linux-kernel - Re: [PATCH v5 2/2] firmware: qcom: scm: Add support for ARM64 SoCs

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Message-Id: <654E72E1-DCCA-486B-80BB-1853873C55F8@codeaurora.org>
Date:	Wed, 29 Apr 2015 12:25:36 -0500
From:	Kumar Gala <galak@...eaurora.org>
To:	Mark Rutland <mark.rutland@....com>
Cc:	"linux-arm-msm@...r.kernel.org" <linux-arm-msm@...r.kernel.org>,
	Lina Iyer <lina.iyer@...aro.org>,
	"arm@...nel.org" <arm@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	Catalin Marinas <Catalin.Marinas@....com>,
	Lorenzo Pieralisi <Lorenzo.Pieralisi@....com>
Subject: Re: [PATCH v5 2/2] firmware: qcom: scm: Add support for ARM64 SoCs


> On Apr 29, 2015, at 11:38 AM, Mark Rutland <mark.rutland@....com> wrote:
> 
> On Wed, Apr 29, 2015 at 05:18:04PM +0100, Kumar Gala wrote:
>> 
>>> On Apr 29, 2015, at 10:42 AM, Mark Rutland <mark.rutland@....com> wrote:
>>> 
>>> Hi Kumar,
>>> 
>>> On Tue, Apr 28, 2015 at 08:23:58PM +0100, Kumar Gala wrote:
>>>> Add an implementation of the SCM interface that works on ARM64/64-bit SoCs
>>> 
>>> What is the intended use of this on arm64 SoCs?
>>> 
>>> Given the negative reaction to the SMP bringup [1] code that seems to be
>>> the only user, I'm somewhat confused as to why this is being pushed as a
>>> non-RFC in the mean time.
>>> 
>>> Are there other users of this interface code? If so, could you please
>>> mention that in the commit message. I'd also ask that you would Cc me on
>>> future postings of this series.
>>> 
>>> […]
>> 
>> The SCM interface is needed for other things like display:
>> 
>> https://patchwork.kernel.org/patch/6198691/
> 
> Thanks for the link. It would be good if you could mention some users in
> the commit message.

I’ll update the commit message

> 
>>>> +static int qcom_scm_set_boot_addr(void *entry, const cpumask_t *cpus, int flags)
>>>> +{
>>>> +       struct qcom_scm_desc desc = {0};
>>>> +       unsigned int cpu = cpumask_first(cpus);
>>>> +       u64 mpidr_el1 = cpu_logical_map(cpu);
>>>> +
>>>> +       /* For now we assume only a single cpu is set in the mask */
>>>> +       WARN_ON(cpumask_weight(cpus) != 1);
>>>> +
>>>> +       if (mpidr_el1 & ~MPIDR_HWID_BITMASK) {
>>>> +               pr_err("CPU%d:Failed to set boot address\n", cpu);
>>>> +               return -ENOSYS;
>>>> +       }
>>>> +
>>>> +       desc.args[0] = virt_to_phys(entry);
>>>> +       desc.args[1] = BIT(MPIDR_AFFINITY_LEVEL(mpidr_el1, 0));
>>>> +       desc.args[2] = BIT(MPIDR_AFFINITY_LEVEL(mpidr_el1, 1));
>>>> +       desc.args[3] = BIT(MPIDR_AFFINITY_LEVEL(mpidr_el1, 2));
>>>> +       desc.args[4] = ~0ULL;
>>>> +       desc.args[5] = QCOM_SCM_FLAG_HLOS | flags;
>>>> +       desc.arginfo = QCOM_SCM_ARGS(6);
>>>> +
>>>> +       return qcom_scm_call(QCOM_SCM_SVC_BOOT, QCOM_SCM_BOOT_ADDR_MC, &desc);
>>>> +}
>>>> +
>>>> +int __qcom_scm_set_cold_boot_addr(void *entry, const cpumask_t *cpus)
>>>> +{
>>>> +       int flags = QCOM_SCM_FLAG_COLDBOOT_MC;
>>>> +
>>>> +       return qcom_scm_set_boot_addr(entry, cpus, flags);
>>>> +}
>>>> +
>>>> +int __qcom_scm_set_warm_boot_addr(void *entry, const cpumask_t *cpus)
>>>> +{
>>>> +       int flags = QCOM_SCM_FLAG_WARMBOOT_MC;
>>>> +
>>>> +       return qcom_scm_set_boot_addr(entry, cpus, flags);
>>>> +}
>>>> +
>>>> +void __qcom_scm_cpu_power_down(u32 flags)
>>>> +{
>>>> +       struct qcom_scm_desc desc = {0};
>>>> +       desc.args[0] = flags & QCOM_SCM_FLUSH_FLAG_MASK;
>>>> +       desc.arginfo = QCOM_SCM_ARGS(1);
>>>> +
>>>> +       qcom_scm_call_atomic(QCOM_SCM_SVC_BOOT, QCOM_SCM_CMD_TERMINATE_PC, &desc);
>>>> +}
>>> 
>>> As mentioned in the other thread, I don't want to see this for arm64,
>>> and must NAK this portion.
>> 
>> I can have these return an error code, but we want to keep the interface the same between the 32-bit and 64-bit.
> 
> I don't follow. If nothing calls these on the 64-bit side, then there's
> no interface they need to be there for.
> 
> Thanks,
> Mark.

While nothing may call them, its still easier to try and keep the interface the same between 32 and 64-bit side of things.  Its the equivalent of when we have a CONFIG_ option disabled, but still allow things to build.

- k

-- 
Qualcomm Innovation Center, Inc.
The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum,
a Linux Foundation Collaborative Project

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