drm/arm/hdlcd: Convert to Linux IRQ interfaces

Drop the DRM IRQ midlayer in favor of Linux IRQ interfaces. DRM's
IRQ helpers are mostly useful for UMS drivers. Modern KMS drivers
don't benefit from using it.

DRM IRQ callbacks are now being called directly or inlined.

Calls to platform_get_irq() can fail with a negative errno code.
Abort initialization in this case. The DRM IRQ midlayer does not
handle this case correctly.

v2:
	* name struct drm_device variables 'drm' (Sam)
Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Acked-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210803090704.32152-3-tzimmermann@suse.de

drivers/gpu/drm/arm/hdlcd_drv.c

@@ -29,7 +29,6 @@
 #include <drm/drm_fb_helper.h>
 #include <drm/drm_gem_cma_helper.h>
 #include <drm/drm_gem_framebuffer_helper.h>
-#include <drm/drm_irq.h>
 #include <drm/drm_modeset_helper.h>
 #include <drm/drm_of.h>
 #include <drm/drm_probe_helper.h>
@@ -38,6 +37,94 @@
 #include "hdlcd_drv.h"
 #include "hdlcd_regs.h"
 
+static irqreturn_t hdlcd_irq(int irq, void *arg)
+{
+	struct drm_device *drm = arg;
+	struct hdlcd_drm_private *hdlcd = drm->dev_private;
+	unsigned long irq_status;
+
+	irq_status = hdlcd_read(hdlcd, HDLCD_REG_INT_STATUS);
+
+#ifdef CONFIG_DEBUG_FS
+	if (irq_status & HDLCD_INTERRUPT_UNDERRUN)
+		atomic_inc(&hdlcd->buffer_underrun_count);
+
+	if (irq_status & HDLCD_INTERRUPT_DMA_END)
+		atomic_inc(&hdlcd->dma_end_count);
+
+	if (irq_status & HDLCD_INTERRUPT_BUS_ERROR)
+		atomic_inc(&hdlcd->bus_error_count);
+
+	if (irq_status & HDLCD_INTERRUPT_VSYNC)
+		atomic_inc(&hdlcd->vsync_count);
+
+#endif
+	if (irq_status & HDLCD_INTERRUPT_VSYNC)
+		drm_crtc_handle_vblank(&hdlcd->crtc);
+
+	/* acknowledge interrupt(s) */
+	hdlcd_write(hdlcd, HDLCD_REG_INT_CLEAR, irq_status);
+
+	return IRQ_HANDLED;
+}
+
+static void hdlcd_irq_preinstall(struct drm_device *drm)
+{
+	struct hdlcd_drm_private *hdlcd = drm->dev_private;
+	/* Ensure interrupts are disabled */
+	hdlcd_write(hdlcd, HDLCD_REG_INT_MASK, 0);
+	hdlcd_write(hdlcd, HDLCD_REG_INT_CLEAR, ~0);
+}
+
+static void hdlcd_irq_postinstall(struct drm_device *drm)
+{
+#ifdef CONFIG_DEBUG_FS
+	struct hdlcd_drm_private *hdlcd = drm->dev_private;
+	unsigned long irq_mask = hdlcd_read(hdlcd, HDLCD_REG_INT_MASK);
+
+	/* enable debug interrupts */
+	irq_mask |= HDLCD_DEBUG_INT_MASK;
+
+	hdlcd_write(hdlcd, HDLCD_REG_INT_MASK, irq_mask);
+#endif
+}
+
+static int hdlcd_irq_install(struct drm_device *drm, int irq)
+{
+	int ret;
+
+	if (irq == IRQ_NOTCONNECTED)
+		return -ENOTCONN;
+
+	hdlcd_irq_preinstall(drm);
+
+	ret = request_irq(irq, hdlcd_irq, 0, drm->driver->name, drm);
+	if (ret)
+		return ret;
+
+	hdlcd_irq_postinstall(drm);
+
+	return 0;
+}
+
+static void hdlcd_irq_uninstall(struct drm_device *drm)
+{
+	struct hdlcd_drm_private *hdlcd = drm->dev_private;
+	/* disable all the interrupts that we might have enabled */
+	unsigned long irq_mask = hdlcd_read(hdlcd, HDLCD_REG_INT_MASK);
+
+#ifdef CONFIG_DEBUG_FS
+	/* disable debug interrupts */
+	irq_mask &= ~HDLCD_DEBUG_INT_MASK;
+#endif
+
+	/* disable vsync interrupts */
+	irq_mask &= ~HDLCD_INTERRUPT_VSYNC;
+	hdlcd_write(hdlcd, HDLCD_REG_INT_MASK, irq_mask);
+
+	free_irq(hdlcd->irq, drm);
+}
+
 static int hdlcd_load(struct drm_device *drm, unsigned long flags)
 {
 	struct hdlcd_drm_private *hdlcd = drm->dev_private;
@@ -90,7 +177,12 @@ static int hdlcd_load(struct drm_device *drm, unsigned long flags)
 		goto setup_fail;
 	}
 
-	ret = drm_irq_install(drm, platform_get_irq(pdev, 0));
+	ret = platform_get_irq(pdev, 0);
+	if (ret < 0)
+		goto irq_fail;
+	hdlcd->irq = ret;
+
+	ret = hdlcd_irq_install(drm, hdlcd->irq);
 	if (ret < 0) {
 		DRM_ERROR("failed to install IRQ handler\n");
 		goto irq_fail;
@@ -122,76 +214,6 @@ static void hdlcd_setup_mode_config(struct drm_device *drm)
 	drm->mode_config.funcs = &hdlcd_mode_config_funcs;
 }
 
-static irqreturn_t hdlcd_irq(int irq, void *arg)
-{
-	struct drm_device *drm = arg;
-	struct hdlcd_drm_private *hdlcd = drm->dev_private;
-	unsigned long irq_status;
-
-	irq_status = hdlcd_read(hdlcd, HDLCD_REG_INT_STATUS);
-
-#ifdef CONFIG_DEBUG_FS
-	if (irq_status & HDLCD_INTERRUPT_UNDERRUN)
-		atomic_inc(&hdlcd->buffer_underrun_count);
-
-	if (irq_status & HDLCD_INTERRUPT_DMA_END)
-		atomic_inc(&hdlcd->dma_end_count);
-
-	if (irq_status & HDLCD_INTERRUPT_BUS_ERROR)
-		atomic_inc(&hdlcd->bus_error_count);
-
-	if (irq_status & HDLCD_INTERRUPT_VSYNC)
-		atomic_inc(&hdlcd->vsync_count);
-
-#endif
-	if (irq_status & HDLCD_INTERRUPT_VSYNC)
-		drm_crtc_handle_vblank(&hdlcd->crtc);
-
-	/* acknowledge interrupt(s) */
-	hdlcd_write(hdlcd, HDLCD_REG_INT_CLEAR, irq_status);
-
-	return IRQ_HANDLED;
-}
-
-static void hdlcd_irq_preinstall(struct drm_device *drm)
-{
-	struct hdlcd_drm_private *hdlcd = drm->dev_private;
-	/* Ensure interrupts are disabled */
-	hdlcd_write(hdlcd, HDLCD_REG_INT_MASK, 0);
-	hdlcd_write(hdlcd, HDLCD_REG_INT_CLEAR, ~0);
-}
-
-static int hdlcd_irq_postinstall(struct drm_device *drm)
-{
-#ifdef CONFIG_DEBUG_FS
-	struct hdlcd_drm_private *hdlcd = drm->dev_private;
-	unsigned long irq_mask = hdlcd_read(hdlcd, HDLCD_REG_INT_MASK);
-
-	/* enable debug interrupts */
-	irq_mask |= HDLCD_DEBUG_INT_MASK;
-
-	hdlcd_write(hdlcd, HDLCD_REG_INT_MASK, irq_mask);
-#endif
-	return 0;
-}
-
-static void hdlcd_irq_uninstall(struct drm_device *drm)
-{
-	struct hdlcd_drm_private *hdlcd = drm->dev_private;
-	/* disable all the interrupts that we might have enabled */
-	unsigned long irq_mask = hdlcd_read(hdlcd, HDLCD_REG_INT_MASK);
-
-#ifdef CONFIG_DEBUG_FS
-	/* disable debug interrupts */
-	irq_mask &= ~HDLCD_DEBUG_INT_MASK;
-#endif
-
-	/* disable vsync interrupts */
-	irq_mask &= ~HDLCD_INTERRUPT_VSYNC;
-
-	hdlcd_write(hdlcd, HDLCD_REG_INT_MASK, irq_mask);
-}
-
 #ifdef CONFIG_DEBUG_FS
 static int hdlcd_show_underrun_count(struct seq_file *m, void *arg)
 {
@@ -236,10 +258,6 @@ DEFINE_DRM_GEM_CMA_FOPS(fops);
 
 static const struct drm_driver hdlcd_driver = {
 	.driver_features = DRIVER_GEM | DRIVER_MODESET | DRIVER_ATOMIC,
-	.irq_handler = hdlcd_irq,
-	.irq_preinstall = hdlcd_irq_preinstall,
-	.irq_postinstall = hdlcd_irq_postinstall,
-	.irq_uninstall = hdlcd_irq_uninstall,
 	DRM_GEM_CMA_DRIVER_OPS,
 #ifdef CONFIG_DEBUG_FS
 	.debugfs_init = hdlcd_debugfs_init,
@@ -316,7 +334,7 @@ static int hdlcd_drm_bind(struct device *dev)
 err_unload:
 	of_node_put(hdlcd->crtc.port);
 	hdlcd->crtc.port = NULL;
-	drm_irq_uninstall(drm);
+	hdlcd_irq_uninstall(drm);
 	of_reserved_mem_device_release(drm->dev);
 err_free:
 	drm_mode_config_cleanup(drm);
@@ -338,7 +356,7 @@ static void hdlcd_drm_unbind(struct device *dev)
 	hdlcd->crtc.port = NULL;
 	pm_runtime_get_sync(dev);
 	drm_atomic_helper_shutdown(drm);
-	drm_irq_uninstall(drm);
+	hdlcd_irq_uninstall(drm);
 	pm_runtime_put(dev);
 	if (pm_runtime_enabled(dev))
 		pm_runtime_disable(dev);

drivers/gpu/drm/arm/hdlcd_drv.h

@@ -11,6 +11,7 @@ struct hdlcd_drm_private {
 	struct clk			*clk;
 	struct drm_crtc			crtc;
 	struct drm_plane		*plane;
+	unsigned int			irq;
 #ifdef CONFIG_DEBUG_FS
 	atomic_t buffer_underrun_count;
 	atomic_t bus_error_count;