From: Juergen Beisert <[email protected]> Reflect the possibilities via device tree and configure the RTC correctly
Signed-off-by: Juergen Beisert <[email protected]> Signed-off-by: Steffen Trumtrar <[email protected]> --- 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"; }; i2c0: i2c@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"); + 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 _______________________________________________ devicetree-discuss mailing list [email protected] https://lists.ozlabs.org/listinfo/devicetree-discuss
