Re: [PATCH v4] watchdog: nic7018_wdt: Add NIC7018 watchdog driver

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Hi,

On 12/15/2016 02:05 AM, Hui Chun Ong wrote:
Add support for the watchdog timer on PXI Embedded Controller.

Signed-off-by: Hui Chun Ong <hui.chun.ong@xxxxxx>
---
v3: Update timeout calculation from miliseconds to seconds.
    Reorder watchdog_regiser_device() call to prevent potential race condition.

v2: Remove mutex lock and platform_device *pdev fields from struct nic7018_wdt.
    Update config NIC7018_WDT description.
    Update nic7018_get_config() to never return error.
    Remove checking for IO resource size in nic7018_probe().

v1: Remove non-standard attributes.
    Change from acpi_driver to platform_driver.
    Rename driver from ni7018_wdt to nic7018_wdt.
---
 Documentation/watchdog/watchdog-parameters.txt |   5 +
 drivers/watchdog/Kconfig                       |  10 +
 drivers/watchdog/Makefile                      |   1 +
 drivers/watchdog/nic7018_wdt.c                 | 265 +++++++++++++++++++++++++
 4 files changed, 281 insertions(+)
 create mode 100644 drivers/watchdog/nic7018_wdt.c


[ ... ]

+
+static int nic7018_probe(struct platform_device *pdev)
+{
+	struct device *dev = &pdev->dev;
+	struct watchdog_device *wdd;
+	struct nic7018_wdt *wdt;
+	struct resource *io_rc;
+	int ret;
+
+	wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
+	if (!wdt)
+		return -ENOMEM;
+
+	platform_set_drvdata(pdev, wdt);
+
+	io_rc = platform_get_resource(pdev, IORESOURCE_IO, 0);
+	if (!io_rc) {
+		dev_err(dev, "missing IO resources\n");
+		return -EINVAL;
+	}
+
+	if (!devm_request_region(dev, io_rc->start, resource_size(io_rc),
+				 KBUILD_MODNAME)) {
+		dev_err(dev, "failed to get IO region\n");
+		return -EBUSY;
+	}
+
+	wdt->io_base = io_rc->start;
+	wdd = &wdt->wdd;
+	wdd->info = &nic7018_wdd_info;
+	wdd->ops = &nic7018_wdd_ops;
+	wdd->min_timeout = WDT_MIN_TIMEOUT;
+	wdd->max_timeout = WDT_MAX_TIMEOUT;
+	wdd->timeout = WDT_DEFAULT_TIMEOUT;
+	wdd->parent = dev;
+
+	watchdog_set_drvdata(wdd, wdt);
+	watchdog_set_nowayout(wdd, nowayout);
+
+	ret = watchdog_init_timeout(wdd, timeout, dev);
+	if (ret)
+		dev_warn(dev, "unable to set timeout value, using default\n");
+
+	/* Unlock WDT register */
+	outb(UNLOCK, wdt->io_base + WDT_REG_LOCK);
+
+	ret = watchdog_register_device(wdd);
+	if (ret) {
+		dev_err(dev, "failed to register watchdog\n");

I don't want to be annoying, but for consistency you'll need to lock the device here.

+		return ret;
+	}
+
+	dev_dbg(dev, "io_base=0x%04X, timeout=%d, nowayout=%d\n",
+		wdt->io_base, timeout, nowayout);
+	return 0;
+}
+
+static int nic7018_remove(struct platform_device *pdev)
+{
+	struct nic7018_wdt *wdt = platform_get_drvdata(pdev);
+
+	nic7018_stop(&wdt->wdd);

This always bothers me. I _think_ the core will prevent a driver from unloading
while the watchdog is running open (and thus might be running), which would make
this unnecessary. But I am never really sure and will have to look it up.

Guenter

+	watchdog_unregister_device(&wdt->wdd);
+
+	/* Lock WDT register */
+	outb(LOCK, wdt->io_base + WDT_REG_LOCK);
+
+	return 0;
+}
+
+static const struct acpi_device_id nic7018_device_ids[] = {
+	{"NIC7018", 0},
+	{"", 0},
+};
+MODULE_DEVICE_TABLE(acpi, nic7018_device_ids);
+
+static struct platform_driver watchdog_driver = {
+	.probe = nic7018_probe,
+	.remove = nic7018_remove,
+	.driver = {
+		.name = KBUILD_MODNAME,
+		.acpi_match_table = ACPI_PTR(nic7018_device_ids),
+	},
+};
+
+module_platform_driver(watchdog_driver);
+
+MODULE_DESCRIPTION("National Instruments NIC7018 Watchdog driver");
+MODULE_AUTHOR("Hui Chun Ong <hui.chun.ong@xxxxxx>");
+MODULE_LICENSE("GPL");
--
2.7.4

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