From c6065bf78ed0803dfea16a0b5061ab88dd8ee18e Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Fri, 20 Oct 2023 15:21:34 +0100
Subject: [PATCH] Revert "vc4/fkms: Remove use of SMI peripheral"

This reverts commit 3fb20da9f3bff93f20b1a1fe2c950c6c8f4d1e1e.
---
 drivers/gpu/drm/vc4/vc4_firmware_kms.c | 24 +++++++++++++++++-------
 1 file changed, 17 insertions(+), 7 deletions(-)

--- a/drivers/gpu/drm/vc4/vc4_firmware_kms.c
+++ b/drivers/gpu/drm/vc4/vc4_firmware_kms.c
@@ -255,6 +255,13 @@ static const struct vc_image_format *vc4
 /* The firmware delivers a vblank interrupt to us through the SMI
  * hardware, which has only this one register.
  */
+#define SMICS 0x0
+#define SMIDSW0 0x14
+#define SMIDSW1 0x1C
+#define SMICS_INTERRUPTS (BIT(9) | BIT(10) | BIT(11))
+
+/* Flag to denote that the firmware is giving multiple display callbacks */
+#define SMI_NEW 0xabcd0000
 
 #define vc4_crtc vc4_kms_crtc
 #define to_vc4_crtc to_vc4_kms_crtc
@@ -1214,13 +1221,16 @@ static irqreturn_t vc4_crtc_irq_handler(
 {
 	struct vc4_crtc **crtc_list = data;
 	int i;
+	u32 stat = readl(crtc_list[0]->regs + SMICS);
 	irqreturn_t ret = IRQ_NONE;
 	u32 chan;
-	if (1) {
 
-		chan = 0;
+	if (stat & SMICS_INTERRUPTS) {
+		writel(0, crtc_list[0]->regs + SMICS);
+
+		chan = readl(crtc_list[0]->regs + SMIDSW0);
 
-		if (1) {
+		if ((chan & 0xFFFF0000) != SMI_NEW) {
 			/* Older firmware. Treat the one interrupt as vblank/
 			 * complete for all crtcs.
 			 */
@@ -1231,7 +1241,7 @@ static irqreturn_t vc4_crtc_irq_handler(
 			}
 		} else {
 			if (chan & 1) {
-				//writel(SMI_NEW, crtc_list[0]->regs + SMIDSW0);
+				writel(SMI_NEW, crtc_list[0]->regs + SMIDSW0);
 				if (crtc_list[0]->vblank_enabled)
 					drm_crtc_handle_vblank(&crtc_list[0]->base);
 				vc4_crtc_handle_page_flip(crtc_list[0]);
@@ -1239,10 +1249,10 @@ static irqreturn_t vc4_crtc_irq_handler(
 
 			if (crtc_list[1]) {
 				/* Check for the secondary display too */
-				//chan = readl(crtc_list[0]->regs + SMIDSW1);
+				chan = readl(crtc_list[0]->regs + SMIDSW1);
 
 				if (chan & 1) {
-					//writel(SMI_NEW, crtc_list[0]->regs + SMIDSW1);
+					writel(SMI_NEW, crtc_list[0]->regs + SMIDSW1);
 
 					if (crtc_list[1]->vblank_enabled)
 						drm_crtc_handle_vblank(&crtc_list[1]->base);
@@ -1982,7 +1992,7 @@ static int vc4_fkms_bind(struct device *
 		if (IS_ERR(crtc_list[0]->regs))
 			DRM_ERROR("Oh dear, failed to map registers\n");
 
-		//writel(0, crtc_list[0]->regs + SMICS);
+		writel(0, crtc_list[0]->regs + SMICS);
 		ret = devm_request_irq(dev, platform_get_irq(pdev, 0),
 				       vc4_crtc_irq_handler, 0,
 				       "vc4 firmware kms", crtc_list);