[PATCH v3 6/7] ARM: smp_twd: add clock api support

[ccross@android.com (Colin Cross)]

On Tue, Mar 8, 2011 at 3:34 PM, Rob Herring <robherring2@gmail.com> wrote:
> From: Rob Herring <rob.herring@calxeda.com>
>
> The private timer freq is currently dynamically detected
> using jiffies count to determine the rate. This method adds
> a delay to boot-up, so use the clock api instead to get the
> clock rate.
>
> Signed-off-by: Rob Herring <rob.herring@calxeda.com>
> ---
> v3: Save struct clk pointer for later use (cpufreq).
>
> ?arch/arm/include/asm/smp_twd.h | ? ?1 +
> ?arch/arm/kernel/smp_twd.c ? ? ?| ? 14 ++++++++++++++
> ?2 files changed, 15 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/include/asm/smp_twd.h b/arch/arm/include/asm/smp_twd.h
> index fed9981..6b0f591 100644
> --- a/arch/arm/include/asm/smp_twd.h
> +++ b/arch/arm/include/asm/smp_twd.h
> @@ -24,5 +24,6 @@ extern void __iomem *twd_base;
>
> ?int twd_timer_ack(void);
> ?void twd_timer_setup(struct clock_event_device *);
> +void twd_timer_init(void __iomem *base);
>
> ?#endif
> diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c
> index 60636f4..cce1171 100644
> --- a/arch/arm/kernel/smp_twd.c
> +++ b/arch/arm/kernel/smp_twd.c
> @@ -8,6 +8,8 @@
> ?* it under the terms of the GNU General Public License version 2 as
> ?* published by the Free Software Foundation.
> ?*/
> +#include <linux/clk.h>
> +#include <linux/err.h>
> ?#include <linux/init.h>
> ?#include <linux/kernel.h>
> ?#include <linux/delay.h>
> @@ -24,6 +26,7 @@
> ?/* set up by the platform code */
> ?void __iomem *twd_base;
>
> +static struct clk *twd_clk;
> ?static unsigned long twd_timer_rate;
>
> ?static void twd_set_mode(enum clock_event_mode mode,
> @@ -142,3 +145,14 @@ void __cpuinit twd_timer_setup(struct clock_event_device *clk)
>
> ? ? ? ?clockevents_register_device(clk);
> ?}
> +
> +void __init twd_timer_init(void __iomem *base)
> +{
> + ? ? ? twd_clk = clk_get_sys("smp_twd", NULL);
> + ? ? ? if (!IS_ERR(twd_clk))
> + ? ? ? ? ? ? ? twd_timer_rate = clk_get_rate(twd_clk);
> + ? ? ? else
> + ? ? ? ? ? ? ? twd_clk = NULL;
> +
> + ? ? ? twd_base = base;
> +}
Why not leave the old twd_base intitialization and put the clock stuff
in twd_timer_setup?

Would it make sense to drop twd_calibrate_rate entirely and require a twd clock?