Date:   Tue, 12 Sep 2017 19:40:09 +0800
From:   Eric Long <eric.long@...eadtrum.com>
To:     Wim Van Sebroeck <wim@...ana.be>, Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>
CC:     <baolin.wang@...aro.org>, Guenter Roeck <linux@...ck-us.net>,
        <linux-watchdog@...r.kernel.org>, <devicetree@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>, <eric.long@...eadtrum.com>
Subject: [PATCH v2 2/2] watchdog: Add Spreadtrum watchdog driver

This patch adds the watchdog driver for Spreadtrum SC9860 platform.

Signed-off-by: Eric Long <eric.long@...eadtrum.com>
---
Changes since v1:
 - Use pretimeout instead of own implementation.
 - Fix timeout loop when loading timeout values.
 - use the infrastructure to read and set "timeout-sec" property.
 - Add conditions when start or stop watchdog.
 - Change the position of enabling watchdog.
 - Other optimization.
---
 drivers/watchdog/Kconfig    |   8 +
 drivers/watchdog/Makefile   |   1 +
 drivers/watchdog/sprd_wdt.c | 384 ++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 393 insertions(+)
 create mode 100644 drivers/watchdog/sprd_wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index c722cbf..ea07718 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -787,6 +787,14 @@ config UNIPHIER_WATCHDOG
 	  To compile this driver as a module, choose M here: the
 	  module will be called uniphier_wdt.
 
+config SPRD_WATCHDOG
+	tristate "Spreadtrum watchdog support"
+	depends on ARCH_SPRD
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include support watchdog timer embedded
+	  into the Spreadtrum system.
+
 # AVR32 Architecture
 
 config AT32AP700X_WDT
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 56adf9f..187cca2 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -87,6 +87,7 @@ obj-$(CONFIG_ASPEED_WATCHDOG) += aspeed_wdt.o
 obj-$(CONFIG_ZX2967_WATCHDOG) += zx2967_wdt.o
 obj-$(CONFIG_STM32_WATCHDOG) += stm32_iwdg.o
 obj-$(CONFIG_UNIPHIER_WATCHDOG) += uniphier_wdt.o
+obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o
 
 # AVR32 Architecture
 obj-$(CONFIG_AT32AP700X_WDT) += at32ap700x_wdt.o
diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
new file mode 100644
index 0000000..dedbca6fd
--- /dev/null
+++ b/drivers/watchdog/sprd_wdt.c
@@ -0,0 +1,384 @@
+/*
+ * Spreadtrum watchdog driver
+ * Copyright (C) 2017 Spreadtrum - http://www.spreadtrum.com
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+
+#define WDT_LOAD_LOW		0x0
+#define WDT_LOAD_HIGH		0x4
+#define WDT_CTRL		0x8
+#define WDT_INT_CLR		0xc
+#define WDT_INT_RAW		0x10
+#define WDT_INT_MSK		0x14
+#define WDT_CNT_LOW		0x18
+#define WDT_CNT_HIGH		0x1c
+#define WDT_LOCK		0x20
+#define WDT_IRQ_LOAD_LOW	0x2c
+#define WDT_IRQ_LOAD_HIGH	0x30
+
+/* WDT_CTRL */
+#define WDT_INT_EN_BIT		BIT(0)
+#define WDT_CNT_EN_BIT		BIT(1)
+#define WDT_NEW_VER_EN		BIT(2)
+#define WDT_RST_EN_BIT		BIT(3)
+
+/* WDT_INT_CLR */
+#define WDT_INT_CLEAR_BIT	BIT(0)
+#define WDT_RST_CLEAR_BIT	BIT(3)
+
+/* WDT_INT_RAW */
+#define WDT_INT_RAW_BIT		BIT(0)
+#define WDT_RST_RAW_BIT		BIT(3)
+#define WDT_LD_BUSY_BIT		BIT(4)
+
+#define WDT_CLK			32768
+#define WDT_UNLOCK_KEY		0xe551
+#define WDT_DEFAULT_PRETMROUT	3
+
+#define WDT_CNT_VALUE_SIZE	16
+#define WDT_CNT_VALUE_MASK	GENMASK(15, 0)
+#define WDT_LOAD_TIMEOUT_NUM	10000
+
+struct sprd_wdt {
+	void __iomem *base;
+	struct watchdog_device wdd;
+	struct clk *enable;
+	struct clk *rtc_enable;
+	unsigned int irq;
+};
+
+static inline struct sprd_wdt *to_sprd_wdt(struct watchdog_device *wdd)
+{
+	return container_of(wdd, struct sprd_wdt, wdd);
+}
+
+static inline void sprd_wdt_lock(void __iomem *addr)
+{
+	writel_relaxed(0x0, addr + WDT_LOCK);
+}
+
+static inline void sprd_wdt_unlock(void __iomem *addr)
+{
+	writel_relaxed(WDT_UNLOCK_KEY, addr + WDT_LOCK);
+}
+
+static inline bool sprd_wdt_is_running(struct sprd_wdt *wdt)
+{
+	u32 val;
+
+	val = readl_relaxed(wdt->base + WDT_CTRL);
+	return val & WDT_NEW_VER_EN;
+}
+
+static irqreturn_t sprd_wdt_isr(int irq, void *dev_id)
+{
+	struct sprd_wdt *wdt = (struct sprd_wdt *)dev_id;
+
+	sprd_wdt_unlock(wdt->base);
+	writel_relaxed(WDT_INT_CLEAR_BIT, wdt->base + WDT_INT_CLR);
+	sprd_wdt_lock(wdt->base);
+	watchdog_notify_pretimeout(&wdt->wdd);
+	return IRQ_HANDLED;
+}
+
+static u32 sprd_wdt_get_cnt_value(struct sprd_wdt *wdt)
+{
+	u32 val;
+
+	val = readl_relaxed(wdt->base + WDT_CNT_HIGH) << WDT_CNT_VALUE_SIZE;
+	val |= readl_relaxed(wdt->base + WDT_CNT_LOW) & WDT_CNT_VALUE_MASK;
+
+	return val;
+}
+
+static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
+			       u32 pretimeout)
+{
+	u32 val, cnt = 0;
+
+	if (timeout < pretimeout)
+		return -EINVAL;
+
+	if (!pretimeout)
+		pretimeout = WDT_DEFAULT_PRETMROUT;
+
+	sprd_wdt_unlock(wdt->base);
+	writel_relaxed(((timeout * WDT_CLK) >> WDT_CNT_VALUE_SIZE) &
+		       WDT_CNT_VALUE_MASK, wdt->base + WDT_LOAD_HIGH);
+	writel_relaxed(((timeout * WDT_CLK) & WDT_CNT_VALUE_MASK),
+		       wdt->base + WDT_LOAD_LOW);
+	writel_relaxed(((pretimeout * WDT_CLK) >> WDT_CNT_VALUE_SIZE) &
+			WDT_CNT_VALUE_MASK, wdt->base + WDT_IRQ_LOAD_HIGH);
+	writel_relaxed((pretimeout * WDT_CLK) & WDT_CNT_VALUE_MASK,
+		       wdt->base + WDT_IRQ_LOAD_LOW);
+	sprd_wdt_lock(wdt->base);
+
+	/*
+	 * Waiting the load value operation done,
+	 * it needs two or three RTC clock cycles.
+	 */
+	do {
+		val = readl_relaxed(wdt->base + WDT_INT_RAW);
+		if (!(val & WDT_LD_BUSY_BIT))
+			break;
+
+		cpu_relax();
+	} while (cnt++ < WDT_LOAD_TIMEOUT_NUM);
+
+	if (cnt >= WDT_LOAD_TIMEOUT_NUM)
+		return -EBUSY;
+	return 0;
+}
+
+static void sprd_wdt_enable(struct sprd_wdt *wdt)
+{
+	u32 val;
+
+	clk_prepare_enable(wdt->enable);
+	clk_prepare_enable(wdt->rtc_enable);
+
+	sprd_wdt_unlock(wdt->base);
+	val = readl_relaxed(wdt->base + WDT_CTRL);
+	val |= WDT_NEW_VER_EN;
+	writel_relaxed(val, wdt->base + WDT_CTRL);
+	sprd_wdt_lock(wdt->base);
+	set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
+}
+
+static void sprd_wdt_disable(struct sprd_wdt *wdt)
+{
+	sprd_wdt_unlock(wdt->base);
+	writel_relaxed(0x0, wdt->base + WDT_CTRL);
+	sprd_wdt_lock(wdt->base);
+
+	clk_disable(wdt->enable);
+	clk_disable(wdt->rtc_enable);
+}
+
+static int sprd_wdt_start(struct watchdog_device *wdd)
+{
+	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
+	u32 val;
+	int ret;
+
+	ret = sprd_wdt_load_value(wdt, wdd->timeout, wdd->pretimeout);
+	if (ret)
+		return ret;
+
+	sprd_wdt_unlock(wdt->base);
+	val = readl_relaxed(wdt->base + WDT_CTRL);
+	val |= WDT_CNT_EN_BIT | WDT_INT_EN_BIT | WDT_RST_EN_BIT;
+	writel_relaxed(val, wdt->base + WDT_CTRL);
+	sprd_wdt_lock(wdt->base);
+	set_bit(WDOG_HW_RUNNING, &wdd->status);
+
+	return 0;
+}
+
+static int sprd_wdt_stop(struct watchdog_device *wdd)
+{
+	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
+	u32 val;
+
+	sprd_wdt_unlock(wdt->base);
+	val = readl_relaxed(wdt->base + WDT_CTRL);
+	val &= ~(WDT_CNT_EN_BIT | WDT_RST_EN_BIT | WDT_INT_EN_BIT);
+	writel_relaxed(val, wdt->base + WDT_CTRL);
+	sprd_wdt_lock(wdt->base);
+	return 0;
+}
+
+static int sprd_wdt_set_timeout(struct watchdog_device *wdd,
+				u32 timeout)
+{
+	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
+
+	wdd->timeout = timeout;
+
+	return sprd_wdt_load_value(wdt, timeout, wdd->pretimeout);
+}
+
+static int sprd_wdt_set_pretimeout(struct watchdog_device *wdd,
+				   u32 new_pretimeout)
+{
+	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
+
+	wdd->pretimeout = new_pretimeout;
+
+	return sprd_wdt_load_value(wdt, wdd->timeout, new_pretimeout);
+}
+
+static u32 sprd_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct sprd_wdt *wdt = to_sprd_wdt(wdd);
+	u32 val;
+
+	val = sprd_wdt_get_cnt_value(wdt);
+	val = val / WDT_CLK;
+
+	return val;
+}
+
+static const struct watchdog_ops sprd_wdt_ops = {
+	.owner = THIS_MODULE,
+	.start = sprd_wdt_start,
+	.stop = sprd_wdt_stop,
+	.set_timeout = sprd_wdt_set_timeout,
+	.set_pretimeout = sprd_wdt_set_pretimeout,
+	.get_timeleft = sprd_wdt_get_timeleft,
+};
+
+static const struct watchdog_info sprd_wdt_info = {
+	.options = WDIOF_SETTIMEOUT |
+		   WDIOF_PRETIMEOUT |
+		   WDIOF_MAGICCLOSE |
+		   WDIOF_KEEPALIVEPING,
+	.identity = "Spreadtrum Watchdog Timer",
+};
+
+static int sprd_wdt_probe(struct platform_device *pdev)
+{
+	struct resource *wdt_res;
+	struct sprd_wdt *wdt;
+	int ret;
+
+	wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	wdt_res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!wdt_res) {
+		dev_err(&pdev->dev, "failed to memory resource\n");
+		return -ENOMEM;
+	}
+
+	wdt->base = devm_ioremap_nocache(&pdev->dev, wdt_res->start,
+					 resource_size(wdt_res));
+	if (!wdt->base)
+		return -ENOMEM;
+
+	wdt->enable = devm_clk_get(&pdev->dev, "enable");
+	if (IS_ERR(wdt->enable)) {
+		dev_err(&pdev->dev, "can't get the enable clock\n");
+		return PTR_ERR(wdt->enable);
+	}
+
+	wdt->rtc_enable = devm_clk_get(&pdev->dev, "rtc_enable");
+	if (IS_ERR(wdt->rtc_enable)) {
+		dev_err(&pdev->dev, "can't get the rtc enable clock\n");
+		return PTR_ERR(wdt->rtc_enable);
+	}
+
+	wdt->irq = platform_get_irq(pdev, 0);
+	if (wdt->irq < 0) {
+		dev_err(&pdev->dev, "failed to get IRQ resource\n");
+		return wdt->irq;
+	}
+
+	ret = devm_request_irq(&pdev->dev, wdt->irq, sprd_wdt_isr,
+			       IRQF_NO_SUSPEND, "sprd-wdt", (void *)wdt);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register irq\n");
+		return ret;
+	}
+
+	wdt->wdd.info = &sprd_wdt_info;
+	wdt->wdd.ops = &sprd_wdt_ops;
+	wdt->wdd.parent = &pdev->dev;
+
+	sprd_wdt_enable(wdt);
+
+	watchdog_init_timeout(&wdt->wdd, 0, &pdev->dev);
+
+	ret = watchdog_register_device(&wdt->wdd);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to register watchdog\n");
+		return ret;
+	}
+	platform_set_drvdata(pdev, wdt);
+
+	return 0;
+}
+
+static int sprd_wdt_remove(struct platform_device *pdev)
+{
+	struct sprd_wdt *wdt = platform_get_drvdata(pdev);
+
+	if (sprd_wdt_is_running(wdt)) {
+		sprd_wdt_stop(&wdt->wdd);
+		sprd_wdt_disable(wdt);
+	}
+	watchdog_unregister_device(&wdt->wdd);
+
+	return 0;
+}
+
+static int __maybe_unused sprd_wdt_pm_suspend(struct device *dev)
+{
+	struct sprd_wdt *wdt = dev_get_drvdata(dev);
+
+	if (sprd_wdt_is_running(wdt)) {
+		sprd_wdt_stop(&wdt->wdd);
+		sprd_wdt_disable(wdt);
+	}
+
+	return 0;
+}
+
+static int __maybe_unused sprd_wdt_pm_resume(struct device *dev)
+{
+	struct watchdog_device *wdd = dev_get_drvdata(dev);
+	struct sprd_wdt *wdt = dev_get_drvdata(dev);
+
+	if (watchdog_active(wdd) && !sprd_wdt_is_running(wdt)) {
+		sprd_wdt_enable(wdt);
+		sprd_wdt_start(&wdt->wdd);
+	}
+
+	return 0;
+}
+
+static const struct dev_pm_ops sprd_wdt_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(sprd_wdt_pm_suspend,
+				sprd_wdt_pm_resume)
+};
+
+static const struct of_device_id sprd_wdt_match_table[] = {
+	{ .compatible = "sprd,sp9860-wdt", },
+	{},
+};
+MODULE_DEVICE_TABLE(of, sprd_wdt_match_table);
+
+static struct platform_driver sprd_watchdog_driver = {
+	.probe	= sprd_wdt_probe,
+	.remove	= sprd_wdt_remove,
+	.driver	= {
+		.name = "sprd-wdt",
+		.of_match_table = sprd_wdt_match_table,
+		.pm = &sprd_wdt_pm_ops,
+	},
+};
+module_platform_driver(sprd_watchdog_driver);
+
+MODULE_AUTHOR("Eric Long <eric.long@...eadtrum.com>");
+MODULE_DESCRIPTION("Spreadtrum Watchdog Timer Controller Driver");
+MODULE_LICENSE("GPL v2");
-- 
1.9.1

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