On 03/09/2014 at 10:45:33 +0200, Boris Brezillon wrote : > The RTT block is using the slow clock and expect it to run at 32KHz. > Now that we moved to the CCF it's better to retain the clk reference so > that the CCF can't disable the slow clock considering it is unused. > > Signed-off-by: Boris BREZILLON <[email protected]> > --- > drivers/rtc/rtc-at91sam9.c | 24 ++++++++++++++++++++++++ > 1 file changed, 24 insertions(+) > > diff --git a/drivers/rtc/rtc-at91sam9.c b/drivers/rtc/rtc-at91sam9.c > index 57014b7..5c5093b 100644 > --- a/drivers/rtc/rtc-at91sam9.c > +++ b/drivers/rtc/rtc-at91sam9.c > @@ -21,6 +21,7 @@ > #include <linux/slab.h> > #include <linux/platform_data/atmel.h> > #include <linux/io.h> > +#include <linux/clk.h> > > /* > * This driver uses two configurable hardware resources that live in the > @@ -74,6 +75,7 @@ struct sam9_rtc { > u32 imr; > void __iomem *gpbr; > int irq; > + struct clk *sclk; > }; > > #define rtt_readl(rtc, field) \ > @@ -373,6 +375,25 @@ static int at91_rtc_probe(struct platform_device *pdev) > return ret; > } > > + /* Retain slow clk if it is specified in the DT. > + * Do not complain if slow clk is missing, but check its rate > + * if it is available. > + */ > + rtc->sclk = devm_clk_get(&pdev->dev, NULL); > + if (!IS_ERR(rtc->sclk)) { > + if (clk_get_rate(rtc->sclk) != AT91_SLOW_CLOCK) {
I would not bother doing that check but use the value for MR instead of AT91_SLOW_CLOCK (see my previous mail). > + dev_err(&pdev->dev, > + "Invalid slow clock rate (expecting %lu got > %lu)", > + (unsigned long)AT91_SLOW_CLOCK, > + clk_get_rate(rtc->sclk)); > + return -EINVAL; > + } > + > + ret = clk_prepare_enable(rtc->sclk); > + if (ret) > + return ret; > + } > + > /* NOTE: sam9260 rev A silicon has a ROM bug which resets the > * RTT on at least some reboots. If you have that chip, you must > * initialize the time from some external source like a GPS, wall > @@ -397,6 +418,9 @@ static int at91_rtc_remove(struct platform_device *pdev) > /* disable all interrupts */ > rtt_writel(rtc, MR, mr & ~(AT91_RTT_ALMIEN | AT91_RTT_RTTINCIEN)); > > + if (!IS_ERR(rtc->sclk)) > + clk_disable_unprepare(rtc->sclk); > + > return 0; > } > > -- > 1.9.1 > -- Alexandre Belloni, Free Electrons Embedded Linux, Kernel and Android engineering http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
