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Subject[PATCH] watchdog: support for max63xx watchdog timer chips
This driver adds support for the max63{69,70,71,72,73,74} family of
watchdog timer chips.
It has been tested on an Arcom Zeus (max6369).

Signed-off-by: Marc Zyngier <maz@misterjones.org>
---
drivers/watchdog/Kconfig | 5 +
drivers/watchdog/Makefile | 1 +
drivers/watchdog/max63xx_wdt.c | 397 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 403 insertions(+), 0 deletions(-)
create mode 100644 drivers/watchdog/max63xx_wdt.c
diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
index 088f32f..42a70ed 100644
--- a/drivers/watchdog/Kconfig
+++ b/drivers/watchdog/Kconfig
@@ -55,6 +55,11 @@ config SOFT_WATCHDOG
To compile this driver as a module, choose M here: the
module will be called softdog.

+config MAX63XX_WATCHDOG
+ tristate "Max63xx watchdog"
+ help
+ Support for memory mapped max63{69,70,71,72,73,74} watchdog timer.
+
config WM831X_WATCHDOG
tristate "WM831x watchdog"
depends on MFD_WM831X
diff --git a/drivers/watchdog/Makefile b/drivers/watchdog/Makefile
index 475c611..041caf2 100644
--- a/drivers/watchdog/Makefile
+++ b/drivers/watchdog/Makefile
@@ -142,4 +142,5 @@ obj-$(CONFIG_WATCHDOG_CP1XXX) += cpwd.o
# Architecture Independant
obj-$(CONFIG_WM831X_WATCHDOG) += wm831x_wdt.o
obj-$(CONFIG_WM8350_WATCHDOG) += wm8350_wdt.o
+obj-$(CONFIG_MAX63XX_WATCHDOG) += max63xx_wdt.o
obj-$(CONFIG_SOFT_WATCHDOG) += softdog.o
diff --git a/drivers/watchdog/max63xx_wdt.c b/drivers/watchdog/max63xx_wdt.c
new file mode 100644
index 0000000..ae8b2c3
--- /dev/null
+++ b/drivers/watchdog/max63xx_wdt.c
@@ -0,0 +1,397 @@
+/*
+ * drivers/char/watchdog/max63xx_wdt.c
+ *
+ * Driver for max63{69,70,71,72,73,74} watchdog timers
+ *
+ * Copyright (C) 2009 Marc Zyngier <maz@misterjones.org>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ *
+ * This driver assumes the watchdog pins are memory mapped (as it is
+ * the case for the Arcom Zeus). Should it be connected over GPIOs or
+ * another interface, some abstraction will have to be introduced.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/fs.h>
+#include <linux/miscdevice.h>
+#include <linux/watchdog.h>
+#include <linux/init.h>
+#include <linux/bitops.h>
+#include <linux/platform_device.h>
+#include <linux/spinlock.h>
+#include <linux/uaccess.h>
+#include <linux/io.h>
+#include <linux/device.h>
+
+#define DEFAULT_HEARTBEAT 60
+#define MAX_HEARTBEAT 60
+
+static int heartbeat = DEFAULT_HEARTBEAT;
+static int nowayout = WATCHDOG_NOWAYOUT;
+
+/*
+ * Memory mapping: a single byte, 3 first lower bits to select bit 3
+ * to ping the watchdog.
+ */
+#define MAX6369_WDSET (7 << 0)
+#define MAX6369_WDI (1 << 3)
+
+static DEFINE_SPINLOCK(io_lock);
+
+static unsigned long wdt_status;
+#define WDT_IN_USE 0
+#define WDT_RUNNING 1
+#define WDT_OK_TO_CLOSE 2
+
+static int nodelay;
+static struct resource *wdt_mem;
+static void __iomem *wdt_base;
+static struct platform_device *max63xx_pdev;
+
+/*
+ * The timeout values used are actually the absolute minimum the chip
+ * offers. Typical values on my board are slightly over twice as long
+ * (10s setting ends up with a 25s timeout), and can be up to 3 times
+ * the nominal setting (according to the datasheet). So please take
+ * these values with a grain of salt. Same goes for the initial delay
+ * "feature". Only max6373/74 have a few settings without this initial
+ * delay (selected with the "nodelay" parameter).
+ *
+ * I also decided to remove from the tables any timeout smaller than a
+ * second, as it looked completly overkill...
+ */
+
+/* Timeouts in second */
+struct max63xx_timeout {
+ u8 wdset;
+ u8 tdelay;
+ u8 twd;
+};
+
+static struct max63xx_timeout max6369_table[] = {
+ { 5, 1, 1 },
+ { 6, 10, 10 },
+ { 7, 60, 60 },
+ { },
+};
+
+static struct max63xx_timeout max6371_table[] = {
+ { 6, 60, 3 },
+ { 7, 60, 60 },
+ { },
+};
+
+static struct max63xx_timeout max6373_table[] = {
+ { 2, 60, 1 },
+ { 5, 0, 1 },
+ { 1, 3, 3 },
+ { 7, 60, 10 },
+ { 6, 0, 10 },
+ { },
+};
+
+static struct max63xx_timeout *current_timeout;
+
+static struct max63xx_timeout *
+max63xx_select_timeout(struct max63xx_timeout *table, int value)
+{
+ while (table->twd) {
+ if (value <= table->twd) {
+ if (nodelay && table->tdelay == 0)
+ return table;
+
+ if (!nodelay)
+ return table;
+ }
+
+ table++;
+ }
+
+ return NULL;
+}
+
+static void max63xx_wdt_ping(void)
+{
+ u8 val;
+
+ spin_lock(&io_lock);
+
+ val = __raw_readb(wdt_base);
+
+ __raw_writeb(val | MAX6369_WDI, wdt_base);
+ __raw_writeb(val & ~MAX6369_WDI, wdt_base);
+
+ spin_unlock(&io_lock);
+}
+
+static void max63xx_wdt_enable(struct max63xx_timeout *entry)
+{
+ u8 val;
+
+ if (test_and_set_bit(WDT_RUNNING, &wdt_status))
+ return;
+
+ spin_lock(&io_lock);
+
+ val = __raw_readb(wdt_base);
+ val &= ~MAX6369_WDSET;
+ val |= entry->wdset;
+ __raw_writeb(val, wdt_base);
+
+ spin_unlock(&io_lock);
+
+ /* check for a edge triggered startup */
+ if (entry->tdelay == 0)
+ max63xx_wdt_ping();
+}
+
+static void max63xx_wdt_disable(void)
+{
+ spin_lock(&io_lock);
+
+ __raw_writeb(3, wdt_base);
+
+ spin_unlock(&io_lock);
+
+ clear_bit(WDT_RUNNING, &wdt_status);
+}
+
+static int max63xx_wdt_open(struct inode *inode, struct file *file)
+{
+ if (test_and_set_bit(WDT_IN_USE, &wdt_status))
+ return -EBUSY;
+
+ max63xx_wdt_enable(current_timeout);
+ clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+ return nonseekable_open(inode, file);
+}
+
+static ssize_t max63xx_wdt_write(struct file *file, const char *data,
+ size_t len, loff_t *ppos)
+{
+ if (len) {
+ if (!nowayout) {
+ size_t i;
+
+ clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+ for (i = 0; i != len; i++) {
+ char c;
+
+ if (get_user(c, data + i))
+ return -EFAULT;
+
+ if (c == 'V')
+ set_bit(WDT_OK_TO_CLOSE, &wdt_status);
+ }
+ }
+
+ max63xx_wdt_ping();
+ }
+
+ return len;
+}
+
+static struct watchdog_info ident = {
+ .options = WDIOF_MAGICCLOSE | WDIOF_KEEPALIVEPING,
+ .identity = "max63xx Watchdog",
+};
+
+static long max63xx_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 *)arg, &ident,
+ sizeof(ident)) ? -EFAULT : 0;
+ break;
+
+ case WDIOC_GETSTATUS:
+ case WDIOC_GETBOOTSTATUS:
+ ret = put_user(0, (int *)arg);
+ break;
+
+ case WDIOC_KEEPALIVE:
+ max63xx_wdt_ping();
+ ret = 0;
+ break;
+
+ case WDIOC_GETTIMEOUT:
+ ret = put_user(heartbeat, (int *)arg);
+ break;
+ }
+ return ret;
+}
+
+static int max63xx_wdt_release(struct inode *inode, struct file *file)
+{
+ if (test_bit(WDT_OK_TO_CLOSE, &wdt_status))
+ max63xx_wdt_disable();
+ else
+ dev_crit(&max63xx_pdev->dev,
+ "device closed unexpectedly - timer will not stop\n");
+
+ clear_bit(WDT_IN_USE, &wdt_status);
+ clear_bit(WDT_OK_TO_CLOSE, &wdt_status);
+
+ return 0;
+}
+
+static const struct file_operations max63xx_wdt_fops = {
+ .owner = THIS_MODULE,
+ .llseek = no_llseek,
+ .write = max63xx_wdt_write,
+ .unlocked_ioctl = max63xx_wdt_ioctl,
+ .open = max63xx_wdt_open,
+ .release = max63xx_wdt_release,
+};
+
+static struct miscdevice max63xx_wdt_miscdev = {
+ .minor = WATCHDOG_MINOR,
+ .name = "watchdog",
+ .fops = &max63xx_wdt_fops,
+};
+
+static int __devinit max63xx_wdt_probe(struct platform_device *pdev)
+{
+ int ret = 0;
+ int size;
+ struct resource *res;
+ struct device *dev = &pdev->dev;
+ struct max63xx_timeout *table;
+
+ table = (struct max63xx_timeout *)pdev->id_entry->driver_data;
+
+ if (heartbeat < 1 || heartbeat > MAX_HEARTBEAT)
+ heartbeat = DEFAULT_HEARTBEAT;
+
+ dev_info(dev, "requesting %ds heartbeat\n", heartbeat);
+ current_timeout = max63xx_select_timeout(table, heartbeat);
+
+ if (!current_timeout) {
+ dev_err(dev, "unable to satisfy heartbeat request\n");
+ return -EINVAL;
+ }
+
+ dev_info(dev, "using %ds heartbeat with %ds initial delay\n",
+ current_timeout->twd, current_timeout->tdelay);
+
+ heartbeat = current_timeout->twd;
+
+ max63xx_pdev = pdev;
+
+ res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+ if (res == NULL) {
+ dev_err(dev, "failed to get memory region resource\n");
+ return -ENOENT;
+ }
+
+ size = resource_size(res);
+ wdt_mem = request_mem_region(res->start, size, pdev->name);
+
+ if (wdt_mem == NULL) {
+ dev_err(dev, "failed to get memory region\n");
+ return -ENOENT;
+ }
+
+ wdt_base = ioremap(res->start, size);
+ if (!wdt_base) {
+ dev_err(dev, "failed to map memory region\n");
+ ret = -ENOMEM;
+ goto out_request;
+ }
+
+ ret = misc_register(&max63xx_wdt_miscdev);
+ if (ret < 0) {
+ dev_err(dev, "cannot register misc device\n");
+ goto out_unmap;
+ }
+
+ return 0;
+
+out_unmap:
+ iounmap(wdt_base);
+out_request:
+ release_resource(wdt_mem);
+ kfree(wdt_mem);
+
+ return ret;
+}
+
+static int __devexit max63xx_wdt_remove(struct platform_device *pdev)
+{
+ misc_deregister(&max63xx_wdt_miscdev);
+ if (wdt_mem) {
+ release_resource(wdt_mem);
+ kfree(wdt_mem);
+ wdt_mem = NULL;
+ }
+
+ if (wdt_base)
+ iounmap(wdt_base);
+
+ return 0;
+}
+
+static struct platform_device_id max63xx_id_table[] = {
+ { "max6369_wdt", (kernel_ulong_t)max6369_table, },
+ { "max6370_wdt", (kernel_ulong_t)max6369_table, },
+ { "max6371_wdt", (kernel_ulong_t)max6371_table, },
+ { "max6372_wdt", (kernel_ulong_t)max6371_table, },
+ { "max6373_wdt", (kernel_ulong_t)max6373_table, },
+ { "max6374_wdt", (kernel_ulong_t)max6373_table, },
+ { },
+};
+MODULE_DEVICE_TABLE(platform, max63xx_id_table);
+
+static struct platform_driver max63xx_wdt_driver = {
+ .probe = max63xx_wdt_probe,
+ .remove = __devexit_p(max63xx_wdt_remove),
+ .id_table = max63xx_id_table,
+ .driver = {
+ .name = "max63xx_wdt",
+ .owner = THIS_MODULE,
+ },
+};
+
+static int __init max63xx_wdt_init(void)
+{
+ return platform_driver_register(&max63xx_wdt_driver);
+}
+
+static void __exit max63xx_wdt_exit(void)
+{
+ platform_driver_unregister(&max63xx_wdt_driver);
+}
+
+module_init(max63xx_wdt_init);
+module_exit(max63xx_wdt_exit);
+
+MODULE_AUTHOR("Marc Zyngier <maz@misterjones.org>");
+MODULE_DESCRIPTION("max63xx Watchdog Driver");
+
+module_param(heartbeat, int, 0);
+MODULE_PARM_DESC(heartbeat,
+ "Watchdog heartbeat period in seconds from 1 to "
+ __MODULE_STRING(MAX_HEARTBEAT) ", default "
+ __MODULE_STRING(DEFAULT_HEARTBEAT));
+
+module_param(nowayout, int, 0);
+MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default="
+ __MODULE_STRING(WATCHDOG_NOWAYOUT) ")");
+
+module_param(nodelay, int, 0);
+MODULE_PARM_DESC(nodelay,
+ "Force selection of a timeout setting without initial delay "
+ "(max6373/74 only, default=0)");
+
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_MISCDEV(WATCHDOG_MINOR);
--
1.6.6.1


--
I'm the slime oozin' out from your TV set...


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