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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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