[PATCH v3 17/22] firmware: arm_scmi: add device power domain support using genpd

[Ulf Hansson]

On 28 September 2017 at 15:11, Sudeep Holla <sudeep.holla at arm.com> wrote:
> This patch hooks up the support for device power domain provided by
> SCMI using the Linux generic power domain infrastructure.
>
> Cc: Kevin Hilman <khilman at baylibre.com>
> Cc: Ulf Hansson <ulf.hansson at linaro.org>
> Signed-off-by: Sudeep Holla <sudeep.holla at arm.com>
> ---
>  drivers/firmware/Kconfig                   |  13 +++
>  drivers/firmware/arm_scmi/Makefile         |   1 +
>  drivers/firmware/arm_scmi/scmi_pm_domain.c | 134 +++++++++++++++++++++++++++++
>  3 files changed, 148 insertions(+)
>  create mode 100644 drivers/firmware/arm_scmi/scmi_pm_domain.c
>
> diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
> index c3d1a12763ce..a4462bc661c8 100644
> --- a/drivers/firmware/Kconfig
> +++ b/drivers/firmware/Kconfig
> @@ -40,6 +40,19 @@ config ARM_SCMI_PROTOCOL
>           This protocol library provides interface for all the client drivers
>           making use of the features offered by the SCMI.
>
> +config ARM_SCMI_POWER_DOMAIN
> +       tristate "SCMI power domain driver"
> +       depends on ARM_SCMI_PROTOCOL || (COMPILE_TEST && OF)
> +       default y
> +       select PM_GENERIC_DOMAINS if PM
> +       help
> +         This enables support for the SCMI power domains which can be
> +         enabled or disabled via the SCP firmware
> +
> +         This driver can also be built as a module.  If so, the module
> +         will be called scmi_pm_domain. Note this may needed early in boot
> +         before rootfs may be available.
> +
>  config ARM_SCPI_PROTOCOL
>         tristate "ARM System Control and Power Interface (SCPI) Message Protocol"
>         depends on ARM || ARM64 || COMPILE_TEST
> diff --git a/drivers/firmware/arm_scmi/Makefile b/drivers/firmware/arm_scmi/Makefile
> index 7fb026c71833..289e9e5a4764 100644
> --- a/drivers/firmware/arm_scmi/Makefile
> +++ b/drivers/firmware/arm_scmi/Makefile
> @@ -1,3 +1,4 @@
>  obj-$(CONFIG_ARM_SCMI_PROTOCOL)        = arm_scmi.o
>  arm_scmi-y = base.o clock.o driver.o mbox_if.o perf.o power.o sensors.o
>  arm_scmi-$(CONFIG_ARM_MHU) += arm_mhu_if.o
> +obj-$(CONFIG_ARM_SCMI_POWER_DOMAIN) += scmi_pm_domain.o
> diff --git a/drivers/firmware/arm_scmi/scmi_pm_domain.c b/drivers/firmware/arm_scmi/scmi_pm_domain.c
> new file mode 100644
> index 000000000000..e53aa9d0af6e
> --- /dev/null
> +++ b/drivers/firmware/arm_scmi/scmi_pm_domain.c
> @@ -0,0 +1,134 @@
> +/*
> + * SCMI Generic power domain support.
> + *
> + * Copyright (C) 2017 ARM Ltd.
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms and conditions of the GNU General Public License,
> + * version 2, as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope it will be useful, but WITHOUT
> + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
> + * more details.
> + *
> + * You should have received a copy of the GNU General Public License along
> + * with this program. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of_platform.h>
> +#include <linux/pm_domain.h>
> +#include <linux/scmi_protocol.h>
> +
> +struct scmi_pm_domain {
> +       struct generic_pm_domain genpd;
> +       const struct scmi_handle *handle;
> +       const char *name;
> +       u32 domain;
> +};
> +
> +#define to_scmi_pd(gpd) container_of(gpd, struct scmi_pm_domain, genpd)
> +
> +static int scmi_pd_power(struct generic_pm_domain *domain, bool power_on)
> +{
> +       int ret;
> +       u32 state, ret_state;
> +       struct scmi_pm_domain *pd = to_scmi_pd(domain);
> +       const struct scmi_power_ops *ops = pd->handle->power_ops;
> +
> +       if (power_on)
> +               state = SCMI_POWER_STATE_GENERIC_ON;
> +       else
> +               state = SCMI_POWER_STATE_GENERIC_OFF;
> +
> +       ret = ops->state_set(pd->handle, pd->domain, state);
> +       if (!ret)
> +               ret = ops->state_get(pd->handle, pd->domain, &ret_state);
> +       if (!ret && state != ret_state)
> +               return -EIO;
> +
> +       return ret;
> +}
> +
> +static int scmi_pd_power_on(struct generic_pm_domain *domain)
> +{
> +       return scmi_pd_power(domain, true);
> +}
> +
> +static int scmi_pd_power_off(struct generic_pm_domain *domain)
> +{
> +       return scmi_pd_power(domain, false);
> +}
> +
> +static int scmi_pm_domain_probe(struct platform_device *pdev)
> +{
> +       struct device *dev = &pdev->dev;
> +       struct device_node *np = dev->of_node;
> +       struct scmi_pm_domain *scmi_pd;
> +       struct genpd_onecell_data *scmi_pd_data;
> +       struct generic_pm_domain **domains;
> +       int num_domains, i;
> +       const struct scmi_handle *handle = devm_scmi_handle_get(dev);
> +
> +       if (IS_ERR_OR_NULL(handle) || !handle->power_ops)
> +               return -EPROBE_DEFER;
> +
> +       num_domains = handle->power_ops->num_domains_get(handle);
> +       if (num_domains < 0) {
> +               dev_err(dev, "number of domains not found\n");
> +               return num_domains;
> +       }
> +
> +       scmi_pd = devm_kcalloc(dev, num_domains, sizeof(*scmi_pd), GFP_KERNEL);
> +       if (!scmi_pd)
> +               return -ENOMEM;
> +
> +       scmi_pd_data = devm_kzalloc(dev, sizeof(*scmi_pd_data), GFP_KERNEL);
> +       if (!scmi_pd_data)
> +               return -ENOMEM;
> +
> +       domains = devm_kcalloc(dev, num_domains, sizeof(*domains), GFP_KERNEL);
> +       if (!domains)
> +               return -ENOMEM;
> +
> +       for (i = 0; i < num_domains; i++, scmi_pd++) {
> +               domains[i] = &scmi_pd->genpd;
> +
> +               scmi_pd->domain = i;
> +               scmi_pd->handle = handle;
> +               scmi_pd->name = handle->power_ops->name_get(handle, i);
> +               scmi_pd->genpd.name = scmi_pd->name;
> +               scmi_pd->genpd.power_off = scmi_pd_power_off;
> +               scmi_pd->genpd.power_on = scmi_pd_power_on;
> +
> +               /*
> +                * Treat all power domains as off at boot.
> +                *
> +                * The SCP firmware itself may have switched on some domains,
> +                * but for reference counting purpose, keep it this way.
> +                */

I think it would be better to give the correct information about the
state of the PM domain. Otherwise genpd may end up thinking a PM
domain is off, while in fact it's on - thus wasting power.

> +               pm_genpd_init(&scmi_pd->genpd, NULL, true);
> +       }
> +
> +       scmi_pd_data->domains = domains;
> +       scmi_pd_data->num_domains = num_domains;
> +
> +       of_genpd_add_provider_onecell(np, scmi_pd_data);
> +
> +       return 0;
> +}
> +
> +static struct platform_driver scmi_power_domain_driver = {
> +       .driver = {
> +               .name = "scmi-power-domain",
> +       },
> +       .probe = scmi_pm_domain_probe,
> +};
> +module_platform_driver(scmi_power_domain_driver);
> +
> +MODULE_AUTHOR("Sudeep Holla <sudeep.holla at arm.com>");
> +MODULE_DESCRIPTION("ARM SCMI power domain driver");
> +MODULE_LICENSE("GPL v2");
> --
> 2.7.4
>

Otherwise this looks good to me.

Kind regards
Uffe