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};
 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 */
 26enum 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
 33static 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
 50static 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
 57static 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
 64static 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
139static const struct of_device_id scpi_power_domain_ids[] = {
140	{ .compatible = "arm,scpi-power-domains", },
141	{ /* sentinel */ }
142};
143MODULE_DEVICE_TABLE(of, scpi_power_domain_ids);
144
145static 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};
152module_platform_driver(scpi_power_domain_driver);
153
154MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
155MODULE_DESCRIPTION("ARM SCPI power domain driver");
156MODULE_LICENSE("GPL v2");