Implement the Automated Built-In Self-Test ABIST functionality
provided by the HDMIv2 IP and expose it through the "hdmi_abist"
debugfs file.

Write "1" to this file to activate ABIST, or "0" to deactivate.

Signed-off-by: AngeloGioacchino Del Regno 
<angelogioacchino.delre...@collabora.com>
---
 drivers/gpu/drm/mediatek/mtk_hdmi_v2.c | 123 +++++++++++++++++++++++++
 1 file changed, 123 insertions(+)

diff --git a/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c 
b/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c
index 36b7f8d8d218..f4a086b92dae 100644
--- a/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c
+++ b/drivers/gpu/drm/mediatek/mtk_hdmi_v2.c
@@ -1170,6 +1170,128 @@ static int mtk_hdmi_v2_hdmi_write_infoframe(struct 
drm_bridge *bridge,
        return 0;
 }
 
+static int mtk_hdmi_v2_set_abist(struct mtk_hdmi *hdmi, bool enable)
+{
+       struct drm_display_mode *mode = &hdmi->mode;
+       int abist_format = -EINVAL;
+       bool interlaced;
+
+       if (!enable) {
+               regmap_clear_bits(hdmi->regs, TOP_CFG00, HDMI_ABIST_ENABLE);
+               return 0;
+       }
+
+       if (!mode->hdisplay || !mode->vdisplay)
+               return -EINVAL;
+
+       interlaced = mode->flags & DRM_MODE_FLAG_INTERLACE;
+
+       switch (mode->hdisplay) {
+       case 720:
+               if (mode->vdisplay == 480)
+                       abist_format = 2;
+               else if (mode->vdisplay == 576)
+                       abist_format = 11;
+               break;
+       case 1280:
+               if (mode->vdisplay == 720)
+                       abist_format = 3;
+               break;
+       case 1440:
+               if (mode->vdisplay == 480)
+                       abist_format = interlaced ? 5 : 9;
+               else if (mode->vdisplay == 576)
+                       abist_format = interlaced ? 14 : 18;
+               break;
+       case 1920:
+               if (mode->vdisplay == 1080)
+                       abist_format = interlaced ? 4 : 10;
+               break;
+       case 3840:
+               if (mode->vdisplay == 2160)
+                       abist_format = 25;
+               break;
+       case 4096:
+               if (mode->vdisplay == 2160)
+                       abist_format = 26;
+               break;
+       default:
+               break;
+       }
+       if (!abist_format)
+               return -EINVAL;
+
+       regmap_update_bits(hdmi->regs, TOP_CFG00, HDMI_ABIST_VIDEO_FORMAT,
+                          FIELD_PREP(HDMI_ABIST_VIDEO_FORMAT, abist_format));
+       regmap_set_bits(hdmi->regs, TOP_CFG00, HDMI_ABIST_ENABLE);
+       return 0;
+}
+
+static int mtk_hdmi_v2_debug_abist_show(struct seq_file *m, void *arg)
+{
+       struct mtk_hdmi *hdmi = m->private;
+       bool en;
+       u32 val;
+       int ret;
+
+       if (!hdmi)
+               return -EINVAL;
+
+       ret = regmap_read(hdmi->regs, TOP_CFG00, &val);
+       if (ret)
+               return ret;
+
+       en = FIELD_GET(HDMI_ABIST_ENABLE, val);
+
+       seq_printf(m, "HDMI Automated Built-In Self Test: %s\n",
+                  en ? "Enabled" : "Disabled");
+
+       return 0;
+}
+
+static ssize_t mtk_hdmi_v2_debug_abist_write(struct file *file,
+                                            const char __user *ubuf,
+                                            size_t len, loff_t *offp)
+{
+       struct seq_file *m = file->private_data;
+       int ret;
+       u32 en;
+
+       if (!m || !m->private || *offp)
+               return -EINVAL;
+
+       ret = kstrtouint_from_user(ubuf, len, 0, &en);
+       if (ret)
+               return ret;
+
+       if (en < 0 || en > 1)
+               return -EINVAL;
+
+       mtk_hdmi_v2_set_abist((struct mtk_hdmi *)m->private, en);
+       return len;
+}
+
+static int mtk_hdmi_v2_debug_abist_open(struct inode *inode, struct file *file)
+{
+       return single_open(file, mtk_hdmi_v2_debug_abist_show, 
inode->i_private);
+}
+
+static const struct file_operations mtk_hdmi_debug_abist_fops = {
+       .owner = THIS_MODULE,
+       .open = mtk_hdmi_v2_debug_abist_open,
+       .read = seq_read,
+       .write = mtk_hdmi_v2_debug_abist_write,
+       .llseek = seq_lseek,
+       .release = single_release,
+};
+
+static void mtk_hdmi_v2_debugfs_init(struct drm_bridge *bridge, struct dentry 
*root)
+{
+       struct mtk_hdmi *dpi = hdmi_ctx_from_bridge(bridge);
+
+       debugfs_create_file("hdmi_abist", 0640, root, dpi, 
&mtk_hdmi_debug_abist_fops);
+}
+
 static const struct drm_bridge_funcs mtk_v2_hdmi_bridge_funcs = {
        .attach = mtk_hdmi_v2_bridge_attach,
        .detach = mtk_hdmi_v2_bridge_detach,
@@ -1189,6 +1311,7 @@ static const struct drm_bridge_funcs 
mtk_v2_hdmi_bridge_funcs = {
        .hdmi_tmds_char_rate_valid = mtk_hdmi_v2_hdmi_tmds_char_rate_valid,
        .hdmi_clear_infoframe = mtk_hdmi_v2_hdmi_clear_infoframe,
        .hdmi_write_infoframe = mtk_hdmi_v2_hdmi_write_infoframe,
+       .debugfs_init = mtk_hdmi_v2_debugfs_init,
 };
 
 /*
-- 
2.48.1

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