Re: [PATCH v2 3/3] clocksource: Add clockevent support to NPS400 driver

Rob Herring
2016-10-30T20:43:19Z

On Sun, Oct 23, 2016 at 03:12:28PM +0300, Noam Camus wrote:
> From: Noam Camus <noamca@mellanox.com>
>
> Till now we used clockevent from generic ARC driver.
> This was enough as long as we worked with simple multicore SoC.
> When we are working with multithread SoC each HW thread can be
> scheduled to receive timer interrupt using timer mask register.
> This patch will provide a way to control clock events per HW thread.
>
> The design idea is that for each core there is dedicated regirtser
> (TSI) serving all 16 HW threads.
> The register is a bitmask with one bit for each HW thread.
> When HW thread wants that next expiration of timer interrupt will
> hit it then the proper bit should be set in this dedicated register.
> When timer expires all HW threads within this core which their bit
> is set at the TSI register will be interrupted.
>
> Driver can be used from device tree by:
> compatible = "ezchip,nps400-timer0" <-- for clocksource
> compatible = "ezchip,nps400-timer1" <-- for clockevent
>
> Note that name convention for timer0/timer1 was taken from legacy
> ARC design. This design is our base before adding HW threads.
>
> Signed-off-by: Noam Camus <noamca@mellanox.com>
>
> Change-Id: Ib351e6fc7a6b691293040ae655f202f3cc2c1298
> ---
> .../bindings/timer/ezchip,nps400-timer.txt | 15 --
> .../bindings/timer/ezchip,nps400-timer0.txt | 17 ++
> .../bindings/timer/ezchip,nps400-timer1.txt | 15 ++

For the binding,

Acked-by: Rob Herring <robh@kernel.org>

However, one issue below...

> drivers/clocksource/timer-nps.c | 220 +++++++++++++++++++-
> include/linux/cpuhotplug.h | 1 +
> 5 files changed, 248 insertions(+), 20 deletions(-)
> delete mode 100644 Documentation/devicetree/bindings/timer/ezchip,nps400-timer.txt
> create mode 100644 Documentation/devicetree/bindings/timer/ezchip,nps400-timer0.txt
> create mode 100644 Documentation/devicetree/bindings/timer/ezchip,nps400-timer1.txt

> diff --git a/drivers/clocksource/timer-nps.c b/drivers/clocksource/timer-nps.c
> index 6156e54..0757328 100644
> --- a/drivers/clocksource/timer-nps.c
> +++ b/drivers/clocksource/timer-nps.c
> @@ -46,7 +46,7 @@
> /* This array is per cluster of CPUs (Each NPS400 cluster got 256 CPUs) */
> static void *nps_msu_reg_low_addr[NPS_CLUSTER_NUM] __read_mostly;
>
> -static unsigned long nps_timer_rate;
> +static unsigned long nps_timer1_freq;
> static int nps_get_timer_clk(struct device_node *node,
> unsigned long *timer_freq,
> struct clk *clk)
> @@ -87,10 +87,10 @@ static int __init nps_setup_clocksource(struct device_node *node)
> nps_host_reg((cluster << NPS_CLUSTER_OFFSET),
> NPS_MSU_BLKID, NPS_MSU_TICK_LOW);
>
> - nps_get_timer_clk(node, &nps_timer_rate, clk);
> + nps_get_timer_clk(node, &nps_timer1_freq, clk);
>
> - ret = clocksource_mmio_init(nps_msu_reg_low_addr, "EZnps-tick",
> - nps_timer_rate, 301, 32, nps_clksrc_read);
> + ret = clocksource_mmio_init(nps_msu_reg_low_addr, "nps-tick",
> + nps_timer1_freq, 301, 32, nps_clksrc_read);
> if (ret) {
> pr_err("Couldn't register clock source.\n");
> clk_disable_unprepare(clk);
> @@ -99,5 +99,215 @@ static int __init nps_setup_clocksource(struct device_node *node)
> return ret;
> }
>
> -CLOCKSOURCE_OF_DECLARE(ezchip_nps400_clksrc, "ezchip,nps400-timer",
> +CLOCKSOURCE_OF_DECLARE(ezchip_nps400_clksrc, "ezchip,nps400-timer1",
> nps_setup_clocksource);

You should keep the old string here for backwards compatiblity.

Rob