On 02/06/2016 05:16 PM, Noam Camus wrote:
> From: Noam Camus <noamc at ezchip.com>
>
> Add internal tick generator which is shared by all cores.
> Each cluster of cores view it through dedicated address.
> This is used for SMP system where all CPUs synced by same
> clock source.
>
> Signed-off-by: Noam Camus <noamc at ezchip.com>
> Cc: Daniel Lezcano <daniel.lezcano at linaro.org>
> Cc: Rob Herring <robh+dt at kernel.org>
> Cc: Thomas Gleixner <tglx at linutronix.de>
> Cc: John Stultz <john.stultz at linaro.org>
> Acked-by: Vineet Gupta <vgupta at synopsys.com>
> ---
[ ... ]
> +static cycle_t nps_clksrc_read(struct clocksource *clksrc)
> +{
> + int cluster = raw_smp_processor_id() >> NPS_CLUSTER_OFFSET;
> +
> + return (cycle_t)ioread32be(nps_msu_reg_low_addr[cluster]);
> +}
> +
> +static struct clocksource nps_counter = {
> + .name = "EZnps-tick",
> + .rating = 301,
> + .read = nps_clksrc_read,
> + .mask = CLOCKSOURCE_MASK(32),
> + .flags = CLOCK_SOURCE_IS_CONTINUOUS,
> +};
> +
> +static void __init nps_setup_clocksource(struct device_node *node,
> + struct clk *clk)
> +{
> + struct clocksource *clksrc = &nps_counter;
> + int ret, cluster;
> +
> + for (cluster = 0; cluster < NPS_CLUSTER_NUM; cluster++)
> + nps_msu_reg_low_addr[cluster] =
> + nps_host_reg((cluster << NPS_CLUSTER_OFFSET),
> + NPS_MSU_BLKID, NPS_MSU_TICK_LOW);
> +
> + ret = clk_prepare_enable(clk);
> + if (ret)
> + pr_err("Couldn't enable parent clock\n");
> +
> + nps_timer_rate = clk_get_rate(clk);
If there is an error, you continue the execution of the code. I guess
you expect the system to hang in any case with the error in the console,
right ?
> + ret = clocksource_register_hz(clksrc, nps_timer_rate);
You can simplify the driver even more by using clocksource_mmio_init.
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