LXR linux/drivers/firmware/scpi_pm

   1/*
   2 * SCPI Generic power domain support.
   3 *
   4 * Copyright (C) 2016 ARM Ltd.
   5 *
   6 * This program is free software; you can redistribute it and/or modify it
   7 * under the terms and conditions of the GNU General Public License,
   8 * version 2, as published by the Free Software Foundation.
   9 *
  10 * This program is distributed in the hope it will be useful, but WITHOUT
  11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  13 * more details.
  14 *
  15 * You should have received a copy of the GNU General Public License along
  16 * with this program. If not, see <http://www.gnu.org/licenses/>.
  17 */
  18
  19#include <linux/err.h>
  20#include <linux/io.h>
  21#include <linux/module.h>
  22#include <linux/of_platform.h>
  23#include <linux/pm_domain.h>
  24#include <linux/scpi_protocol.h>
  25
  26struct scpi_pm_domain {
  27        struct generic_pm_domain genpd;
  28        struct scpi_ops *ops;
  29        u32 domain;
  30        char name[30];
  31};
  32
  33/*
  34 * These device power state values are not well-defined in the specification.
  35 * In case, different implementations use different values, we can make these
  36 * specific to compatibles rather than getting these values from device tree.
  37 */
  38enum scpi_power_domain_state {
  39        SCPI_PD_STATE_ON = 0,
  40        SCPI_PD_STATE_OFF = 3,
  41};
  42
  43#define to_scpi_pd(gpd) container_of(gpd, struct scpi_pm_domain, genpd)
  44
  45static int scpi_pd_power(struct scpi_pm_domain *pd, bool power_on)
  46{
  47        int ret;
  48        enum scpi_power_domain_state state;
  49
  50        if (power_on)
  51                state = SCPI_PD_STATE_ON;
  52        else
  53                state = SCPI_PD_STATE_OFF;
  54
  55        ret = pd->ops->device_set_power_state(pd->domain, state);
  56        if (ret)
  57                return ret;
  58
  59        return !(state == pd->ops->device_get_power_state(pd->domain));
  60}
  61
  62static int scpi_pd_power_on(struct generic_pm_domain *domain)
  63{
  64        struct scpi_pm_domain *pd = to_scpi_pd(domain);
  65
  66        return scpi_pd_power(pd, true);
  67}
  68
  69static int scpi_pd_power_off(struct generic_pm_domain *domain)
  70{
  71        struct scpi_pm_domain *pd = to_scpi_pd(domain);
  72
  73        return scpi_pd_power(pd, false);
  74}
  75
  76static int scpi_pm_domain_probe(struct platform_device *pdev)
  77{
  78        struct device *dev = &pdev->dev;
  79        struct device_node *np = dev->of_node;
  80        struct scpi_pm_domain *scpi_pd;
  81        struct genpd_onecell_data *scpi_pd_data;
  82        struct generic_pm_domain **domains;
  83        struct scpi_ops *scpi_ops;
  84        int ret, num_domains, i;
  85
  86        scpi_ops = get_scpi_ops();
  87        if (!scpi_ops)
  88                return -EPROBE_DEFER;
  89
  90        if (!np) {
  91                dev_err(dev, "device tree node not found\n");
  92                return -ENODEV;
  93        }
  94
  95        if (!scpi_ops->device_set_power_state ||
  96            !scpi_ops->device_get_power_state) {
  97                dev_err(dev, "power domains not supported in the firmware\n");
  98                return -ENODEV;
  99        }
 100
 101        ret = of_property_read_u32(np, "num-domains", &num_domains);
 102        if (ret) {
 103                dev_err(dev, "number of domains not found\n");
 104                return -EINVAL;
 105        }
 106
 107        scpi_pd = devm_kcalloc(dev, num_domains, sizeof(*scpi_pd), GFP_KERNEL);
 108        if (!scpi_pd)
 109                return -ENOMEM;
 110
 111        scpi_pd_data = devm_kzalloc(dev, sizeof(*scpi_pd_data), GFP_KERNEL);
 112        if (!scpi_pd_data)
 113                return -ENOMEM;
 114
 115        domains = devm_kcalloc(dev, num_domains, sizeof(*domains), GFP_KERNEL);
 116        if (!domains)
 117                return -ENOMEM;
 118
 119        for (i = 0; i < num_domains; i++, scpi_pd++) {
 120                domains[i] = &scpi_pd->genpd;
 121
 122                scpi_pd->domain = i;
 123                scpi_pd->ops = scpi_ops;
 124                sprintf(scpi_pd->name, "%s.%d", np->name, i);
 125                scpi_pd->genpd.name = scpi_pd->name;
 126                scpi_pd->genpd.power_off = scpi_pd_power_off;
 127                scpi_pd->genpd.power_on = scpi_pd_power_on;
 128
 129                /*
 130                 * Treat all power domains as off at boot.
 131                 *
 132                 * The SCP firmware itself may have switched on some domains,
 133                 * but for reference counting purpose, keep it this way.
 134                 */
 135                pm_genpd_init(&scpi_pd->genpd, NULL, true);
 136        }
 137
 138        scpi_pd_data->domains = domains;
 139        scpi_pd_data->num_domains = num_domains;
 140
 141        of_genpd_add_provider_onecell(np, scpi_pd_data);
 142
 143        return 0;
 144}
 145
 146static const struct of_device_id scpi_power_domain_ids[] = {
 147        { .compatible = "arm,scpi-power-domains", },
 148        { /* sentinel */ }
 149};
 150MODULE_DEVICE_TABLE(of, scpi_power_domain_ids);
 151
 152static struct platform_driver scpi_power_domain_driver = {
 153        .driver = {
 154                .name = "scpi_power_domain",
 155                .of_match_table = scpi_power_domain_ids,
 156        },
 157        .probe = scpi_pm_domain_probe,
 158};
 159module_platform_driver(scpi_power_domain_driver);
 160
 161MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 162MODULE_DESCRIPTION("ARM SCPI power domain driver");
 163MODULE_LICENSE("GPL v2");
 164