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

[Mark Rutland <mark.rutland@arm.com>]

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@arm.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.

> >> +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.