Hi Guenter,
Thanks for the feedback.
On Tue, 30 Jan 2024 at 06:26, Guenter Roeck <linux@xxxxxxxxxxxx> wrote:
>
> On 1/29/24 13:19, Peter Griffin wrote:
> > Some Exynos based SoCs like Tensor gs101 protect the PMU registers for
> > security hardening reasons so that they are only accessible in el3 via an
> > SMC call.
> >
> > As most Exynos drivers that need to write PMU registers currently obtain a
> > regmap via syscon (phys, pinctrl, watchdog). Support for the above usecase
> > is implemented in this driver using a custom regmap similar to syscon to
> > handle the SMC call. Platforms that don't secure PMU registers, get a mmio
> > regmap like before. As regmaps abstract out the underlying register access
> > changes to the leaf drivers are minimal.
> >
> > A new API exynos_get_pmu_regmap_by_phandle() is provided for leaf drivers
> > that currently use syscon_regmap_lookup_by_phandle(). This also handles
> > deferred probing.
> >
> > Signed-off-by: Peter Griffin <peter.griffin@xxxxxxxxxx>
> > ---
> [ ... ]
>
> > +/**
> > + * exynos_get_pmu_regmap
> > + * Find the pmureg previously configured in probe() and return regmap property.
> > + * Return: regmap if found or error if not found.
> > + */
> > struct regmap *exynos_get_pmu_regmap(void)
> > {
> > struct device_node *np = of_find_matching_node(NULL,
> > exynos_pmu_of_device_ids);
> > if (np)
> > - return syscon_node_to_regmap(np);
> > + return exynos_get_pmu_regmap_by_phandle(np, NULL);
> > return ERR_PTR(-ENODEV);
> > }
> > EXPORT_SYMBOL_GPL(exynos_get_pmu_regmap);
> >
> > +/**
> > + * exynos_get_pmu_regmap_by_phandle
> > + * Find the pmureg previously configured in probe() and return regmap property.
> > + * Return: regmap if found or error if not found.
> > + *
> > + * @np: Pointer to device's Device Tree node
> > + * @property: Device Tree property name which references the pmu
> > + */
> > +struct regmap *exynos_get_pmu_regmap_by_phandle(struct device_node *np,
> > + const char *property)
> > +{
> > + struct device *dev;
> > + struct exynos_pmu_context *ctx;
> > + struct device_node *pmu_np;
> > +
> > + if (property)
> > + pmu_np = of_parse_phandle(np, property, 0);
> > + else
> > + pmu_np = np;
> > +
> > + if (!pmu_np)
> > + return ERR_PTR(-ENODEV);
> > +
> > + dev = driver_find_device_by_of_node(&exynos_pmu_driver.driver,
> > + (void *)pmu_np);
> > + of_node_put(pmu_np);
> > + if (!dev)
> > + return ERR_PTR(-EPROBE_DEFER);
> > +
> > + ctx = dev_get_drvdata(dev);
> > +
> > + return ctx->pmureg;
> > +}
> > +EXPORT_SYMBOL_GPL(exynos_get_pmu_regmap_by_phandle);
> > +
>
> I think there should be a detailed comment explaining why the complexity
> is necessary instead of just returning pmu_context->pmureg.
Ok, I'll add a detailed comment for v3.
Thanks,
Peter
