[RFC PATCH v2 4/5] ARM: dts: stm32: support display on stm32f469-disco board

[Dario Binacchi]

Add support to Orise Tech OTM8009A display on stm32f469-disco board.

It was necessary to retrieve the framebuffer address from the device tree
because the address returned by the video-uclass driver pointed to a memory
area that was not usable.

Furthermore, unlike Linux, the DSI driver requires the LTDC clock to be
properly probed. Hence, the changes made to the DSI node in
stm32f469-disco-u-boot.dtsi.

Signed-off-by: Dario Binacchi <dario.binacchi at amarulasolutions.com>

---

Changes in v2:
- Add DRAM_SIZE macro.
- Fix frame buffer allocation function so that it is backward compatible
  with boards other than the one it was introduced for (i. e. stm32f469-disco).
  Tested on stm32f469-disco and stm32mp157f-dk2 boards.

 arch/arm/dts/stm32f469-disco-u-boot.dtsi |  4 +++
 configs/stm32f469-discovery_defconfig    | 13 ++++++++++
 drivers/video/stm32/stm32_ltdc.c         | 31 ++++++++++++++++++++++++
 3 files changed, 48 insertions(+)

diff --git a/arch/arm/dts/stm32f469-disco-u-boot.dtsi b/arch/arm/dts/stm32f469-disco-u-boot.dtsi
index 8e781c5a7b23..47ba9fa4a783 100644
--- a/arch/arm/dts/stm32f469-disco-u-boot.dtsi
+++ b/arch/arm/dts/stm32f469-disco-u-boot.dtsi
@@ -92,7 +92,9 @@
 
 &dsi {
 	clocks = <&rcc 0 STM32F4_APB2_CLOCK(DSI)>,
+		 <&rcc 0 STM32F4_APB2_CLOCK(LTDC)>,
 		 <&clk_hse>;
+	clock-names = "pclk", "px_clk", "ref";
 };
 
 &gpioa {
@@ -140,6 +142,8 @@
 };
 
 &ltdc {
+	bootph-all;
+
 	clocks = <&rcc 0 STM32F4_APB2_CLOCK(LTDC)>;
 };
 
diff --git a/configs/stm32f469-discovery_defconfig b/configs/stm32f469-discovery_defconfig
index 21c5498466cd..85e795e83e7d 100644
--- a/configs/stm32f469-discovery_defconfig
+++ b/configs/stm32f469-discovery_defconfig
@@ -21,6 +21,7 @@ CONFIG_CMD_GPT=y
 # CONFIG_RANDOM_UUID is not set
 CONFIG_CMD_MMC=y
 # CONFIG_CMD_SETEXPR is not set
+CONFIG_CMD_BMP=y
 CONFIG_CMD_CACHE=y
 CONFIG_CMD_TIMER=y
 # CONFIG_ISO_PARTITION is not set
@@ -40,3 +41,15 @@ CONFIG_SPI_FLASH_STMICRO=y
 CONFIG_SPI=y
 CONFIG_DM_SPI=y
 CONFIG_STM32_QSPI=y
+CONFIG_VIDEO=y
+CONFIG_BACKLIGHT_GPIO=y
+CONFIG_VIDEO_LCD_ORISETECH_OTM8009A=y
+CONFIG_VIDEO_STM32=y
+CONFIG_VIDEO_STM32_DSI=y
+CONFIG_VIDEO_STM32_MAX_XRES=480
+CONFIG_VIDEO_STM32_MAX_YRES=800
+CONFIG_BMP_16BPP=y
+CONFIG_BMP_24BPP=y
+CONFIG_BMP_32BPP=y
+CONFIG_DM_REGULATOR=y
+CONFIG_DM_REGULATOR_FIXED=y
diff --git a/drivers/video/stm32/stm32_ltdc.c b/drivers/video/stm32/stm32_ltdc.c
index 6fd90e33919d..9054db1d78b3 100644
--- a/drivers/video/stm32/stm32_ltdc.c
+++ b/drivers/video/stm32/stm32_ltdc.c
@@ -495,6 +495,33 @@ static void stm32_ltdc_set_layer1(struct stm32_ltdc_priv *priv, ulong fb_addr)
 	setbits_le32(priv->regs + LTDC_L1CR, LXCR_LEN);
 }
 
+#if IS_ENABLED(CONFIG_TARGET_STM32F469_DISCOVERY)
+static int stm32_ltdc_alloc_fb(struct udevice *dev)
+{
+#define SDRAM_SIZE 0x1000000 /* 128Mbit = 16 Mbyte = 0x1000000 */
+	struct video_uc_plat *uc_plat = dev_get_uclass_plat(dev);
+	phys_addr_t cpu;
+	dma_addr_t bus;
+	u64 dma_size;
+	int ret;
+
+	ret = dev_get_dma_range(dev, &cpu, &bus, &dma_size);
+	if (ret) {
+		dev_err(dev, "failed to get dma address\n");
+		return ret;
+	}
+
+	uc_plat->base = bus + SDRAM_SIZE - ALIGN(uc_plat->size, uc_plat->align);
+	return 0;
+}
+#else
+static inline int stm32_ltdc_alloc_fb(struct udevice *dev)
+{
+	/* Delegate framebuffer allocation to video-uclass */
+	return 0;
+}
+#endif
+
 static int stm32_ltdc_probe(struct udevice *dev)
 {
 	struct video_uc_plat *uc_plat = dev_get_uclass_plat(dev);
@@ -605,6 +632,10 @@ static int stm32_ltdc_probe(struct udevice *dev)
 	priv->crop_h = timings.vactive.typ;
 	priv->alpha = 0xFF;
 
+	ret = stm32_ltdc_alloc_fb(dev);
+	if (ret)
+		return ret;
+
 	dev_dbg(dev, "%dx%d %dbpp frame buffer at 0x%lx\n",
 		timings.hactive.typ, timings.vactive.typ,
 		VNBITS(priv->l2bpp), uc_plat->base);
-- 
2.42.0