From: "Friday Yang" <friday.yang@mediatek.com>

In order to avoid the bus glitch issue, add a reset-controller
driver for performing reset management of SMI LARBs on MediaTek
platform.

Signed-off-by: Friday Yang <friday.yang@mediatek.com>
---
 drivers/reset/Kconfig              |   9 ++
 drivers/reset/Makefile             |   1 +
 drivers/reset/reset-mediatek-smi.c | 156 +++++++++++++++++++++++++++++
 3 files changed, 166 insertions(+)
 create mode 100644 drivers/reset/reset-mediatek-smi.c

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index 5b3abb6db248..07e606e530fc 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -153,6 +153,15 @@ config RESET_MCHP_SPARX5
 	help
 	  This driver supports switch core reset for the Microchip Sparx5 SoC.

+config RESET_MTK_SMI
+	bool "MediaTek SMI Reset Driver"
+	depends on MTK_SMI || COMPILE_TEST
+	help
+	  This option enables the reset controller driver for MediaTek SMI.
+	  This reset driver is responsible for managing the reset signals
+	  for SMI larbs. Say Y if you want to control reset signals for
+	  MediaTek SMI larbs. Otherwise, say N.
+
 config RESET_NPCM
 	bool "NPCM BMC Reset Driver" if COMPILE_TEST
 	default ARCH_NPCM
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 677c4d1e2632..1f5ba5696872 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -22,6 +22,7 @@ obj-$(CONFIG_RESET_K210) += reset-k210.o
 obj-$(CONFIG_RESET_LANTIQ) += reset-lantiq.o
 obj-$(CONFIG_RESET_LPC18XX) += reset-lpc18xx.o
 obj-$(CONFIG_RESET_MCHP_SPARX5) += reset-microchip-sparx5.o
+obj-$(CONFIG_RESET_MTK_SMI) += reset-mediatek-smi.o
 obj-$(CONFIG_RESET_NPCM) += reset-npcm.o
 obj-$(CONFIG_RESET_NUVOTON_MA35D1) += reset-ma35d1.o
 obj-$(CONFIG_RESET_PISTACHIO) += reset-pistachio.o
diff --git a/drivers/reset/reset-mediatek-smi.c b/drivers/reset/reset-mediatek-smi.c
new file mode 100644
index 000000000000..0a2ffd9db670
--- /dev/null
+++ b/drivers/reset/reset-mediatek-smi.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Reset driver for MediaTek SMI module
+ *
+ * Copyright (C) 2024 MediaTek Inc.
+ */
+
+#include <linux/io.h>
+#include <linux/mfd/syscon.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/reset-controller.h>
+
+#include <dt-bindings/reset/mt8188-resets.h>
+
+#define to_mtk_smi_reset_data(_rcdev)	\
+	container_of(_rcdev, struct mtk_smi_reset_data, rcdev)
+
+struct mtk_smi_larb_reset {
+	unsigned int	offset;
+	unsigned int	value;
+};
+
+static const struct mtk_smi_larb_reset rst_signal_mt8188[] = {
+	[MT8188_SMI_RST_LARB10]		= { 0xC, BIT(0) },
+	[MT8188_SMI_RST_LARB11A]	= { 0xC, BIT(0) },
+	[MT8188_SMI_RST_LARB11C]	= { 0xC, BIT(0) },
+	[MT8188_SMI_RST_LARB12]		= { 0xC, BIT(8) },
+	[MT8188_SMI_RST_LARB11B]	= { 0xC, BIT(0) },
+	[MT8188_SMI_RST_LARB15]		= { 0xC, BIT(0) },
+	[MT8188_SMI_RST_LARB16B]	= { 0xA0, BIT(4) },
+	[MT8188_SMI_RST_LARB17B]	= { 0xA0, BIT(4) },
+	[MT8188_SMI_RST_LARB16A]	= { 0xA0, BIT(4) },
+	[MT8188_SMI_RST_LARB17A]	= { 0xA0, BIT(4) },
+};
+
+struct mtk_smi_larb_plat {
+	const struct mtk_smi_larb_reset	*reset_signal;
+	const unsigned int		larb_reset_nr;
+};
+
+struct mtk_smi_reset_data {
+	const struct mtk_smi_larb_plat	*larb_plat;
+	struct reset_controller_dev	rcdev;
+	void __iomem			*base;
+};
+
+static const struct mtk_smi_larb_plat mtk_smi_larb_mt8188 = {
+	.reset_signal = rst_signal_mt8188,
+	.larb_reset_nr = ARRAY_SIZE(rst_signal_mt8188),
+};
+
+static int mtk_smi_larb_reset_assert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct mtk_smi_reset_data *data = to_mtk_smi_reset_data(rcdev);
+	const struct mtk_smi_larb_plat *larb_plat = data->larb_plat;
+	const struct mtk_smi_larb_reset *larb_rst = larb_plat->reset_signal + id;
+	unsigned int val, offset = larb_rst->offset;
+	void __iomem *base = data->base;
+
+	val = readl(base + offset);
+	val |= larb_rst->value;
+	writel(val, base + offset);
+
+	return 0;
+}
+
+static int mtk_smi_larb_reset_deassert(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	struct mtk_smi_reset_data *data = to_mtk_smi_reset_data(rcdev);
+	const struct mtk_smi_larb_plat *larb_plat = data->larb_plat;
+	const struct mtk_smi_larb_reset *larb_rst = larb_plat->reset_signal + id;
+	unsigned int val, offset = larb_rst->offset;
+	void __iomem *base = data->base;
+
+	val = readl(base + offset);
+	val &= ~larb_rst->value;
+	writel(val, base + offset);
+
+	return 0;
+}
+
+static int mtk_smi_larb_reset(struct reset_controller_dev *rcdev, unsigned long id)
+{
+	mtk_smi_larb_reset_assert(rcdev, id);
+
+	return mtk_smi_larb_reset_deassert(rcdev, id);
+}
+
+static const struct reset_control_ops mtk_smi_reset_ops = {
+	.reset		= mtk_smi_larb_reset,
+	.assert		= mtk_smi_larb_reset_assert,
+	.deassert	= mtk_smi_larb_reset_deassert,
+};
+
+static int mtk_smi_reset_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	const struct mtk_smi_larb_plat *larb_plat = of_device_get_match_data(dev);
+	struct device_node *np = dev->of_node, *reset_node;
+	struct mtk_smi_reset_data *data;
+	struct resource res;
+	void __iomem *base;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	reset_node = of_parse_phandle(np, "mediatek,larb-rst", 0);
+	if (!reset_node)
+		return -EINVAL;
+
+	if (of_address_to_resource(reset_node, 0, &res)) {
+		of_node_put(reset_node);
+		return -EINVAL;
+	}
+
+	base = devm_ioremap_resource(dev, &res);
+	if (IS_ERR(base)) {
+		of_node_put(reset_node);
+		return PTR_ERR(base);
+	}
+
+	of_node_put(reset_node);
+	data->larb_plat = larb_plat;
+	data->base = base;
+	data->rcdev.owner = THIS_MODULE;
+	data->rcdev.ops = &mtk_smi_reset_ops;
+	data->rcdev.of_node = np;
+	data->rcdev.nr_resets = larb_plat->larb_reset_nr;
+	data->rcdev.dev = dev;
+	platform_set_drvdata(pdev, data);
+
+	return devm_reset_controller_register(dev, &data->rcdev);
+}
+
+static const struct of_device_id mtk_smi_larb_reset_of_match[] = {
+	{ .compatible = "mediatek,mt8188-smi-reset", .data = &mtk_smi_larb_mt8188 },
+	{ },
+};
+MODULE_DEVICE_TABLE(of, mtk_smi_larb_reset_of_match);
+
+static struct platform_driver mtk_smi_reset_driver = {
+	.probe = mtk_smi_reset_probe,
+	.driver = {
+		.name = "mediatek-smi-reset",
+		.of_match_table = mtk_smi_larb_reset_of_match,
+	},
+};
+module_platform_driver(mtk_smi_reset_driver);
+
+MODULE_AUTHOR("Friday.Yang@mediatek.com");
+MODULE_DESCRIPTION("MediaTek SMI Reset Driver");
+MODULE_LICENSE("GPL");
--
2.46.0