Dear Daniel, On Fri, 30 Oct 2015 16:27:39 +0800 Jisheng Zhang <jszh...@marvell.com> 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. The commit msg doesn't follow "clocksource/drivers/...: Dnnn.." But I guess I'll need to post v2, v3 ..., I'll change the msg style in v2. Thanks, Jisheng > > Signed-off-by: Jisheng Zhang <jszh...@marvell.com> > --- > drivers/clocksource/Kconfig | 10 ++++++++++ > drivers/clocksource/dw_apb_timer_of.c | 16 ++++++++++++++++ > 2 files changed, 26 insertions(+) > > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig > index a7726db..7b081805 100644 > --- a/drivers/clocksource/Kconfig > +++ b/drivers/clocksource/Kconfig > @@ -29,6 +29,16 @@ config DW_APB_TIMER_OF > select DW_APB_TIMER > select CLKSRC_OF > > +config DW_APB_TIMER_BASED_DELAY > + bool "DW APB timer based delay" > + depends on ARM && DW_APB_TIMER_OF > + default n > + help > + This option enables support for using the DW APB timer to > + implement timer-based delay. It is useful for skiping the > + delay loop calibration at boot on some platforms. And the > + udelay() will be unaffected by CPU frequency changes. > + > config ROCKCHIP_TIMER > bool > select CLKSRC_OF > diff --git a/drivers/clocksource/dw_apb_timer_of.c > b/drivers/clocksource/dw_apb_timer_of.c > index a19a3f6..4bab048 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 +131,17 @@ static void __init init_sched_clock(void) > sched_clock_register(read_sched_clock, 32, sched_rate); > } > > +#ifdef CONFIG_DW_APB_TIMER_BASED_DELAY > +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, > +}; > +#endif > + > static int num_called; > static void __init dw_apb_timer_init(struct device_node *timer) > { > @@ -142,6 +154,10 @@ 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(); > +#ifdef CONFIG_DW_APB_TIMER_BASED_DELAY > + dw_apb_delay_timer.freq = sched_rate; > + register_current_timer_delay(&dw_apb_delay_timer); > +#endif > break; > default: > break; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
