LXR linux/drivers/firmware/scpi_pm

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * SCPI Generic power domain support.
   4 *
   5 * Copyright (C) 2016 ARM Ltd.
   6 */
   7
   8#include <linux/err.h>
   9#include <linux/io.h>
  10#include <linux/module.h>
  11#include <linux/of_platform.h>
  12#include <linux/pm_domain.h>
  13#include <linux/scpi_protocol.h>
  14
  15struct scpi_pm_domain {
  16        struct generic_pm_domain genpd;
  17        struct scpi_ops *ops;
  18        u32 domain;
  19        char name[30];
  20};
  21
  22/*
  23 * These device power state values are not well-defined in the specification.
  24 * In case, different implementations use different values, we can make these
  25 * specific to compatibles rather than getting these values from device tree.
  26 */
  27enum scpi_power_domain_state {
  28        SCPI_PD_STATE_ON = 0,
  29        SCPI_PD_STATE_OFF = 3,
  30};
  31
  32#define to_scpi_pd(gpd) container_of(gpd, struct scpi_pm_domain, genpd)
  33
  34static int scpi_pd_power(struct scpi_pm_domain *pd, bool power_on)
  35{
  36        int ret;
  37        enum scpi_power_domain_state state;
  38
  39        if (power_on)
  40                state = SCPI_PD_STATE_ON;
  41        else
  42                state = SCPI_PD_STATE_OFF;
  43
  44        ret = pd->ops->device_set_power_state(pd->domain, state);
  45        if (ret)
  46                return ret;
  47
  48        return !(state == pd->ops->device_get_power_state(pd->domain));
  49}
  50
  51static int scpi_pd_power_on(struct generic_pm_domain *domain)
  52{
  53        struct scpi_pm_domain *pd = to_scpi_pd(domain);
  54
  55        return scpi_pd_power(pd, true);
  56}
  57
  58static int scpi_pd_power_off(struct generic_pm_domain *domain)
  59{
  60        struct scpi_pm_domain *pd = to_scpi_pd(domain);
  61
  62        return scpi_pd_power(pd, false);
  63}
  64
  65static int scpi_pm_domain_probe(struct platform_device *pdev)
  66{
  67        struct device *dev = &pdev->dev;
  68        struct device_node *np = dev->of_node;
  69        struct scpi_pm_domain *scpi_pd;
  70        struct genpd_onecell_data *scpi_pd_data;
  71        struct generic_pm_domain **domains;
  72        struct scpi_ops *scpi_ops;
  73        int ret, num_domains, i;
  74
  75        scpi_ops = get_scpi_ops();
  76        if (!scpi_ops)
  77                return -EPROBE_DEFER;
  78
  79        if (!np) {
  80                dev_err(dev, "device tree node not found\n");
  81                return -ENODEV;
  82        }
  83
  84        if (!scpi_ops->device_set_power_state ||
  85            !scpi_ops->device_get_power_state) {
  86                dev_err(dev, "power domains not supported in the firmware\n");
  87                return -ENODEV;
  88        }
  89
  90        ret = of_property_read_u32(np, "num-domains", &num_domains);
  91        if (ret) {
  92                dev_err(dev, "number of domains not found\n");
  93                return -EINVAL;
  94        }
  95
  96        scpi_pd = devm_kcalloc(dev, num_domains, sizeof(*scpi_pd), GFP_KERNEL);
  97        if (!scpi_pd)
  98                return -ENOMEM;
  99
 100        scpi_pd_data = devm_kzalloc(dev, sizeof(*scpi_pd_data), GFP_KERNEL);
 101        if (!scpi_pd_data)
 102                return -ENOMEM;
 103
 104        domains = devm_kcalloc(dev, num_domains, sizeof(*domains), GFP_KERNEL);
 105        if (!domains)
 106                return -ENOMEM;
 107
 108        for (i = 0; i < num_domains; i++, scpi_pd++) {
 109                domains[i] = &scpi_pd->genpd;
 110
 111                scpi_pd->domain = i;
 112                scpi_pd->ops = scpi_ops;
 113                sprintf(scpi_pd->name, "%pOFn.%d", np, i);
 114                scpi_pd->genpd.name = scpi_pd->name;
 115                scpi_pd->genpd.power_off = scpi_pd_power_off;
 116                scpi_pd->genpd.power_on = scpi_pd_power_on;
 117
 118                /*
 119                 * Treat all power domains as off at boot.
 120                 *
 121                 * The SCP firmware itself may have switched on some domains,
 122                 * but for reference counting purpose, keep it this way.
 123                 */
 124                pm_genpd_init(&scpi_pd->genpd, NULL, true);
 125        }
 126
 127        scpi_pd_data->domains = domains;
 128        scpi_pd_data->num_domains = num_domains;
 129
 130        of_genpd_add_provider_onecell(np, scpi_pd_data);
 131
 132        return 0;
 133}
 134
 135static const struct of_device_id scpi_power_domain_ids[] = {
 136        { .compatible = "arm,scpi-power-domains", },
 137        { /* sentinel */ }
 138};
 139MODULE_DEVICE_TABLE(of, scpi_power_domain_ids);
 140
 141static struct platform_driver scpi_power_domain_driver = {
 142        .driver = {
 143                .name = "scpi_power_domain",
 144                .of_match_table = scpi_power_domain_ids,
 145        },
 146        .probe = scpi_pm_domain_probe,
 147};
 148module_platform_driver(scpi_power_domain_driver);
 149
 150MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 151MODULE_DESCRIPTION("ARM SCPI power domain driver");
 152MODULE_LICENSE("GPL v2");
 153