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Date: Thu, 2 Jan 2014 23:54:47 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: eric.ernst@...ux.intel.com
Cc: wim@...ana.be, linux-watchdog@...r.kernel.org,
linux-kernel@...r.kernel.org,
Gabriel Touzeau <gabrielx.touzeau@...el.com>,
Yann Puech <yann.puech@...el.com>,
Jeremy Compostella <jeremy.compostella@...el.com>,
David Cohen <david.a.cohen@...ux.intel.com>
Subject: Re: [PATCH 1/1] watchdog: Adding Merrifield watchdog driver support
Hi Gabriel,
On Thu, Jan 02, 2014 at 04:56:42PM -0800, eric.ernst@...ux.intel.com wrote:
> +
> +/* Statics */
> +static struct intel_scu_watchdog_dev watchdog_device;
> +
> +/* Module params */
> +static bool disable_kernel_watchdog;
> +module_param(disable_kernel_watchdog, bool, S_IRUGO);
> +MODULE_PARM_DESC(disable_kernel_watchdog,
> + "Disable kernel watchdog"
> + "Set to 0, watchdog started at boot"
> + "and left running; Set to 1; watchdog"
> + "is not started until user space"
> + "watchdog daemon is started; also if the"
> + "timer is started by the iafw firmware, it"
> + "will be disabled upon initialization of this"
> + "driver if disable_kernel_watchdog is set");
You need to add spaces at the end of your strings otheriwse
concatenation will produce a mess.
> +
> +static int pre_timeout = DEFAULT_PRETIMEOUT;
> +module_param(pre_timeout, int, S_IRUGO | S_IWUSR);
> +MODULE_PARM_DESC(pre_timeout,
> + "Watchdog pre timeout"
> + "Time between interrupt and resetting the system"
> + "The range is from 1 to 160");
> +
> +static int timeout = DEFAULT_TIMEOUT;
> +module_param(timeout, int, S_IRUGO | S_IWUSR);
> +MODULE_PARM_DESC(timeout,
> + "Default Watchdog timer setting"
> + "Complete cycle time"
> + "The range is from 1 to 170"
> + "This is the time for all keep alives to arrive");
> +
> +/* Setting reset_on_release will cause an immediate reset when the watchdog
> + * is released. If false, the watchdog timer is refreshed for one more
> + * interval. At the end of that interval, the watchdog timer will reset the
> + * system.
> + */
Multi-line comments in majority of kernel code are in form of
/*
* Multi-line comment should be
* formatted like this.
*/
> +static bool reset_on_release = true;
> +
> +/* Check current timeouts */
> +static int check_timeouts(int pre_timeout_time, int timeout_time)
> +{
> + if (pre_timeout_time < timeout_time)
> + return 0;
> +
> + return -EINVAL;
> +}
> +
> +/* Set the different timeouts needed by the SCU FW and start the
> + * kernel watchdog */
> +static int watchdog_set_timeouts_and_start(int pretimeout,
> + int timeout)
> +{
> + int ret, input_size;
> + struct ipc_wd_start {
> + u32 pretimeout;
> + u32 timeout;
> + } ipc_wd_start = { pretimeout, timeout };
> +
> + /* SCU expects the input size for watchdog IPC to
> + * be based on double-word */
> + input_size = (sizeof(ipc_wd_start) + 3) / 4;
> +
> + ret = intel_scu_ipc_command(IPC_WATCHDOG,
> + SCU_WATCHDOG_START, (u32 *)&ipc_wd_start,
> + input_size, NULL, 0);
> + if (ret) {
> + pr_crit("Error configuring and starting watchdog: %d\n",
> + ret);
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> +/* Provisioning function for future enhancement : allow to fine tune timing
> + according to watchdog action settings */
> +static int watchdog_set_appropriate_timeouts(void)
> +{
> + pr_debug("Setting shutdown timeouts\n");
> + return watchdog_set_timeouts_and_start(pre_timeout, timeout);
> +}
> +
> +/* Keep alive */
> +static int watchdog_keepalive(void)
> +{
> + int ret;
> +
> + /* Pet the watchdog */
> + ret = intel_scu_ipc_command(IPC_WATCHDOG,
> + SCU_WATCHDOG_KEEPALIVE, NULL, 0, NULL, 0);
> + if (ret) {
> + pr_crit("Error executing keepalive: %x\n", ret);
> + return -EIO;
> + }
> +
> + return 0;
> +}
> +
> +/* stops the timer */
> +static int watchdog_stop(void)
> +{
> + int ret;
> +
> + watchdog_device.started = false;
> +
> + ret = intel_scu_ipc_command(IPC_WATCHDOG,
> + SCU_WATCHDOG_STOP, NULL, 0, NULL, 0);
> + if (ret) {
> + pr_crit("Error stopping watchdog: %x\n", ret);
> + return -EIO;
> + }
> + return 0;
> +}
> +
> +/* warning interrupt handler */
> +static irqreturn_t watchdog_warning_interrupt(int irq, void *dev_id)
> +{
> + pr_warn("[SHTDWN] %s, WATCHDOG TIMEOUT!\n", __func__);
> +
> + /* Let's reset the platform after dumping some data */
> + trigger_all_cpu_backtrace();
> + panic("Kernel Watchdog");
> +
> + /* This code should not be reached */
> + return IRQ_HANDLED;
> +}
> +
> +/* Program and starts the timer */
> +static int watchdog_config_and_start(u32 newtimeout, u32 newpretimeout)
> +{
> + int ret;
> +
> + timeout = newtimeout;
> + pre_timeout = newpretimeout;
> +
> + pr_info("timeout=%ds, pre_timeout=%ds\n", timeout, pre_timeout);
> +
> + /* Configure the watchdog */
> + ret = watchdog_set_timeouts_and_start(pre_timeout, timeout);
> + if (ret) {
> + pr_err("%s: Cannot configure the watchdog\n", __func__);
> +
> + /* Make sure the watchdog timer is stopped */
> + watchdog_stop();
> + return ret;
> + }
> +
> + watchdog_device.started = true;
> +
> + return 0;
> +}
> +
> +/* Open */
> +static int intel_scu_open(struct inode *inode, struct file *file)
> +{
> + /* Set flag to indicate that watchdog device is open */
> + if (test_and_set_bit(0, &watchdog_device.driver_open)) {
> + pr_err("watchdog device is busy\n");
You probably do not want to spam the logs. Returning -EBUSY should be
enough.
> + return -EBUSY;
> + }
> +
> + return nonseekable_open(inode, file);
> +}
> +
> +/* Release */
> +static int intel_scu_release(struct inode *inode, struct file *file)
> +{
> + /*
> + * This watchdog should not be closed after the timer
> + * is started with the WDIPC_SETTIMEOUT ioctl.
> + * If reset_on_release is set this will cause an
> + * immediate reset. If reset_on_release is not set, the watchdog
> + * timer is refreshed for one more interval. At the end
> + * of that interval, the watchdog timer will reset the system.
> + */
> +
> + if (!test_bit(0, &watchdog_device.driver_open)) {
> + pr_err("intel_scu_release, without open\n");
> + return -ENOTTY;
> + }
> +
> + if (!watchdog_device.started) {
> + /* Just close, since timer has not been started */
> + pr_err("Closed, without starting timer\n");
Why pr_err? It looks like it might be useful when debugging the driver,
but not for production code.
Thanks.
--
Dmitry
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