linux-kernel - Re: [PATCH v2 2/5] irqchip/gic-v3-its: add ability to save/restore ITS state

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Message-ID: <20180126205954.cikwitw7sgdt2yn3@ban.mtv.corp.google.com>
Date:   Fri, 26 Jan 2018 12:59:56 -0800
From:   Brian Norris <briannorris@...omium.org>
To:     Derek Basehore <dbasehore@...omium.org>
Cc:     linux-kernel@...r.kernel.org, Soby.Mathew@....com,
        sudeep.holla@....com, devicetree@...r.kernel.org,
        robh+dt@...nel.org, mark.rutland@....com, linux-pm@...r.kernel.org,
        rafael.j.wysocki@...el.com, tglx@...utronix.de,
        marc.zyngier@....com
Subject: Re: [PATCH v2 2/5] irqchip/gic-v3-its: add ability to save/restore
 ITS state

One trivial comment:

On Thu, Jan 25, 2018 at 11:38:32PM -0800, Derek Basehore wrote:
> Some platforms power off GIC logic in suspend, so we need to
> save/restore state. The distributor and redistributor registers need
> to be handled in platform code due to access permissions on those
> registers, but the ITS registers can be restored in the kernel.
> 
> Signed-off-by: Derek Basehore <dbasehore@...omium.org>
> ---
>  drivers/irqchip/irq-gic-v3-its.c | 86 ++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 86 insertions(+)
> 
> diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c
> index 06f025fd5726..4727b447610f 100644
> --- a/drivers/irqchip/irq-gic-v3-its.c
> +++ b/drivers/irqchip/irq-gic-v3-its.c

...

> @@ -3042,6 +3054,75 @@ static void its_enable_quirks(struct its_node *its)
>  	gic_enable_quirks(iidr, its_quirks, its);
>  }
>  
> +int its_save_disable(void)

This (and its_restore_enable()) should be static, now that you're only
using them in this file.

Brian

> +{
> +	struct its_node *its;
> +	int err = 0;
> +
> +	spin_lock(&its_lock);
> +	list_for_each_entry(its, &its_nodes, entry) {
> +		if (its->flags & ITS_FLAGS_SAVE_SUSPEND_STATE) {
> +			struct its_ctx *ctx = &its->its_ctx;
> +			void __iomem *base = its->base;
> +
> +			ctx->ctlr = readl_relaxed(base + GITS_CTLR);
> +			err = its_force_quiescent(base);
> +			if (err) {
> +				writel_relaxed(ctx->ctlr, base + GITS_CTLR);
> +				goto err;
> +			}
> +
> +			ctx->cbaser = gits_read_cbaser(base + GITS_CBASER);
> +		}
> +	}
> +
> +err:
> +	if (err) {
> +		list_for_each_entry_continue_reverse(its, &its_nodes, entry) {
> +			if (its->flags & ITS_FLAGS_SAVE_SUSPEND_STATE) {
> +				struct its_ctx *ctx = &its->its_ctx;
> +				void __iomem *base = its->base;
> +
> +				writel_relaxed(ctx->ctlr, base + GITS_CTLR);
> +			}
> +		}
> +	}
> +
> +	spin_unlock(&its_lock);
> +
> +	return err;
> +}
> +
> +void its_restore_enable(void)
> +{
> +	struct its_node *its;
> +
> +	spin_lock(&its_lock);
> +	list_for_each_entry(its, &its_nodes, entry) {
> +		struct its_ctx *ctx = &its->its_ctx;
> +		struct its_baser *baser;
> +		void __iomem *base;
> +		int i;
> +
> +		if (its->flags & ITS_FLAGS_SAVE_SUSPEND_STATE) {
> +			base = its->base;
> +			gits_write_cbaser(ctx->cbaser, base + GITS_CBASER);
> +			/* Restore GITS_BASER from the value cache. */
> +			for (i = 0; i < GITS_BASER_NR_REGS; i++) {
> +				baser = &its->tables[i];
> +				its_write_baser(its, baser, baser->val);
> +			}
> +			writel_relaxed(ctx->ctlr, base + GITS_CTLR);
> +		}
> +	}
> +	spin_unlock(&its_lock);
> +}
> +
> +static struct syscore_ops its_syscore_ops = {
> +	.suspend = its_save_disable,
> +	.resume = its_restore_enable,
> +};
> +
>  static int its_init_domain(struct fwnode_handle *handle, struct its_node *its)
>  {
>  	struct irq_domain *inner_domain;