[PATCH v4 1/4] drm/rockchip: vop: export line flag function

[Yakir Yang]

VOP have integrated a hardware counter which indicate the exact display
line that vop is scanning. And if we're interested in a specific line,
we can set the line number to vop line_flag register, and then vop would
generate a line_flag interrupt for it.

For example eDP PSR function is interested in the vertical blanking
period, then driver could set the line number to zero.

This patch have exported a symbol that allow other driver to listen the
line flag event with given timeout limit:
-  rockchip_drm_wait_line_flag()

Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx>
---
Changes in v4:
- Avoid the weird behavior in rockchip_drm_wait_line_flag(). (Sean)
- Make line_flag_num_x to an array. (Sean)
- Remove the unused vop_cfg_done() in vop_line_flag_irq_enable(). (Stephane, reviewed in Google gerrit)
    [https://chromium-review.googlesource.com/#/c/349084/33/drivers/gpu/drm/rockchip/rockchip_drm_vop.c@466]

Changes in v3:
- Export the 'rockchip_drm_wait_line_flag' symbol, and document it.
- Add 'line_flag_num_0' for RK3288/RK3036
- Remove the notify for waiting line_flag event (Daniel)

Changes in v2:
- Introduce in v2, split VOP line flag changes out

 drivers/gpu/drm/rockchip/rockchip_drm_drv.h |   3 +
 drivers/gpu/drm/rockchip/rockchip_drm_vop.c | 118 ++++++++++++++++++++++++++++
 drivers/gpu/drm/rockchip/rockchip_drm_vop.h |   2 +
 drivers/gpu/drm/rockchip/rockchip_vop_reg.c |   4 +
 4 files changed, 127 insertions(+)

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
index ea39329..239b830 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
@@ -70,4 +70,7 @@ int rockchip_drm_dma_attach_device(struct drm_device *drm_dev,
 				   struct device *dev);
 void rockchip_drm_dma_detach_device(struct drm_device *drm_dev,
 				    struct device *dev);
+int rockchip_drm_wait_line_flag(struct drm_crtc *crtc, unsigned int line_num,
+				unsigned int mstimeout);
+
 #endif /* _ROCKCHIP_DRM_DRV_H_ */
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
index c8a62a8..69d32f1 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.c
@@ -121,6 +121,8 @@ struct vop {
 	/* protected by dev->event_lock */
 	struct drm_pending_vblank_event *event;
 
+	struct completion line_flag_completion;
+
 	const struct vop_data *data;
 
 	uint32_t *regsbak;
@@ -431,6 +433,71 @@ static void vop_dsp_hold_valid_irq_disable(struct vop *vop)
 	spin_unlock_irqrestore(&vop->irq_lock, flags);
 }
 
+/*
+ * (1) each frame starts at the start of the Vsync pulse which is signaled by
+ *     the "FRAME_SYNC" interrupt.
+ * (2) the active data region of each frame ends at dsp_vact_end
+ * (3) we should program this same number (dsp_vact_end) into dsp_line_frag_num,
+ *      to get "LINE_FLAG" interrupt at the end of the active on screen data.
+ *
+ * VOP_INTR_CTRL0.dsp_line_frag_num = VOP_DSP_VACT_ST_END.dsp_vact_end
+ * Interrupts
+ * LINE_FLAG -------------------------------+
+ * FRAME_SYNC ----+                         |
+ *                |                         |
+ *                v                         v
+ *                | Vsync | Vbp |  Vactive  | Vfp |
+ *                        ^     ^           ^     ^
+ *                        |     |           |     |
+ *                        |     |           |     |
+ * dsp_vs_end ------------+     |           |     |   VOP_DSP_VTOTAL_VS_END
+ * dsp_vact_start --------------+           |     |   VOP_DSP_VACT_ST_END
+ * dsp_vact_end ----------------------------+     |   VOP_DSP_VACT_ST_END
+ * dsp_total -------------------------------------+   VOP_DSP_VTOTAL_VS_END
+ */
+static bool vop_line_flag_irq_is_enabled(struct vop *vop)
+{
+	uint32_t line_flag_irq;
+	unsigned long flags;
+
+	spin_lock_irqsave(&vop->irq_lock, flags);
+
+	line_flag_irq = VOP_INTR_GET_TYPE(vop, enable, LINE_FLAG_INTR);
+
+	spin_unlock_irqrestore(&vop->irq_lock, flags);
+
+	return !!line_flag_irq;
+}
+
+static void vop_line_flag_irq_enable(struct vop *vop, int line_num)
+{
+	unsigned long flags;
+
+	if (WARN_ON(!vop->is_enabled))
+		return;
+
+	spin_lock_irqsave(&vop->irq_lock, flags);
+
+	VOP_CTRL_SET(vop, line_flag_num[0], line_num);
+	VOP_INTR_SET_TYPE(vop, enable, LINE_FLAG_INTR, 1);
+
+	spin_unlock_irqrestore(&vop->irq_lock, flags);
+}
+
+static void vop_line_flag_irq_disable(struct vop *vop)
+{
+	unsigned long flags;
+
+	if (WARN_ON(!vop->is_enabled))
+		return;
+
+	spin_lock_irqsave(&vop->irq_lock, flags);
+
+	VOP_INTR_SET_TYPE(vop, enable, LINE_FLAG_INTR, 0);
+
+	spin_unlock_irqrestore(&vop->irq_lock, flags);
+}
+
 static void vop_enable(struct drm_crtc *crtc)
 {
 	struct vop *vop = to_vop(crtc);
@@ -1157,6 +1224,13 @@ static irqreturn_t vop_isr(int irq, void *data)
 		ret = IRQ_HANDLED;
 	}
 
+	if (active_irqs & LINE_FLAG_INTR) {
+		if (!completion_done(&vop->line_flag_completion))
+			complete(&vop->line_flag_completion);
+		active_irqs &= ~LINE_FLAG_INTR;
+		ret = IRQ_HANDLED;
+	}
+
 	if (active_irqs & FS_INTR) {
 		drm_crtc_handle_vblank(crtc);
 		vop_handle_vblank(vop);
@@ -1255,6 +1329,7 @@ static int vop_create_crtc(struct vop *vop)
 
 	init_completion(&vop->dsp_hold_completion);
 	init_completion(&vop->wait_update_complete);
+	init_completion(&vop->line_flag_completion);
 	crtc->port = port;
 	rockchip_register_crtc_funcs(crtc, &private_crtc_funcs);
 
@@ -1411,6 +1486,49 @@ static void vop_win_init(struct vop *vop)
 	}
 }
 
+/**
+ * rockchip_drm_wait_line_flag - acqiure the give line flag event
+ * @crtc: CRTC to enable line flag
+ * @line_num: interested line number
+ * @mstimeout: millisecond for timeout
+ *
+ * Driver would hold here until the interested line flag interrupt have
+ * happened or timeout to wait.
+ *
+ * Returns:
+ * Zero on success, negative errno on failure.
+ */
+int rockchip_drm_wait_line_flag(struct drm_crtc *crtc, unsigned int line_num,
+				unsigned int mstimeout)
+{
+	struct vop *vop = to_vop(crtc);
+	unsigned long jiffies_left;
+
+	if (!crtc || !vop->is_enabled)
+		return -ENODEV;
+
+	if (line_num > crtc->mode.vtotal || mstimeout <= 0)
+		return -EINVAL;
+
+	if (vop_line_flag_irq_is_enabled(vop))
+		return -EBUSY;
+
+	reinit_completion(&vop->line_flag_completion);
+	vop_line_flag_irq_enable(vop, line_num);
+
+	jiffies_left = wait_for_completion_timeout(&vop->line_flag_completion,
+						   msecs_to_jiffies(mstimeout));
+	vop_line_flag_irq_disable(vop);
+
+	if (jiffies_left == 0) {
+		dev_err(vop->dev, "Timeout waiting for IRQ\n");
+		return -ETIMEDOUT;
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(rockchip_drm_wait_line_flag);
+
 static int vop_bind(struct device *dev, struct device *master, void *data)
 {
 	struct platform_device *pdev = to_platform_device(dev);
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop.h b/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
index ff4f52e..1dbc526 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop.h
@@ -61,6 +61,8 @@ struct vop_ctrl {
 	struct vop_reg hpost_st_end;
 	struct vop_reg vpost_st_end;
 
+	struct vop_reg line_flag_num[2];
+
 	struct vop_reg cfg_done;
 };
 
diff --git a/drivers/gpu/drm/rockchip/rockchip_vop_reg.c b/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
index 6f42e56..eea8427 100644
--- a/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
+++ b/drivers/gpu/drm/rockchip/rockchip_vop_reg.c
@@ -122,6 +122,7 @@ static const struct vop_ctrl rk3036_ctrl_data = {
 	.hact_st_end = VOP_REG(RK3036_DSP_HACT_ST_END, 0x1fff1fff, 0),
 	.vtotal_pw = VOP_REG(RK3036_DSP_VTOTAL_VS_END, 0x1fff1fff, 0),
 	.vact_st_end = VOP_REG(RK3036_DSP_VACT_ST_END, 0x1fff1fff, 0),
+	.line_flag_num[0] = VOP_REG(RK3036_INT_STATUS, 0xfff, 12),
 	.cfg_done = VOP_REG(RK3036_REG_CFG_DONE, 0x1, 0),
 };
 
@@ -221,6 +222,7 @@ static const struct vop_ctrl rk3288_ctrl_data = {
 	.vact_st_end = VOP_REG(RK3288_DSP_VACT_ST_END, 0x1fff1fff, 0),
 	.hpost_st_end = VOP_REG(RK3288_POST_DSP_HACT_INFO, 0x1fff1fff, 0),
 	.vpost_st_end = VOP_REG(RK3288_POST_DSP_VACT_INFO, 0x1fff1fff, 0),
+	.line_flag_num[0] = VOP_REG(RK3288_INTR_CTRL0, 0x1fff, 12),
 	.cfg_done = VOP_REG(RK3288_REG_CFG_DONE, 0x1, 0),
 };
 
@@ -299,6 +301,8 @@ static const struct vop_ctrl rk3399_ctrl_data = {
 	.vact_st_end = VOP_REG(RK3399_DSP_VACT_ST_END, 0x1fff1fff, 0),
 	.hpost_st_end = VOP_REG(RK3399_POST_DSP_HACT_INFO, 0x1fff1fff, 0),
 	.vpost_st_end = VOP_REG(RK3399_POST_DSP_VACT_INFO, 0x1fff1fff, 0),
+	.line_flag_num[0] = VOP_REG(RK3399_LINE_FLAG, 0xffff, 0),
+	.line_flag_num[1] = VOP_REG(RK3399_LINE_FLAG, 0xffff, 16),
 	.cfg_done = VOP_REG_MASK(RK3399_REG_CFG_DONE, 0x1, 0),
 };
 
-- 
1.9.1