Hi
On Fri, 17 Jul 2015, Lokesh Vutla wrote:
> RTC IP have kicker feature which prevents spurious writes to its registers.
> In order to write into any of the RTC registers, KICK values has to be
> written to KICK registers.
> Introduce omap_hwmod_rtc_unlock/lock functions, which writes into these
> KICK registers inorder to lock and unlock RTC registers.
>
> Signed-off-by: Lokesh Vutla <lokeshvutla@xxxxxx>
Please add kerneldoc for the omap_hwmod_rtc_lock() function.
- Paul
> ---
> arch/arm/mach-omap2/omap_hwmod.h | 2 ++
> arch/arm/mach-omap2/omap_hwmod_reset.c | 56 ++++++++++++++++++++++++++++++++++
> 2 files changed, 58 insertions(+)
>
> diff --git a/arch/arm/mach-omap2/omap_hwmod.h b/arch/arm/mach-omap2/omap_hwmod.h
> index c697b57..173a31e 100644
> --- a/arch/arm/mach-omap2/omap_hwmod.h
> +++ b/arch/arm/mach-omap2/omap_hwmod.h
> @@ -748,6 +748,8 @@ const char *omap_hwmod_get_main_clk(struct omap_hwmod *oh);
> */
>
> extern int omap_hwmod_aess_preprogram(struct omap_hwmod *oh);
> +void omap_hwmod_rtc_unlock(struct omap_hwmod *oh);
> +void omap_hwmod_rtc_lock(struct omap_hwmod *oh);
>
> /*
> * Chip variant-specific hwmod init routines - XXX should be converted
> diff --git a/arch/arm/mach-omap2/omap_hwmod_reset.c b/arch/arm/mach-omap2/omap_hwmod_reset.c
> index 65e186c..eebadb2 100644
> --- a/arch/arm/mach-omap2/omap_hwmod_reset.c
> +++ b/arch/arm/mach-omap2/omap_hwmod_reset.c
> @@ -29,6 +29,16 @@
> #include <sound/aess.h>
>
> #include "omap_hwmod.h"
> +#include "common.h"
> +
> +#define OMAP_RTC_STATUS_REG 0x44
> +#define OMAP_RTC_KICK0_REG 0x6c
> +#define OMAP_RTC_KICK1_REG 0x70
> +
> +#define OMAP_RTC_KICK0_VALUE 0x83E70B13
> +#define OMAP_RTC_KICK1_VALUE 0x95A4F1E0
> +#define OMAP_RTC_STATUS_BUSY BIT(0)
> +#define OMAP_RTC_MAX_READY_TIME 50
>
> /**
> * omap_hwmod_aess_preprogram - enable AESS internal autogating
> @@ -51,3 +61,49 @@ int omap_hwmod_aess_preprogram(struct omap_hwmod *oh)
>
> return 0;
> }
> +
> +/**
> + * omap_rtc_wait_not_busy - Wait for the RTC BUSY flag
> + * @oh: struct omap_hwmod *
> + *
> + * For updating certain RTC registers, the MPU must wait
> + * for the BUSY status in OMAP_RTC_STATUS_REG to become zero.
> + * Once the BUSY status is zero, there is a 15-μs access
> + * period in which the MPU can program.
> + */
> +static void omap_rtc_wait_not_busy(struct omap_hwmod *oh)
> +{
> + int i;
> +
> + /* BUSY may stay active for 1/32768 second (~30 usec) */
> + omap_test_timeout(omap_hwmod_read(oh, OMAP_RTC_STATUS_REG)
> + & OMAP_RTC_STATUS_REG, OMAP_RTC_MAX_READY_TIME, i);
> + /* now we have ~15 usec to read/write various registers */
> +}
> +
> +/**
> + * omap_hwmod_rtc_unlock - Unlock the Kicker mechanism.
> + * @oh: struct omap_hwmod *
> + *
> + * RTC IP have kicker feature. This prevents spurious writes to its registers.
> + * In order to write into any of the RTC registers, KICK values has te be
> + * written in respective KICK registers. This is needed for hwmod to write into
> + * sysconfig register.
> + */
> +void omap_hwmod_rtc_unlock(struct omap_hwmod *oh)
> +{
> + local_irq_disable();
> + omap_rtc_wait_not_busy(oh);
> + omap_hwmod_write(OMAP_RTC_KICK0_VALUE, oh, OMAP_RTC_KICK0_REG);
> + omap_hwmod_write(OMAP_RTC_KICK1_VALUE, oh, OMAP_RTC_KICK1_REG);
> + local_irq_enable();
> +}
> +
> +void omap_hwmod_rtc_lock(struct omap_hwmod *oh)
> +{
> + local_irq_disable();
> + omap_rtc_wait_not_busy(oh);
> + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK0_REG);
> + omap_hwmod_write(0x0, oh, OMAP_RTC_KICK1_REG);
> + local_irq_enable();
> +}
> --
> 2.1.4
>
- Paul
