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");