/display/atmel/
+
 DRM DRIVERS FOR BRIDGE CHIPS
 M:     Archit Taneja <arch...@codeaurora.org>
 M:     Andrzej Hajda <a.ha...@samsung.com>
diff --git a/drivers/gpu/drm/atmel/Kconfig b/drivers/gpu/drm/atmel/Kconfig
index 7cd3862f9d18..c4c6150f271a 100644
--- a/drivers/gpu/drm/atmel/Kconfig
+++ b/drivers/gpu/drm/atmel/Kconfig
@@ -14,3 +14,15 @@ config DRM_ATMEL_HLCDC
        help
          Choose this option if you have an ATMEL SoC with an HLCDC display
          controller (i.e. at91sam9n12, at91sam9x5 family or sama5d3 family).
+
+config DRM_ATMEL_LCDC
+       tristate "DRM Support for ATMEL LCDC Display Controller"
+       depends on DRM && OF && COMMON_CLK && MFD_ATMEL_LCDC && ARM
+       select DRM_ATMEL
+       select DRM_GEM_CMA_HELPER
+       select DRM_KMS_HELPER
+       select DRM_KMS_CMA_HELPER
+       select DRM_PANEL
+       help
+         Choose this option if you have an ATMEL SoC with an LCDC display
+         controller (only at91sam9263 or at91sam9rl).
diff --git a/drivers/gpu/drm/atmel/Makefile b/drivers/gpu/drm/atmel/Makefile
index 49dc89f36b73..9fdfada613d2 100644
--- a/drivers/gpu/drm/atmel/Makefile
+++ b/drivers/gpu/drm/atmel/Makefile
@@ -5,3 +5,5 @@ atmel-hlcdc-dc-y := atmel_hlcdc_crtc.o \
                atmel_hlcdc_plane.o
 
 obj-$(CONFIG_DRM_ATMEL_HLCDC)  += atmel-hlcdc-dc.o
+
+obj-$(CONFIG_DRM_ATMEL_LCDC)   += atmel_lcdc-dc.o
diff --git a/drivers/gpu/drm/atmel/atmel_lcdc-dc.c 
b/drivers/gpu/drm/atmel/atmel_lcdc-dc.c
new file mode 100644
index 000000000000..275a09e2e100
--- /dev/null
+++ b/drivers/gpu/drm/atmel/atmel_lcdc-dc.c
@@ -0,0 +1,1094 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2018 Sam Ravnborg
+ *
+ * The driver is based on atmel_lcdfb which is:
+ * Copyright (C) 2007 Atmel Corporation
+ *
+ * Atmel LCD Controller Display Controller.
+ * A sub-device of the Atmel LCDC IP.
+ *
+ * The Atmel LCD Controller supports in the following configuration:
+ * - TFT only, with BGR565, 8 bits/pixel
+ * - Resolution up to 2048x2048
+ * - Single plane, crtc, one fixed output
+ *
+ * Features not (yet) ported from atmel_lcdfb:
+ * - Support for extra modes (and configurable intensify bit)
+ * - Check modesetting support - lcdc_dc_display_check()
+ * - set color / palette handling
+ * - support for STN displays (partly implemented)
+ * - AVR32 support (relevant?)
+ */
+
+#include <linux/regulator/consumer.h>
+#include <linux/mfd/atmel-lcdc.h>
+#include <linux/of_platform.h>
+#include <linux/pm_runtime.h>
+#include <linux/irqreturn.h>
+#include <linux/device.h>
+#include <linux/regmap.h>
+
+#include <video/videomode.h>
+
+#include <drm/drm_gem_framebuffer_helper.h>
+#include <drm/drm_simple_kms_helper.h>
+#include <drm/drm_gem_cma_helper.h>
+#include <drm/drm_atomic_helper.h>
+#include <drm/drm_fb_cma_helper.h>
+#include <drm/drm_crtc_helper.h>
+#include <drm/drm_fb_helper.h>
+#include <drm/drm_fourcc.h>
+#include <drm/drm_vblank.h>
+#include <drm/drm_modes.h>
+#include <drm/drm_panel.h>
+#include <drm/drm_print.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_of.h>
+
+/* Parameters */
+#define ATMEL_LCDC_DMA_BURST_LEN       8       /* words */
+
+/**
+ * struct atmel_lcdc_dc_desc - CPU specific configuration properties
+ */
+struct atmel_lcdc_dc_desc {
+       int guard_time;
+       int fifo_size;
+       int min_width;
+       int min_height;
+       int max_width;
+       int max_height;
+       bool have_hozval;
+       bool have_alt_pixclock;
+};
+
+/* private data */
+struct lcdc_dc {
+       const struct atmel_lcdc_dc_desc *desc;
+       struct atmel_mfd_lcdc *mfd_lcdc;
+       struct regulator *lcd_supply;
+       struct drm_fbdev_cma *fbdev;
+       struct drm_bridge *bridge;
+       struct drm_panel *panel;
+       struct regmap *regmap;
+       struct device *dev;
+
+       struct drm_simple_display_pipe pipe;
+       struct work_struct reset_lcdc_work;
+       struct drm_connector connector;
+};
+
+/* Configuration of individual CPU's */
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9261 = {
+       .guard_time = 1,
+       .fifo_size = 512,
+       .min_width = 0,
+       .min_height = 0,
+       .max_width = 2048,
+       .max_height = 2048,
+       .have_hozval = true,
+       .have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9263 = {
+       .guard_time = 1,
+       .fifo_size = 2048,
+       .min_width = 0,
+       .min_height = 0,
+       .max_width = 2048,
+       .max_height = 2048,
+       .have_hozval = false,
+       .have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9g10 = {
+       .guard_time = 1,
+       .fifo_size = 512,
+       .min_width = 0,
+       .min_height = 0,
+       .max_width = 2048,
+       .max_height = 2048,
+       .have_hozval = true,
+       .have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9g45 = {
+       .guard_time = 1,
+       .fifo_size = 512,
+       .min_width = 0,
+       .min_height = 0,
+       .max_width = 2048,
+       .max_height = 2048,
+       .have_hozval = false,
+       .have_alt_pixclock = true,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9g46 = {
+       .guard_time = 1,
+       .fifo_size = 512,
+       .min_width = 0,
+       .min_height = 0,
+       .max_width = 2048,
+       .max_height = 2048,
+       .have_hozval = false,
+       .have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9m10 = {
+       .guard_time = 1,
+       .fifo_size = 512,
+       .min_width = 0,
+       .min_height = 0,
+       .max_width = 2048,
+       .max_height = 2048,
+       .have_hozval = false,
+       .have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9m11 = {
+       .guard_time = 1,
+       .fifo_size = 512,
+       .min_width = 0,
+       .min_height = 0,
+       .max_width = 2048,
+       .max_height = 2048,
+       .have_hozval = false,
+       .have_alt_pixclock = false,
+};
+
+static const struct atmel_lcdc_dc_desc atmel_lcdc_dc_at91sam9rl = {
+       .guard_time = 1,
+       .fifo_size = 512,
+       .min_width = 0,
+       .min_height = 0,
+       .max_width = 2048,
+       .max_height = 2048,
+       .have_hozval = false,
+       .have_alt_pixclock = false,
+};
+
+static const struct of_device_id atmel_lcdc_of_match[] = {
+       {
+               .compatible = "atmel,at91sam9261-lcdc-mfd",
+               .data = &atmel_lcdc_dc_at91sam9261,
+       }, {
+               .compatible = "atmel,at91sam9263-lcdc-mfd",
+               .data = &atmel_lcdc_dc_at91sam9263,
+       }, {
+               .compatible = "atmel,at91sam9g10-lcdc-mfd",
+               .data = &atmel_lcdc_dc_at91sam9g10,
+       }, {
+               .compatible = "atmel,at91sam9g45-lcdc-mfd",
+               .data = &atmel_lcdc_dc_at91sam9g45,
+       }, {
+               .compatible = "atmel,at91sam9g46-lcdc-mfd",
+               .data = &atmel_lcdc_dc_at91sam9g46,
+       }, {
+               .compatible = "atmel,at91sam9m10-lcdc-mfd",
+               .data = &atmel_lcdc_dc_at91sam9m10,
+       }, {
+               .compatible = "atmel,at91sam9m11-lcdc-mfd",
+               .data = &atmel_lcdc_dc_at91sam9m11,
+       }, {
+               .compatible = "atmel,at91sam9rl-lcdc-mfd",
+               .data = &atmel_lcdc_dc_at91sam9rl,
+       },
+       { /* sentinel */ },
+};
+MODULE_DEVICE_TABLE(of, atmel_lcdc_of_match);
+
+/*
+ * The Atmel LCD controller display-controller supports several formats but
+ * this driver supports only a small subset.
+ * TODO: atmel_lcdfb supports more - port it over
+ * Maybe actual wiring will impact mode support?
+ */
+static const u32 lcdc_dc_formats[] = {
+       DRM_FORMAT_BGR565,
+};
+
+/* Start LCD Controller (DMA + PWR) */
+static void lcdc_dc_start(struct lcdc_dc *lcdc_dc)
+{
+       // Enable DMA
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_DMACON, ATMEL_LCDC_DMAEN);
+       // Enable LCD
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_PWRCON,
+                    (lcdc_dc->desc->guard_time << ATMEL_LCDC_GUARDT_OFFSET)
+                    | ATMEL_LCDC_PWR);
+}
+
+/* Stop LCD Controller (PWR + DMA) */
+static void lcdc_dc_stop(struct lcdc_dc *lcdc_dc)
+{
+       unsigned int pwrcon;
+
+       might_sleep();
+
+       /* Turn off the LCD controller and the DMA controller */
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_PWRCON,
+                       lcdc_dc->desc->guard_time << ATMEL_LCDC_GUARDT_OFFSET);
+
+       /* Wait for the LCDC core to become idle */
+       regmap_read_poll_timeout(lcdc_dc->regmap, ATMEL_LCDC_PWRCON, pwrcon,
+                                !(pwrcon & ATMEL_LCDC_BUSY), 100, 10000);
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_DMACON, !(ATMEL_LCDC_DMAEN));
+}
+
+static void lcdc_dc_start_clock(struct lcdc_dc *lcdc_dc)
+{
+       clk_prepare_enable(lcdc_dc->mfd_lcdc->bus_clk);
+       clk_prepare_enable(lcdc_dc->mfd_lcdc->lcdc_clk);
+}
+
+static void lcdc_dc_stop_clock(struct lcdc_dc *lcdc_dc)
+{
+       clk_disable_unprepare(lcdc_dc->mfd_lcdc->bus_clk);
+       clk_disable_unprepare(lcdc_dc->mfd_lcdc->lcdc_clk);
+}
+
+static int lcdc_dc_display_check(struct drm_simple_display_pipe *pipe,
+                                struct drm_plane_state *pstate,
+                                struct drm_crtc_state *cstate)
+{
+       const struct drm_display_mode *dmode;
+       struct drm_framebuffer *old_fb;
+       struct drm_framebuffer *fb;
+
+       dmode = &cstate->mode;
+       old_fb = pipe->plane.state->fb;
+       fb = pstate->fb;
+
+       /* Check timing? */
+       /* TODO */
+
+       return 0;
+}
+
+/* Horizontal size of LCD module - configuration dependent */
+static unsigned int compute_hozval(struct lcdc_dc *lcdc_dc, unsigned int width)
+{
+       unsigned int valid_lcdd_data_line;
+       unsigned int hoz_display_size;
+       unsigned int disptype;
+       unsigned int scanmode;
+       unsigned int ifwidth;
+       unsigned int lcdcon2;
+
+       if (!lcdc_dc->desc->have_hozval)
+               return width;
+
+       regmap_read(lcdc_dc->regmap, ATMEL_LCDC_LCDCON2, &lcdcon2);
+       disptype = lcdcon2 & ATMEL_LCDC_DISTYPE;
+
+       if (disptype == ATMEL_LCDC_DISTYPE_TFT)
+               return width;
+
+       ifwidth = lcdcon2 & ATMEL_LCDC_IFWIDTH;
+       scanmode = lcdcon2 & ATMEL_LCDC_SCANMOD;
+
+       /*
+        * STN display
+        * Based on algorithm from datasheet calculate hozval
+        */
+       if (disptype == ATMEL_LCDC_DISTYPE_STNCOLOR)
+               hoz_display_size = width * 3;
+       else
+               hoz_display_size = width;
+
+       switch (ifwidth) {
+       case ATMEL_LCDC_IFWIDTH_4:
+               valid_lcdd_data_line = 4;
+               break;
+       case ATMEL_LCDC_IFWIDTH_8:
+               if (scanmode == ATMEL_LCDC_SCANMOD_DUAL)
+                       valid_lcdd_data_line = 4;
+               else
+                       valid_lcdd_data_line = 8;
+               break;
+       default:
+               valid_lcdd_data_line = 8;
+               break;
+       }
+
+       return DIV_ROUND_UP(hoz_display_size, valid_lcdd_data_line);
+}
+
+static void set_vertical_timing(struct lcdc_dc *lcdc_dc,
+                               struct drm_display_mode *dmode)
+{
+       unsigned int tim1;
+       unsigned int vfp;
+       unsigned int vbp;
+       unsigned int vpw;
+       unsigned int vhdly;
+
+       /* VFP: Vertical Front Porch */
+       vfp = dmode->vsync_start - dmode->vdisplay;
+
+       /* VBP: Vertical Back Porch */
+       vbp = dmode->vtotal - dmode->vsync_end;
+
+       /* VPW: Vertical Synchronization pulse width */
+       vpw = dmode->vsync_end - dmode->vsync_start - 1;
+
+       /* VHDLY: Vertical to horizontal delay */
+       vhdly = 0;
+
+       tim1 = vfp << ATMEL_LCDC_VFP_OFFSET |
+              vbp << ATMEL_LCDC_VBP_OFFSET |
+              vpw << ATMEL_LCDC_VPW_OFFSET |
+              vhdly << ATMEL_LCDC_VHDLY_OFFSET;
+
+       DRM_DEV_DEBUG(lcdc_dc->dev, " TIM1 = %08x\n", tim1);
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_TIM1, tim1);
+}
+
+static void set_horizontal_timing(struct lcdc_dc *lcdc_dc,
+                                 struct drm_display_mode *dmode)
+{
+       unsigned int tim2;
+       unsigned int hbp;
+       unsigned int hpw;
+       unsigned int hfp;
+
+       /* HBP: Horizontal Back Porch */
+       hbp = dmode->htotal - dmode->hsync_end - 1;
+
+       /* HPW: Horizontal synchronization pulse width */
+       hpw = dmode->hsync_end - dmode->hsync_start - 1;
+
+       /* HFP: Horizontal Front Porch */
+       hfp = dmode->hsync_start - dmode->hdisplay - 2;
+
+       tim2 = hbp << ATMEL_LCDC_HBP_OFFSET |
+              hpw << ATMEL_LCDC_HPW_OFFSET |
+              hfp << ATMEL_LCDC_HFP_OFFSET;
+
+       DRM_DEV_DEBUG(lcdc_dc->dev, " TIM2 = %08x\n", tim2);
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_TIM2, tim2);
+}
+
+static void lcdc_dc_crtc_mode_set_nofb(struct lcdc_dc *lcdc_dc)
+{
+       struct drm_display_mode *dmode;
+       unsigned int hozval_linesz;
+       unsigned int value;
+
+       dmode = &lcdc_dc->pipe.crtc.state->adjusted_mode;
+
+       /* Vertical & horizontal timing */
+       set_vertical_timing(lcdc_dc, dmode);
+       set_horizontal_timing(lcdc_dc, dmode);
+
+       /* Horizontal value (aka line size) */
+       hozval_linesz = compute_hozval(lcdc_dc, dmode->crtc_hdisplay);
+
+       /* Display size */
+       value = (hozval_linesz - 1) << ATMEL_LCDC_HOZVAL_OFFSET;
+       value |= dmode->crtc_vdisplay - 1;
+       DRM_DEV_DEBUG(lcdc_dc->dev, " LCDFRMCFG = %08x\n", value);
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_LCDFRMCFG, value);
+
+       /* FIFO Threshold: Use formula from data sheet */
+       value = lcdc_dc->desc->fifo_size - (2 * ATMEL_LCDC_DMA_BURST_LEN + 3);
+       DRM_DEV_DEBUG(lcdc_dc->dev, " FIFO = %08x\n", value);
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_FIFO, value);
+
+       /*
+        * Toggle LCD_MODE every frame
+        * Note: register not documented, this is from atmel_lcdfb
+        */
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_MVAL, 0);
+}
+
+static void lcdc_dc_enable(struct lcdc_dc *lcdc_dc,
+                          struct drm_device *drm,
+                          struct drm_crtc *crtc)
+{
+       const struct drm_format_info *format;
+       struct drm_display_mode *dmode;
+       unsigned long clk_value_khz;
+       unsigned int pix_factor;
+       unsigned int lcdcon1;
+       unsigned int lcdcon2;
+       u32 bus_flags;
+
+       dmode = &lcdc_dc->pipe.crtc.state->adjusted_mode;
+       format = crtc->primary->state->fb->format;
+
+       /* Control register 1 */
+
+       /* Set pixel clock */
+       if (lcdc_dc->desc->have_alt_pixclock)
+               pix_factor = 1;
+       else
+               pix_factor = 2;
+
+       clk_value_khz = clk_get_rate(lcdc_dc->mfd_lcdc->lcdc_clk) / 1000;
+       lcdcon1 = DIV_ROUND_UP(clk_value_khz, dmode->clock);
+
+       if (lcdcon1 < pix_factor) {
+               DRM_DEV_INFO(lcdc_dc->dev, "Bypassing pixel clock divider\n");
+               regmap_write(lcdc_dc->regmap,
+                            ATMEL_LCDC_LCDCON1, ATMEL_LCDC_BYPASS);
+       } else {
+
+               lcdcon1 = (lcdcon1 / pix_factor) - 1;
+               DRM_DEV_DEBUG(lcdc_dc->dev, "CLKVAL = 0x%08x\n", lcdcon1);
+               regmap_write(lcdc_dc->regmap, ATMEL_LCDC_LCDCON1,
+                            lcdcon1 << ATMEL_LCDC_CLKVAL_OFFSET);
+               dmode->clock = clk_value_khz / (pix_factor * (lcdcon1 + 1));
+               DRM_DEV_DEBUG(lcdc_dc->dev, "updated pixclk:  %u KHz\n",
+                                       dmode->clock);
+       }
+
+       /* Control register 2 */
+       /* Only TFT supported (Controller supports STN too) */
+       lcdcon2 = ATMEL_LCDC_DISTYPE_TFT;
+
+       /* scan mode (STN only) */
+       if (dmode->flags & DRM_MODE_FLAG_DBLSCAN)
+               lcdcon2 |= ATMEL_LCDC_SCANMOD_DUAL;
+       else
+               lcdcon2 |= ATMEL_LCDC_SCANMOD_SINGLE;
+
+       /* Interface width 4 bits (STN only) */
+       lcdcon2 |= ATMEL_LCDC_IFWIDTH_4;
+
+       /* bits per pixel */
+       switch (format->depth) {
+       case 1:
+               lcdcon2 |= ATMEL_LCDC_PIXELSIZE_1;
+               break;
+       case 2:
+               lcdcon2 |= ATMEL_LCDC_PIXELSIZE_2;
+               break;
+       case 4:
+               lcdcon2 |= ATMEL_LCDC_PIXELSIZE_4;
+               break;
+       case 8:
+               lcdcon2 |= ATMEL_LCDC_PIXELSIZE_8;
+               break;
+       case 15:
+               /* fall through */
+       case 16:
+               lcdcon2 |= ATMEL_LCDC_PIXELSIZE_16;
+               break;
+       case 24:
+               lcdcon2 |= ATMEL_LCDC_PIXELSIZE_24;
+               break;
+       case 32:
+               lcdcon2 |= ATMEL_LCDC_PIXELSIZE_32;
+               break;
+       default:
+               DRM_DEV_ERROR(lcdc_dc->dev, "Unexpected depth (%d)",
+                             format->depth);
+               break;
+       }
+
+       /* Polarity normal */
+       lcdcon2 |= ATMEL_LCDC_INVVD_NORMAL;
+
+       /* vsync polarity */
+       if (dmode->flags & DRM_MODE_FLAG_PVSYNC)
+               lcdcon2 |= ATMEL_LCDC_INVFRAME_INVERTED;
+       else
+               lcdcon2 |= ATMEL_LCDC_INVFRAME_NORMAL;
+
+       /* hsync polarity */
+       if (dmode->flags & DRM_MODE_FLAG_PHSYNC)
+               lcdcon2 |= ATMEL_LCDC_INVLINE_INVERTED;
+       else
+               lcdcon2 |= ATMEL_LCDC_INVLINE_NORMAL;
+
+       bus_flags = lcdc_dc->connector.display_info.bus_flags;
+
+       /* dot clock (pix clock) polarity */
+       if (bus_flags & DRM_BUS_FLAG_PIXDATA_NEGEDGE)
+               lcdcon2 |= ATMEL_LCDC_INVCLK_INVERTED;
+       else
+               lcdcon2 |= ATMEL_LCDC_INVCLK_NORMAL;
+
+       /* Date Enable polarity */
+       if (bus_flags & DRM_BUS_FLAG_DE_LOW)
+               lcdcon2 |= ATMEL_LCDC_INVDVAL_INVERTED;
+       else
+               lcdcon2 |= ATMEL_LCDC_INVDVAL_NORMAL;
+
+       /* Clock is always active */
+       lcdcon2 |= ATMEL_LCDC_CLKMOD_ALWAYSACTIVE;
+
+       /* Memory layout */
+       if (format->format & DRM_FORMAT_BIG_ENDIAN)
+               lcdcon2 |= ATMEL_LCDC_MEMOR_BIG;
+       else
+               lcdcon2 |= ATMEL_LCDC_MEMOR_LITTLE;
+
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_LCDCON2, lcdcon2);
+
+       lcdc_dc_start(lcdc_dc);
+
+       drm_crtc_vblank_on(crtc);
+}
+
+static void lcdc_dc_display_enable(struct drm_simple_display_pipe *pipe,
+                                  struct drm_crtc_state *cstate,
+                                  struct drm_plane_state *plane_state)
+{
+       struct lcdc_dc *lcdc_dc;
+       struct drm_device *drm;
+       struct drm_crtc *crtc;
+       int ret;
+
+       crtc = &pipe->crtc;
+       drm = crtc->dev;
+       lcdc_dc = drm->dev_private;
+
+       ret = regulator_enable(lcdc_dc->lcd_supply);
+       if (ret)
+               DRM_DEV_ERROR(lcdc_dc->dev, "regulator_enable failed (%d)",
+                             ret);
+
+       drm_panel_prepare(lcdc_dc->panel);
+       lcdc_dc_crtc_mode_set_nofb(lcdc_dc);
+
+       /*
+        * drm_simple_kms_helper have no support for gamma setup.
+        * Add: lcdc_dc_setcolor(lcdc_dc, crtc); when we have it
+        */
+       lcdc_dc_enable(lcdc_dc, drm, crtc);
+
+       drm_panel_enable(lcdc_dc->panel);
+}
+
+static void lcdc_dc_display_disable(struct drm_simple_display_pipe *pipe)
+{
+       struct lcdc_dc *lcdc_dc;
+       struct drm_device *drm;
+       struct drm_crtc *crtc;
+
+       crtc = &pipe->crtc;
+       drm = crtc->dev;
+       lcdc_dc = drm->dev_private;
+
+       drm_crtc_vblank_off(crtc);
+
+       drm_panel_disable(lcdc_dc->panel);
+
+       lcdc_dc_stop(lcdc_dc);
+
+       drm_panel_unprepare(lcdc_dc->panel);
+       regulator_disable(lcdc_dc->lcd_supply);
+}
+
+/* Update DMA config */
+static void lcdc_dc_update_dma(struct lcdc_dc *lcdc_dc,
+                              struct drm_simple_display_pipe *pipe)
+{
+       struct drm_plane_state *plane_state;
+       struct drm_framebuffer *fb;
+       unsigned int burst_length;
+       unsigned int frame_size;
+       dma_addr_t dma_addr;
+
+       plane_state = pipe->plane.state;
+       fb = plane_state->fb;
+
+       if (fb) {
+               unsigned int dmafrmcfg;
+
+               dma_addr = drm_fb_cma_get_gem_addr(fb, pipe->plane.state, 0);
+
+               /* Set frame buffer DMA base address */
+               regmap_write(lcdc_dc->regmap, ATMEL_LCDC_DMABADDR1, dma_addr);
+
+               /*
+                * Set frame size and burst length
+                * Frame_size equals size of visible area * bits / 32
+                * (size in 32 bit words)
+                */
+               frame_size = plane_state->crtc_w * plane_state->crtc_h;
+               frame_size = (frame_size * fb->format->depth) / 32;
+
+               burst_length = ATMEL_LCDC_DMA_BURST_LEN - 1;
+
+               dmafrmcfg = frame_size;
+               dmafrmcfg |= burst_length << ATMEL_LCDC_BLENGTH_OFFSET;
+
+               regmap_write(lcdc_dc->regmap, ATMEL_LCDC_DMAFRMCFG, dmafrmcfg);
+       }
+}
+
+static void lcdc_dc_update_event(struct drm_simple_display_pipe *pipe)
+{
+       struct drm_pending_vblank_event *event;
+       struct drm_crtc *crtc;
+
+       crtc = &pipe->crtc;
+       if (!crtc)
+               return;
+
+       spin_lock_irq(&crtc->dev->event_lock);
+       event = crtc->state->event;
+       if (event) {
+               crtc->state->event = NULL;
+
+               if (drm_crtc_vblank_get(crtc) == 0)
+                       drm_crtc_arm_vblank_event(crtc, event);
+               else
+                       drm_crtc_send_vblank_event(crtc, event);
+       }
+       spin_unlock_irq(&crtc->dev->event_lock);
+}
+
+static void lcdc_dc_display_update(struct drm_simple_display_pipe *pipe,
+                                  struct drm_plane_state *old_pstate)
+{
+       struct drm_device *drm;
+       struct lcdc_dc *lcdc_dc;
+
+       drm = pipe->crtc.dev;
+       lcdc_dc = drm->dev_private;
+
+       /* Re-initialize the DMA engine... */
+       lcdc_dc_update_dma(lcdc_dc, pipe);
+
+       /* vblank event handling */
+       lcdc_dc_update_event(pipe);
+}
+
+static int lcdc_dc_display_enable_vblank(struct drm_simple_display_pipe *pipe)
+{
+       struct drm_crtc *crtc;
+       struct lcdc_dc *lcdc_dc;
+
+       crtc  = &pipe->crtc;
+       lcdc_dc = crtc->dev->dev_private;
+
+       /* Last line interrupt enable */
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_IER, ATMEL_LCDC_LSTLNI);
+
+       return 0;
+}
+
+static void lcdc_dc_display_disable_vblank(struct drm_simple_display_pipe 
*pipe)
+{
+       struct drm_crtc *crtc;
+       struct lcdc_dc *lcdc_dc;
+
+       crtc  = &pipe->crtc;
+       lcdc_dc = crtc->dev->dev_private;
+
+       /* Last line interrupt disable */
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_IDR, ATMEL_LCDC_LSTLNI);
+}
+
+static const struct drm_simple_display_pipe_funcs lcdc_dc_display_funcs = {
+       .check = lcdc_dc_display_check,
+       .enable = lcdc_dc_display_enable,
+       .disable = lcdc_dc_display_disable,
+       .update = lcdc_dc_display_update,
+       .prepare_fb = drm_gem_fb_simple_display_pipe_prepare_fb,
+       .enable_vblank = lcdc_dc_display_enable_vblank,
+       .disable_vblank = lcdc_dc_display_disable_vblank,
+};
+
+static const struct drm_mode_config_funcs mode_config_funcs = {
+       .fb_create = drm_gem_fb_create,
+       .atomic_check = drm_atomic_helper_check,
+       .atomic_commit = drm_atomic_helper_commit,
+};
+
+/* scheduled worker to reset LCD */
+static void reset_lcdc_work(struct work_struct *work)
+{
+       struct lcdc_dc *lcdc_dc;
+
+       lcdc_dc = container_of(work, struct lcdc_dc, reset_lcdc_work);
+
+       lcdc_dc_stop(lcdc_dc);
+       lcdc_dc_start(lcdc_dc);
+}
+
+static irqreturn_t lcdc_dc_irq_handler(int irq, void *arg)
+{
+       struct lcdc_dc *lcdc_dc;
+       struct drm_device *drm;
+       unsigned int status;
+       struct device *dev;
+       unsigned int imr;
+       unsigned int isr;
+
+       drm = arg;
+       lcdc_dc = drm->dev_private;
+       dev = lcdc_dc->dev;
+
+       regmap_read(lcdc_dc->regmap, ATMEL_LCDC_IMR, &imr);
+       regmap_read(lcdc_dc->regmap, ATMEL_LCDC_ISR, &isr);
+       status = imr & isr;
+       if (!status)
+               return IRQ_NONE;
+
+       if (status & ATMEL_LCDC_LSTLNI)
+               drm_crtc_handle_vblank(&lcdc_dc->pipe.crtc);
+
+       if (status & ATMEL_LCDC_UFLWI) {
+               DRM_DEV_INFO(dev, "FIFO underflow %#x\n", status);
+               /* reset DMA and FIFO to avoid screen shifting */
+               schedule_work(&lcdc_dc->reset_lcdc_work);
+       }
+       if (status & ATMEL_LCDC_OWRI)
+               DRM_DEV_INFO(dev, "FIFO overwrite interrupt");
+
+       if (status & ATMEL_LCDC_MERI)
+               DRM_DEV_INFO(dev, "DMA memory error");
+
+       /* Clear all reported (from ISR) interrupts */
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_ICR, isr);
+
+       return IRQ_HANDLED;
+}
+
+static int lcdc_dc_irq_postinstall(struct drm_device *dev)
+{
+       struct lcdc_dc *lcdc_dc;
+       unsigned int ier;
+
+       lcdc_dc = dev->dev_private;
+
+       ier = 0;
+       /* FIFO underflow interrupt enable */
+       ier |= ATMEL_LCDC_UFLWI;
+       /* FIFO overwrite interrupt enable */
+       ier |= ATMEL_LCDC_OWRI;
+       /* DMA memory error interrupt enable */
+       ier |= ATMEL_LCDC_MERI;
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_IER, ier);
+
+       return 0;
+}
+
+static void lcdc_dc_irq_uninstall(struct drm_device *dev)
+{
+       struct lcdc_dc *lcdc_dc;
+       unsigned int isr;
+
+       lcdc_dc  = dev->dev_private;
+
+       /* disable all interrupts */
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_IDR, ~0);
+       regmap_write(lcdc_dc->regmap, ATMEL_LCDC_ICR, ~0);
+
+       /* Clear any pending interrupts */
+       regmap_read(lcdc_dc->regmap, ATMEL_LCDC_ISR, &isr);
+}
+
+DEFINE_DRM_GEM_CMA_FOPS(lcdc_dc_drm_fops);
+
+static struct drm_driver lcdc_dc_drm_driver = {
+       .driver_features = DRIVER_HAVE_IRQ |
+                          DRIVER_GEM |
+                          DRIVER_MODESET |
+                          DRIVER_PRIME |
+                          DRIVER_ATOMIC,
+       .name = "atmel-lcdc",
+       .desc = "Atmel LCD Display Controller DRM",
+       .date = "20180808",
+       .major = 1,
+       .minor = 0,
+       .patchlevel = 0,
+
+       .lastclose = drm_fb_helper_lastclose,
+       .fops = &lcdc_dc_drm_fops,
+
+       .irq_handler = lcdc_dc_irq_handler,
+       .irq_preinstall = lcdc_dc_irq_uninstall,
+       .irq_postinstall = lcdc_dc_irq_postinstall,
+       .irq_uninstall = lcdc_dc_irq_uninstall,
+
+       .dumb_create = drm_gem_cma_dumb_create,
+
+       .gem_print_info = drm_gem_cma_print_info,
+       .gem_vm_ops = &drm_gem_cma_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 = drm_gem_cma_prime_get_sg_table,
+       .gem_free_object_unlocked = drm_gem_cma_free_object,
+
+       .gem_prime_import_sg_table = drm_gem_cma_prime_import_sg_table,
+       .gem_prime_vmap = drm_gem_cma_prime_vmap,
+       .gem_prime_vunmap = drm_gem_cma_prime_vunmap,
+       .gem_prime_mmap = drm_gem_cma_prime_mmap,
+};
+
+static int lcdc_dc_modeset_init(struct lcdc_dc *lcdc_dc, struct drm_device 
*drm)
+{
+       struct drm_bridge *bridge;
+       struct drm_panel *panel;
+       struct device_node *np;
+       struct device *dev;
+       int ret;
+
+       dev = drm->dev;
+
+       drm_mode_config_init(drm);
+       drm->mode_config.min_width  = lcdc_dc->desc->min_width;
+       drm->mode_config.min_height = lcdc_dc->desc->min_height;
+       drm->mode_config.max_width  = lcdc_dc->desc->max_width;
+       drm->mode_config.max_height = lcdc_dc->desc->max_height;
+       drm->mode_config.funcs      = &mode_config_funcs;
+
+       np = dev->of_node;
+       /* port@0 is the output port */
+       ret = drm_of_find_panel_or_bridge(np, 0, 0, &panel, &bridge);
+       if (ret && ret != -ENODEV) {
+               DRM_DEV_ERROR(dev, "Failed to find panel (%d)\n", ret);
+               goto err_out;
+       }
+
+       bridge = drm_panel_bridge_add(panel, DRM_MODE_CONNECTOR_Unknown);
+       if (IS_ERR(bridge)) {
+               ret = PTR_ERR(bridge);
+               DRM_DEV_ERROR(dev, "Failed to add bridge (%d)", ret);
+               goto err_panel_remove;
+       }
+
+       lcdc_dc->panel = panel;
+       lcdc_dc->bridge = bridge;
+
+       ret = drm_simple_display_pipe_init(drm,
+                                          &lcdc_dc->pipe,
+                                          &lcdc_dc_display_funcs,
+                                          lcdc_dc_formats,
+                                          ARRAY_SIZE(lcdc_dc_formats),
+                                          NULL,
+                                          &lcdc_dc->connector);
+       if (ret) {
+               DRM_DEV_ERROR(dev, "Failed to init display pipe (%d)\n", ret);
+               goto err_panel_remove;
+       }
+
+       ret = drm_simple_display_pipe_attach_bridge(&lcdc_dc->pipe, bridge);
+       if (ret) {
+               DRM_DEV_ERROR(dev, "failed to attach bridge (%d)", ret);
+               goto err_panel_remove;
+       }
+
+       drm_mode_config_reset(drm);
+
+       return 0;
+
+err_panel_remove:
+       if (panel)
+               drm_panel_bridge_remove(bridge);
+
+err_out:
+       return ret;
+}
+
+static int lcdc_dc_load(struct drm_device *drm)
+{
+       const struct of_device_id *match;
+       struct platform_device *pdev;
+       struct lcdc_dc *lcdc_dc;
+       struct device *dev;
+       int ret;
+
+       dev = drm->dev;
+       pdev = to_platform_device(dev);
+
+       match = of_match_node(atmel_lcdc_of_match, dev->parent->of_node);
+       if (!match) {
+               DRM_DEV_ERROR(dev, "invalid compatible string (node=%s)",
+                             dev->parent->of_node->name);
+               return -ENODEV;
+       }
+
+       if (!match->data) {
+               DRM_DEV_ERROR(dev, "invalid lcdc_dc description\n");
+               return -EINVAL;
+       }
+
+       lcdc_dc = devm_kzalloc(dev, sizeof(*lcdc_dc), GFP_KERNEL);
+       if (!lcdc_dc) {
+               DRM_DEV_ERROR(dev, "Failed to allocate lcdc_dc\n");
+               return -ENOMEM;
+       }
+
+       /* reset of lcdc might sleep and require a preemptible task context */
+       INIT_WORK(&lcdc_dc->reset_lcdc_work, reset_lcdc_work);
+
+       platform_set_drvdata(pdev, drm);
+       dev_set_drvdata(dev, lcdc_dc);
+
+       lcdc_dc->mfd_lcdc = dev_get_drvdata(dev->parent);
+       drm->dev_private = lcdc_dc;
+
+       lcdc_dc->regmap = lcdc_dc->mfd_lcdc->regmap;
+       lcdc_dc->desc = match->data;
+       lcdc_dc->dev = dev;
+
+       lcdc_dc->lcd_supply = devm_regulator_get(dev, "lcd");
+       if (IS_ERR(lcdc_dc->lcd_supply)) {
+               DRM_DEV_ERROR(dev, "Failed to get lcd-supply (%ld)\n",
+                             PTR_ERR(lcdc_dc->lcd_supply));
+               lcdc_dc->lcd_supply = NULL;
+       }
+
+       lcdc_dc_start_clock(lcdc_dc);
+
+       pm_runtime_enable(dev);
+
+       ret = drm_vblank_init(drm, 1);
+       if (ret) {
+               DRM_DEV_ERROR(dev, "failed to initialize vblank (%d)\n",
+                             ret);
+               goto err_pm_runtime_disable;
+       }
+
+       ret = lcdc_dc_modeset_init(lcdc_dc, drm);
+       if (ret) {
+               DRM_DEV_ERROR(dev, "modeset_init failed (%d)", ret);
+               goto err_pm_runtime_disable;
+       }
+
+       pm_runtime_get_sync(dev);
+       ret = drm_irq_install(drm, lcdc_dc->mfd_lcdc->irq);
+       pm_runtime_put_sync(dev);
+       if (ret < 0) {
+               DRM_DEV_ERROR(dev, "Failed to install IRQ (%d)\n", ret);
+
+               goto err_pm_runtime_disable;
+       }
+
+       /*
+        * Passing in 16 here will make the RGB656 mode the default
+        * Passing in 32 will use XRGB8888 mode
+        */
+       drm_fb_cma_fbdev_init(drm, 16, 0);
+
+       drm_kms_helper_poll_init(drm);
+
+       lcdc_dc->fbdev = drm_fbdev_cma_init(drm, 8, 1);
+       if (IS_ERR(lcdc_dc->fbdev)) {
+               ret = PTR_ERR(lcdc_dc->fbdev);
+               DRM_DEV_ERROR(dev, "Failed to init FB CMA area (%d)", ret);
+               goto err_irq_uninstall;
+       }
+
+       drm_helper_hpd_irq_event(drm);
+
+       return 0;
+
+err_irq_uninstall:
+       pm_runtime_get_sync(dev);
+       drm_irq_uninstall(drm);
+       pm_runtime_put_sync(dev);
+
+err_pm_runtime_disable:
+       pm_runtime_disable(dev);
+       lcdc_dc_stop_clock(lcdc_dc);
+
+       cancel_work_sync(&lcdc_dc->reset_lcdc_work);
+
+       return ret;
+}
+
+static void lcdc_dc_unload(struct drm_device *dev)
+{
+       struct lcdc_dc *lcdc_dc = dev->dev_private;
+
+       drm_fb_cma_fbdev_fini(dev);
+       flush_work(&lcdc_dc->reset_lcdc_work);
+       drm_kms_helper_poll_fini(dev);
+       if (lcdc_dc->panel)
+               drm_panel_bridge_remove(lcdc_dc->bridge);
+       drm_mode_config_cleanup(dev);
+
+       pm_runtime_get_sync(dev->dev);
+       drm_irq_uninstall(dev);
+       pm_runtime_put_sync(dev->dev);
+
+       dev->dev_private = NULL;
+
+       pm_runtime_disable(dev->dev);
+       lcdc_dc_stop_clock(lcdc_dc);
+       cancel_work_sync(&lcdc_dc->reset_lcdc_work);
+}
+
+
+static int lcdc_dc_probe(struct platform_device *pdev)
+{
+       struct drm_device *drm;
+       struct device *dev;
+       int ret;
+
+       dev = &pdev->dev;
+
+       drm = drm_dev_alloc(&lcdc_dc_drm_driver, dev);
+       if (IS_ERR(drm)) {
+               DRM_DEV_ERROR(dev, "Failed to allocate drm device\n");
+               return PTR_ERR(drm);
+       }
+
+       ret = lcdc_dc_load(drm);
+       if (ret)
+               goto err_put_ref;
+
+       ret = drm_dev_register(drm, 0);
+       if (ret) {
+               DRM_DEV_ERROR(dev, "Failed to register drm (%d)\n", ret);
+               goto err_unload;
+       }
+
+       return 0;
+
+err_unload:
+       lcdc_dc_unload(drm);
+
+err_put_ref:
+       drm_dev_put(drm);
+       return ret;
+}
+
+static int lcdc_dc_remove(struct platform_device *pdev)
+{
+       struct drm_device *drm;
+
+       drm = platform_get_drvdata(pdev);
+
+       drm_dev_unregister(drm);
+       lcdc_dc_unload(drm);
+       drm_dev_unref(drm);
+
+       return 0;
+}
+
+static const struct of_device_id lcdc_dc_dt_ids[] = {
+       { .compatible = "atmel,lcdc-display-controller", },
+       { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, lcdc_dc_dt_ids);
+
+static struct platform_driver lcdc_dc_driver = {
+       .probe          = lcdc_dc_probe,
+       .remove         = lcdc_dc_remove,
+       .driver         = {
+               .of_match_table = lcdc_dc_dt_ids,
+               .name   = "atmel-lcdc-dc",
+       },
+};
+
+module_platform_driver(lcdc_dc_driver);
+
+MODULE_AUTHOR("Sam Ravnborg <s...@ravnborg.org>");
+MODULE_DESCRIPTION("Atmel LCDC Display Controller DRM Driver");
+MODULE_LICENSE("GPL v2");
+MODULE_ALIAS("platform:atmel-lcdc-dc");
-- 
2.12.0

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