lkml.org 
[lkml]   [2015]   [Oct]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [RFC PATCH] clocksource: dw_apb_timer_of: support timer-based delay
From
Date
On 10/20/2015 10:11 AM, Jisheng Zhang wrote:
> Implement an ARM delay timer to be used for udelay(). This allows us to
> skip the delay loop calibration at boot on Marvell BG2, BG2Q, BG2CD
> platforms. And after this patch, udelay() will be unaffected by CPU
> frequency changes.
>
> But, this driver is not only used on ARM platforms, so I dunno how to
> handle other platforms which don't have the register_current_timer_delay
> That's the reason I mark this patch as RFC.
>
> Any suggestions are appreciated.

hmm, may be a dt-binding makes sense...


> Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
> ---
> drivers/clocksource/dw_apb_timer_of.c | 12 ++++++++++++
> 1 file changed, 12 insertions(+)
>
> diff --git a/drivers/clocksource/dw_apb_timer_of.c b/drivers/clocksource/dw_apb_timer_of.c
> index a19a3f6..09dbf9c 100644
> --- a/drivers/clocksource/dw_apb_timer_of.c
> +++ b/drivers/clocksource/dw_apb_timer_of.c
> @@ -16,6 +16,7 @@
> * You should have received a copy of the GNU General Public License
> * along with this program. If not, see <http://www.gnu.org/licenses/>.
> */
> +#include <linux/delay.h>
> #include <linux/dw_apb_timer.h>
> #include <linux/of.h>
> #include <linux/of_address.h>
> @@ -130,6 +131,15 @@ static void __init init_sched_clock(void)
> sched_clock_register(read_sched_clock, 32, sched_rate);
> }
>
> +static unsigned long dw_apb_delay_timer_read(void)
> +{
> + return ~readl_relaxed(sched_io_base);
> +}
> +
> +static struct delay_timer dw_apb_delay_timer = {
> + .read_current_timer = dw_apb_delay_timer_read,
> +};
> +
> static int num_called;
> static void __init dw_apb_timer_init(struct device_node *timer)
> {
> @@ -142,6 +152,8 @@ static void __init dw_apb_timer_init(struct device_node *timer)
> pr_debug("%s: found clocksource timer\n", __func__);
> add_clocksource(timer);
> init_sched_clock();
> + dw_apb_delay_timer.freq = sched_rate;
> + register_current_timer_delay(&dw_apb_delay_timer);
> break;
> default:
> break;
>


--
<http://www.linaro.org/> Linaro.org │ Open source software for ARM SoCs

Follow Linaro: <http://www.facebook.com/pages/Linaro> Facebook |
<http://twitter.com/#!/linaroorg> Twitter |
<http://www.linaro.org/linaro-blog/> Blog



\
 
 \ /
  Last update: 2015-10-27 02:01    [W:0.035 / U:0.748 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site