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Date: Thu, 10 Jan 2019 23:27:26 +0100
From: Alexandre Belloni <alexandre.belloni@...tlin.com>
To: Jan Kotas <jank@...ence.com>
Cc: a.zummo@...ertech.it, robh+dt@...nel.org, mark.rutland@....com,
linux-rtc@...r.kernel.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] rtc: Add Cadence RTC driver
Hello,
On 08/01/2019 12:22:42+0000, Jan Kotas wrote:
> drivers/rtc/Kconfig | 10 ++
> drivers/rtc/Makefile | 1 +
> drivers/rtc/rtc-cadence.c | 404 ++++++++++++++++++++++++++++++++++++++++++++++
I would prefer a name that is a bit less generic, unless you can
guarantee this driver will be able to handle every RTCs from Cadence.
> +static int cdns_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled)
> +{
> + struct cdns_rtc *crtc = dev_get_drvdata(dev);
> +
> + if (enabled) {
> + writel((CDNS_RTC_AEI_SEC | CDNS_RTC_AEI_MIN | CDNS_RTC_AEI_HOUR
> + | CDNS_RTC_AEI_DATE | CDNS_RTC_AEI_SEC),
CDNS_RTC_AEI_SEC is used twice here.
> + crtc->regs + CDNS_RTC_AENR);
> + writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IENR);
> + } else {
> + writel(0, crtc->regs + CDNS_RTC_AENR);
> + writel(CDNS_RTC_AEI_ALRM, crtc->regs + CDNS_RTC_IDISR);
> + }
> +
> + return 0;
> +}
> +
> +static int cdns_rtc_probe(struct platform_device *pdev)
> +{
> + struct cdns_rtc *crtc;
> + struct resource *res;
> + int ret;
> + unsigned long ref_clk_freq;
> +
> + crtc = devm_kzalloc(&pdev->dev, sizeof(*crtc), GFP_KERNEL);
> + if (!crtc)
> + return -ENOMEM;
> +
> + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> + crtc->regs = devm_ioremap_resource(&pdev->dev, res);
> + if (IS_ERR(crtc->regs))
> + return PTR_ERR(crtc->regs);
> +
> + crtc->irq = platform_get_irq(pdev, 0);
> + if (crtc->irq < 0)
> + return -EINVAL;
> +
> + crtc->pclk = devm_clk_get(&pdev->dev, "pclk");
> + if (IS_ERR(crtc->pclk)) {
> + ret = PTR_ERR(crtc->pclk);
> + dev_err(&pdev->dev,
> + "Failed to retrieve the peripheral clock, %d\n", ret);
> + return ret;
> + }
> +
> + crtc->ref_clk = devm_clk_get(&pdev->dev, "ref_clk");
> + if (IS_ERR(crtc->ref_clk)) {
> + ret = PTR_ERR(crtc->ref_clk);
> + dev_err(&pdev->dev,
> + "Failed to retrieve the reference clock, %d\n", ret);
> + return ret;
> + }
> +
> + ret = clk_prepare_enable(crtc->pclk);
> + if (ret) {
> + dev_err(&pdev->dev,
> + "Failed to enable the peripheral clock, %d\n", ret);
> + return ret;
> + }
> +
> + ret = clk_prepare_enable(crtc->ref_clk);
> + if (ret) {
> + dev_err(&pdev->dev,
> + "Failed to enable the reference clock, %d\n", ret);
> + goto err_disable_pclk;
> + }
> +
> + ref_clk_freq = clk_get_rate(crtc->ref_clk);
> + if ((ref_clk_freq != 1) && (ref_clk_freq != 100)) {
> + dev_err(&pdev->dev,
> + "Invalid reference clock frequency %lu Hz.\n",
> + ref_clk_freq);
> + ret = -EINVAL;
> + goto err_disable_ref_clk;
> + }
> +
> + ret = devm_request_irq(&pdev->dev, crtc->irq,
> + cdns_rtc_irq_handler, 0,
> + dev_name(&pdev->dev), &pdev->dev);
> + if (ret) {
> + dev_err(&pdev->dev,
> + "Unable to request interrupt for the device, %d\n",
> + ret);
> + goto err_disable_ref_clk;
> + }
> +
You should use devm_rtc_allocate_device to allocate crtc->rtc_dev before
requesting the IRQ. Else, this leaves a race condition open.
Also, please set crtc->rtc_dev->range_min and crtc->rtc_dev->range_max
according to the fully contiguous range of time that is supported by the
RTC. You can use
https://git.kernel.org/pub/scm/linux/kernel/git/abelloni/rtc-tools.git/tree/rtc-range.c
to assist you.
> + /* Always use 24-hour mode */
> + writel(0, crtc->regs + CDNS_RTC_HMR);
> +
> + device_init_wakeup(&pdev->dev, 1);
> + platform_set_drvdata(pdev, crtc);
> + cdns_rtc_set_enabled(crtc, true);
Is that really necessary? I guess you could check whether it has already
been enabled to know whether the currently set time is valid so
cdns_rtc_read_time could return -EINVAL when it knows it isn't valid.
cdns_rtc_set_time will enable the RTC once the time has been set anyway.
> +
> + crtc->rtc_dev = devm_rtc_device_register(&pdev->dev,
> + dev_name(&pdev->dev),
> + &cdns_rtc_ops,
> + THIS_MODULE);
> + if (IS_ERR(crtc->rtc_dev)) {
> + ret = PTR_ERR(crtc->rtc_dev);
> + dev_err(&pdev->dev, "Unable to register the rtc device, %d\n",
> + ret);
> + goto err_stop_rtc;
> + }
> +
> + return 0;
> +
> +err_stop_rtc:
> + cdns_rtc_set_enabled(crtc, false);
> +
> +err_disable_ref_clk:
> + clk_disable_unprepare(crtc->ref_clk);
> +
> +err_disable_pclk:
> + clk_disable_unprepare(crtc->pclk);
> +
> + return ret;
> +}
> +
> +static int cdns_rtc_remove(struct platform_device *pdev)
> +{
> + struct cdns_rtc *crtc = platform_get_drvdata(pdev);
> +
> + cdns_rtc_alarm_irq_enable(&pdev->dev, 0);
> + device_init_wakeup(&pdev->dev, 0);
> +
> + clk_disable_unprepare(crtc->pclk);
> + clk_disable_unprepare(crtc->ref_clk);
> +
> + return 0;
> +}
> +
> +#ifdef CONFIG_PM_SLEEP
> +static int cdns_rtc_suspend(struct device *dev)
> +{
> + struct cdns_rtc *crtc = dev_get_drvdata(dev);
> +
> + if (device_may_wakeup(dev))
> + enable_irq_wake(crtc->irq);
> +
> + return 0;
> +}
> +
> +static int cdns_rtc_resume(struct device *dev)
> +{
> + struct cdns_rtc *crtc = dev_get_drvdata(dev);
> +
> + if (device_may_wakeup(dev))
> + disable_irq_wake(crtc->irq);
> +
> + return 0;
> +}
> +#endif
> +
> +static SIMPLE_DEV_PM_OPS(cdns_rtc_pm_ops, cdns_rtc_suspend, cdns_rtc_resume);
> +
> +static const struct of_device_id cdns_rtc_of_match[] = {
> + { .compatible = "cdns,rtc-r109v3" },
Is r109v3 an IP name or a revision?
> + { },
> +};
> +MODULE_DEVICE_TABLE(of, cdns_rtc_of_match);
> +
> +static struct platform_driver cdns_rtc_driver = {
> + .driver = {
> + .name = "cdns-rtc",
> + .of_match_table = cdns_rtc_of_match,
> + .pm = &cdns_rtc_pm_ops,
> + },
> + .probe = cdns_rtc_probe,
> + .remove = cdns_rtc_remove,
> +};
> +module_platform_driver(cdns_rtc_driver);
> +
> +MODULE_AUTHOR("Jan Kotas <jank@...ence.com>");
> +MODULE_DESCRIPTION("Cadence RTC driver");
> +MODULE_LICENSE("GPL v2");
> +MODULE_ALIAS("platform:cdns-rtc");
> --
> 2.15.0
>
--
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com
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