drm/tilcdc: implement palette loading for rev1

Revision 1 of the IP doesn't work if we don't load the palette (even
if it's not used, which is the case for the RGB565 format).

Add a function called from tilcdc_crtc_enable() which performs all
required actions if we're dealing with a rev1 chip.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Tested-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

1 files changed, 87 insertions, 1 deletions

diff --git a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
index 01692409f613..7ea34c21c384 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_crtc.c
@@ -21,11 +21,15 @@
 #include <drm/drm_flip_work.h>
 #include <drm/drm_plane_helper.h>
 #include <linux/workqueue.h>
+#include <linux/completion.h>
+#include <linux/dma-mapping.h>
 
 #include "tilcdc_drv.h"
 #include "tilcdc_regs.h"
 
-#define TILCDC_VBLANK_SAFETY_THRESHOLD_US 1000
+#define TILCDC_VBLANK_SAFETY_THRESHOLD_US       1000
+#define TILCDC_REV1_PALETTE_SIZE                32
+#define TILCDC_REV1_PALETTE_FIRST_ENTRY         0x4000
 
 struct tilcdc_crtc {
         struct drm_crtc base;
@@ -56,6 +60,10 @@ struct tilcdc_crtc {
         int sync_lost_count;
         bool frame_intact;
         struct work_struct recover_work;
+
+        dma_addr_t palette_dma_handle;
+        void *palette_base;
+        struct completion palette_loaded;
 };
 #define to_tilcdc_crtc(x) container_of(x, struct tilcdc_crtc, base)
 
@@ -105,6 +113,55 @@ static void set_scanout(struct drm_crtc *crtc, struct drm_framebuffer *fb)
         tilcdc_crtc->curr_fb = fb;
 }
 
+/*
+ * The driver currently only supports the RGB565 format for revision 1. For
+ * 16 bits-per-pixel the palette block is bypassed, but the first 32 bytes of
+ * the framebuffer are still considered palette. The first 16-bit entry must
+ * be 0x4000 while all other entries must be zeroed.
+ */
+static void tilcdc_crtc_load_palette(struct drm_crtc *crtc)
+{
+        u32 dma_fb_base, dma_fb_ceiling, raster_ctl;
+        struct tilcdc_crtc *tilcdc_crtc;
+        struct drm_device *dev;
+        u16 *first_entry;
+
+        dev = crtc->dev;
+        tilcdc_crtc = to_tilcdc_crtc(crtc);
+        first_entry = tilcdc_crtc->palette_base;
+
+        *first_entry = TILCDC_REV1_PALETTE_FIRST_ENTRY;
+
+        dma_fb_base = tilcdc_read(dev, LCDC_DMA_FB_BASE_ADDR_0_REG);
+        dma_fb_ceiling = tilcdc_read(dev, LCDC_DMA_FB_CEILING_ADDR_0_REG);
+        raster_ctl = tilcdc_read(dev, LCDC_RASTER_CTRL_REG);
+
+        /* Tell the LCDC where the palette is located. */
+        tilcdc_write(dev, LCDC_DMA_FB_BASE_ADDR_0_REG,
+                     tilcdc_crtc->palette_dma_handle);
+        tilcdc_write(dev, LCDC_DMA_FB_CEILING_ADDR_0_REG,
+                     (u32)tilcdc_crtc->palette_dma_handle
+                                + TILCDC_REV1_PALETTE_SIZE - 1);
+
+        /* Load it. */
+        tilcdc_clear(dev, LCDC_RASTER_CTRL_REG,
+                     LCDC_PALETTE_LOAD_MODE(DATA_ONLY));
+        tilcdc_set(dev, LCDC_RASTER_CTRL_REG,
+                   LCDC_PALETTE_LOAD_MODE(PALETTE_ONLY));
+
+        /* Enable the LCDC and wait for palette to be loaded. */
+        tilcdc_set(dev, LCDC_RASTER_CTRL_REG, LCDC_V1_PL_INT_ENA);
+        tilcdc_set(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);
+
+        wait_for_completion(&tilcdc_crtc->palette_loaded);
+
+        /* Restore the registers. */
+        tilcdc_clear(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);
+        tilcdc_write(dev, LCDC_DMA_FB_BASE_ADDR_0_REG, dma_fb_base);
+        tilcdc_write(dev, LCDC_DMA_FB_CEILING_ADDR_0_REG, dma_fb_ceiling);
+        tilcdc_write(dev, LCDC_RASTER_CTRL_REG, raster_ctl);
+}
+
 static void tilcdc_crtc_enable_irqs(struct drm_device *dev)
 {
         struct tilcdc_drm_private *priv = dev->dev_private;
@@ -161,6 +218,7 @@ static void tilcdc_crtc_enable(struct drm_crtc *crtc)
 {
         struct drm_device *dev = crtc->dev;
         struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
+        struct tilcdc_drm_private *priv = dev->dev_private;
 
         WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
         mutex_lock(&tilcdc_crtc->enable_lock);
@@ -173,6 +231,9 @@ static void tilcdc_crtc_enable(struct drm_crtc *crtc)
 
         reset(crtc);
 
+        if (priv->rev == 1 && !completion_done(&tilcdc_crtc->palette_loaded))
+                tilcdc_crtc_load_palette(crtc);
+
         tilcdc_crtc_enable_irqs(dev);
 
         tilcdc_clear(dev, LCDC_DMA_CTRL_REG, LCDC_DUAL_FRAME_BUFFER_ENABLE);
@@ -214,6 +275,13 @@ static void tilcdc_crtc_off(struct drm_crtc *crtc, bool shutdown)
                                 __func__);
         }
 
+        /*
+         * LCDC will not retain the palette when reset. Make sure it gets
+         * reloaded on tilcdc_crtc_enable().
+         */
+        if (priv->rev == 1)
+                reinit_completion(&tilcdc_crtc->palette_loaded);
+
         drm_crtc_vblank_off(crtc);
 
         tilcdc_crtc_disable_irqs(dev);
@@ -847,6 +915,14 @@ irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc)
                 dev_err_ratelimited(dev->dev, "%s(0x%08x): FIFO underflow",
                                     __func__, stat);
 
+        if (priv->rev == 1) {
+                if (stat & LCDC_PL_LOAD_DONE) {
+                        complete(&tilcdc_crtc->palette_loaded);
+                        tilcdc_clear(dev,
+                                     LCDC_RASTER_CTRL_REG, LCDC_V1_PL_INT_ENA);
+                }
+        }
+
         if (stat & LCDC_SYNC_LOST) {
                 dev_err_ratelimited(dev->dev, "%s(0x%08x): Sync lost",
                                     __func__, stat);
@@ -894,6 +970,16 @@ struct drm_crtc *tilcdc_crtc_create(struct drm_device *dev)
                 return NULL;
         }
 
+        if (priv->rev == 1) {
+                init_completion(&tilcdc_crtc->palette_loaded);
+                tilcdc_crtc->palette_base = dmam_alloc_coherent(dev->dev,
+                                        TILCDC_REV1_PALETTE_SIZE,
+                                        &tilcdc_crtc->palette_dma_handle,
+                                        GFP_KERNEL | __GFP_ZERO);
+                if (!tilcdc_crtc->palette_base)
+                        return ERR_PTR(-ENOMEM);
+        }
+
         crtc = &tilcdc_crtc->base;
 
         ret = tilcdc_plane_init(dev, &tilcdc_crtc->primary);