[2/3] watchdog: xilinx_wwdt: Add Versal Window watchdog mode

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 355100dad60a..2ed17f278783 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -307,6 +307,22 @@  config XILINX_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called of_xilinx_wdt.
 
+config XILINX_WINDOW_WATCHDOG
+	tristate "Xilinx Window Watchdog timer"
+	depends on HAS_IOMEM
+	select WATCHDOG_CORE
+	help
+	  Window Watchdog driver for the versal_wwdt ip core.
+	  Window watchdog timer(WWDT) contains closed(first) and
+	  open(second) window with 32 bit width. WWDT will generate
+	  an interrupt after the first window timeout and reset
+	  signal after the second window timeout. Timeout and
+	  Pre-timeout configuration, Stop and Refresh trigger
+	  only in open window.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called xilinx_wwdt.
+
 config ZIIRAVE_WATCHDOG
 	tristate "Zodiac RAVE Watchdog Timer"
 	depends on I2C
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index a7eade8b4d45..97d10c3d39c7 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -148,6 +148,7 @@  obj-$(CONFIG_M54xx_WATCHDOG) += m54xx_wdt.o
 
 # MicroBlaze Architecture
 obj-$(CONFIG_XILINX_WATCHDOG) += of_xilinx_wdt.o
+obj-$(CONFIG_XILINX_WINDOW_WATCHDOG) += xilinx_wwdt.o
 
 # MIPS Architecture
 obj-$(CONFIG_ATH79_WDT) += ath79_wdt.o
diff --git a/drivers/watchdog/xilinx_wwdt.c b/drivers/watchdog/xilinx_wwdt.c
new file mode 100644
index 000000000000..8fa2cb2225e8
--- /dev/null
+++ b/drivers/watchdog/xilinx_wwdt.c
@@ -0,0 +1,382 @@ 
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Window Watchdog Device Driver for Xilinx Versal WWDT
+ *
+ * (C) Copyright 2021 Xilinx, Inc.
+ */
+
+#include <linux/clk.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/ioport.h>
+#include <linux/of_device.h>
+#include <linux/of_address.h>
+#include <linux/module.h>
+#include <linux/watchdog.h>
+
+#define XWWDT_DEFAULT_TIMEOUT	40
+#define XWWDT_MIN_TIMEOUT	1
+#define XWWDT_MAX_TIMEOUT	42
+
+/* Register offsets for the WWdt device */
+#define XWWDT_MWR_OFFSET	0x00
+#define XWWDT_ESR_OFFSET	0x04
+#define XWWDT_FCR_OFFSET	0x08
+#define XWWDT_FWR_OFFSET	0x0c
+#define XWWDT_SWR_OFFSET	0x10
+
+/* Master Write Control Register Masks */
+#define XWWDT_MWR_MASK		BIT(0)
+
+/* Enable and Status Register Masks */
+#define XWWDT_ESR_WINT_MASK	BIT(16)
+#define XWWDT_ESR_WSW_MASK	BIT(8)
+#define XWWDT_ESR_WEN_MASK	BIT(0)
+
+/* Function control Register Masks */
+#define XWWDT_SBC_MASK		0xFF00
+#define XWWDT_SBC_SHIFT		16
+#define XWWDT_BSS_MASK		0xC0
+
+static int wwdt_timeout;
+
+module_param(wwdt_timeout, int, 0644);
+MODULE_PARM_DESC(wwdt_timeout,
+		 "Watchdog time in seconds. (default="
+		 __MODULE_STRING(XWWDT_DEFAULT_TIMEOUT) ")");
+
+struct xwwdt_device {
+	void __iomem *base;
+	spinlock_t spinlock; /* spinlock for register handling */
+	struct watchdog_device xilinx_wwdt_wdd;
+	struct clk *clk;
+	int irq;
+};
+
+static int is_wwdt_in_closed_window(struct watchdog_device *wdd)
+{
+	u32 control_status_reg;
+	struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
+
+	spin_lock(&xdev->spinlock);
+	control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
+	spin_unlock(&xdev->spinlock);
+	if (control_status_reg & XWWDT_ESR_WEN_MASK)
+		if (!(control_status_reg & XWWDT_ESR_WSW_MASK))
+			return 0;
+
+	return 1;
+}
+
+static int xilinx_wwdt_start(struct watchdog_device *wdd)
+{
+	struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
+	struct watchdog_device *xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
+	u64 time_out, pre_timeout, count;
+	u32 control_status_reg, fcr;
+	int ret;
+
+	count = clk_get_rate(xdev->clk);
+	if (!count)
+		return -EINVAL;
+
+	/* Calculate timeout count */
+	pre_timeout = count * wdd->pretimeout;
+	time_out = count * wdd->timeout;
+	if (!watchdog_active(xilinx_wwdt_wdd)) {
+		ret  = clk_enable(xdev->clk);
+		if (ret) {
+			dev_err(wdd->parent, "Failed to enable clock\n");
+			return ret;
+		}
+	}
+
+	spin_lock(&xdev->spinlock);
+	iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
+	iowrite32(~(u32)XWWDT_ESR_WEN_MASK,
+		  xdev->base + XWWDT_ESR_OFFSET);
+
+	if (pre_timeout) {
+		iowrite32((u32)(time_out - pre_timeout),
+			  xdev->base + XWWDT_FWR_OFFSET);
+		iowrite32((u32)pre_timeout, xdev->base + XWWDT_SWR_OFFSET);
+		fcr = ioread32(xdev->base + XWWDT_SWR_OFFSET);
+		fcr = (fcr >> XWWDT_SBC_SHIFT) & XWWDT_SBC_MASK;
+		fcr = fcr | XWWDT_BSS_MASK;
+		iowrite32(fcr, xdev->base + XWWDT_FCR_OFFSET);
+	} else {
+		iowrite32((u32)pre_timeout,
+			  xdev->base + XWWDT_FWR_OFFSET);
+		iowrite32((u32)time_out, xdev->base + XWWDT_SWR_OFFSET);
+		iowrite32(0x0, xdev->base + XWWDT_FCR_OFFSET);
+	}
+
+	/* Enable the window watchdog timer */
+	control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
+	control_status_reg |= XWWDT_ESR_WEN_MASK;
+	iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
+
+	spin_unlock(&xdev->spinlock);
+
+	dev_dbg(xilinx_wwdt_wdd->parent, "Watchdog Started!\n");
+
+	return 0;
+}
+
+static int xilinx_wwdt_stop(struct watchdog_device *wdd)
+{
+	struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
+	struct watchdog_device *xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
+
+	if (!is_wwdt_in_closed_window(wdd)) {
+		dev_warn(xilinx_wwdt_wdd->parent, "timer in closed window");
+		return -EINVAL;
+	}
+
+	spin_lock(&xdev->spinlock);
+
+	iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
+	/* Disable the Window watchdog timer */
+	iowrite32(~(u32)XWWDT_ESR_WEN_MASK,
+		  xdev->base + XWWDT_ESR_OFFSET);
+
+	spin_unlock(&xdev->spinlock);
+
+	if (watchdog_active(xilinx_wwdt_wdd))
+		clk_disable(xdev->clk);
+
+	dev_dbg(xilinx_wwdt_wdd->parent, "Watchdog Stopped!\n");
+
+	return 0;
+}
+
+static int xilinx_wwdt_keepalive(struct watchdog_device *wdd)
+{
+	u32 control_status_reg;
+	struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
+
+	/* Refresh in open window is ignored */
+	if (!is_wwdt_in_closed_window(wdd))
+		return 0;
+
+	spin_lock(&xdev->spinlock);
+
+	iowrite32(XWWDT_MWR_MASK, xdev->base + XWWDT_MWR_OFFSET);
+	control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
+	control_status_reg |= XWWDT_ESR_WINT_MASK;
+	control_status_reg &= ~XWWDT_ESR_WSW_MASK;
+	iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
+	control_status_reg = ioread32(xdev->base + XWWDT_ESR_OFFSET);
+	control_status_reg |= XWWDT_ESR_WSW_MASK;
+	iowrite32(control_status_reg, xdev->base + XWWDT_ESR_OFFSET);
+
+	spin_unlock(&xdev->spinlock);
+
+	return 0;
+}
+
+static int xilinx_wwdt_set_timeout(struct watchdog_device *wdd,
+				   unsigned int new_time)
+{
+	u32 ret = 0;
+	struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
+	struct watchdog_device *xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
+
+	if (!is_wwdt_in_closed_window(wdd)) {
+		dev_warn(xilinx_wwdt_wdd->parent, "timer in closed window");
+		return -EINVAL;
+	}
+
+	if (new_time < XWWDT_MIN_TIMEOUT ||
+	    new_time > XWWDT_MAX_TIMEOUT) {
+		dev_warn(xilinx_wwdt_wdd->parent,
+			 "timeout value must be %d<=x<=%d, using %d\n",
+			 XWWDT_MIN_TIMEOUT,
+			 XWWDT_MAX_TIMEOUT, new_time);
+		return -EINVAL;
+	}
+
+	wdd->timeout = new_time;
+	wdd->pretimeout = 0;
+
+	if (watchdog_active(xilinx_wwdt_wdd)) {
+		ret = xilinx_wwdt_start(wdd);
+		if (ret)
+			dev_dbg(xilinx_wwdt_wdd->parent, "timer start failed");
+	}
+
+	return ret;
+}
+
+static int xilinx_wwdt_set_pretimeout(struct watchdog_device *wdd,
+				      u32 new_pretimeout)
+{
+	u32 ret = 0;
+	struct xwwdt_device *xdev = watchdog_get_drvdata(wdd);
+	struct watchdog_device *xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
+
+	if (!is_wwdt_in_closed_window(wdd)) {
+		dev_warn(xilinx_wwdt_wdd->parent, "timer in closed window");
+		return -EINVAL;
+	}
+
+	if (new_pretimeout < wdd->min_timeout ||
+	    new_pretimeout >= wdd->timeout)
+		return -EINVAL;
+
+	wdd->pretimeout = new_pretimeout;
+
+	if (watchdog_active(xilinx_wwdt_wdd)) {
+		ret = xilinx_wwdt_start(wdd);
+		if (ret)
+			dev_dbg(xilinx_wwdt_wdd->parent, "timer start failed");
+	}
+
+	return ret;
+}
+
+static void xwwdt_clk_disable_unprepare(void *data)
+{
+	clk_disable_unprepare(data);
+}
+
+static irqreturn_t xilinx_wwdt_isr(int irq, void *wdog_arg)
+{
+	struct xwwdt_device *xdev = wdog_arg;
+
+	watchdog_notify_pretimeout(&xdev->xilinx_wwdt_wdd);
+
+	return IRQ_HANDLED;
+}
+
+static const struct watchdog_info xilinx_wwdt_ident = {
+	.options = WDIOF_MAGICCLOSE |
+		   WDIOF_KEEPALIVEPING |
+		   WDIOF_SETTIMEOUT,
+	.firmware_version = 1,
+	.identity = "xlnx_window watchdog",
+};
+
+static const struct watchdog_info xilinx_wwdt_pretimeout_ident = {
+	.options = WDIOF_MAGICCLOSE |
+		   WDIOF_KEEPALIVEPING |
+		   WDIOF_PRETIMEOUT |
+		   WDIOF_SETTIMEOUT,
+	.firmware_version = 1,
+	.identity = "xlnx_window watchdog",
+};
+
+static const struct watchdog_ops xilinx_wwdt_ops = {
+	.owner = THIS_MODULE,
+	.start = xilinx_wwdt_start,
+	.stop = xilinx_wwdt_stop,
+	.ping = xilinx_wwdt_keepalive,
+	.set_timeout = xilinx_wwdt_set_timeout,
+	.set_pretimeout = xilinx_wwdt_set_pretimeout,
+};
+
+static int xwwdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *xilinx_wwdt_wdd;
+	struct xwwdt_device *xdev;
+	u32 pre_timeout = 0;
+	int ret;
+
+	xdev = devm_kzalloc(dev, sizeof(*xdev), GFP_KERNEL);
+	if (!xdev)
+		return -ENOMEM;
+
+	xilinx_wwdt_wdd = &xdev->xilinx_wwdt_wdd;
+	xilinx_wwdt_wdd->info = &xilinx_wwdt_ident;
+	xilinx_wwdt_wdd->ops = &xilinx_wwdt_ops;
+	xilinx_wwdt_wdd->parent = dev;
+
+	xdev->base = devm_platform_ioremap_resource(pdev, 0);
+	if (IS_ERR(xdev->base))
+		return PTR_ERR(xdev->base);
+
+	ret = of_property_read_u32(dev->of_node, "pretimeout-sec",
+				   &pre_timeout);
+	if (ret)
+		dev_dbg(dev,
+			"Parameter \"pretimeout-sec\" not found\n");
+
+	xdev->clk = devm_clk_get(dev, NULL);
+	if (IS_ERR(xdev->clk))
+		return PTR_ERR(xdev->clk);
+
+	ret = clk_get_rate(xdev->clk);
+	if (!ret)
+		return -EINVAL;
+
+	ret = clk_prepare_enable(xdev->clk);
+	if (ret) {
+		dev_err(dev, "unable to enable clock\n");
+		return ret;
+	}
+	ret = devm_add_action_or_reset(dev, xwwdt_clk_disable_unprepare,
+				       xdev->clk);
+	if (ret)
+		goto err_clk_disable;
+
+	xilinx_wwdt_wdd->pretimeout = pre_timeout;
+	xilinx_wwdt_wdd->timeout = XWWDT_DEFAULT_TIMEOUT;
+	xilinx_wwdt_wdd->min_timeout = XWWDT_MIN_TIMEOUT;
+	xilinx_wwdt_wdd->max_timeout = XWWDT_MAX_TIMEOUT;
+
+	xdev->irq = platform_get_irq_byname(pdev, "wdt");
+	if (xdev->irq < 0) {
+		ret = xdev->irq;
+		goto err_clk_disable;
+	}
+
+	if (!devm_request_irq(dev, xdev->irq, xilinx_wwdt_isr,
+			      0, dev_name(dev), xdev)) {
+		xilinx_wwdt_wdd->info = &xilinx_wwdt_pretimeout_ident;
+	}
+
+	ret = watchdog_init_timeout(xilinx_wwdt_wdd,
+				    wwdt_timeout, &pdev->dev);
+	if (ret)
+		dev_info(&pdev->dev, "Configured default timeout value\n");
+
+	spin_lock_init(&xdev->spinlock);
+	watchdog_set_drvdata(xilinx_wwdt_wdd, xdev);
+
+	ret = devm_watchdog_register_device(dev, xilinx_wwdt_wdd);
+	if (ret)
+		goto err_clk_disable;
+
+	clk_disable_unprepare(xdev->clk);
+
+	dev_info(dev, "Xilinx Window Watchdog Timer with timeout %ds\n",
+		 xilinx_wwdt_wdd->timeout);
+
+	return 0;
+
+err_clk_disable:
+	clk_disable_unprepare(xdev->clk);
+	return ret;
+}
+
+/* Mat for of_platform binding */
+static const struct of_device_id xwwdt_of_match[] = {
+	{ .compatible = "xlnx,versal-wwdt-1.0", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, xwwdt_of_match);
+
+static struct platform_driver xwwdt_driver = {
+	.probe = xwwdt_probe,
+	.driver = {
+		.name = "Xilinx Window Watchdog",
+		.of_match_table = xwwdt_of_match,
+	},
+};
+
+module_platform_driver(xwwdt_driver);
+
+MODULE_AUTHOR("Neeli Srinivas <sneeli@xilinx.com>");
+MODULE_DESCRIPTION("Xilinx Window Watchdog driver");
+MODULE_LICENSE("GPL");