Re: [PATCH v6 7/9] rtc: at91sam9: use clk API instead of relying on AT91_SLOW_CLOCK

Nicolas Ferre
2014-09-23T08:21:35Z

On 22/09/2014 17:42, Boris BREZILLON :
> The RTT block is using the slow clock which is accessible through the clk
> API.
> Use the clk API to retrieve, enable and get the slow clk rate instead of
> the AT91_SLOW_CLOCK macro (which hardcodes the slow clk rate).
> Doing this allows us to reference the clk thus preventing the CCF from
> disabling it during the "disable unused" phase.
>
> Signed-off-by: Boris BREZILLON <boris.brezillon@free-electrons.com>
> Acked-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>

> ---
> drivers/rtc/rtc-at91sam9.c | 28 ++++++++++++++++++++++++----
> 1 file changed, 24 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/rtc/rtc-at91sam9.c b/drivers/rtc/rtc-at91sam9.c
> index 902cd01..d20e118 100644
> --- a/drivers/rtc/rtc-at91sam9.c
> +++ b/drivers/rtc/rtc-at91sam9.c
> @@ -23,6 +23,7 @@
> #include <linux/io.h>
> #include <linux/mfd/syscon.h>
> #include <linux/regmap.h>
> +#include <linux/clk.h>
>
> /*
> * This driver uses two configurable hardware resources that live in the
> @@ -61,8 +62,6 @@
> #define AT91_RTT_ALMS (1 << 0) /* Real-time Alarm Status */
> #define AT91_RTT_RTTINC (1 << 1) /* Real-time Timer Increment */
>
> -#define AT91_SLOW_CLOCK 32768
> -
> /*
> * We store ALARM_DISABLED in ALMV to record that no alarm is set.
> * It's also the reset value for that field.
> @@ -77,6 +76,7 @@ struct sam9_rtc {
> struct regmap *gpbr;
> unsigned int gpbr_offset;
> int irq;
> + struct clk *sclk;
> };
>
> #define rtt_readl(rtc, field) \
> @@ -328,6 +328,7 @@ static int at91_rtc_probe(struct platform_device *pdev)
> struct sam9_rtc *rtc;
> int ret, irq;
> u32 mr;
> + unsigned int sclk_rate;
>
> irq = platform_get_irq(pdev, 0);
> if (irq < 0) {
> @@ -385,11 +386,27 @@ static int at91_rtc_probe(struct platform_device *pdev)
> return -ENOMEM;
> }
>
> + rtc->sclk = devm_clk_get(&pdev->dev, NULL);
> + if (IS_ERR(rtc->sclk))
> + return PTR_ERR(rtc->sclk);
> +
> + sclk_rate = clk_get_rate(rtc->sclk);
> + if (!sclk_rate || sclk_rate > AT91_RTT_RTTRST) {
> + dev_err(&pdev->dev, "Invalid slow clock rate");
> + return -EINVAL;
> + }
> +
> + ret = clk_prepare_enable(rtc->sclk);
> + if (ret) {
> + dev_err(&pdev->dev, "Could not enable slow clock");
> + return ret;
> + }
> +
> mr = rtt_readl(rtc, MR);
>
> /* unless RTT is counting at 1 Hz, re-initialize it */
> - if ((mr & AT91_RTT_RTPRES) != AT91_SLOW_CLOCK) {
> - mr = AT91_RTT_RTTRST | (AT91_SLOW_CLOCK & AT91_RTT_RTPRES);
> + if ((mr & AT91_RTT_RTPRES) != sclk_rate) {
> + mr = AT91_RTT_RTTRST | (sclk_rate & AT91_RTT_RTPRES);
> gpbr_writel(rtc, 0);
> }
>
> @@ -434,6 +451,9 @@ 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;
> }
>
>

--
Nicolas Ferre