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");
157