wdt: nuvoton: Add support for Nuvoton

Add watchdog controller driver for NPCM7xx/npcm8xx

the wdt design of npcm750 and npcm845 is the same.
so the driver can work on npcm750 and npcm845.
about npcm845 wdt dtsi i will followed kernel dts name
to use nuvoton,npcm750-wdt.

Signed-off-by: Jim Liu <JJLIU0@nuvoton.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/watchdog/Kconfig

@@ -197,6 +197,14 @@ config WDT_MTK
 	  The watchdog timer is stopped when initialized.
 	  It performs full SoC reset.
 
+config WDT_NPCM
+	bool "Nuvoton watchdog timer support"
+	depends on WDT && ARCH_NPCM
+	help
+	  This enables Nuvoton npcm7xx/npcm8xx watchdog timer driver,
+	  The watchdog timer is stopped when initialized.
+	  It performs full SoC reset.
+
 config WDT_OCTEONTX
 	bool "OcteonTX core watchdog support"
 	depends on WDT && (ARCH_OCTEONTX || ARCH_OCTEONTX2)

drivers/watchdog/Makefile

@@ -31,6 +31,7 @@ obj-$(CONFIG_WDT_MPC8xx) += mpc8xx_wdt.o
 obj-$(CONFIG_WDT_MT7620) += mt7620_wdt.o
 obj-$(CONFIG_WDT_MT7621) += mt7621_wdt.o
 obj-$(CONFIG_WDT_MTK) += mtk_wdt.o
+obj-$(CONFIG_WDT_NPCM) += npcm_wdt.o
 obj-$(CONFIG_WDT_OCTEONTX) += octeontx_wdt.o
 obj-$(CONFIG_WDT_OMAP3) += omap_wdt.o
 obj-$(CONFIG_WDT_SBSA) += sbsa_gwdt.o

drivers/watchdog/npcm_wdt.c

@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2022 Nuvoton Technology, Inc
+ */
+
+#include <dm.h>
+#include <errno.h>
+#include <log.h>
+#include <wdt.h>
+#include <asm/io.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+
+#define NPCM_WTCLK	(BIT(10) | BIT(11))	/* Clock divider */
+#define NPCM_WTE	BIT(7)			/* Enable */
+#define NPCM_WTIE	BIT(6)			/* Enable irq */
+#define NPCM_WTIS	(BIT(4) | BIT(5))	/* Interval selection */
+#define NPCM_WTIF	BIT(3)			/* Interrupt flag*/
+#define NPCM_WTRF	BIT(2)			/* Reset flag */
+#define NPCM_WTRE	BIT(1)			/* Reset enable */
+#define NPCM_WTR	BIT(0)			/* Reset counter */
+
+struct npcm_wdt_priv {
+	void __iomem *regs;
+};
+
+static int npcm_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
+{
+	struct npcm_wdt_priv *priv = dev_get_priv(dev);
+	u32 time_out, val;
+
+	time_out = (u32)(timeout_ms) / 1000;
+	if (time_out < 2)
+		val = 0x800;
+	else if (time_out < 3)
+		val = 0x420;
+	else if (time_out < 6)
+		val = 0x810;
+	else if (time_out < 11)
+		val = 0x430;
+	else if (time_out < 22)
+		val = 0x820;
+	else if (time_out < 44)
+		val = 0xc00;
+	else if (time_out < 87)
+		val = 0x830;
+	else if (time_out < 173)
+		val = 0xc10;
+	else if (time_out < 688)
+		val = 0xc20;
+	else
+		val = 0xc30;
+
+	val |= NPCM_WTRE | NPCM_WTE | NPCM_WTR | NPCM_WTIE;
+	writel(val, priv->regs);
+
+	return 0;
+}
+
+static int npcm_wdt_stop(struct udevice *dev)
+{
+	struct npcm_wdt_priv *priv = dev_get_priv(dev);
+
+	writel(0, priv->regs);
+
+	return 0;
+}
+
+static int npcm_wdt_reset(struct udevice *dev)
+{
+	struct npcm_wdt_priv *priv = dev_get_priv(dev);
+
+	writel(NPCM_WTR | NPCM_WTRE | NPCM_WTE, priv->regs);
+
+	return 0;
+}
+
+static int npcm_wdt_of_to_plat(struct udevice *dev)
+{
+	struct npcm_wdt_priv *priv = dev_get_priv(dev);
+
+	priv->regs = dev_read_addr_ptr(dev);
+	if (!priv->regs)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const struct wdt_ops npcm_wdt_ops = {
+	.start = npcm_wdt_start,
+	.reset = npcm_wdt_reset,
+	.stop = npcm_wdt_stop,
+};
+
+static const struct udevice_id npcm_wdt_ids[] = {
+	{ .compatible = "nuvoton,npcm750-wdt" },
+	{ }
+};
+
+static int npcm_wdt_probe(struct udevice *dev)
+{
+	debug("%s() wdt%u\n", __func__, dev_seq(dev));
+	npcm_wdt_stop(dev);
+
+	return 0;
+}
+
+U_BOOT_DRIVER(npcm_wdt) = {
+	.name = "npcm_wdt",
+	.id = UCLASS_WDT,
+	.of_match = npcm_wdt_ids,
+	.probe = npcm_wdt_probe,
+	.priv_auto = sizeof(struct npcm_wdt_priv),
+	.of_to_plat = npcm_wdt_of_to_plat,
+	.ops = &npcm_wdt_ops,
+};