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SubjectRe: [PATCH v2] rtc: add support for Freescale SNVS RTC
On Sat, Apr 14, 2012 at 03:07:17PM +0800, Ying-Chun Liu (PaulLiu) wrote:
> From: "Ying-Chun Liu (PaulLiu)" <paul.liu@linaro.org>
>
> This adds an RTC driver for the Low Power (LP) section of SNVS.
> It hooks into the /dev/rtc interface and supports ioctl to complete RTC
> features. This driver supports device tree bindings.
> It only uses the RTC hw in non-secure mode.
>
> Signed-off-by: Anish Trivedi <anish@freescale.com>
> Signed-off-by: Eric Miao <eric.miao@linaro.org>
> Signed-off-by: Anson Huang <b20788@freescale.com>
> Signed-off-by: Ying-Chun Liu (PaulLiu) <paul.liu@linaro.org>
> Cc: Alessandro Zummo <a.zummo@towertech.it>
> Cc: Shawn Guo <shawn.guo@linaro.org>
> Cc: Sascha Hauer <s.hauer@pengutronix.de>
> ---
> Documentation/devicetree/bindings/rtc/snvs-rtc.txt | 18 +
> drivers/rtc/Kconfig | 10 +
> drivers/rtc/Makefile | 1 +
> drivers/rtc/rtc-snvs.c | 644 ++++++++++++++++++++
> 4 files changed, 673 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/rtc/snvs-rtc.txt
> create mode 100644 drivers/rtc/rtc-snvs.c
>
> +#define CNTR_TO_SECS_SH 15 /* Converts 47-bit counter to 32-bit seconds */
> +
> +struct rtc_drv_data {
> + struct rtc_device *rtc;
> + void __iomem *ioaddr;
> + int irq;
> + bool irq_enable;
> +};
> +
> +static DEFINE_SPINLOCK(rtc_lock);

Put this three lines above.

> + writel(time >> (32 - CNTR_TO_SECS_SH), ioaddr + SNVS_LPSRTCMR);
> +
> + /* Enable RTC again */
> + writel(lp_cr | SNVS_LPCR_SRTC_ENV, ioaddr + SNVS_LPCR);
> + timeout = jiffies + msecs_to_jiffies(3000);
> + while (!(readl(ioaddr + SNVS_LPCR) & SNVS_LPCR_SRTC_ENV)) {
> + if (time_after(jiffies, timeout)) {
> + dev_err(dev, "timeout on enabling RTC back\n");
> + return -EBUSY;
> + }
> + }
> +
> + rtc_write_sync_lp(ioaddr);
> +
> + new_time_47bit = (((u64) (readl(ioaddr + SNVS_LPSRTCMR) &
> + ((0x1 << CNTR_TO_SECS_SH) - 1)) << 32) |
> + ((u64) readl(ioaddr + SNVS_LPSRTCLR)));
> +
> + time_diff = new_time_47bit - old_time_47bit;

time_diff, old_time_47bit and new_time_47bit are set and never read.
Remove.

> +
> + return 0;
> +}
> +
> +static int snvs_rtc_proc(struct device *dev, struct seq_file *seq)
> +{
> + struct rtc_drv_data *pdata = dev_get_drvdata(dev);
> + void __iomem *ioaddr = pdata->ioaddr;
> +
> + seq_printf(seq, "alarm_IRQ\t: %s\n",
> + (((readl(ioaddr + SNVS_LPCR)) & SNVS_LPCR_LPTA_EN) !=
> + 0) ? "yes" : "no");
> +
> + return 0;
> +}
> +
> +static int snvs_rtc_alarm_irq_enable(struct device *dev, unsigned int enable)
> +{
> + struct rtc_drv_data *pdata = dev_get_drvdata(dev);
> + void __iomem *ioaddr = pdata->ioaddr;
> + u32 lp_cr;
> + unsigned long lock_flags = 0;
> +
> + spin_lock_irqsave(&rtc_lock, lock_flags);
> +
> + if (enable) {
> + if (!pdata->irq_enable) {
> + enable_irq(pdata->irq);
> + pdata->irq_enable = true;
> + }

Why this enable_irq/disable_irq everywhere? You seem to have irq enable
bits in your registers which should be enough.

> +/* SNVS RTC Power management control */
> +static int __devinit snvs_rtc_probe(struct platform_device *pdev)
> +{
> + struct timespec tv;
> + struct rtc_device *rtc;
> + struct rtc_drv_data *pdata = NULL;

No need to initialize this. I think you should use another name for this
variable. People usually expect pdata for platform_data. Driver data is
usually called priv, or snvs_rtc in this case.


> + void __iomem *ioaddr;
> + u32 lp_cr;
> + int ret = 0;

No need to initialize this.

> +
> + ioaddr = of_iomap(pdev->dev.of_node, 0);
> + if (!ioaddr)
> + return -EADDRNOTAVAIL;
> +
> + pdata = devm_kzalloc(&pdev->dev, sizeof(*pdata), GFP_KERNEL);
> + if (!pdata)
> + return -ENOMEM;
> +
> + pdata->ioaddr = ioaddr;
> +
> + /* Configure and enable the RTC */
> + pdata->irq = platform_get_irq(pdev, 0);
> + if (pdata->irq >= 0) {

Is there any hardware without an interrupt? If no, just bail out here
and get rid of the additional complexity.

> + if (request_irq(pdata->irq, snvs_rtc_interrupt, IRQF_SHARED,
> + pdev->name, pdev) < 0) {
> + dev_warn(&pdev->dev, "interrupt not available.\n");
> + pdata->irq = -1;
> + } else {
> + disable_irq(pdata->irq);
> + pdata->irq_enable = false;
> + }
> + }
> +
> + /* initialize glitch detect */
> + writel(SNVS_LPPGDR_INIT, ioaddr + SNVS_LPPGDR);
> + udelay(100);
> +
> + /* clear lp interrupt status */
> + writel(0xFFFFFFFF, ioaddr + SNVS_LPSR);
> +
> + /* Enable RTC */
> + lp_cr = readl(ioaddr + SNVS_LPCR);
> + if ((lp_cr & SNVS_LPCR_SRTC_ENV) == 0)
> + writel(lp_cr | SNVS_LPCR_SRTC_ENV, ioaddr + SNVS_LPCR);
> + udelay(100);
> +
> + writel(0xFFFFFFFF, ioaddr + SNVS_LPSR);
> + udelay(100);
> +
> + platform_set_drvdata(pdev, pdata);
> +
> + rtc = rtc_device_register(pdev->name, &pdev->dev,
> + &snvs_rtc_ops, THIS_MODULE);
> + if (IS_ERR(rtc)) {
> + ret = PTR_ERR(rtc);
> + goto err_out;
> + }
> +
> + pdata->rtc = rtc;
> +
> + tv.tv_nsec = 0;
> + tv.tv_sec = rtc_read_lp_counter(ioaddr);
> +
> + /* By default, devices should wakeup if they can */
> + /* So snvs is set as "should wakeup" as it can */
> + device_init_wakeup(&pdev->dev, 1);
> +
> + return ret;

return 0 here instead to make it clear that this is the success path.

> +
> +err_out:
> + iounmap(ioaddr);
> + if (pdata->irq >= 0)
> + free_irq(pdata->irq, pdev);
> +
> + return ret;
> +}
> +
> +static int __devexit snvs_rtc_remove(struct platform_device *pdev)
> +{
> + struct rtc_drv_data *pdata = platform_get_drvdata(pdev);
> + rtc_device_unregister(pdata->rtc);
> + if (pdata->irq >= 0)
> + free_irq(pdata->irq, pdev);
> + iounmap(pdata->ioaddr);
> +
> + return 0;
> +}
> +

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