[PATCH] Add Linux Driver for Intel Langwell Watchdog

From: Mark Allyn
Date: Mon Jan 18 2010 - 16:20:49 EST


This patch adds a Linux device driver for the Intel Langwell
Watchdog device found on the Intel Mobile Internet device.

The purpose of the watchdog driver is to force a system reboot
in the event that a critical system process either terminates or
gets currupted so that it cannot perform its required duties.

This patch is referenced off the linux-next repository as pulled
on Sunday, January 17, 2010

Signed-off-by: Mark Allyn <mark.a.allyn@xxxxxxxxx>

Date: January 17, 2010
---
drivers/watchdog/Kconfig | 7 +
drivers/watchdog/Makefile | 1 +
drivers/watchdog/langwell_watchdog.c | 551 ++++++++++++++++++++++++++++++++++
drivers/watchdog/langwell_watchdog.h | 60 ++++
4 files changed, 619 insertions(+), 0 deletions(-)
create mode 100644 drivers/watchdog/langwell_watchdog.c
create mode 100644 drivers/watchdog/langwell_watchdog.h

diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 088f32f..4902157 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -448,6 +448,13 @@ config IBMASR
To compile this driver as a module, choose M here: the
module will be called ibmasr.

+config LANGWELL_WATCHDOG
+ tristate "Intel Langwell Watchdog for Mobil Platforms"
+ depends on WATCHDOG
+ help
+ This driver is for the Intel Mobile Platform. If
+ in doubt, set it to N.
+
config WAFER_WDT
tristate "ICP Single Board Computer Watchdog Timer"
depends on X86
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 475c611..67f936f 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -96,6 +96,7 @@ obj-$(CONFIG_W83877F_WDT) += w83877f_wdt.o
obj-$(CONFIG_W83977F_WDT) += w83977f_wdt.o
obj-$(CONFIG_MACHZ_WDT) += machzwd.o
obj-$(CONFIG_SBC_EPX_C3_WATCHDOG) += sbc_epx_c3.o
+obj-$(CONFIG_LANGWELL_WATCHDOG) += langwell_watchdog.o

# M32R Architecture

diff --git a/drivers/watchdog/langwell_watchdog.c b/drivers/watchdog/langwell_watchdog.c
new file mode 100644
index 0000000..050b036
--- /dev/null
+++ b/drivers/watchdog/langwell_watchdog.c
@@ -0,0 +1,551 @@
+/*
+ * Langwell 0.2: An Intel Langwell IOH Based Watchdog Device
+ *
+ * Copyright (C) 2009 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General
+ * Public License 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.
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ * The full GNU General Public License is included in this
+ * distribution in the file called COPYING.
+ *
+ */
+
+#include <linux/compiler.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/fs.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/init.h>
+#include <linux/jiffies.h>
+#include <linux/uaccess.h>
+#include <linux/slab.h>
+#include <linux/io.h>
+#include <linux/interrupt.h>
+#include <linux/delay.h>
+#include <linux/sched.h>
+#include <linux/signal.h>
+#include <linux/sfi.h>
+#include <linux/types.h>
+#include <asm/irq.h>
+#include <asm/atomic.h>
+
+/* See arch/x86/kernel/ipc_mrst.c */
+#include <asm/ipc_defs.h>
+#include <linux/sftbl.h>
+/* #include <asm/mrst.h> */
+
+#include "langwell_watchdog.h"
+
+
+static DECLARE_WAIT_QUEUE_HEAD(read_wq);
+
+static int flag;
+static int timer_margin = DEFAULT_SOFT_TO_HARD_MARGIN;
+module_param(timer_margin, int, 0);
+
+MODULE_PARM_DESC(timer_margin,
+ "Watchdog timer margin"
+ "Time between interrupt and resetting the system"
+ "The range is from 1 to 160"
+ "This is the time for all keep alives to arrive");
+
+static int timer_set = DEFAULT_TIME;
+module_param(timer_set, int, 0);
+
+MODULE_PARM_DESC(timer_set,
+ "Default Watchdog timer setting"
+ "Complete cycle time"
+ "The range is from 1 to 170"
+ "This is the time for all keep alives to arrive");
+
+/* driver will force boot on closure of device file */
+static int force_boot = 1;
+
+module_param(force_boot, int, 0);
+MODULE_PARM_DESC(force_boot,
+ "A value of 1 means that the driver will reboot"
+ "the system if the /dev/watchdog device is closed"
+ );
+
+/* there is only one device in the system now; this can be made into
+ * an array in the future if we have more than one device */
+
+static struct langwell_watchdog_dev watchdog_device;
+
+/* This is used to force reboot if anyone tries to close this device */
+static void watchdog_fire(void)
+{
+ module_put(THIS_MODULE);
+
+ if (force_boot) {
+ printk(KERN_CRIT PFX "Initiating system reboot.\n");
+ emergency_restart();
+ printk(KERN_CRIT PFX "Reboot didn't ?????\n");
+ }
+
+ else {
+ printk(KERN_CRIT PFX "Reboot would have happend\n");
+ printk(KERN_CRIT PFX "You now have force_boot set to 0\n");
+ printk(KERN_CRIT PFX "I am not rebooting\n");
+ }
+}
+
+/*
+ * Langwell operations
+ */
+
+/* timer interrupt handler */
+irqreturn_t watchdog_timer_interrupt(int irq, void *dev_id)
+{
+ int int_status;
+ int_status = ioread32(watchdog_device.timer_interrupt_status_addr);
+
+ pr_debug("Watchdog timer - irq 7 interrupt received\n");
+
+ if (int_status != 0)
+ return IRQ_NONE;
+
+ /* is the driver open; if not, then this is spurious */
+ if (watchdog_device.timer_started == 0)
+ return IRQ_HANDLED;
+
+ pr_debug("Watchdog timer - watchdog interrupt received\n");
+
+ /* wake up read to send data to user (reminder for keep alive */
+ flag = 1;
+
+ wake_up_interruptible(&read_wq);
+
+ pr_debug("Watchdog timer - interrupt wakes up read_wq\n");
+
+ return IRQ_HANDLED;
+}
+
+static int langwell_keepalive(void)
+{
+
+ pr_debug("Watchdog timer - langwell keep alive \n");
+ /* read eoi register - clears interrupt */
+ ioread32(watchdog_device.timer_clear_interrupt_addr);
+
+ return 0;
+}
+
+static int langwell_stop(void)
+{
+ pr_debug("Watchdog timer - langwell stop\n");
+
+ iowrite32(0, watchdog_device.timer_control_addr);
+ return 0;
+}
+
+static int langwell_set_heartbeat(u32 t)
+{
+ struct watchdog_reg_data reg_data;
+
+ watchdog_device.timer_set = t;
+ watchdog_device.threshold =
+ timer_margin * watchdog_device.mtmr_ptr->freq;
+ watchdog_device.soft_threshold =
+ (watchdog_device.timer_set - timer_margin)
+ * watchdog_device.mtmr_ptr->freq;
+
+ pr_debug("Watchdog timer - timer_margin is %x (hex) seconds\n",
+ timer_margin);
+
+ pr_debug("Watchdog timer - following are in clock cycles\n");
+
+ pr_debug("Watchdog timer - there are %x (hex) clock cycles\n",
+ watchdog_device.mtmr_ptr->freq);
+
+ pr_debug("Watchdog timer - per second\n");
+
+ pr_debug("Watchdog timer - thres is %x (hex) and warm is %x (hex)\n",
+ watchdog_device.threshold, watchdog_device.soft_threshold);
+
+ pr_debug("Watchdog timer - setting timer_set is %x (hex) seconds\n",
+ watchdog_device.timer_set);
+
+ /* temporarily disable the timer */
+ iowrite32(0x00000002, watchdog_device.timer_control_addr);
+
+ /* send the threshold and soft_threshold via IPC to the Lincroft */
+ reg_data.payload1 = watchdog_device.soft_threshold;
+ reg_data.payload2 = watchdog_device.threshold;
+ ipc_set_watchdog(&reg_data);
+
+ pr_debug("Watchdog timer - setting timer to %x (hex)\n",
+ watchdog_device.soft_threshold);
+
+ /* set the timer to the soft threshold */
+ iowrite32(watchdog_device.soft_threshold,
+ watchdog_device.timer_load_count_addr);
+
+ /* read the timer to verify that it has been set */
+ pr_debug("Watchdog timer - watchdog - timer value is %x (hex)\n",
+ ioread32(watchdog_device.timer_current_value_addr));
+
+ /* allow the timer to run */
+ iowrite32(0x00000003, watchdog_device.timer_control_addr);
+
+ watchdog_device.timer_started = 1;
+
+ return 0;
+}
+
+/*
+ * /dev/watchdog handling
+ */
+static int langwell_open(struct inode *inode, struct file *file)
+{
+ /* Miscdevice structure pointer already saved in private_data */
+
+ struct watchdog_reg_data reg_data;
+
+ if (!capable(CAP_SYS_ADMIN))
+ return -EPERM;
+
+ if (test_and_set_bit(0, &watchdog_device.driver_open))
+ return -ENOTTY;
+
+ /* make sure that the timer set value is within boundaries */
+ if ((timer_set < MIN_TIME_CYCLE) ||
+ (timer_set > MAX_TIME - MIN_TIME_CYCLE)) {
+ pr_debug("Watchdog timer - timer open; timer value %x (hex)"
+ "is out of range from %x to %x (hex)\n",
+ timer_set, MIN_TIME_CYCLE, MAX_TIME - MIN_TIME_CYCLE);
+ return -EINVAL;
+ }
+
+ /* make sure that the timer margin value is within boundaries */
+ if ((timer_margin < MIN_TIME_CYCLE) ||
+ (timer_margin > MAX_TIME - timer_set)) {
+ pr_debug("Watchdog timer - timer open; "
+ "timer margin value %x is out of range from %x to %x (hex)\n",
+ timer_margin, MIN_TIME_CYCLE, MAX_TIME - timer_set);
+ return -EINVAL;
+ }
+
+ /* now set the watchpoints (using the IPC) */
+
+ watchdog_device.timer_set = timer_set;
+ watchdog_device.threshold =
+ timer_margin * watchdog_device.mtmr_ptr->freq;
+ watchdog_device.soft_threshold =
+ (watchdog_device.timer_set - timer_margin)
+ * watchdog_device.mtmr_ptr->freq;
+
+ pr_debug("Watchdog timer - threshold is %x and soft to %x (hex)\n",
+ watchdog_device.threshold, watchdog_device.soft_threshold);
+
+ pr_debug("Watchdog timer - setting heartbeat timer_set is %x (hex)\n",
+ watchdog_device.timer_set);
+
+ /* temporarily disable the timer */
+ iowrite32(0x00000002, watchdog_device.timer_control_addr);
+
+ /* send the threshold and soft_threshold via IPC to the Lincroft */
+ reg_data.payload1 = watchdog_device.soft_threshold;
+ reg_data.payload2 = watchdog_device.threshold;
+ ipc_set_watchdog(&reg_data);
+
+ pr_debug("Watchdog timer - setting timer to %x (hex)\n",
+ watchdog_device.soft_threshold);
+
+ /* set the timer to the soft threshold */
+ iowrite32(watchdog_device.soft_threshold,
+ watchdog_device.timer_load_count_addr);
+
+ /* read the timer to verify that it has been set */
+ pr_debug("Watchdog timer - watchdog - timer value is %x (hex)\n",
+ ioread32(watchdog_device.timer_current_value_addr));
+
+ /* allow the timer to run */
+ iowrite32(0x00000003, watchdog_device.timer_control_addr);
+
+ watchdog_device.timer_started = 1;
+
+ return nonseekable_open(inode, file);
+}
+
+static int langwell_release(struct inode *inode, struct file *file)
+{
+ /*
+ * This watchdog may not be closed! Reboot immediately.
+ */
+ printk(KERN_CRIT PFX
+ "Unexpected close, firing off the watchdog!\n");
+
+ clear_bit(0, &watchdog_device.driver_open);
+
+ /* Reboot system (if force_boot is set) */
+ watchdog_fire();
+
+ /* We should never reach this point. */
+ return 0;
+}
+
+static ssize_t langwell_write(struct file *file,
+ char const *data,
+ size_t len,
+ loff_t *ppos)
+{
+ pr_debug("Langwell Watchdog - write; calling keepalive\n");
+
+ langwell_keepalive();
+
+ return len;
+}
+
+static ssize_t langwell_read(struct file *file,
+ char __user *user_data,
+ size_t len,
+ loff_t *user_ppos)
+{
+ int result;
+ u8 buf = 0;
+
+ pr_debug("Langwell Watchdog - read function called;"
+ " wait for interrupt\n");
+
+ /* we wait for the next interrupt; if more than one */
+ /* interrupt has occurered since the last read, we */
+ /* dont care. The data is not critical. We will do */
+ /* a copy to user each time we get and interrupt */
+ /* It is up to the Watchdog daemon to be ready to */
+ /* do the read (shich signifies that the driver is */
+ /* awaiting a keep alive and that a limited time */
+ /* is available for the keep alive before the system */
+ /* is rebooted by the timer */
+ wait_event_interruptible(read_wq, flag != 0);
+ flag = 0;
+
+ pr_debug("Langwell Watchdog read - interrupt received\n");
+
+ /* Please note that the content of the data is irrelevent */
+ /* All that matters is that the read is available to the user */
+ result = copy_to_user(user_data, (void *)&buf, 1);
+
+ if (result != 0)
+ return -EFAULT;
+ else
+ return 1;
+
+}
+
+static long langwell_ioctl(struct file *file,
+ unsigned int cmd,
+ unsigned long arg)
+{
+ void __user *argp = (void __user *)arg;
+ u32 __user *p = argp;
+ u32 new_margin;
+
+ static const struct watchdog_info ident = {
+ .options = WDIOF_SETTIMEOUT
+ | WDIOF_KEEPALIVEPING,
+ .firmware_version = 0, /* @todo Get from SCU via
+ ipc_get_scu_fw_version()? */
+ .identity = "Langwell IOH Watchdog" /* len < 32 */
+ };
+
+ switch (cmd) {
+ case WDIOC_GETSUPPORT:
+ return copy_to_user(argp,
+ &ident,
+ sizeof(ident)) ? -EFAULT : 0;
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ pr_debug("Watchdog timer - watchdog - timer current value is %x\n",
+ ioread32(watchdog_device.timer_current_value_addr));
+ return put_user(0, p);
+ case WDIOC_KEEPALIVE:
+ langwell_keepalive();
+
+ return 0;
+ case WDIOC_SETTIMEOUT:
+ if (get_user(new_margin, p))
+ return -EFAULT;
+
+ if ((new_margin < 0) || (new_margin > MAX_TIME)) {
+ pr_debug("Watchdog timer - value out of range\n"
+ "Value submitted is %d is out of range of %d"
+ " and %d\n", new_margin, MIN_TIME_CYCLE, MAX_TIME);
+ return -EINVAL;
+ }
+
+ pr_debug("Langwell Watchdog - set time out timer is %d\n",
+ new_margin);
+ if (langwell_set_heartbeat(new_margin))
+ return -EINVAL;
+ return 0;
+ case WDIOC_GETTIMEOUT:
+ return put_user(watchdog_device.soft_threshold, p);
+
+ default:
+ return -ENOTTY;
+ }
+}
+
+/*
+ * Notifier for system down
+ */
+static int langwell_notify_sys(struct notifier_block *this,
+ unsigned long code,
+ void *another_unused)
+{
+ if (code == SYS_DOWN || code == SYS_HALT)
+ /* Turn off the watchdog timer. */
+ langwell_stop();
+ return NOTIFY_DONE;
+}
+
+/*
+ * Kernel Interfaces
+ */
+static const struct file_operations langwell_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = langwell_write,
+ .read = langwell_read,
+ .unlocked_ioctl = langwell_ioctl,
+ .open = langwell_open,
+ .release = langwell_release,
+};
+
+static int __init watchdog_init(void)
+{
+ int ret;
+ u32 __iomem *tmp_addr;
+
+ watchdog_device.mtmr_ptr = sfi_get_mtmr(sfi_mtimer_num-1);
+
+ /* make sure the timer exists */
+ if (watchdog_device.mtmr_ptr->phy_addr == 0) {
+ pr_debug("Watchdog timer - langwell watchdog - timer %d does"
+ " not valid physical memory\n", sfi_mtimer_num);
+ return -ENODEV;
+ }
+
+ pr_debug("Watchdog timer timer sfi_mtimer_num is %d\n",
+ sfi_mtimer_num);
+ pr_debug("Watchdog timer timer phy_addr is %08x\n",
+ (unsigned int)watchdog_device.mtmr_ptr->phy_addr);
+ pr_debug("Watchdog timer timer IRQ is %d\n",
+ watchdog_device.mtmr_ptr->irq);
+ pr_debug("Watchdog timer timer freq is %d\n",
+ watchdog_device.mtmr_ptr->freq);
+
+ if (watchdog_device.mtmr_ptr->irq == 0) {
+ pr_debug("Watchdog timer - timer %d invalid irq\n",
+ sfi_mtimer_num);
+ return -ENODEV;
+ }
+
+ tmp_addr = ioremap_nocache(watchdog_device.mtmr_ptr->phy_addr, 20);
+
+ if (tmp_addr == NULL) {
+ pr_debug("Watchdog timer timer unable to ioremap\n");
+ return -ENOMEM;
+ }
+
+ watchdog_device.timer_load_count_addr = tmp_addr++;
+ watchdog_device.timer_current_value_addr = tmp_addr++;
+ watchdog_device.timer_control_addr = tmp_addr++;
+ watchdog_device.timer_clear_interrupt_addr = tmp_addr++;
+ watchdog_device.timer_interrupt_status_addr = tmp_addr++;
+
+ pr_debug("Watchdog timer base logical_addr is %08x\n",
+ (unsigned int)tmp_addr);
+ pr_debug("Watchdog timer - watchdog - timer load count is %08x\n",
+ ioread32(watchdog_device.timer_load_count_addr));
+ pr_debug("Watchdog timer - watchdog - timer current value is %08x\n",
+ ioread32(watchdog_device.timer_current_value_addr));
+ pr_debug("Watchdog timer - watchdog - timer control is %08x\n",
+ ioread32(watchdog_device.timer_control_addr));
+
+ watchdog_device.langwell_notifier.notifier_call =
+ langwell_notify_sys;
+
+ ret = register_reboot_notifier(&watchdog_device.langwell_notifier);
+ if (ret) {
+ printk(KERN_ERR PFX
+ "Watchdog timer - cannot register notifier %d)\n", ret);
+ goto register_reboot_error;
+ }
+
+ watchdog_device.miscdev.minor = WATCHDOG_MINOR,
+ watchdog_device.miscdev.name = "watchdog",
+ watchdog_device.miscdev.fops = &langwell_fops,
+
+ ret = misc_register(&watchdog_device.miscdev);
+ if (ret) {
+ printk(KERN_ERR PFX
+ "Watchdog timer - cannot register miscdev %d err =%d\n",
+ WATCHDOG_MINOR,
+ ret);
+ goto misc_register_error;
+ }
+
+ ret = request_irq((unsigned int)watchdog_device.mtmr_ptr->irq,
+ watchdog_timer_interrupt,
+ IRQF_SHARED, "watchdog", &watchdog_device.timer_load_count_addr);
+ if (ret) {
+ printk(KERN_ERR "Watchdog timer - error requesting irq\n");
+ printk(KERN_ERR "Watchdog timer - error value returned is %d\n",
+ ret);
+ goto request_irq_error;
+ }
+
+ return 0;
+
+/* error cleanup */
+
+request_irq_error:
+
+ misc_deregister(&watchdog_device.miscdev);
+
+misc_register_error:
+
+ unregister_reboot_notifier(&watchdog_device.langwell_notifier);
+
+register_reboot_error:
+
+ iounmap(watchdog_device.timer_load_count_addr);
+ return ret;
+}
+
+static void __exit watchdog_exit(void)
+{
+
+ misc_deregister(&watchdog_device.miscdev);
+ unregister_reboot_notifier(&watchdog_device.langwell_notifier);
+ /* disable the timer */
+ iowrite32(0x00000002, watchdog_device.timer_control_addr);
+ iounmap(watchdog_device.timer_load_count_addr);
+}
+
+module_init(watchdog_init);
+module_exit(watchdog_exit);
+
+MODULE_AUTHOR("Intel Corporation");
+MODULE_DESCRIPTION("Langwell Watchdog Device Driver");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
+MODULE_VERSION(WDT_VER);
+
diff --git a/drivers/watchdog/langwell_watchdog.h b/drivers/watchdog/langwell_watchdog.h
new file mode 100644
index 0000000..fa4280d
--- /dev/null
+++ b/drivers/watchdog/langwell_watchdog.h
@@ -0,0 +1,60 @@
+/*
+ * Langwell 0.2: An Intel Langwell IOH Based Watchdog Device
+ *
+ * Copyright (C) 2009 Intel Corporation. All rights reserved.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of version 2 of the GNU General
+ * Public License 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.
+ * You should have received a copy of the GNU General Public
+ * License along with this program; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place - Suite 330,
+ * Boston, MA 02111-1307, USA.
+ * The full GNU General Public License is included in this
+ * distribution in the file called COPYING.
+ *
+ */
+
+#ifndef __LANGWELL_WATCHDOG_H
+#define __LANGWELL_WATCHDOG_H
+
+#define PFX "Langwell: "
+#define WDT_VER "0.2"
+
+/* minimum time between interrupts */
+#define MIN_TIME_CYCLE 1
+
+/* Time from warning to reboot is 2 seconds */
+#define DEFAULT_SOFT_TO_HARD_MARGIN 2
+
+#define MAX_TIME 170
+
+#define DEFAULT_TIME 5
+
+#define MAX_SOFT_TO_HARD_MARGIN (MAX_TIME-MIN_TIME_CYCLE)
+
+struct langwell_watchdog_dev {
+ unsigned long driver_open;
+ u32 timer_started;
+ u32 timer_set;
+ u32 threshold;
+ u32 soft_threshold;
+ u32 __iomem *timer_load_count_addr;
+ u32 __iomem *timer_current_value_addr;
+ u32 __iomem *timer_control_addr;
+ u32 __iomem *timer_clear_interrupt_addr;
+ u32 __iomem *timer_interrupt_status_addr;
+ struct sfi_mtimer_entry *mtmr_ptr;
+ struct notifier_block langwell_notifier;
+ struct miscdevice miscdev;
+};
+
+extern int sfi_mtimer_num;
+
+/* extern struct sfi_timer_table_entry *sfi_get_mtmr(int hint); */
+#endif /* __LANGWELL_WATCHDOG_H */
--
1.6.0.6

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