On Sun, Nov 5, 2017 at 7:47 AM, Johan Hovold <jo...@kernel.org> wrote:
> On Tue, Oct 31, 2017 at 09:36:55AM -0700, Andrey Smirnov wrote:
>> This driver provides access to RAVE SP watchdog functionality.
>>
>> Cc: linux-kernel@vger.kernel.org
>> Cc: linux-watch...@vger.kernel.org
>> Cc: cphe...@gmail.com
>> Cc: Lucas Stach <l.st...@pengutronix.de>
>> Cc: Nikita Yushchenko <nikita.yo...@cogentembedded.com>
>> Cc: Lee Jones <lee.jo...@linaro.org>
>> Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
>> Cc: Pavel Machek <pa...@ucw.cz>
>> Cc: Andy Shevchenko <andy.shevche...@gmail.com>
>> Cc: Guenter Roeck <li...@roeck-us.net>
>> Cc: Rob Herring <r...@kernel.org>
>> Cc: Johan Hovold <jo...@kernel.org>
>> Cc: Sebastian Reichel <sebastian.reic...@collabora.co.uk>
>> Signed-off-by: Nikita Yushchenko <nikita.yo...@cogentembedded.com>
>> Signed-off-by: Andrey Smirnov <andrew.smir...@gmail.com>
>
>> +static const struct of_device_id rave_sp_wdt_of_match[] = {
>> + { .compatible = "zii,rave-sp-watchdog" },
>> + {}
>> +};
>
>> +static const struct of_device_id rave_sp_wdt_variants[] = {
>> + { .compatible = COMPATIBLE_RAVE_SP_NIU, .data = &rave_sp_wdt_legacy },
>> + { .compatible = COMPATIBLE_RAVE_SP_MEZZ, .data = &rave_sp_wdt_legacy },
>> + { .compatible = COMPATIBLE_RAVE_SP_ESB, .data = &rave_sp_wdt_legacy },
>> + { .compatible = COMPATIBLE_RAVE_SP_RDU1, .data = &rave_sp_wdt_rdu },
>> + { .compatible = COMPATIBLE_RAVE_SP_RDU2, .data = &rave_sp_wdt_rdu },
>> + { /* sentinel */ }
>> +};
>> +
>> +static int rave_sp_wdt_probe(struct platform_device *pdev)
>> +{
>> + struct device *dev = &pdev->dev;
>> + const struct of_device_id *id;
>> + struct watchdog_device *wdd;
>> + struct rave_sp_wdt *sp_wd;
>> + struct nvmem_cell *cell;
>> + __le16 timeout = 0;
>> + int ret;
>> +
>> + id = of_match_device(rave_sp_wdt_variants, dev->parent);
>
> So as I already mentioned in a comment on an earlier version of the MFD
> driver, I find this matching on the parent of_node to be an odd
> pattern, which also does not seem to have any precedent in mainline.
>
> It seems you really should be using two compatible strings for the
> watchdog (for the legacy and rdu variants) rather than keep an entry for
> every parent compatible-string in every child/cell driver (which all
> need to be kept in sync).
>
That's doable, for sure, but the downside is that it opens the door
for nonsensical configurations as, for example, "zii,rave-sp-niu" as a
parent SP device and "zii,rave-watchdog-rdu" as child watchdog and it
forces majority of child device drivers to split their compatibility
strings into 2 or more "flavors". My preference was to avoid that and
instead deal with having to having to keep things in sync.
> But let's see what Rob and Lee says about this.
>
>> + if (!id) {
>> + dev_err(dev, "Unknown parent device variant. Bailing out\n");
>> + return -ENODEV;
>> + }
>> +
>> + sp_wd = devm_kzalloc(dev, sizeof(*sp_wd), GFP_KERNEL);
>> + if (!sp_wd)
>> + return -ENOMEM;
>> +
>> + sp_wd->variant = id->data;
>> + sp_wd->sp = dev_get_drvdata(dev->parent);
>> +
>> + wdd = &sp_wd->wdd;
>> + wdd->parent = dev;
>> + wdd->info = &rave_sp_wdt_info;
>> + wdd->ops = &rave_sp_wdt_ops;
>> + wdd->min_timeout = sp_wd->variant->min_timeout;
>> + wdd->max_timeout = sp_wd->variant->max_timeout;
>> + wdd->status = WATCHDOG_NOWAYOUT_INIT_STATUS;
>> + wdd->timeout = 60;
>> +
>> + cell = nvmem_cell_get(dev, "wdt-timeout");
>> + if (!IS_ERR(cell)) {
>> + size_t len;
>> + void *value = nvmem_cell_read(cell, &len);
>> +
>> + if (!IS_ERR(value)) {
>> + memcpy(&timeout, value, min(len, sizeof(timeout)));
>> + kfree(value);
>> + }
>> + nvmem_cell_put(cell);
>> + }
>> + watchdog_init_timeout(wdd, le16_to_cpu(timeout), dev);
>> + watchdog_set_restart_priority(wdd, 255);
>> +
>> + sp_wd->reboot_notifier.notifier_call = rave_sp_wdt_reboot_notifier;
>> + ret = devm_register_reboot_notifier(dev, &sp_wd->reboot_notifier);
>> + if (ret) {
>> + dev_err(dev, "Failed to register reboot notifier\n");
>> + return ret;
>> + }
>> +
>> + /*
>> + * We don't know if watchdog is running now. To be sure, let's
>> + * start it and depend on watchdog core to ping it
>> + */
>> + wdd->max_hw_heartbeat_ms = wdd->max_timeout * 1000;
>> + ret = rave_sp_wdt_start(wdd);
>> + if (ret) {
>> + dev_err(dev, "Watchdog didn't start\n");
>> + return ret;
>> + }
>> +
>> + return devm_watchdog_register_device(dev, wdd);
>
> What about stopping the watchdog on errors here?
>
> And does watchdog core take care of calling stop() on unregister (i.e.
> at unbind)?
>
I think Guenter already addressed those, so I'll update the code with
his suggestions in v11.
Thanks,
Andrey Smirnov
