1 /*
2  * System Control and Power Interface (SCPI) based CPUFreq Interface driver
3  *
4  * It provides necessary ops to arm_big_little cpufreq driver.
5  *
6  * Copyright (C) 2015 ARM Ltd.
7  * Sudeep Holla <sudeep.holla@arm.com>
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12  *
13  * This program is distributed "as is" WITHOUT ANY WARRANTY of any
14  * kind, whether express or implied; without even the implied warranty
15  * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16  * GNU General Public License for more details.
17  */
18 
19 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
20 
21 #include <linux/cpu.h>
22 #include <linux/cpufreq.h>
23 #include <linux/module.h>
24 #include <linux/platform_device.h>
25 #include <linux/pm_opp.h>
26 #include <linux/scpi_protocol.h>
27 #include <linux/types.h>
28 
29 #include "arm_big_little.h"
30 
31 static struct scpi_ops *scpi_ops;
32 
33 static struct scpi_dvfs_info *scpi_get_dvfs_info(struct device *cpu_dev)
34 {
35 	int domain = topology_physical_package_id(cpu_dev->id);
36 
37 	if (domain < 0)
38 		return ERR_PTR(-EINVAL);
39 	return scpi_ops->dvfs_get_info(domain);
40 }
41 
42 static int scpi_get_transition_latency(struct device *cpu_dev)
43 {
44 	struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
45 
46 	if (IS_ERR(info))
47 		return PTR_ERR(info);
48 	return info->latency;
49 }
50 
51 static int scpi_init_opp_table(const struct cpumask *cpumask)
52 {
53 	int idx, ret;
54 	struct scpi_opp *opp;
55 	struct device *cpu_dev = get_cpu_device(cpumask_first(cpumask));
56 	struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
57 
58 	if (IS_ERR(info))
59 		return PTR_ERR(info);
60 
61 	if (!info->opps)
62 		return -EIO;
63 
64 	for (opp = info->opps, idx = 0; idx < info->count; idx++, opp++) {
65 		ret = dev_pm_opp_add(cpu_dev, opp->freq, opp->m_volt * 1000);
66 		if (ret) {
67 			dev_warn(cpu_dev, "failed to add opp %uHz %umV\n",
68 				 opp->freq, opp->m_volt);
69 			while (idx-- > 0)
70 				dev_pm_opp_remove(cpu_dev, (--opp)->freq);
71 			return ret;
72 		}
73 	}
74 
75 	ret = dev_pm_opp_set_sharing_cpus(cpu_dev, cpumask);
76 	if (ret)
77 		dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
78 			__func__, ret);
79 	return ret;
80 }
81 
82 static struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
83 	.name	= "scpi",
84 	.get_transition_latency = scpi_get_transition_latency,
85 	.init_opp_table = scpi_init_opp_table,
86 	.free_opp_table = dev_pm_opp_cpumask_remove_table,
87 };
88 
89 static int scpi_cpufreq_probe(struct platform_device *pdev)
90 {
91 	scpi_ops = get_scpi_ops();
92 	if (!scpi_ops)
93 		return -EIO;
94 
95 	return bL_cpufreq_register(&scpi_cpufreq_ops);
96 }
97 
98 static int scpi_cpufreq_remove(struct platform_device *pdev)
99 {
100 	bL_cpufreq_unregister(&scpi_cpufreq_ops);
101 	scpi_ops = NULL;
102 	return 0;
103 }
104 
105 static struct platform_driver scpi_cpufreq_platdrv = {
106 	.driver = {
107 		.name	= "scpi-cpufreq",
108 		.owner	= THIS_MODULE,
109 	},
110 	.probe		= scpi_cpufreq_probe,
111 	.remove		= scpi_cpufreq_remove,
112 };
113 module_platform_driver(scpi_cpufreq_platdrv);
114 
115 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
116 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
117 MODULE_LICENSE("GPL v2");
118