// SPDX-License-Identifier: GPL-2.0-only
/*
 * SCPI Generic power domain support.
 *
 * Copyright (C) 2016 ARM Ltd.
 */

#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pm_domain.h>
#include <linux/scpi_protocol.h>

struct scpi_pm_domain {
        struct generic_pm_domain genpd;
        struct scpi_ops *ops;
        u32 domain;
};

/*
 * These device power state values are not well-defined in the specification.
 * In case, different implementations use different values, we can make these
 * specific to compatibles rather than getting these values from device tree.
 */
enum scpi_power_domain_state {
        SCPI_PD_STATE_ON = 0,
        SCPI_PD_STATE_OFF = 3,
};

#define to_scpi_pd(gpd) container_of(gpd, struct scpi_pm_domain, genpd)

static int scpi_pd_power(struct scpi_pm_domain *pd, bool power_on)
{
        int ret;
        enum scpi_power_domain_state state;

        if (power_on)
                state = SCPI_PD_STATE_ON;
        else
                state = SCPI_PD_STATE_OFF;

        ret = pd->ops->device_set_power_state(pd->domain, state);
        if (ret)
                return ret;

        return !(state == pd->ops->device_get_power_state(pd->domain));
}

static int scpi_pd_power_on(struct generic_pm_domain *domain)
{
        struct scpi_pm_domain *pd = to_scpi_pd(domain);

        return scpi_pd_power(pd, true);
}

static int scpi_pd_power_off(struct generic_pm_domain *domain)
{
        struct scpi_pm_domain *pd = to_scpi_pd(domain);

        return scpi_pd_power(pd, false);
}

static int scpi_pm_domain_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct device_node *np = dev->of_node;
        struct scpi_pm_domain *scpi_pd;
        struct genpd_onecell_data *scpi_pd_data;
        struct generic_pm_domain **domains;
        struct scpi_ops *scpi_ops;
        int ret, num_domains, i;

        scpi_ops = get_scpi_ops();
        if (!scpi_ops)
                return -EPROBE_DEFER;

        if (!np) {
                dev_err(dev, "device tree node not found\n");
                return -ENODEV;
        }

        if (!scpi_ops->device_set_power_state ||
            !scpi_ops->device_get_power_state) {
                dev_err(dev, "power domains not supported in the firmware\n");
                return -ENODEV;
        }

        ret = of_property_read_u32(np, "num-domains", &num_domains);
        if (ret) {
                dev_err(dev, "number of domains not found\n");
                return -EINVAL;
        }

        scpi_pd = devm_kcalloc(dev, num_domains, sizeof(*scpi_pd), GFP_KERNEL);
        if (!scpi_pd)
                return -ENOMEM;

        scpi_pd_data = devm_kzalloc(dev, sizeof(*scpi_pd_data), GFP_KERNEL);
        if (!scpi_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++, scpi_pd++) {
                domains[i] = &scpi_pd->genpd;

                scpi_pd->domain = i;
                scpi_pd->ops = scpi_ops;
                scpi_pd->genpd.name = devm_kasprintf(dev, GFP_KERNEL,
                                                     "%pOFn.%d", np, i);
                if (!scpi_pd->genpd.name) {
                        dev_err(dev, "Failed to allocate genpd name:%pOFn.%d\n",
                                np, i);
                        continue;
                }
                scpi_pd->genpd.power_off = scpi_pd_power_off;
                scpi_pd->genpd.power_on = scpi_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.
                 */
                pm_genpd_init(&scpi_pd->genpd, NULL, true);
        }

        scpi_pd_data->domains = domains;
        scpi_pd_data->num_domains = num_domains;

        of_genpd_add_provider_onecell(np, scpi_pd_data);

        return 0;
}

static const struct of_device_id scpi_power_domain_ids[] = {
        { .compatible = "arm,scpi-power-domains", },
        { /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, scpi_power_domain_ids);

static struct platform_driver scpi_power_domain_driver = {
        .driver = {
                .name = "scpi_power_domain",
                .of_match_table = scpi_power_domain_ids,
        },
        .probe = scpi_pm_domain_probe,
};
module_platform_driver(scpi_power_domain_driver);

MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
MODULE_DESCRIPTION("ARM SCPI power domain driver");
MODULE_LICENSE("GPL v2");