Remove the requirement of a VDEC_SYS reg iospace for MT8183. To achieve
that, rely on a vdecsys syscon to be passed through the DT, and use it
to directly read the VDEC_HW_ACTIVE bit during IRQ handling to check
whether the HW is active.

The old behavior is still present when reg-names aren't supplied, as
MT8173 still relies on it.

Signed-off-by: Nícolas F. R. A. Prado <redacted>

---
I dropped the tags from this commit since a syscon is now used instead
of an extra clock.

Changes in v3:
- Switched handling of VDEC_HW_ACTIVE to use a syscon instead of the
   'active' clock
- Reworded commit
- Removed changes to subdev part of driver, since they aren't used by
   MT8183

  .../mediatek/vcodec/mtk_vcodec_dec_drv.c      | 71 ++++++++++++++++---
  .../platform/mediatek/vcodec/mtk_vcodec_drv.h |  1 +
  2 files changed, 61 insertions(+), 11 deletions(-)

diff --git a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec_drv.c b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec_drv.c
index 83780d29a9cf..387ed26d6d5d 100644
--- a/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec_drv.c
+++ b/drivers/media/platform/mediatek/vcodec/mtk_vcodec_dec_drv.c

@@ -8,10 +8,12 @@
  #include <linux/slab.h>
  #include <linux/interrupt.h>
  #include <linux/irq.h>
+#include <linux/mfd/syscon.h>
  #include <linux/module.h>
  #include <linux/of_device.h>
  #include <linux/of.h>
  #include <linux/pm_runtime.h>
+#include <linux/regmap.h>
  #include <media/v4l2-event.h>
  #include <media/v4l2-mem2mem.h>
  #include <media/videobuf2-dma-contig.h>

@@ -38,22 +40,37 @@ static int mtk_vcodec_get_hw_count(struct mtk_vcodec_dev *dev)
  	}
  }
  
+static bool mtk_vcodec_is_hw_active(struct mtk_vcodec_dev *dev)
+{
+	u32 cg_status = 0;
+	int val, ret;
+
+	if (!dev->reg_base[VDEC_SYS]) {
+		ret = regmap_read(dev->vdecsys_regmap, VDEC_HW_ACTIVE_ADDR, &val);
+		if (ret) {
+			mtk_v4l2_err("Failed to read VDEC active status");
+			return false;
+		}
+
+		return (val & VDEC_HW_ACTIVE_MASK) == 0;
+	}
+
+	cg_status = readl(dev->reg_base[VDEC_SYS] + VDEC_HW_ACTIVE_ADDR);
+	return (cg_status & VDEC_HW_ACTIVE_MASK) == 0;

+}
+
  static irqreturn_t mtk_vcodec_dec_irq_handler(int irq, void *priv)
  {
  	struct mtk_vcodec_dev *dev = priv;
  	struct mtk_vcodec_ctx *ctx;
-	u32 cg_status = 0;
  	unsigned int dec_done_status = 0;
  	void __iomem *vdec_misc_addr = dev->reg_base[VDEC_MISC] +
  					VDEC_IRQ_CFG_REG;
  
  	ctx = mtk_vcodec_get_curr_ctx(dev, MTK_VDEC_CORE);
  
-	/* check if HW active or not */
-	cg_status = readl(dev->reg_base[0] + VDEC_HW_ACTIVE_ADDR);
-	if ((cg_status & VDEC_HW_ACTIVE_MASK) != 0) {
-		mtk_v4l2_err("DEC ISR, VDEC active is not 0x0 (0x%08x)",
-			     cg_status);
+	if (!mtk_vcodec_is_hw_active(dev)) {
+		mtk_v4l2_err("DEC ISR, VDEC active is not 0x0");
  		return IRQ_HANDLED;
  	}
  

@@ -82,6 +99,25 @@ static int mtk_vcodec_get_reg_bases(struct mtk_vcodec_dev *dev)
  {
  	struct platform_device *pdev = dev->plat_dev;
  	int reg_num, i;
+	struct resource *res;
+	bool no_vdecsys_reg = false;

+	if (res)
+		no_vdecsys_reg = true;
  
  	/* Sizeof(u32) * 4 bytes for each register base. */
  	reg_num = of_property_count_elems_of_size(pdev->dev.of_node, "reg",

@@ -91,12 +127,22 @@ static int mtk_vcodec_get_reg_bases(struct mtk_vcodec_dev *dev)
  		return -EINVAL;
  	}
  
-	for (i = 0; i < reg_num; i++) {
-		dev->reg_base[i] = devm_platform_ioremap_resource(pdev, i);
-		if (IS_ERR(dev->reg_base[i]))
-			return PTR_ERR(dev->reg_base[i]);
+	if (!no_vdecsys_reg) {

+		for (i = 0; i < reg_num; i++) {
+			dev->reg_base[i] = devm_platform_ioremap_resource(pdev, i);
+			if (IS_ERR(dev->reg_base[i]))
+				return PTR_ERR(dev->reg_base[i]);
+
+			mtk_v4l2_debug(2, "reg[%d] base=%p", i, dev->reg_base[i]);
+		}
+	} else {
+		for (i = 0; i < reg_num; i++) {
+			dev->reg_base[i+1] = devm_platform_ioremap_resource_byname(pdev, mtk_dec_reg_names[i]);
+			if (IS_ERR(dev->reg_base[i+1]))
+				return PTR_ERR(dev->reg_base[i+1]);
  
-		mtk_v4l2_debug(2, "reg[%d] base=%p", i, dev->reg_base[i]);
+			mtk_v4l2_debug(2, "reg[%d] base=%p", i+1, dev->reg_base[i+1]);
+		}
  	}
  
  	return 0;

@@ -118,6 +164,9 @@ static int mtk_vcodec_init_dec_resources(struct mtk_vcodec_dev *dev)
  	if (dev->dec_irq < 0)
  		return dev->dec_irq;
  
+	dev->vdecsys_regmap = syscon_regmap_lookup_by_phandle_optional(pdev->dev.of_node,
+								       "mediatek,vdecsys");
+