drivers/firmware/scpi_pm_domain.c

   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
  26 struct 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  */
  38 enum 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
  45 static 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
  62 static 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
  69 static 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
  76 static 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, "%pOFn.%d", np, 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
 146 static const struct of_device_id scpi_power_domain_ids[] = {
 147         { .compatible = "arm,scpi-power-domains", },
 148         { /* sentinel */ }
 149 };
 150 MODULE_DEVICE_TABLE(of, scpi_power_domain_ids);
 151
 152 static 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 };
 159 module_platform_driver(scpi_power_domain_driver);
 160
 161 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
 162 MODULE_DESCRIPTION("ARM SCPI power domain driver");
 163 MODULE_LICENSE("GPL v2");