drm/loongson: Add interrupt driver for LS7A.

Add LS7A DC vsync interrupt enable and close function, and
register irq_handler function interface.
Add vbrank event processing flow.

v4:
- Replace drm_irq_install with devm_request_irq.
- Delete the irq_ hooks in drm_driver.

v3:
- Improve code readability.
- Use the to_pci_dev function to get pci_dev.

v2:
- Added error handling in the loongson_drm_load function.

Signed-off-by: Chenyang Li <lichenyang@loongson.cn>

drivers/gpu/drm/loongson/Makefile

@@ -10,5 +10,6 @@ loongson-y := loongson_connector.o \
 	loongson_drv.o \
 	loongson_encoder.o \
 	loongson_i2c.o \
+	loongson_irq.o \
 	loongson_plane.o
 obj-$(CONFIG_DRM_LOONGSON) += loongson.o

drivers/gpu/drm/loongson/loongson_crtc.c

@@ -4,6 +4,7 @@
  */
 
 #include <drm/drm_fourcc.h>
+#include <drm/drm_vblank.h>
 
 #include "loongson_drv.h"
 
@@ -167,8 +168,14 @@ static void loongson_crtc_atomic_enable(struct drm_crtc *crtc,
 	struct loongson_crtc *lcrtc = to_loongson_crtc(crtc);
 	u32 reg_offset = lcrtc->reg_offset;
 
+	if (lcrtc->cfg_reg & CFG_ENABLE)
+		goto vblank_on;
+
 	lcrtc->cfg_reg |= CFG_ENABLE;
 	ls7a_mm_wreg(ldev, FB_CFG_REG + reg_offset, lcrtc->cfg_reg);
+
+vblank_on:
+	drm_crtc_vblank_on(crtc);
 }
 
 static void loongson_crtc_atomic_disable(struct drm_crtc *crtc,
@@ -181,6 +188,33 @@ static void loongson_crtc_atomic_disable(struct drm_crtc *crtc,
 
 	lcrtc->cfg_reg &= ~CFG_ENABLE;
 	ls7a_mm_wreg(ldev, FB_CFG_REG + reg_offset, lcrtc->cfg_reg);
+
+	spin_lock_irq(&crtc->dev->event_lock);
+	if (crtc->state->event) {
+		drm_crtc_send_vblank_event(crtc, crtc->state->event);
+		crtc->state->event = NULL;
+	}
+	spin_unlock_irq(&crtc->dev->event_lock);
+
+	drm_crtc_vblank_off(crtc);
+}
+
+static void loongson_crtc_atomic_flush(struct drm_crtc *crtc,
+				       struct drm_atomic_state *state)
+{
+	struct drm_pending_vblank_event *event = crtc->state->event;
+
+	if (!event)
+		return;
+
+	crtc->state->event = NULL;
+
+	spin_lock_irq(&crtc->dev->event_lock);
+	if (drm_crtc_vblank_get(crtc) == 0)
+		drm_crtc_arm_vblank_event(crtc, event);
+	else
+		drm_crtc_send_vblank_event(crtc, event);
+	spin_unlock_irq(&crtc->dev->event_lock);
 }
 
 static enum drm_mode_status loongson_mode_valid(struct drm_crtc *crtc,
@@ -200,6 +234,7 @@ static enum drm_mode_status loongson_mode_valid(struct drm_crtc *crtc,
 
 static const struct drm_crtc_helper_funcs loongson_crtc_helper_funcs = {
 	.mode_valid = loongson_mode_valid,
+	.atomic_flush = loongson_crtc_atomic_flush,
 	.atomic_enable = loongson_crtc_atomic_enable,
 	.atomic_disable = loongson_crtc_atomic_disable,
 	.mode_set_nofb = loongson_crtc_mode_set_nofb,
@@ -211,6 +246,8 @@ static const struct drm_crtc_funcs loongson_crtc_funcs = {
 	.reset = drm_atomic_helper_crtc_reset,
 	.atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
 	.atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
+	.enable_vblank = loongson_crtc_enable_vblank,
+	.disable_vblank = loongson_crtc_disable_vblank,
 };
 
 int loongson_crtc_init(struct loongson_device *ldev, int index)

drivers/gpu/drm/loongson/loongson_drv.c

@@ -23,9 +23,10 @@
 /* Interface history:
  * 0.1 - original.
  * 0.2 - add i2c and connector detect.
+ * 0.3 - Vblank and vsync interrupt support.
  */
 #define DRIVER_MAJOR 0
-#define DRIVER_MINOR 2
+#define DRIVER_MINOR 3
 
 static const struct drm_mode_config_funcs loongson_mode_funcs = {
 	.fb_create = drm_gem_fb_create,
@@ -167,6 +168,12 @@ static int loongson_driver_init(struct drm_device *dev)
 		goto err;
 	}
 
+	ret = loongson_irq_init(ldev);
+	if (ret) {
+		dev_err(dev->dev, "Fatal error during irq init: %d\n", ret);
+		goto err;
+	}
+
 	drm_kms_helper_poll_init(dev);
 	drm_mode_config_reset(dev);
 

drivers/gpu/drm/loongson/loongson_drv.h

@@ -40,6 +40,7 @@
 #define FB_HSYNC_REG (0x1420)
 #define FB_VDISPLAY_REG (0x1480)
 #define FB_VSYNC_REG (0x14a0)
+#define FB_INT_REG (0x1570)
 
 #define CFG_FMT GENMASK(2, 0)
 #define CFG_FBSWITCH BIT(7)
@@ -51,6 +52,10 @@
 #define FB_PANCFG_DEF 0x80001311
 #define FB_HSYNC_PULSE (1 << 30)
 #define FB_VSYNC_PULSE (1 << 30)
+#define FB_VSYNC1_ENABLE (1 << 16)
+#define FB_VSYNC0_ENABLE (1 << 18)
+#define FB_VSYNC1_INT (1 << 0)
+#define FB_VSYNC0_INT (1 << 2)
 
 /* PIX PLL */
 #define LOOPC_MIN 24
@@ -128,6 +133,11 @@ struct loongson_plane *loongson_plane_init(struct drm_device *dev, int index);
 /* i2c */
 int loongson_dc_gpio_init(struct loongson_device *ldev);
 
+/* irq */
+int loongson_irq_init(struct loongson_device *ldev);
+int loongson_crtc_enable_vblank(struct drm_crtc *crtc);
+void loongson_crtc_disable_vblank(struct drm_crtc *crtc);
+
 /* device */
 u32 loongson_gpu_offset(struct drm_plane_state *state,
 			struct loongson_device *dev);

drivers/gpu/drm/loongson/loongson_irq.c

@@ -0,0 +1,84 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2020-2022 Loongson Technology Corporation Limited
+ */
+
+#include <linux/pci.h>
+
+#include <drm/drm_vblank.h>
+
+#include "loongson_drv.h"
+
+static irqreturn_t loongson_irq_handler(int irq, void *arg)
+{
+	struct drm_device *dev = (struct drm_device *) arg;
+	struct loongson_device *ldev = to_loongson_device(dev);
+	struct loongson_crtc *lcrtc;
+	u32 val;
+
+	val = ls7a_mm_rreg(ldev, FB_INT_REG);
+	ls7a_mm_wreg(ldev, FB_INT_REG, val & (0xffff << 16));
+
+	if (val & FB_VSYNC0_INT)
+		lcrtc = ldev->mode_info[0].crtc;
+	else if (val & FB_VSYNC1_INT)
+		lcrtc = ldev->mode_info[1].crtc;
+
+	drm_crtc_handle_vblank(&lcrtc->base);
+
+	return IRQ_HANDLED;
+}
+
+int loongson_irq_init(struct loongson_device *ldev)
+{
+	int ret;
+	struct drm_device *dev = &ldev->dev;
+	int irq = to_pci_dev(dev->dev)->irq;
+
+	ret = drm_vblank_init(dev, ldev->num_crtc);
+	if (ret) {
+		dev_err(dev->dev, "Fatal error during vblank init: %d\n", ret);
+		return ret;
+	}
+	DRM_INFO("drm vblank init finished\n");
+
+	ret = devm_request_irq(dev->dev, irq, loongson_irq_handler, 0,
+			       "loongson-drm", dev);
+	if (ret) {
+		dev_err(dev->dev, "Fatal error during irq install: %d\n", ret);
+		return ret;
+	}
+	DRM_INFO("loongson irq initialized\n");
+
+	return 0;
+}
+
+int loongson_crtc_enable_vblank(struct drm_crtc *crtc)
+{
+	struct loongson_crtc *lcrtc = to_loongson_crtc(crtc);
+	struct loongson_device *ldev = lcrtc->ldev;
+	u32 reg_val = ls7a_mm_rreg(ldev, FB_INT_REG);
+
+	if (lcrtc->crtc_id)
+		reg_val |= FB_VSYNC1_ENABLE;
+	else
+		reg_val |= FB_VSYNC0_ENABLE;
+
+	ls7a_mm_wreg(ldev, FB_INT_REG, reg_val);
+
+	return 0;
+}
+
+void loongson_crtc_disable_vblank(struct drm_crtc *crtc)
+{
+	struct loongson_crtc *lcrtc = to_loongson_crtc(crtc);
+	struct loongson_device *ldev = lcrtc->ldev;
+	u32 reg_val = ls7a_mm_rreg(ldev, FB_INT_REG);
+
+	if (lcrtc->crtc_id)
+		reg_val &= ~FB_VSYNC1_ENABLE;
+	else
+		reg_val &= ~FB_VSYNC0_ENABLE;
+
+	ls7a_mm_wreg(ldev, FB_INT_REG, reg_val);
+}