drivers/firmware/scpi_pm_domain.c

   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
  15 struct 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  */
  27 enum 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
  34 static 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
  51 static 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
  58 static 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
  65 static 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
 135 static const struct of_device_id scpi_power_domain_ids[] = {
 136         { .compatible = "arm,scpi-power-domains", },
 137         { /* sentinel */ }
 138 };
 139 MODULE_DEVICE_TABLE(of, scpi_power_domain_ids);
 140
 141 static 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 };
 148 module_platform_driver(scpi_power_domain_driver);
 149
 150 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 151 MODULE_DESCRIPTION("ARM SCPI power domain driver");
 152 MODULE_LICENSE("GPL v2");