[PATCH v2 4/5] reset: ast2700: add reset driver support

[Ryan Chen]

Add reset controller driver for the dual-die AST2700 SoC. The
controller manages module-level reset signals via the modrst
register block at offset 0x200 within each SCU.

Signed-off-by: Ryan Chen <ryan_chen at aspeedtech.com>
---
 drivers/reset/Kconfig         |  9 +++++
 drivers/reset/Makefile        |  1 +
 drivers/reset/reset-ast2700.c | 82 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 92 insertions(+)

diff --git a/drivers/reset/Kconfig b/drivers/reset/Kconfig
index ebf484d9df4..0af5d4b104e 100644
--- a/drivers/reset/Kconfig
+++ b/drivers/reset/Kconfig
@@ -91,6 +91,15 @@ config RESET_AST2600
 	  Say Y if you want to control reset signals of different peripherals
 	  through System Control Unit (SCU).
 
+config RESET_AST2700
+	bool "Reset controller driver for AST2700 SoCs"
+	depends on DM_RESET && ASPEED_AST2700
+	default y if ASPEED_AST2700
+	help
+	  Support for reset controller on AST2700 SoC.
+	  Say Y if you want to control reset signals of different peripherals
+	  through System Control Unit (SCU).
+
 config RESET_ROCKCHIP
 	bool "Reset controller driver for Rockchip SoCs"
 	depends on DM_RESET && ARCH_ROCKCHIP && CLK
diff --git a/drivers/reset/Makefile b/drivers/reset/Makefile
index 088545c6473..e722b940e9c 100644
--- a/drivers/reset/Makefile
+++ b/drivers/reset/Makefile
@@ -16,6 +16,7 @@ obj-$(CONFIG_RESET_BCM6345) += reset-bcm6345.o
 obj-$(CONFIG_RESET_UNIPHIER) += reset-uniphier.o
 obj-$(CONFIG_RESET_AST2500) += reset-ast2500.o
 obj-$(CONFIG_RESET_AST2600) += reset-ast2600.o
+obj-$(CONFIG_RESET_AST2700) += reset-ast2700.o
 obj-$(CONFIG_RESET_ROCKCHIP) += reset-rockchip.o rst-rk3506.o rst-rk3528.o rst-rk3576.o rst-rk3588.o
 obj-$(CONFIG_RESET_MESON) += reset-meson.o
 obj-$(CONFIG_RESET_SOCFPGA) += reset-socfpga.o
diff --git a/drivers/reset/reset-ast2700.c b/drivers/reset/reset-ast2700.c
new file mode 100644
index 00000000000..2dd9e36cc0a
--- /dev/null
+++ b/drivers/reset/reset-ast2700.c
@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) ASPEED Technology Inc.
+ */
+
+#include <asm/io.h>
+#include <dm.h>
+#include <linux/err.h>
+#include <reset.h>
+#include <reset-uclass.h>
+
+/* Offset of the modrst register block within the SCU. */
+#define AST2700_RESET_OFFSET	0x200
+
+struct ast2700_reset_priv {
+	void __iomem *base;
+};
+
+static int ast2700_reset_assert(struct reset_ctl *reset_ctl)
+{
+	struct ast2700_reset_priv *priv = dev_get_priv(reset_ctl->dev);
+
+	if (reset_ctl->id < 32)
+		writel(BIT(reset_ctl->id), priv->base);
+	else
+		writel(BIT(reset_ctl->id - 32), priv->base + 0x20);
+
+	return 0;
+}
+
+static int ast2700_reset_deassert(struct reset_ctl *reset_ctl)
+{
+	struct ast2700_reset_priv *priv = dev_get_priv(reset_ctl->dev);
+
+	if (reset_ctl->id < 32)
+		writel(BIT(reset_ctl->id), priv->base + 0x04);
+	else
+		writel(BIT(reset_ctl->id - 32), priv->base + 0x24);
+
+	return 0;
+}
+
+static int ast2700_reset_status(struct reset_ctl *reset_ctl)
+{
+	struct ast2700_reset_priv *priv = dev_get_priv(reset_ctl->dev);
+	int status;
+
+	if (reset_ctl->id < 32)
+		status = BIT(reset_ctl->id) & readl(priv->base);
+	else
+		status = BIT(reset_ctl->id - 32) & readl(priv->base + 0x20);
+
+	return !!status;
+}
+
+static int ast2700_reset_probe(struct udevice *dev)
+{
+	struct ast2700_reset_priv *priv = dev_get_priv(dev);
+	void __iomem *scu_base;
+
+	scu_base = dev_read_addr_ptr(dev);
+	if (!scu_base)
+		return -EINVAL;
+
+	priv->base = scu_base + AST2700_RESET_OFFSET;
+
+	return 0;
+}
+
+static const struct reset_ops ast2700_reset_ops = {
+	.rst_assert = ast2700_reset_assert,
+	.rst_deassert = ast2700_reset_deassert,
+	.rst_status = ast2700_reset_status,
+};
+
+U_BOOT_DRIVER(ast2700_reset) = {
+	.name = "ast2700_reset",
+	.id = UCLASS_RESET,
+	.probe = ast2700_reset_probe,
+	.ops = &ast2700_reset_ops,
+	.priv_auto = sizeof(struct ast2700_reset_priv),
+};

-- 
2.34.1