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[PATCH][MIPS][5/7] AR7: watchdog timer

To: linux-mips@linux-mips.org
Subject: [PATCH][MIPS][5/7] AR7: watchdog timer
From: Matteo Croce <technoboy85@gmail.com>
Date: Sat, 8 Sep 2007 02:21:47 +0200
Cc: Nicolas Thill <nico@openwrt.org>, Enrik Berkhan <Enrik.Berkhan@akk.org>, Christer Weinigel <wingel@nano-system.com>, wim@iguana.be, openwrt-devel@lists.openwrt.org, Andrew Morton <akpm@linux-foundation.org>
Delivered-to: technoboy85@gmail.com
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Driver for the watchdog timer. It worked with 2.4, doesn't does with 2.6.
Apart that it doesn't reboots the device it works :)

Signed-off-by: Matteo Croce <technoboy85@gmail.com>
Signed-off-by: Nicolas Thill <nico@openwrt.org>
Signed-off-by: Enrik Berkhan <Enrik.Berkhan@akk.org>
Signed-off-by: Christer Weinigel <wingel@nano-system.com>

diff --git a/drivers/char/watchdog/Kconfig b/drivers/char/watchdog/Kconfig
index 37bddc1..78d4940 100644
--- a/drivers/char/watchdog/Kconfig
+++ b/drivers/char/watchdog/Kconfig
@@ -583,6 +583,12 @@ config SBC_EPX_C3_WATCHDOG
 
 # MIPS Architecture
 
+config AR7_WDT
+       tristate "TI AR7 Watchdog Timer"
+       depends on WATCHDOG && AR7
+       help
+         Hardware driver for the TI AR7 Watchdog Timer.
+
 config INDYDOG
        tristate "Indy/I2 Hardware Watchdog"
        depends on SGI_IP22
diff --git a/drivers/char/watchdog/Makefile b/drivers/char/watchdog/Makefile
index 389f8b1..76424f2 100644
--- a/drivers/char/watchdog/Makefile
+++ b/drivers/char/watchdog/Makefile
@@ -87,6 +87,7 @@ obj-$(CONFIG_SBC_EPX_C3_WATCHDOG) += sbc_epx_c3.o
 # M68KNOMMU Architecture
 
 # MIPS Architecture
+obj-$(CONFIG_AR7_WDT) += ar7_wdt.o
 obj-$(CONFIG_INDYDOG) += indydog.o
 obj-$(CONFIG_WDT_MTX1) += mtx-1_wdt.o
 obj-$(CONFIG_WDT_RM9K_GPI) += rm9k_wdt.o
diff --git a/drivers/char/watchdog/ar7_wdt.c b/drivers/char/watchdog/ar7_wdt.c
new file mode 100644
index 0000000..3117ffc
--- /dev/null
+++ b/drivers/char/watchdog/ar7_wdt.c
@@ -0,0 +1,346 @@
+/*
+ * 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>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * 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., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/notifier.h>
+#include <linux/reboot.h>
+#include <linux/fs.h>
+#include <linux/ioport.h>
+#include <linux/io.h>
+#include <linux/uaccess.h>
+
+#include <asm/addrspace.h>
+#include <asm/ar7/ar7.h>
+
+#define DRVNAME "ar7_wdt"
+#define LONGNAME "TI AR7 Watchdog Timer"
+
+MODULE_AUTHOR("Nicolas Thill <nico@openwrt.org>");
+MODULE_DESCRIPTION(LONGNAME);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
+
+static int margin = 60;
+module_param(margin, int, 0);
+MODULE_PARM_DESC(margin, "Watchdog margin in seconds");
+
+static int nowayout = WATCHDOG_NOWAYOUT;
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Disable watchdog shutdown on close");
+
+struct ar7_wdt {
+       u32 kick_lock;
+       u32 kick;
+       u32 change_lock;
+       u32 change ;
+       u32 disable_lock;
+       u32 disable;
+       u32 prescale_lock;
+       u32 prescale;
+};
+
+static struct semaphore open_semaphore;
+static unsigned expect_close;
+
+/* XXX currently fixed, allows max margin ~68.72 secs */
+#define prescale_value 0xFFFF
+
+/* Offset of the WDT registers */
+static unsigned long ar7_regs_wdt;
+/* Pointer to the remapped WDT IO space */
+static struct ar7_wdt *ar7_wdt;
+static void ar7_wdt_get_regs(void)
+{
+       u16 chip_id = ar7_chip_id();
+       switch (chip_id) {
+       case AR7_CHIP_7100:
+       case AR7_CHIP_7200:
+               ar7_regs_wdt = AR7_REGS_WDT;
+               break;
+       default:
+               ar7_regs_wdt = UR8_REGS_WDT;
+               break;
+       }
+}
+
+
+static void ar7_wdt_kick(u32 value)
+{
+       ar7_wdt->kick_lock = 0x5555;
+       if ((ar7_wdt->kick_lock & 3) == 1) {
+               ar7_wdt->kick_lock = 0xAAAA;
+               if ((ar7_wdt->kick_lock & 3) == 3) {
+                       ar7_wdt->kick = value;
+                       return;
+               }
+       }
+       printk(KERN_ERR DRVNAME ": failed to unlock WDT kick reg\n");
+}
+
+static void ar7_wdt_prescale(u32 value)
+{
+       ar7_wdt->prescale_lock = 0x5A5A;
+       if ((ar7_wdt->prescale_lock & 3) == 1) {
+               ar7_wdt->prescale_lock = 0xA5A5;
+               if ((ar7_wdt->prescale_lock & 3) == 3) {
+                       ar7_wdt->prescale = value;
+                       return;
+               }
+       }
+       printk(KERN_ERR DRVNAME ": failed to unlock WDT prescale reg\n");
+}
+
+static void ar7_wdt_change(u32 value)
+{
+       ar7_wdt->change_lock = 0x6666;
+       if ((ar7_wdt->change_lock & 3) == 1) {
+               ar7_wdt->change_lock = 0xBBBB;
+               if ((ar7_wdt->change_lock & 3) == 3) {
+                       ar7_wdt->change = value;
+                       return;
+               }
+       }
+       printk(KERN_ERR DRVNAME ": failed to unlock WDT change reg\n");
+}
+
+static void ar7_wdt_disable(u32 value)
+{
+       ar7_wdt->disable_lock = 0x7777;
+       if ((ar7_wdt->disable_lock & 3) == 1) {
+               ar7_wdt->disable_lock = 0xCCCC;
+               if ((ar7_wdt->disable_lock & 3) == 2) {
+                       ar7_wdt->disable_lock = 0xDDDD;
+                       if ((ar7_wdt->disable_lock & 3) == 3) {
+                               ar7_wdt->disable = value;
+                               return;
+                       }
+               }
+       }
+       printk(KERN_ERR DRVNAME ": failed to unlock WDT disable reg\n");
+}
+
+static void ar7_wdt_update_margin(int new_margin)
+{
+       u32 change;
+
+       change = new_margin * (ar7_vbus_freq() / prescale_value);
+       if (change < 1) change = 1;
+       if (change > 0xFFFF) change = 0xFFFF;
+       ar7_wdt_change(change);
+       margin = change * prescale_value / ar7_vbus_freq();
+       printk(KERN_INFO DRVNAME
+              ": timer margin %d seconds (prescale %d, change %d, freq %d)\n",
+              margin, prescale_value, change, ar7_vbus_freq());
+}
+
+static void ar7_wdt_enable_wdt(void)
+{
+       printk(KERN_DEBUG DRVNAME ": enabling watchdog timer\n");
+       ar7_wdt_disable(1);
+       ar7_wdt_kick(1);
+}
+
+static void ar7_wdt_disable_wdt(void)
+{
+       printk(KERN_DEBUG DRVNAME ": 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 (down_trylock(&open_semaphore))
+               return -EBUSY;
+       ar7_wdt_enable_wdt();
+       expect_close = 0;
+
+       return 0;
+}
+
+static int ar7_wdt_release(struct inode *inode, struct file *file)
+{
+       if (!expect_close) {
+               printk(KERN_WARNING DRVNAME
+               ": watchdog device closed unexpectedly,"
+               "will not disable the watchdog timer\n");
+       } else if (!nowayout) {
+               ar7_wdt_disable_wdt();
+       }
+       up(&open_semaphore);
+
+       return 0;
+}
+
+static int ar7_wdt_notify_sys(struct notifier_block *this,
+                             unsigned long code, void *unused)
+{
+       if (code == SYS_HALT || code == SYS_POWER_OFF)
+               if (!nowayout)
+                       ar7_wdt_disable_wdt();
+
+       return NOTIFY_DONE;
+}
+
+static struct notifier_block ar7_wdt_notifier = {
+       .notifier_call = ar7_wdt_notify_sys
+};
+
+static ssize_t ar7_wdt_write(struct file *file, const char *data,
+                            size_t len, loff_t *ppos)
+{
+       if (ppos != &file->f_pos)
+               return -ESPIPE;
+
+       /* check for a magic close character */
+       if (len) {
+               size_t i;
+
+               ar7_wdt_kick(1);
+
+               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 int ar7_wdt_ioctl(struct inode *inode, struct file *file,
+                        unsigned int cmd, unsigned long arg)
+{
+       static struct watchdog_info ident = {
+               .identity = LONGNAME,
+               .firmware_version = 1,
+               .options = (WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING),
+       };
+       int new_margin;
+
+       switch (cmd) {
+       default:
+               return -ENOTTY;
+       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;
+
+               ar7_wdt_update_margin(new_margin);
+               ar7_wdt_kick(1);
+
+       case WDIOC_GETTIMEOUT:
+               if (put_user(margin, (int *)arg))
+                       return -EFAULT;
+               return 0;
+       }
+}
+
+static struct file_operations ar7_wdt_fops = {
+       .owner   = THIS_MODULE,
+       .write   = ar7_wdt_write,
+       .ioctl   = ar7_wdt_ioctl,
+       .open    = ar7_wdt_open,
+       .release = ar7_wdt_release,
+};
+
+static struct miscdevice ar7_wdt_miscdev = {
+       .minor = WATCHDOG_MINOR,
+       .name  = "watchdog",
+       .fops  = &ar7_wdt_fops,
+};
+
+static int __init ar7_wdt_init(void)
+{
+       int rc;
+
+    ar7_wdt_get_regs();
+
+       if (!request_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt),
+                                                       LONGNAME)) {
+               printk(KERN_WARNING DRVNAME ": watchdog I/O region busy\n");
+               return -EBUSY;
+       }
+
+       ar7_wdt = (struct ar7_wdt *)
+                       ioremap(ar7_regs_wdt, sizeof(struct ar7_wdt));
+
+       ar7_wdt_disable_wdt();
+       ar7_wdt_prescale(prescale_value);
+       ar7_wdt_update_margin(margin);
+
+       sema_init(&open_semaphore, 1);
+
+       rc = misc_register(&ar7_wdt_miscdev);
+       if (rc) {
+               printk(KERN_ERR DRVNAME ": unable to register misc device\n");
+               goto out_alloc;
+       }
+
+       rc = register_reboot_notifier(&ar7_wdt_notifier);
+       if (rc) {
+               printk(KERN_ERR DRVNAME
+                       ": unable to register reboot notifier\n");
+               goto out_register;
+       }
+       goto out;
+
+out_register:
+       misc_deregister(&ar7_wdt_miscdev);
+out_alloc:
+       release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
+out:
+       return rc;
+}
+
+static void __exit ar7_wdt_cleanup(void)
+{
+       unregister_reboot_notifier(&ar7_wdt_notifier);
+       misc_deregister(&ar7_wdt_miscdev);
+       iounmap(ar7_wdt);
+       release_mem_region(ar7_regs_wdt, sizeof(struct ar7_wdt));
+}
+
+module_init(ar7_wdt_init);
+module_exit(ar7_wdt_cleanup);

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