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From:   nick.hawkins@hpe.com
To:     verdun@hpe.com, nick@hpe.com, joel@jms.id.au, arnd@arndb.de
Cc:     Nick Hawkins <nick.hawkins@hpe.com>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Guenter Roeck <linux@roeck-us.net>,
        linux-kernel@vger.kernel.org, linux-watchdog@vger.kernel.org
Subject: [PATCH v4 03/11] drivers: wdt: Introduce HPE GXP SoC Watchdog
Date:   Wed, 20 Apr 2022 10:01:47 -0500
Message-Id: <20220420150156.47405-3-nick.hawkins@hpe.com>
In-Reply-To: <20220420150156.47405-1-nick.hawkins@hpe.com>
References: <20220420150156.47405-1-nick.hawkins@hpe.com>
Precedence: bulk

From: Nick Hawkins <nick.hawkins@hpe.com>

Adding support for the HPE GXP Watchdog. It is new to the linux
community and this along with several other patches is the first
support for it. The GXP asic contains a full compliment of
timers one of which is the watchdog timer. The watchdog timer
is 16 bit and has 10ms resolution. The watchdog is now
created as a child device of timer since the same register
range is used. This was done due to changes requested with
the device tree.

---
v2:
*Made watchdog a child of timer as they share the same register
region per change request on dtsi.
*Removed extra parenthesis
*Fixed u8 u32 u64 usage
*Fixed alignment issue
*Removed unused gxp_wdt_remove function

Signed-off-by: Nick Hawkins <nick.hawkins@hpe.com>
---
 drivers/watchdog/Kconfig   |   8 ++
 drivers/watchdog/Makefile  |   1 +
 drivers/watchdog/gxp-wdt.c | 166 +++++++++++++++++++++++++++++++++++++
 3 files changed, 175 insertions(+)
 create mode 100644 drivers/watchdog/gxp-wdt.c

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index c8fa79da23b3..cb210d2978d2 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -1820,6 +1820,14 @@ config RALINK_WDT
 	help
 	  Hardware driver for the Ralink SoC Watchdog Timer.
 
+config GXP_WATCHDOG
+	tristate "HPE GXP watchdog support"
+	depends on ARCH_HPE_GXP
+	select WATCHDOG_CORE
+	help
+	  Say Y here to include support for the watchdog timer
+	  in HPE GXP SoCs.
+
 config MT7621_WDT
 	tristate "Mediatek SoC watchdog"
 	select WATCHDOG_CORE
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index f7da867e8782..e2acf3a0d0fc 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -92,6 +92,7 @@ obj-$(CONFIG_RTD119X_WATCHDOG) += rtd119x_wdt.o
 obj-$(CONFIG_SPRD_WATCHDOG) += sprd_wdt.o
 obj-$(CONFIG_PM8916_WATCHDOG) += pm8916_wdt.o
 obj-$(CONFIG_ARM_SMC_WATCHDOG) += arm_smc_wdt.o
+obj-$(CONFIG_GXP_WATCHDOG) += gxp-wdt.o
 obj-$(CONFIG_VISCONTI_WATCHDOG) += visconti_wdt.o
 obj-$(CONFIG_MSC313E_WATCHDOG) += msc313e_wdt.o
 obj-$(CONFIG_APPLE_WATCHDOG) += apple_wdt.o
diff --git a/drivers/watchdog/gxp-wdt.c b/drivers/watchdog/gxp-wdt.c
new file mode 100644
index 000000000000..f45ab9a826d6
--- /dev/null
+++ b/drivers/watchdog/gxp-wdt.c
@@ -0,0 +1,166 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) 2022 Hewlett-Packard Enterprise Development Company, L.P. */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/platform_device.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/types.h>
+#include <linux/watchdog.h>
+
+#define MASK_WDGCS_ENABLE	0x01
+#define MASK_WDGCS_RELOAD	0x04
+#define MASK_WDGCS_NMIEN	0x08
+#define MASK_WDGCS_WARN		0x80
+
+#define WDT_MAX_TIMEOUT_MS	655000
+#define WDT_DEFAULT_TIMEOUT	30
+#define SECS_TO_WDOG_TICKS(x) ((x) * 100)
+#define WDOG_TICKS_TO_SECS(x) ((x) / 100)
+
+#define GXP_WDT_CNT_OFS		0x10
+#define GXP_WDT_CTRL_OFS	0x16
+
+struct gxp_wdt {
+	void __iomem *base;
+	struct watchdog_device wdd;
+};
+
+static void gxp_wdt_enable_reload(struct gxp_wdt *drvdata)
+{
+	u8 val;
+
+	val = readb(drvdata->base + GXP_WDT_CTRL_OFS);
+	val |= (MASK_WDGCS_ENABLE | MASK_WDGCS_RELOAD);
+	writeb(val, drvdata->base + GXP_WDT_CTRL_OFS);
+}
+
+static int gxp_wdt_start(struct watchdog_device *wdd)
+{
+	struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
+
+	writew(SECS_TO_WDOG_TICKS(wdd->timeout), drvdata->base + GXP_WDT_CNT_OFS);
+	gxp_wdt_enable_reload(drvdata);
+	return 0;
+}
+
+static int gxp_wdt_stop(struct watchdog_device *wdd)
+{
+	struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
+	u8 val;
+
+	val = readb_relaxed(drvdata->base + GXP_WDT_CTRL_OFS);
+	val &= ~MASK_WDGCS_ENABLE;
+	writeb(val, drvdata->base + GXP_WDT_CTRL_OFS);
+	return 0;
+}
+
+static int gxp_wdt_set_timeout(struct watchdog_device *wdd,
+			       unsigned int timeout)
+{
+	struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
+	u32 actual;
+
+	wdd->timeout = timeout;
+	actual = min(timeout, wdd->max_hw_heartbeat_ms / 1000);
+	writew(SECS_TO_WDOG_TICKS(actual), drvdata->base + GXP_WDT_CNT_OFS);
+
+	return 0;
+}
+
+static unsigned int gxp_wdt_get_timeleft(struct watchdog_device *wdd)
+{
+	struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
+	u32 val = readw(drvdata->base + GXP_WDT_CNT_OFS);
+
+	return WDOG_TICKS_TO_SECS(val);
+}
+
+static int gxp_wdt_ping(struct watchdog_device *wdd)
+{
+	struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
+
+	gxp_wdt_enable_reload(drvdata);
+	return 0;
+}
+
+static int gxp_restart(struct watchdog_device *wdd, unsigned long action,
+		       void *data)
+{
+	struct gxp_wdt *drvdata = watchdog_get_drvdata(wdd);
+
+	writew(10, drvdata->base + GXP_WDT_CNT_OFS);
+	gxp_wdt_enable_reload(drvdata);
+	mdelay(100);
+	return 0;
+}
+
+static const struct watchdog_ops gxp_wdt_ops = {
+	.owner =	THIS_MODULE,
+	.start =	gxp_wdt_start,
+	.stop =		gxp_wdt_stop,
+	.ping =		gxp_wdt_ping,
+	.set_timeout =	gxp_wdt_set_timeout,
+	.get_timeleft =	gxp_wdt_get_timeleft,
+	.restart =	gxp_restart,
+};
+
+static const struct watchdog_info gxp_wdt_info = {
+	.options = WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
+	.identity = "HPE GXP Watchdog timer",
+};
+
+static int gxp_wdt_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct gxp_wdt *drvdata;
+	int err;
+	u8 val;
+
+	drvdata = devm_kzalloc(dev, sizeof(struct gxp_wdt), GFP_KERNEL);
+	if (!drvdata)
+		return -ENOMEM;
+
+	drvdata->base = (void __iomem *)dev->platform_data;
+
+	drvdata->wdd.info = &gxp_wdt_info;
+	drvdata->wdd.ops = &gxp_wdt_ops;
+	drvdata->wdd.max_hw_heartbeat_ms = WDT_MAX_TIMEOUT_MS;
+	drvdata->wdd.parent = dev;
+	drvdata->wdd.timeout = WDT_DEFAULT_TIMEOUT;
+
+	watchdog_set_drvdata(&drvdata->wdd, drvdata);
+	watchdog_set_nowayout(&drvdata->wdd, WATCHDOG_NOWAYOUT);
+
+	val = readb(drvdata->base + GXP_WDT_CTRL_OFS);
+
+	if (val & MASK_WDGCS_ENABLE)
+		set_bit(WDOG_HW_RUNNING, &drvdata->wdd.status);
+
+	watchdog_set_restart_priority(&drvdata->wdd, 128);
+
+	watchdog_stop_on_reboot(&drvdata->wdd);
+	err = devm_watchdog_register_device(dev, &drvdata->wdd);
+	if (err) {
+		dev_err(dev, "Failed to register watchdog device");
+		return err;
+	}
+
+	dev_info(dev, "HPE GXP watchdog timer");
+
+	return 0;
+}
+
+static struct platform_driver gxp_wdt_driver = {
+	.probe = gxp_wdt_probe,
+	.driver = {
+		.name =	"gxp-wdt",
+	},
+};
+module_platform_driver(gxp_wdt_driver);
+
+MODULE_AUTHOR("Nick Hawkins <nick.hawkins@hpe.com>");
+MODULE_AUTHOR("Jean-Marie Verdun <verdun@hpe.com>");
+MODULE_DESCRIPTION("Driver for GXP watchdog timer");
-- 
2.17.1