soc: mediatek: mmsys: Add reset controller support

Among other features the mmsys driver should implement a reset
controller to be able to reset different bits from their space.

Cc: Jitao Shi <jitao.shi@mediatek.com>
Suggested-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>
Signed-off-by: Enric Balletbo i Serra <enric.balletbo@collabora.com>
Reviewed-by: Philipp Zabel <p.zabel@pengutronix.de>
Link: https://lore.kernel.org/r/20210930103105.v4.6.I15e2419141a69b2e5c7e700c34d92a69df47e04d@changeidSigned-off-by: Matthias Brugger <matthias.bgg@gmail.com>

drivers/soc/mediatek/mtk-mmsys.c

@@ -4,10 +4,12 @@
  * Author: James Liao <jamesjj.liao@mediatek.com>
  */
 
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/io.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/reset-controller.h>
 #include <linux/soc/mediatek/mtk-mmsys.h>
 
 #include "mtk-mmsys.h"
@@ -69,6 +71,8 @@ static const struct mtk_mmsys_driver_data mt8365_mmsys_driver_data = {
 struct mtk_mmsys {
 	void __iomem *regs;
 	const struct mtk_mmsys_driver_data *data;
+	spinlock_t lock; /* protects mmsys_sw_rst_b reg */
+	struct reset_controller_dev rcdev;
 };
 
 void mtk_mmsys_ddp_connect(struct device *dev,
@@ -108,6 +112,58 @@ void mtk_mmsys_ddp_disconnect(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(mtk_mmsys_ddp_disconnect);
 
+static int mtk_mmsys_reset_update(struct reset_controller_dev *rcdev, unsigned long id,
+				  bool assert)
+{
+	struct mtk_mmsys *mmsys = container_of(rcdev, struct mtk_mmsys, rcdev);
+	unsigned long flags;
+	u32 reg;
+
+	spin_lock_irqsave(&mmsys->lock, flags);
+
+	reg = readl_relaxed(mmsys->regs + MMSYS_SW0_RST_B);
+
+	if (assert)
+		reg &= ~BIT(id);
+	else
+		reg |= BIT(id);
+
+	writel_relaxed(reg, mmsys->regs + MMSYS_SW0_RST_B);
+
+	spin_unlock_irqrestore(&mmsys->lock, flags);
+
+	return 0;
+}
+
+static int mtk_mmsys_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	return mtk_mmsys_reset_update(rcdev, id, true);
+}
+
+static int mtk_mmsys_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	return mtk_mmsys_reset_update(rcdev, id, false);
+}
+
+static int mtk_mmsys_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	int ret;
+
+	ret = mtk_mmsys_reset_assert(rcdev, id);
+	if (ret)
+		return ret;
+
+	usleep_range(1000, 1100);
+
+	return mtk_mmsys_reset_deassert(rcdev, id);
+}
+
+static const struct reset_control_ops mtk_mmsys_reset_ops = {
+	.assert = mtk_mmsys_reset_assert,
+	.deassert = mtk_mmsys_reset_deassert,
+	.reset = mtk_mmsys_reset,
+};
+
 static int mtk_mmsys_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
@@ -127,6 +183,18 @@ static int mtk_mmsys_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	spin_lock_init(&mmsys->lock);
+
+	mmsys->rcdev.owner = THIS_MODULE;
+	mmsys->rcdev.nr_resets = 32;
+	mmsys->rcdev.ops = &mtk_mmsys_reset_ops;
+	mmsys->rcdev.of_node = pdev->dev.of_node;
+	ret = devm_reset_controller_register(&pdev->dev, &mmsys->rcdev);
+	if (ret) {
+		dev_err(&pdev->dev, "Couldn't register mmsys reset controller: %d\n", ret);
+		return ret;
+	}
+
 	mmsys->data = of_device_get_match_data(&pdev->dev);
 	platform_set_drvdata(pdev, mmsys);
 

drivers/soc/mediatek/mtk-mmsys.h

@@ -78,6 +78,8 @@
 #define DSI_SEL_IN_RDMA				0x1
 #define DSI_SEL_IN_MASK				0x1
 
+#define MMSYS_SW0_RST_B				0x140
+
 struct mtk_mmsys_routes {
 	u32 from_comp;
 	u32 to_comp;