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