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