1 files changed, 316 insertions, 0 deletions
diff --git a/drivers/watchdog/ar7_wdt.c b/drivers/watchdog/ar7_wdt.c
new file mode 100644
index 000000000..743e171d9
--- /dev/null
+++ b/drivers/watchdog/ar7_wdt.c
@@ -0,0 +1,316 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * drivers/watchdog/ar7_wdt.c
+ *
+ * Copyright (C) 2007 Nicolas Thill <nico@openwrt.org>
+ * Copyright (c) 2005 Enrik Berkhan <Enrik.Berkhan@akk.org>
+ *
+ * Some code taken from:
+ * National Semiconductor SCx200 Watchdog support
+ * Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com>
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/errno.h>
+#include <linux/miscdevice.h>
+#include <linux/platform_device.h>
+#include <linux/watchdog.h>
+#include <linux/fs.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+#include <linux/clk.h>
+
+#include <asm/addrspace.h>
+#include <asm/mach-ar7/ar7.h>
+
+#define LONGNAME "TI AR7 Watchdog Timer"
+
+MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
+MODULE_DESCRIPTION(LONGNAME);
+MODULE_LICENSE("GPL");
+
+static int margin = 60;
+module_param(margin, int, 0);
+MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
+
+static bool nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, bool, 0);
+MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
+
+#define READ_REG(x) readl((void __iomem *)&(x))
+#define WRITE_REG(x, v) writel((v), (void __iomem *)&(x))
+
+struct ar7_wdt {
+	u32 kick_lock;
+	u32 kick;
+	u32 change_lock;
+	u32 change;
+	u32 disable_lock;
+	u32 disable;
+	u32 prescale_lock;
+	u32 prescale;
+};
+
+static unsigned long wdt_is_open;
+static unsigned expect_close;
+static DEFINE_SPINLOCK(wdt_lock);
+
+/* XXX currently fixed, allows max margin ~68.72 secs */
+#define prescale_value 0xffff
+
+/* Pointer to the remapped WDT IO space */
+static struct ar7_wdt *ar7_wdt;
+
+static struct clk *vbus_clk;
+
+static void ar7_wdt_kick(u32 value)
+{
+	WRITE_REG(ar7_wdt->kick_lock, 0x5555);
+	if ((READ_REG(ar7_wdt->kick_lock) & 3) == 1) {
+		WRITE_REG(ar7_wdt->kick_lock, 0xaaaa);
+		if ((READ_REG(ar7_wdt->kick_lock) & 3) == 3) {
+			WRITE_REG(ar7_wdt->kick, value);
+			return;
+		}
+	}
+	pr_err("failed to unlock WDT kick reg\n");
+}
+
+static void ar7_wdt_prescale(u32 value)
+{
+	WRITE_REG(ar7_wdt->prescale_lock, 0x5a5a);
+	if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 1) {
+		WRITE_REG(ar7_wdt->prescale_lock, 0xa5a5);
+		if ((READ_REG(ar7_wdt->prescale_lock) & 3) == 3) {
+			WRITE_REG(ar7_wdt->prescale, value);
+			return;
+		}
+	}
+	pr_err("failed to unlock WDT prescale reg\n");
+}
+
+static void ar7_wdt_change(u32 value)
+{
+	WRITE_REG(ar7_wdt->change_lock, 0x6666);
+	if ((READ_REG(ar7_wdt->change_lock) & 3) == 1) {
+		WRITE_REG(ar7_wdt->change_lock, 0xbbbb);
+		if ((READ_REG(ar7_wdt->change_lock) & 3) == 3) {
+			WRITE_REG(ar7_wdt->change, value);
+			return;
+		}
+	}
+	pr_err("failed to unlock WDT change reg\n");
+}
+
+static void ar7_wdt_disable(u32 value)
+{
+	WRITE_REG(ar7_wdt->disable_lock, 0x7777);
+	if ((READ_REG(ar7_wdt->disable_lock) & 3) == 1) {
+		WRITE_REG(ar7_wdt->disable_lock, 0xcccc);
+		if ((READ_REG(ar7_wdt->disable_lock) & 3) == 2) {
+			WRITE_REG(ar7_wdt->disable_lock, 0xdddd);
+			if ((READ_REG(ar7_wdt->disable_lock) & 3) == 3) {
+				WRITE_REG(ar7_wdt->disable, value);
+				return;
+			}
+		}
+	}
+	pr_err("failed to unlock WDT disable reg\n");
+}
+
+static void ar7_wdt_update_margin(int new_margin)
+{
+	u32 change;
+	u32 vbus_rate;
+
+	vbus_rate = clk_get_rate(vbus_clk);
+	change = new_margin * (vbus_rate / prescale_value);
+	if (change < 1)
+		change = 1;
+	if (change > 0xffff)
+		change = 0xffff;
+	ar7_wdt_change(change);
+	margin = change * prescale_value / vbus_rate;
+	pr_info("timer margin %d seconds (prescale %d, change %d, freq %d)\n",
+		margin, prescale_value, change, vbus_rate);
+}
+
+static void ar7_wdt_enable_wdt(void)
+{
+	pr_debug("enabling watchdog timer\n");
+	ar7_wdt_disable(1);
+	ar7_wdt_kick(1);
+}
+
+static void ar7_wdt_disable_wdt(void)
+{
+	pr_debug("disabling watchdog timer\n");
+	ar7_wdt_disable(0);
+}
+
+static int ar7_wdt_open(struct inode *inode, struct file *file)
+{
+	/* only allow one at a time */
+	if (test_and_set_bit(0, &wdt_is_open))
+		return -EBUSY;
+	ar7_wdt_enable_wdt();
+	expect_close = 0;
+
+	return stream_open(inode, file);
+}
+
+static int ar7_wdt_release(struct inode *inode, struct file *file)
+{
+	if (!expect_close)
+		pr_warn("watchdog device closed unexpectedly, will not disable the watchdog timer\n");
+	else if (!nowayout)
+		ar7_wdt_disable_wdt();
+	clear_bit(0, &wdt_is_open);
+	return 0;
+}
+
+static ssize_t ar7_wdt_write(struct file *file, const char *data,
+			     size_t len, loff_t *ppos)
+{
+	/* check for a magic close character */
+	if (len) {
+		size_t i;
+
+		spin_lock(&wdt_lock);
+		ar7_wdt_kick(1);
+		spin_unlock(&wdt_lock);
+
+		expect_close = 0;
+		for (i = 0; i < len; ++i) {
+			char c;
+			if (get_user(c, data + i))
+				return -EFAULT;
+			if (c == 'V')
+				expect_close = 1;
+		}
+
+	}
+	return len;
+}
+
+static long ar7_wdt_ioctl(struct file *file,
+					unsigned int cmd, unsigned long arg)
+{
+	static const struct watchdog_info ident = {
+		.identity = LONGNAME,
+		.firmware_version = 1,
+		.options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
+						WDIOF_MAGICCLOSE),
+	};
+	int new_margin;
+
+	switch (cmd) {
+	case WDIOC_GETSUPPORT:
+		if (copy_to_user((struct watchdog_info *)arg, &ident,
+				sizeof(ident)))
+			return -EFAULT;
+		return 0;
+	case WDIOC_GETSTATUS:
+	case WDIOC_GETBOOTSTATUS:
+		if (put_user(0, (int *)arg))
+			return -EFAULT;
+		return 0;
+	case WDIOC_KEEPALIVE:
+		ar7_wdt_kick(1);
+		return 0;
+	case WDIOC_SETTIMEOUT:
+		if (get_user(new_margin, (int *)arg))
+			return -EFAULT;
+		if (new_margin < 1)
+			return -EINVAL;
+
+		spin_lock(&wdt_lock);
+		ar7_wdt_update_margin(new_margin);
+		ar7_wdt_kick(1);
+		spin_unlock(&wdt_lock);
+		fallthrough;
+	case WDIOC_GETTIMEOUT:
+		if (put_user(margin, (int *)arg))
+			return -EFAULT;
+		return 0;
+	default:
+		return -ENOTTY;
+	}
+}
+
+static const struct file_operations ar7_wdt_fops = {
+	.owner		= THIS_MODULE,
+	.write		= ar7_wdt_write,
+	.unlocked_ioctl	= ar7_wdt_ioctl,
+	.compat_ioctl	= compat_ptr_ioctl,
+	.open		= ar7_wdt_open,
+	.release	= ar7_wdt_release,
+	.llseek		= no_llseek,
+};
+
+static struct miscdevice ar7_wdt_miscdev = {
+	.minor		= WATCHDOG_MINOR,
+	.name		= "watchdog",
+	.fops		= &ar7_wdt_fops,
+};
+
+static int ar7_wdt_probe(struct platform_device *pdev)
+{
+	int rc;
+
+	ar7_wdt = devm_platform_ioremap_resource_byname(pdev, "regs");
+	if (IS_ERR(ar7_wdt))
+		return PTR_ERR(ar7_wdt);
+
+	vbus_clk = clk_get(NULL, "vbus");
+	if (IS_ERR(vbus_clk)) {
+		pr_err("could not get vbus clock\n");
+		return PTR_ERR(vbus_clk);
+	}
+
+	ar7_wdt_disable_wdt();
+	ar7_wdt_prescale(prescale_value);
+	ar7_wdt_update_margin(margin);
+
+	rc = misc_register(&ar7_wdt_miscdev);
+	if (rc) {
+		pr_err("unable to register misc device\n");
+		goto out;
+	}
+	return 0;
+
+out:
+	clk_put(vbus_clk);
+	vbus_clk = NULL;
+	return rc;
+}
+
+static int ar7_wdt_remove(struct platform_device *pdev)
+{
+	misc_deregister(&ar7_wdt_miscdev);
+	clk_put(vbus_clk);
+	vbus_clk = NULL;
+	return 0;
+}
+
+static void ar7_wdt_shutdown(struct platform_device *pdev)
+{
+	if (!nowayout)
+		ar7_wdt_disable_wdt();
+}
+
+static struct platform_driver ar7_wdt_driver = {
+	.probe = ar7_wdt_probe,
+	.remove = ar7_wdt_remove,
+	.shutdown = ar7_wdt_shutdown,
+	.driver = {
+		.name = "ar7_wdt",
+	},
+};
+
+module_platform_driver(ar7_wdt_driver);