[PATCH 4/9] MXS/i.MX28: there is more than one way to clock the RTC
Steffen Trumtrar
s.trumtrar at pengutronix.de
Thu Mar 7 19:19:08 EST 2013
Hi Shawn!
On Thu, Mar 07, 2013 at 02:48:26PM +0800, Shawn Guo wrote:
> On Mon, Mar 04, 2013 at 03:05:43PM +0100, Steffen Trumtrar wrote:
> > From: Juergen Beisert <jbe at pengutronix.de>
> >
> > Reflect the possibilities via device tree and configure the RTC correctly
> >
> > Signed-off-by: Juergen Beisert <jbe at pengutronix.de>
> > Signed-off-by: Steffen Trumtrar <s.trumtrar at pengutronix.de>
> > ---
> > arch/arm/boot/dts/imx28.dtsi | 2 ++
> > drivers/rtc/rtc-stmp3xxx.c | 76 ++++++++++++++++++++++++++++++++++++++++++
> > 2 files changed, 78 insertions(+)
> >
> > diff --git a/arch/arm/boot/dts/imx28.dtsi b/arch/arm/boot/dts/imx28.dtsi
> > index dcd0844..d89af79 100644
> > --- a/arch/arm/boot/dts/imx28.dtsi
> > +++ b/arch/arm/boot/dts/imx28.dtsi
> > @@ -818,6 +818,8 @@
> > compatible = "fsl,imx28-rtc", "fsl,stmp3xxx-rtc";
> > reg = <0x80056000 0x2000>;
> > interrupts = <29>;
> > + clocks = <&clks 65>, <&clks 40> ;
> > + clock-names = "32k", "24m";
>
> The changes should be in some mxs/arch patch.
>
> > };
> >
> > i2c0: i2c at 80058000 {
> > diff --git a/drivers/rtc/rtc-stmp3xxx.c b/drivers/rtc/rtc-stmp3xxx.c
> > index 7311292..fb4b823 100644
> > --- a/drivers/rtc/rtc-stmp3xxx.c
> > +++ b/drivers/rtc/rtc-stmp3xxx.c
> > @@ -21,6 +21,7 @@
> > #include <linux/module.h>
> > #include <linux/io.h>
> > #include <linux/init.h>
> > +#include <linux/clk.h>
> > #include <linux/platform_device.h>
> > #include <linux/interrupt.h>
> > #include <linux/rtc.h>
> > @@ -176,11 +177,55 @@ static irqreturn_t stmp3xxx_rtc_interrupt(int irq, void *dev_id)
> > return IRQ_NONE;
> > }
> >
> > +/*
> > + * To keep the energy consumption low, keep only
> > + * the really used oscillator running when the power is down
> > + */
> > +static void stmp3xxx_alarm_keep_oscillator(const struct stmp3xxx_rtc_data *rtc_data)
> > +{
> > + switch (rtc_data->clk_src) {
> > + case MXS_OSC_24M:
> > + /* keep the 24 MHz oscillator running even in power down */
> > + writel(STMP3XXX_RTC_PERSISTENT0_XTAL32_FREQ | /* 24 MHz / 750 */
> > + STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP,
> > + rtc_data->io + STMP3XXX_RTC_PERSISTENT0_SET);
> > + writel(STMP3XXX_RTC_PERSISTENT0_XTAL32KHZ_PWRUP |
> > + STMP3XXX_RTC_PERSISTENT0_CLOCKSOURCE,
> > + rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);
> > + break;
> > + case MXS_OSC_32K:
> > + /* keep the 32 kHz oscillator running even in power down */
> > + writel(STMP3XXX_RTC_PERSISTENT0_XTAL32_FREQ | /* 32 kHz */
> > + STMP3XXX_RTC_PERSISTENT0_XTAL32KHZ_PWRUP |
> > + STMP3XXX_RTC_PERSISTENT0_CLOCKSOURCE,
> > + rtc_data->io + STMP3XXX_RTC_PERSISTENT0_SET);
> > + writel(STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP,
> > + rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);
> > + break;
> > + case MXS_OSC_32K768:
> > + /* keep the 32 kHz oscillator running even in power down */
> > + writel(STMP3XXX_RTC_PERSISTENT0_XTAL32KHZ_PWRUP |
> > + STMP3XXX_RTC_PERSISTENT0_CLOCKSOURCE,
> > + rtc_data->io + STMP3XXX_RTC_PERSISTENT0_SET);
> > + writel(STMP3XXX_RTC_PERSISTENT0_XTAL32_FREQ | /* 32.768 kHz */
> > + STMP3XXX_RTC_PERSISTENT0_XTAL24MHZ_PWRUP,
> > + rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);
> > + break;
> > + case MXS_UNKNOWN:
> > + default:
> > + break;
> > + }
> > +}
> > +
> > static int stmp3xxx_alarm_irq_enable(struct device *dev, unsigned int enabled)
> > {
> > struct stmp3xxx_rtc_data *rtc_data = dev_get_drvdata(dev);
> >
> > + stmp3xxx_alarm_keep_oscillator(rtc_data);
> > +
> > if (enabled) {
> > + writel(STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE, /* to be able to sleep */
> > + rtc_data->io + STMP3XXX_RTC_PERSISTENT0_CLR);
> > writel(STMP3XXX_RTC_PERSISTENT0_ALARM_EN |
> > STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE_EN,
> > rtc_data->io + STMP3XXX_RTC_PERSISTENT0_SET);
> > @@ -248,6 +293,8 @@ static int stmp3xxx_rtc_probe(struct platform_device *pdev)
> > {
> > struct stmp3xxx_rtc_data *rtc_data;
> > struct resource *r;
> > + struct clk *clk;
> > + unsigned long rate;
> > int err;
> >
> > rtc_data = kzalloc(sizeof *rtc_data, GFP_KERNEL);
> > @@ -280,6 +327,35 @@ static int stmp3xxx_rtc_probe(struct platform_device *pdev)
> > platform_set_drvdata(pdev, rtc_data);
> >
> > mxs_reset_block(rtc_data->io);
> > +
> > + /*
> > + * configure the RTC to provide the correct time
> > + */
> > + clk = clk_get(&pdev->dev, "32k");
>
> devm_clk_get
>
> Shawn
>
> > + if (IS_ERR(clk)) {
> > + /* just a fall back */
> > + dev_warn(&pdev->dev, "RTC's input clock undefined\n");
> > + rtc_data->clk_src = MXS_OSC_24M;
> > + } else {
> > + rate = clk_get_rate(clk);
> > + if (rate == 0) {
> > + /* no dedicated external crystal */
> > + rtc_data->clk_src = MXS_OSC_24M;
> > + dev_info(&pdev->dev, "Using 24 MHz as RTC's clock\n");
> > + } else if (rate == 32000) {
> > + rtc_data->clk_src = MXS_OSC_32K;
> > + dev_info(&pdev->dev, "Using 32.0 kHz as RTC's clock\n");
> > + } else if (rate == 32768) {
> > + rtc_data->clk_src = MXS_OSC_32K768;
> > + dev_info(&pdev->dev, "Using 32.768 kHz as RTC's clock\n");
> > + } else
> > + dev_warn(&pdev->dev,
> > + "Cannot init the RTC's clock source\n");
> > + }
> > +
> > + /* basically configure the RTC's input clock */
> > + stmp3xxx_alarm_keep_oscillator(rtc_data);
> > +
> > writel(STMP3XXX_RTC_PERSISTENT0_ALARM_EN |
> > STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE_EN |
> > STMP3XXX_RTC_PERSISTENT0_ALARM_WAKE,
> > --
> > 1.7.10.4
> >
>
>
I can agree to all your comments to this patch and the others in this series
and will take care of all of them.
Thanks,
Steffen
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