watchdog: ftwdt010: return a previously deleted driver now ported to DM

The ftwdt010 watchdog driver was deleted by
commit 11232139e3 ("nds32: Remove the architecture")

Return it to the codebase in a DM compatible form. Enable it in
sandbox_defconfig to test compilability.
Another platform using ftwdt010 will be submitted later.

Signed-off-by: Sergei Antonov <saproj@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>

configs/sandbox_defconfig

@@ -323,6 +323,7 @@ CONFIG_WDT=y
 CONFIG_WDT_GPIO=y
 CONFIG_WDT_SANDBOX=y
 CONFIG_WDT_ALARM_SANDBOX=y
+CONFIG_WDT_FTWDT010=y
 CONFIG_FS_CBFS=y
 CONFIG_FS_CRAMFS=y
 CONFIG_ADDR_MAP=y

drivers/watchdog/Kconfig

@@ -368,4 +368,11 @@ config SPL_WDT
 	  Enable driver model for watchdog timer in SPL.
 	  This is similar to CONFIG_WDT in U-Boot.
 
+config WDT_FTWDT010
+	bool "Faraday Technology ftwdt010 watchdog timer support"
+	depends on WDT
+	imply WATCHDOG
+	help
+	  Faraday Technology ftwdt010 watchdog is an architecture independent
+	  watchdog. It is usually used in SoC chip design.
 endmenu

drivers/watchdog/Makefile

@@ -27,6 +27,7 @@ obj-$(CONFIG_WDT_BOOKE) += booke_wdt.o
 obj-$(CONFIG_WDT_CORTINA) += cortina_wdt.o
 obj-$(CONFIG_WDT_ORION) += orion_wdt.o
 obj-$(CONFIG_WDT_CDNS) += cdns_wdt.o
+obj-$(CONFIG_WDT_FTWDT010) += ftwdt010_wdt.o
 obj-$(CONFIG_WDT_GPIO) += gpio_wdt.o
 obj-$(CONFIG_WDT_MAX6370) += max6370_wdt.o
 obj-$(CONFIG_WDT_MESON_GXBB) += meson_gxbb_wdt.o

drivers/watchdog/ftwdt010_wdt.c

@@ -0,0 +1,132 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Watchdog driver for the FTWDT010 Watch Dog Driver
+ *
+ * (c) Copyright 2004 Faraday Technology Corp. (www.faraday-tech.com)
+ * Based on sa1100_wdt.c by Oleg Drokin <green@crimea.edu>
+ * Based on SoftDog driver by Alan Cox <alan@redhat.com>
+ *
+ * Copyright (C) 2011 Andes Technology Corporation
+ * Macpaul Lin, Andes Technology Corporation <macpaul@andestech.com>
+ *
+ * 27/11/2004 Initial release, Faraday.
+ * 12/01/2011 Port to u-boot, Macpaul Lin.
+ * 22/08/2022 Port to DM
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <wdt.h>
+#include <log.h>
+#include <asm/io.h>
+#include <faraday/ftwdt010_wdt.h>
+
+struct ftwdt010_wdt_priv {
+	struct ftwdt010_wdt __iomem *regs;
+};
+
+/*
+ * Set the watchdog time interval.
+ * Counter is 32 bit.
+ */
+static int ftwdt010_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
+{
+	struct ftwdt010_wdt_priv *priv = dev_get_priv(dev);
+	struct ftwdt010_wdt *wd = priv->regs;
+	unsigned int reg;
+
+	debug("Activating WDT %llu ms\n", timeout_ms);
+
+	/* Check if disabled */
+	if (readl(&wd->wdcr) & ~FTWDT010_WDCR_ENABLE) {
+		printf("sorry, watchdog is disabled\n");
+		return -1;
+	}
+
+	/*
+	 * In a 66MHz system,
+	 * if you set WDLOAD as 0x03EF1480 (66000000)
+	 * the reset timer is 1 second.
+	 */
+	reg = FTWDT010_WDLOAD(timeout_ms * FTWDT010_TIMEOUT_FACTOR);
+
+	writel(reg, &wd->wdload);
+
+	return 0;
+}
+
+static int ftwdt010_wdt_reset(struct udevice *dev)
+{
+	struct ftwdt010_wdt_priv *priv = dev_get_priv(dev);
+	struct ftwdt010_wdt *wd = priv->regs;
+
+	/* clear control register */
+	writel(0, &wd->wdcr);
+
+	/* Write Magic number */
+	writel(FTWDT010_WDRESTART_MAGIC, &wd->wdrestart);
+
+	/* Enable WDT */
+	writel((FTWDT010_WDCR_RST | FTWDT010_WDCR_ENABLE), &wd->wdcr);
+
+	return 0;
+}
+
+static int ftwdt010_wdt_stop(struct udevice *dev)
+{
+	struct ftwdt010_wdt_priv *priv = dev_get_priv(dev);
+	struct ftwdt010_wdt *wd = priv->regs;
+
+	debug("Deactivating WDT..\n");
+
+	/*
+	 * It was defined with CONFIG_WATCHDOG_NOWAYOUT in Linux
+	 *
+	 * Shut off the timer.
+	 * Lock it in if it's a module and we defined ...NOWAYOUT
+	 */
+	writel(0, &wd->wdcr);
+	return 0;
+}
+
+static int ftwdt010_wdt_expire_now(struct udevice *dev, ulong flags)
+{
+	struct ftwdt010_wdt_priv *priv = dev_get_priv(dev);
+	struct ftwdt010_wdt *wd = priv->regs;
+
+	debug("Expiring WDT..\n");
+	writel(FTWDT010_WDLOAD(0), &wd->wdload);
+	return ftwdt010_wdt_reset(dev);
+}
+
+static int ftwdt010_wdt_probe(struct udevice *dev)
+{
+	struct ftwdt010_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 ftwdt010_wdt_ops = {
+	.start = ftwdt010_wdt_start,
+	.reset = ftwdt010_wdt_reset,
+	.stop = ftwdt010_wdt_stop,
+	.expire_now = ftwdt010_wdt_expire_now,
+};
+
+static const struct udevice_id ftwdt010_wdt_ids[] = {
+	{ .compatible = "faraday,ftwdt010" },
+	{}
+};
+
+U_BOOT_DRIVER(ftwdt010_wdt) = {
+	.name = "ftwdt010_wdt",
+	.id = UCLASS_WDT,
+	.of_match = ftwdt010_wdt_ids,
+	.ops = &ftwdt010_wdt_ops,
+	.probe = ftwdt010_wdt_probe,
+	.priv_auto = sizeof(struct ftwdt010_wdt_priv),
+};

include/faraday/ftwdt010_wdt.h

@@ -89,7 +89,4 @@ struct ftwdt010_wdt {
  */
 #define FTWDT010_TIMEOUT_FACTOR		(get_board_sys_clk() / 1000) /* 1 ms */
 
-void ftwdt010_wdt_reset(void);
-void ftwdt010_wdt_disable(void);
-
 #endif /* __FTWDT010_H */