1 files changed, 331 insertions, 0 deletions
diff --git a/drivers/watchdog/gef_wdt.c b/drivers/watchdog/gef_wdt.c
new file mode 100644
index 000000000..df5406aa7
--- /dev/null
+++ b/drivers/watchdog/gef_wdt.c
@@ -0,0 +1,331 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * GE watchdog userspace interface
+ *
+ * Author:  Martyn Welch <martyn.welch@ge.com>
+ *
+ * Copyright 2008 GE Intelligent Platforms Embedded Systems, Inc.
+ *
+ * Based on: mv64x60_wdt.c (MV64X60 watchdog userspace interface)
+ *   Author: James Chapman <jchapman@katalix.com>
+ */
+
+/* TODO:
+ * This driver does not provide support for the hardwares capability of sending
+ * an interrupt at a programmable threshold.
+ *
+ * This driver currently can only support 1 watchdog - there are 2 in the
+ * hardware that this driver supports. Thus one could be configured as a
+ * process-based watchdog (via /dev/watchdog), the second (using the interrupt
+ * capabilities) a kernel-based watchdog.
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/kernel.h>
+#include <linux/compiler.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/fs.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+
+#include <sysdev/fsl_soc.h>
+
+/*
+ * The watchdog configuration register contains a pair of 2-bit fields,
+ *   1.  a reload field, bits 27-26, which triggers a reload of
+ *       the countdown register, and
+ *   2.  an enable field, bits 25-24, which toggles between
+ *       enabling and disabling the watchdog timer.
+ * Bit 31 is a read-only field which indicates whether the
+ * watchdog timer is currently enabled.
+ *
+ * The low 24 bits contain the timer reload value.
+ */
+#define GEF_WDC_ENABLE_SHIFT	24
+#define GEF_WDC_SERVICE_SHIFT	26
+#define GEF_WDC_ENABLED_SHIFT	31
+
+#define GEF_WDC_ENABLED_TRUE	1
+#define GEF_WDC_ENABLED_FALSE	0
+
+/* Flags bits */
+#define GEF_WDOG_FLAG_OPENED	0
+
+static unsigned long wdt_flags;
+static int wdt_status;
+static void __iomem *gef_wdt_regs;
+static int gef_wdt_timeout;
+static int gef_wdt_count;
+static unsigned int bus_clk;
+static char expect_close;
+static DEFINE_SPINLOCK(gef_wdt_spinlock);
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+	__MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+
+static int gef_wdt_toggle_wdc(int enabled_predicate, int field_shift)
+{
+	u32 data;
+	u32 enabled;
+	int ret = 0;
+
+	spin_lock(&gef_wdt_spinlock);
+	data = ioread32be(gef_wdt_regs);
+	enabled = (data >> GEF_WDC_ENABLED_SHIFT) & 1;
+
+	/* only toggle the requested field if enabled state matches predicate */
+	if ((enabled ^ enabled_predicate) == 0) {
+		/* We write a 1, then a 2 -- to the appropriate field */
+		data = (1 << field_shift) | gef_wdt_count;
+		iowrite32be(data, gef_wdt_regs);
+
+		data = (2 << field_shift) | gef_wdt_count;
+		iowrite32be(data, gef_wdt_regs);
+		ret = 1;
+	}
+	spin_unlock(&gef_wdt_spinlock);
+
+	return ret;
+}
+
+static void gef_wdt_service(void)
+{
+	gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
+		GEF_WDC_SERVICE_SHIFT);
+}
+
+static void gef_wdt_handler_enable(void)
+{
+	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_FALSE,
+				   GEF_WDC_ENABLE_SHIFT)) {
+		gef_wdt_service();
+		pr_notice("watchdog activated\n");
+	}
+}
+
+static void gef_wdt_handler_disable(void)
+{
+	if (gef_wdt_toggle_wdc(GEF_WDC_ENABLED_TRUE,
+				   GEF_WDC_ENABLE_SHIFT))
+		pr_notice("watchdog deactivated\n");
+}
+
+static void gef_wdt_set_timeout(unsigned int timeout)
+{
+	/* maximum bus cycle count is 0xFFFFFFFF */
+	if (timeout > 0xFFFFFFFF / bus_clk)
+		timeout = 0xFFFFFFFF / bus_clk;
+
+	/* Register only holds upper 24 bits, bit shifted into lower 24 */
+	gef_wdt_count = (timeout * bus_clk) >> 8;
+	gef_wdt_timeout = timeout;
+}
+
+
+static ssize_t gef_wdt_write(struct file *file, const char __user *data,
+				 size_t len, loff_t *ppos)
+{
+	if (len) {
+		if (!nowayout) {
+			size_t i;
+
+			expect_close = 0;
+
+			for (i = 0; i != len; i++) {
+				char c;
+				if (get_user(c, data + i))
+					return -EFAULT;
+				if (c == 'V')
+					expect_close = 42;
+			}
+		}
+		gef_wdt_service();
+	}
+
+	return len;
+}
+
+static long gef_wdt_ioctl(struct file *file, unsigned int cmd,
+							unsigned long arg)
+{
+	int timeout;
+	int options;
+	void __user *argp = (void __user *)arg;
+	static const struct watchdog_info info = {
+		.options =	WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE |
+				WDIOF_KEEPALIVEPING,
+		.firmware_version = 0,
+		.identity = "GE watchdog",
+	};
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		if (copy_to_user(argp, &info, sizeof(info)))
+			return -EFAULT;
+		break;
+
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		if (put_user(wdt_status, (int __user *)argp))
+			return -EFAULT;
+		wdt_status &= ~WDIOF_KEEPALIVEPING;
+		break;
+
+	case WDIOC_SETOPTIONS:
+		if (get_user(options, (int __user *)argp))
+			return -EFAULT;
+
+		if (options & WDIOS_DISABLECARD)
+			gef_wdt_handler_disable();
+
+		if (options & WDIOS_ENABLECARD)
+			gef_wdt_handler_enable();
+		break;
+
+	case WDIOC_KEEPALIVE:
+		gef_wdt_service();
+		wdt_status |= WDIOF_KEEPALIVEPING;
+		break;
+
+	case WDIOC_SETTIMEOUT:
+		if (get_user(timeout, (int __user *)argp))
+			return -EFAULT;
+		gef_wdt_set_timeout(timeout);
+		fallthrough;
+
+	case WDIOC_GETTIMEOUT:
+		if (put_user(gef_wdt_timeout, (int __user *)argp))
+			return -EFAULT;
+		break;
+
+	default:
+		return -ENOTTY;
+	}
+
+	return 0;
+}
+
+static int gef_wdt_open(struct inode *inode, struct file *file)
+{
+	if (test_and_set_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags))
+		return -EBUSY;
+
+	if (nowayout)
+		__module_get(THIS_MODULE);
+
+	gef_wdt_handler_enable();
+
+	return stream_open(inode, file);
+}
+
+static int gef_wdt_release(struct inode *inode, struct file *file)
+{
+	if (expect_close == 42)
+		gef_wdt_handler_disable();
+	else {
+		pr_crit("unexpected close, not stopping timer!\n");
+		gef_wdt_service();
+	}
+	expect_close = 0;
+
+	clear_bit(GEF_WDOG_FLAG_OPENED, &wdt_flags);
+
+	return 0;
+}
+
+static const struct file_operations gef_wdt_fops = {
+	.owner = THIS_MODULE,
+	.llseek = no_llseek,
+	.write = gef_wdt_write,
+	.unlocked_ioctl = gef_wdt_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+	.open = gef_wdt_open,
+	.release = gef_wdt_release,
+};
+
+static struct miscdevice gef_wdt_miscdev = {
+	.minor = WATCHDOG_MINOR,
+	.name = "watchdog",
+	.fops = &gef_wdt_fops,
+};
+
+
+static int gef_wdt_probe(struct platform_device *dev)
+{
+	int timeout = 10;
+	u32 freq;
+
+	bus_clk = 133; /* in MHz */
+
+	freq = fsl_get_sys_freq();
+	if (freq != -1)
+		bus_clk = freq;
+
+	/* Map devices registers into memory */
+	gef_wdt_regs = of_iomap(dev->dev.of_node, 0);
+	if (gef_wdt_regs == NULL)
+		return -ENOMEM;
+
+	gef_wdt_set_timeout(timeout);
+
+	gef_wdt_handler_disable();	/* in case timer was already running */
+
+	return misc_register(&gef_wdt_miscdev);
+}
+
+static int gef_wdt_remove(struct platform_device *dev)
+{
+	misc_deregister(&gef_wdt_miscdev);
+
+	gef_wdt_handler_disable();
+
+	iounmap(gef_wdt_regs);
+
+	return 0;
+}
+
+static const struct of_device_id gef_wdt_ids[] = {
+	{
+		.compatible = "gef,fpga-wdt",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, gef_wdt_ids);
+
+static struct platform_driver gef_wdt_driver = {
+	.driver = {
+		.name = "gef_wdt",
+		.of_match_table = gef_wdt_ids,
+	},
+	.probe		= gef_wdt_probe,
+	.remove		= gef_wdt_remove,
+};
+
+static int __init gef_wdt_init(void)
+{
+	pr_info("GE watchdog driver\n");
+	return platform_driver_register(&gef_wdt_driver);
+}
+
+static void __exit gef_wdt_exit(void)
+{
+	platform_driver_unregister(&gef_wdt_driver);
+}
+
+module_init(gef_wdt_init);
+module_exit(gef_wdt_exit);
+
+MODULE_AUTHOR("Martyn Welch <martyn.welch@ge.com>");
+MODULE_DESCRIPTION("GE watchdog driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:gef_wdt");