MIPS: Lantiq: Add watchdog support

This patch adds the driver for the watchdog found inside the Lantiq SoC family.

Signed-off-by: John Crispin <blogic@openwrt.org>
Signed-off-by: Ralph Hempel <ralph.hempel@lantiq.com>
Cc: Wim Van Sebroeck <wim@iguana.be>
Cc: linux-mips@linux-mips.org
Cc: linux-watchdog@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/2327/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

3 files changed, 268 insertions, 0 deletions

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 1b0f98bc51b5..022f9eb0b7bf 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -990,6 +990,12 @@ config BCM63XX_WDT
           To compile this driver as a loadable module, choose M here.
           The module will be called bcm63xx_wdt.
 
+config LANTIQ_WDT
+        tristate "Lantiq SoC watchdog"
+        depends on LANTIQ
+        help
+          Hardware driver for the Lantiq SoC Watchdog Timer.
+
 # PARISC Architecture
 
 # POWERPC Architecture
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 3f8608b922a7..ed26f7094e47 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -123,6 +123,7 @@ obj-$(CONFIG_AR7_WDT) += ar7_wdt.o
 obj-$(CONFIG_TXX9_WDT) += txx9wdt.o
 obj-$(CONFIG_OCTEON_WDT) += octeon-wdt.o
 octeon-wdt-y := octeon-wdt-main.o octeon-wdt-nmi.o
+obj-$(CONFIG_LANTIQ_WDT) += lantiq_wdt.o
 
 # PARISC Architecture
 
diff --git a/drivers/watchdog/lantiq_wdt.c b/drivers/watchdog/lantiq_wdt.c
new file mode 100644
index 000000000000..7d82adac1cb2
--- /dev/null
+++ b/drivers/watchdog/lantiq_wdt.c
@@ -0,0 +1,261 @@
+/*
+ *  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.
+ *
+ *  Copyright (C) 2010 John Crispin <blogic@openwrt.org>
+ *  Based on EP93xx wdt driver
+ */
+
+#include <linux/module.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/platform_device.h>
+#include <linux/uaccess.h>
+#include <linux/clk.h>
+#include <linux/io.h>
+
+#include <lantiq.h>
+
+/* Section 3.4 of the datasheet
+ * The password sequence protects the WDT control register from unintended
+ * write actions, which might cause malfunction of the WDT.
+ *
+ * essentially the following two magic passwords need to be written to allow
+ * IO access to the WDT core
+ */
+#define LTQ_WDT_PW1             0x00BE0000
+#define LTQ_WDT_PW2             0x00DC0000
+
+#define LTQ_WDT_CR              0x0     /* watchdog control register */
+#define LTQ_WDT_SR              0x8     /* watchdog status register */
+
+#define LTQ_WDT_SR_EN           (0x1 << 31)     /* enable bit */
+#define LTQ_WDT_SR_PWD          (0x3 << 26)     /* turn on power */
+#define LTQ_WDT_SR_CLKDIV       (0x3 << 24)     /* turn on clock and set */
+                                                /* divider to 0x40000 */
+#define LTQ_WDT_DIVIDER         0x40000
+#define LTQ_MAX_TIMEOUT         ((1 << 16) - 1) /* the reload field is 16 bit */
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+
+static void __iomem *ltq_wdt_membase;
+static unsigned long ltq_io_region_clk_rate;
+
+static unsigned long ltq_wdt_bootstatus;
+static unsigned long ltq_wdt_in_use;
+static int ltq_wdt_timeout = 30;
+static int ltq_wdt_ok_to_close;
+
+static void
+ltq_wdt_enable(void)
+{
+        ltq_wdt_timeout = ltq_wdt_timeout *
+                        (ltq_io_region_clk_rate / LTQ_WDT_DIVIDER) + 0x1000;
+        if (ltq_wdt_timeout > LTQ_MAX_TIMEOUT)
+                ltq_wdt_timeout = LTQ_MAX_TIMEOUT;
+
+        /* write the first password magic */
+        ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR);
+        /* write the second magic plus the configuration and new timeout */
+        ltq_w32(LTQ_WDT_SR_EN | LTQ_WDT_SR_PWD | LTQ_WDT_SR_CLKDIV |
+                LTQ_WDT_PW2 | ltq_wdt_timeout, ltq_wdt_membase + LTQ_WDT_CR);
+}
+
+static void
+ltq_wdt_disable(void)
+{
+        /* write the first password magic */
+        ltq_w32(LTQ_WDT_PW1, ltq_wdt_membase + LTQ_WDT_CR);
+        /* write the second password magic with no config
+         * this turns the watchdog off
+         */
+        ltq_w32(LTQ_WDT_PW2, ltq_wdt_membase + LTQ_WDT_CR);
+}
+
+static ssize_t
+ltq_wdt_write(struct file *file, const char __user *data,
+                size_t len, loff_t *ppos)
+{
+        if (len) {
+                if (!nowayout) {
+                        size_t i;
+
+                        ltq_wdt_ok_to_close = 0;
+                        for (i = 0; i != len; i++) {
+                                char c;
+
+                                if (get_user(c, data + i))
+                                        return -EFAULT;
+                                if (c == 'V')
+                                        ltq_wdt_ok_to_close = 1;
+                                else
+                                        ltq_wdt_ok_to_close = 0;
+                        }
+                }
+                ltq_wdt_enable();
+        }
+
+        return len;
+}
+
+static struct watchdog_info ident = {
+        .options = WDIOF_MAGICCLOSE | WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING |
+                        WDIOF_CARDRESET,
+        .identity = "ltq_wdt",
+};
+
+static long
+ltq_wdt_ioctl(struct file *file,
+                unsigned int cmd, unsigned long arg)
+{
+        int ret = -ENOTTY;
+
+        switch (cmd) {
+        case WDIOC_GETSUPPORT:
+                ret = copy_to_user((struct watchdog_info __user *)arg, &ident,
+                                sizeof(ident)) ? -EFAULT : 0;
+                break;
+
+        case WDIOC_GETBOOTSTATUS:
+                ret = put_user(ltq_wdt_bootstatus, (int __user *)arg);
+                break;
+
+        case WDIOC_GETSTATUS:
+                ret = put_user(0, (int __user *)arg);
+                break;
+
+        case WDIOC_SETTIMEOUT:
+                ret = get_user(ltq_wdt_timeout, (int __user *)arg);
+                if (!ret)
+                        ltq_wdt_enable();
+                /* intentional drop through */
+        case WDIOC_GETTIMEOUT:
+                ret = put_user(ltq_wdt_timeout, (int __user *)arg);
+                break;
+
+        case WDIOC_KEEPALIVE:
+                ltq_wdt_enable();
+                ret = 0;
+                break;
+        }
+        return ret;
+}
+
+static int
+ltq_wdt_open(struct inode *inode, struct file *file)
+{
+        if (test_and_set_bit(0, &ltq_wdt_in_use))
+                return -EBUSY;
+        ltq_wdt_in_use = 1;
+        ltq_wdt_enable();
+
+        return nonseekable_open(inode, file);
+}
+
+static int
+ltq_wdt_release(struct inode *inode, struct file *file)
+{
+        if (ltq_wdt_ok_to_close)
+                ltq_wdt_disable();
+        else
+                pr_err("ltq_wdt: watchdog closed without warning\n");
+        ltq_wdt_ok_to_close = 0;
+        clear_bit(0, &ltq_wdt_in_use);
+
+        return 0;
+}
+
+static const struct file_operations ltq_wdt_fops = {
+        .owner          = THIS_MODULE,
+        .write          = ltq_wdt_write,
+        .unlocked_ioctl = ltq_wdt_ioctl,
+        .open           = ltq_wdt_open,
+        .release        = ltq_wdt_release,
+        .llseek         = no_llseek,
+};
+
+static struct miscdevice ltq_wdt_miscdev = {
+        .minor  = WATCHDOG_MINOR,
+        .name   = "watchdog",
+        .fops   = &ltq_wdt_fops,
+};
+
+static int __init
+ltq_wdt_probe(struct platform_device *pdev)
+{
+        struct resource *res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+        struct clk *clk;
+
+        if (!res) {
+                dev_err(&pdev->dev, "cannot obtain I/O memory region");
+                return -ENOENT;
+        }
+        res = devm_request_mem_region(&pdev->dev, res->start,
+                resource_size(res), dev_name(&pdev->dev));
+        if (!res) {
+                dev_err(&pdev->dev, "cannot request I/O memory region");
+                return -EBUSY;
+        }
+        ltq_wdt_membase = devm_ioremap_nocache(&pdev->dev, res->start,
+                resource_size(res));
+        if (!ltq_wdt_membase) {
+                dev_err(&pdev->dev, "cannot remap I/O memory region\n");
+                return -ENOMEM;
+        }
+
+        /* we do not need to enable the clock as it is always running */
+        clk = clk_get(&pdev->dev, "io");
+        WARN_ON(!clk);
+        ltq_io_region_clk_rate = clk_get_rate(clk);
+        clk_put(clk);
+
+        if (ltq_reset_cause() == LTQ_RST_CAUSE_WDTRST)
+                ltq_wdt_bootstatus = WDIOF_CARDRESET;
+
+        return misc_register(&ltq_wdt_miscdev);
+}
+
+static int __devexit
+ltq_wdt_remove(struct platform_device *pdev)
+{
+        misc_deregister(&ltq_wdt_miscdev);
+
+        if (ltq_wdt_membase)
+                iounmap(ltq_wdt_membase);
+
+        return 0;
+}
+
+
+static struct platform_driver ltq_wdt_driver = {
+        .remove = __devexit_p(ltq_wdt_remove),
+        .driver = {
+                .name = "ltq_wdt",
+                .owner = THIS_MODULE,
+        },
+};
+
+static int __init
+init_ltq_wdt(void)
+{
+        return platform_driver_probe(&ltq_wdt_driver, ltq_wdt_probe);
+}
+
+static void __exit
+exit_ltq_wdt(void)
+{
+        return platform_driver_unregister(&ltq_wdt_driver);
+}
+
+module_init(init_ltq_wdt);
+module_exit(exit_ltq_wdt);
+
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started");
+
+MODULE_AUTHOR("John Crispin <blogic@openwrt.org>");
+MODULE_DESCRIPTION("Lantiq SoC Watchdog");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);