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

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Date:   Fri, 26 Jan 2018 13:13:00 -0800
From:   "dbasehore ." <dbasehore@...omium.org>
To:     Brian Norris <briannorris@...omium.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        Soby Mathew <Soby.Mathew@....com>,
        Sudeep Holla <sudeep.holla@....com>,
        devicetree@...r.kernel.org, robh+dt@...nel.org,
        Mark Rutland <mark.rutland@....com>,
        Linux-pm mailing list <linux-pm@...r.kernel.org>,
        "Wysocki, Rafael J" <rafael.j.wysocki@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Marc Zyngier <marc.zyngier@....com>
Subject: Re: [PATCH v2 2/5] irqchip/gic-v3-its: add ability to save/restore
 ITS state

On Fri, Jan 26, 2018 at 12:59 PM, Brian Norris <briannorris@...omium.org> wrote:
> 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.

Oops. I'll change that and add a pr_err in the its_force_quiescent
error case in the next patch set.

>
> 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;