watchdog: Add StarFive Watchdog driver

Add to support StarFive watchdog driver. The driver is imported from
linux kernel's drivers/watchdog/starfive-wdt.c without jh7100 support
because there is no support of jh7100 SoC in u-boot yet.
Howver, this patch has been kept the variant coding style because JH7100
can be added later and have a consistency with the linux driver.

Signed-off-by: Chanho Park <chanho61.park@samsung.com>
Reviewed-by: Leo Yu-Chi Liang <ycliang@andestech.com>

3 files changed, 337 insertions, 0 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 07fc494..5697261 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -344,6 +344,13 @@ config WDT_STM32MP
 	  Enable the STM32 watchdog (IWDG) driver. Enable support to
 	  configure STM32's on-SoC watchdog.
 
+config WDT_STARFIVE
+	bool "StarFive watchdog timer support"
+	depends on WDT
+	imply WATCHDOG
+	help
+	  Enable support for the watchdog timer of StarFive JH7110 SoC.
+
 config WDT_SUNXI
 	bool "Allwinner sunxi watchdog timer support"
 	depends on WDT && ARCH_SUNXI
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index eef786f..5520d3d 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -44,6 +44,7 @@ obj-$(CONFIG_WDT_SBSA) += sbsa_gwdt.o
 obj-$(CONFIG_WDT_K3_RTI) += rti_wdt.o
 obj-$(CONFIG_WDT_SL28CPLD) += sl28cpld-wdt.o
 obj-$(CONFIG_WDT_SP805) += sp805_wdt.o
+obj-$(CONFIG_WDT_STARFIVE) += starfive_wdt.o
 obj-$(CONFIG_WDT_STM32MP) += stm32mp_wdt.o
 obj-$(CONFIG_WDT_SUNXI) += sunxi_wdt.o
 obj-$(CONFIG_WDT_TANGIER) += tangier_wdt.o
diff --git a/drivers/watchdog/starfive_wdt.c b/drivers/watchdog/starfive_wdt.c
new file mode 100644
index 0000000..ee9ec4c
--- /dev/null
+++ b/drivers/watchdog/starfive_wdt.c
@@ -0,0 +1,329 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Starfive Watchdog driver
+ *
+ * Copyright (C) 2022 StarFive Technology Co., Ltd.
+ */
+
+#include <clk.h>
+#include <dm.h>
+#include <reset.h>
+#include <wdt.h>
+#include <linux/iopoll.h>
+
+/* JH7110 Watchdog register define */
+#define STARFIVE_WDT_JH7110_LOAD	0x000
+#define STARFIVE_WDT_JH7110_VALUE	0x004
+#define STARFIVE_WDT_JH7110_CONTROL	0x008	/*
+						 * [0]: reset enable;
+						 * [1]: interrupt enable && watchdog enable
+						 * [31:2]: reserved.
+						 */
+#define STARFIVE_WDT_JH7110_INTCLR	0x00c	/* clear intterupt and reload the counter */
+#define STARFIVE_WDT_JH7110_IMS		0x014
+#define STARFIVE_WDT_JH7110_LOCK	0xc00	/* write 0x1ACCE551 to unlock */
+
+/* WDOGCONTROL */
+#define STARFIVE_WDT_ENABLE			0x1
+#define STARFIVE_WDT_EN_SHIFT			0
+#define STARFIVE_WDT_RESET_EN			0x1
+#define STARFIVE_WDT_JH7110_RST_EN_SHIFT	1
+
+/* WDOGLOCK */
+#define STARFIVE_WDT_JH7110_UNLOCK_KEY		0x1acce551
+
+/* WDOGINTCLR */
+#define STARFIVE_WDT_INTCLR			0x1
+#define STARFIVE_WDT_JH7100_INTCLR_AVA_SHIFT	1	/* Watchdog can clear interrupt when 0 */
+
+#define STARFIVE_WDT_MAXCNT			0xffffffff
+#define STARFIVE_WDT_DEFAULT_TIME		(15)
+#define STARFIVE_WDT_DELAY_US			0
+#define STARFIVE_WDT_TIMEOUT_US			10000
+
+/* module parameter */
+#define STARFIVE_WDT_EARLY_ENA			0
+
+struct starfive_wdt_variant {
+	unsigned int control;		/* Watchdog Control Resgister for reset enable */
+	unsigned int load;		/* Watchdog Load register */
+	unsigned int reload;		/* Watchdog Reload Control register */
+	unsigned int enable;		/* Watchdog Enable Register */
+	unsigned int value;		/* Watchdog Counter Value Register */
+	unsigned int int_clr;		/* Watchdog Interrupt Clear Register */
+	unsigned int unlock;		/* Watchdog Lock Register */
+	unsigned int int_status;	/* Watchdog Interrupt Status Register */
+
+	u32 unlock_key;
+	char enrst_shift;
+	char en_shift;
+	bool intclr_check;		/*  whether need to check it before clearing interrupt */
+	char intclr_ava_shift;
+	bool double_timeout;		/* The watchdog need twice timeout to reboot */
+};
+
+struct starfive_wdt_priv {
+	void __iomem *base;
+	struct clk *core_clk;
+	struct clk *apb_clk;
+	struct reset_ctl_bulk *rst;
+	const struct starfive_wdt_variant *variant;
+	unsigned long freq;
+	u32 count;			/* count of timeout */
+	u32 reload;			/* restore the count */
+};
+
+/* Register layout and configuration for the JH7110 */
+static const struct starfive_wdt_variant starfive_wdt_jh7110_variant = {
+	.control = STARFIVE_WDT_JH7110_CONTROL,
+	.load = STARFIVE_WDT_JH7110_LOAD,
+	.enable = STARFIVE_WDT_JH7110_CONTROL,
+	.value = STARFIVE_WDT_JH7110_VALUE,
+	.int_clr = STARFIVE_WDT_JH7110_INTCLR,
+	.unlock = STARFIVE_WDT_JH7110_LOCK,
+	.unlock_key = STARFIVE_WDT_JH7110_UNLOCK_KEY,
+	.int_status = STARFIVE_WDT_JH7110_IMS,
+	.enrst_shift = STARFIVE_WDT_JH7110_RST_EN_SHIFT,
+	.en_shift = STARFIVE_WDT_EN_SHIFT,
+	.intclr_check = false,
+	.double_timeout = true,
+};
+
+static int starfive_wdt_enable_clock(struct starfive_wdt_priv *wdt)
+{
+	int ret;
+
+	ret = clk_enable(wdt->apb_clk);
+	if (ret)
+		return ret;
+
+	ret = clk_enable(wdt->core_clk);
+	if (ret) {
+		clk_disable(wdt->apb_clk);
+		return ret;
+	}
+
+	return 0;
+}
+
+static void starfive_wdt_disable_clock(struct starfive_wdt_priv *wdt)
+{
+	clk_disable(wdt->core_clk);
+	clk_disable(wdt->apb_clk);
+}
+
+/* Write unlock-key to unlock. Write other value to lock. */
+static void starfive_wdt_unlock(struct starfive_wdt_priv *wdt)
+{
+	writel(wdt->variant->unlock_key, wdt->base + wdt->variant->unlock);
+}
+
+static void starfive_wdt_lock(struct starfive_wdt_priv *wdt)
+{
+	writel(~wdt->variant->unlock_key, wdt->base + wdt->variant->unlock);
+}
+
+/* enable watchdog interrupt to reset/reboot */
+static void starfive_wdt_enable_reset(struct starfive_wdt_priv *wdt)
+{
+	u32 val;
+
+	val = readl(wdt->base + wdt->variant->control);
+	val |= STARFIVE_WDT_RESET_EN << wdt->variant->enrst_shift;
+	writel(val, wdt->base + wdt->variant->control);
+}
+
+/* waiting interrupt can be free to clear */
+static int starfive_wdt_wait_int_free(struct starfive_wdt_priv *wdt)
+{
+	u32 value;
+
+	return readl_poll_timeout(wdt->base + wdt->variant->int_clr, value,
+				  !(value & BIT(wdt->variant->intclr_ava_shift)),
+				  STARFIVE_WDT_TIMEOUT_US);
+}
+
+/* clear interrupt signal before initialization or reload */
+static int starfive_wdt_int_clr(struct starfive_wdt_priv *wdt)
+{
+	int ret;
+
+	if (wdt->variant->intclr_check) {
+		ret = starfive_wdt_wait_int_free(wdt);
+		if (ret)
+			return ret;
+	}
+	writel(STARFIVE_WDT_INTCLR, wdt->base + wdt->variant->int_clr);
+
+	return 0;
+}
+
+static inline void starfive_wdt_set_count(struct starfive_wdt_priv *wdt,
+					  u32 val)
+{
+	writel(val, wdt->base + wdt->variant->load);
+}
+
+/* enable watchdog */
+static inline void starfive_wdt_enable(struct starfive_wdt_priv *wdt)
+{
+	u32 val;
+
+	val = readl(wdt->base + wdt->variant->enable);
+	val |= STARFIVE_WDT_ENABLE << wdt->variant->en_shift;
+	writel(val, wdt->base + wdt->variant->enable);
+}
+
+/* disable watchdog */
+static inline void starfive_wdt_disable(struct starfive_wdt_priv *wdt)
+{
+	u32 val;
+
+	val = readl(wdt->base + wdt->variant->enable);
+	val &= ~(STARFIVE_WDT_ENABLE << wdt->variant->en_shift);
+	writel(val, wdt->base + wdt->variant->enable);
+}
+
+static inline void starfive_wdt_set_reload_count(struct starfive_wdt_priv *wdt,
+						 u32 count)
+{
+	starfive_wdt_set_count(wdt, count);
+
+	/* 7100 need set any value to reload register and could reload value to counter */
+	if (wdt->variant->reload)
+		writel(0x1, wdt->base + wdt->variant->reload);
+}
+
+static int starfive_wdt_start(struct udevice *dev, u64 timeout_ms, ulong flags)
+{
+	int ret;
+	struct starfive_wdt_priv *wdt = dev_get_priv(dev);
+
+	starfive_wdt_unlock(wdt);
+	/* disable watchdog, to be safe */
+	starfive_wdt_disable(wdt);
+
+	starfive_wdt_enable_reset(wdt);
+	ret = starfive_wdt_int_clr(wdt);
+	if (ret)
+		goto exit;
+
+	wdt->count = (timeout_ms / 1000) * wdt->freq;
+	if (wdt->variant->double_timeout)
+		wdt->count /= 2;
+
+	starfive_wdt_set_count(wdt, wdt->count);
+	starfive_wdt_enable(wdt);
+
+exit:
+	starfive_wdt_lock(wdt);
+	return ret;
+}
+
+static int starfive_wdt_stop(struct udevice *dev)
+{
+	struct starfive_wdt_priv *wdt = dev_get_priv(dev);
+
+	starfive_wdt_unlock(wdt);
+	starfive_wdt_disable(wdt);
+	starfive_wdt_lock(wdt);
+
+	return 0;
+}
+
+static int starfive_wdt_reset(struct udevice *dev)
+{
+	int ret;
+	struct starfive_wdt_priv *wdt = dev_get_priv(dev);
+
+	starfive_wdt_unlock(wdt);
+	ret = starfive_wdt_int_clr(wdt);
+	if (ret)
+		goto exit;
+
+	starfive_wdt_set_reload_count(wdt, wdt->count);
+
+exit:
+	starfive_wdt_lock(wdt);
+
+	return ret;
+}
+
+static const struct wdt_ops starfive_wdt_ops = {
+	.start = starfive_wdt_start,
+	.stop = starfive_wdt_stop,
+	.reset = starfive_wdt_reset,
+};
+
+static int starfive_wdt_probe(struct udevice *dev)
+{
+	struct starfive_wdt_priv *wdt = dev_get_priv(dev);
+	int ret;
+
+	ret = starfive_wdt_enable_clock(wdt);
+	if (ret)
+		return ret;
+
+	ret = reset_deassert_bulk(wdt->rst);
+	if (ret)
+		goto err_reset;
+
+	wdt->variant = (const struct starfive_wdt_variant *)dev_get_driver_data(dev);
+
+	wdt->freq = clk_get_rate(wdt->core_clk);
+	if (!wdt->freq) {
+		ret = -EINVAL;
+		goto err_get_freq;
+	}
+
+	return 0;
+
+err_get_freq:
+	reset_assert_bulk(wdt->rst);
+err_reset:
+	starfive_wdt_disable_clock(wdt);
+
+	return ret;
+}
+
+static int starfive_wdt_of_to_plat(struct udevice *dev)
+{
+	struct starfive_wdt_priv *wdt = dev_get_priv(dev);
+
+	wdt->base = (void *)dev_read_addr(dev);
+	if (!wdt->base)
+		return -ENODEV;
+
+	wdt->apb_clk = devm_clk_get(dev, "apb");
+	if (IS_ERR(wdt->apb_clk))
+		return -ENODEV;
+
+	wdt->core_clk = devm_clk_get(dev, "core");
+	if (IS_ERR(wdt->core_clk))
+		return -ENODEV;
+
+	wdt->rst = devm_reset_bulk_get(dev);
+	if (IS_ERR(wdt->rst))
+		return -ENODEV;
+
+	return 0;
+}
+
+static const struct udevice_id starfive_wdt_ids[] = {
+	{
+		.compatible = "starfive,jh7110-wdt",
+		.data = (ulong)&starfive_wdt_jh7110_variant
+	}, {
+		/* sentinel */
+	}
+};
+
+U_BOOT_DRIVER(starfive_wdt) = {
+	.name = "starfive_wdt",
+	.id = UCLASS_WDT,
+	.of_match = starfive_wdt_ids,
+	.priv_auto = sizeof(struct starfive_wdt_priv),
+	.probe = starfive_wdt_probe,
+	.of_to_plat = starfive_wdt_of_to_plat,
+	.ops = &starfive_wdt_ops,
+};