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/cpufreq.h>
22 #include <linux/module.h>
23 #include <linux/platform_device.h>
24 #include <linux/pm_opp.h>
25 #include <linux/scpi_protocol.h>
26 #include <linux/types.h>
27 
28 #include "arm_big_little.h"
29 
30 static struct scpi_ops *scpi_ops;
31 
32 static struct scpi_dvfs_info *scpi_get_dvfs_info(struct device *cpu_dev)
33 {
34 	u8 domain = topology_physical_package_id(cpu_dev->id);
35 
36 	if (domain < 0)
37 		return ERR_PTR(-EINVAL);
38 	return scpi_ops->dvfs_get_info(domain);
39 }
40 
41 static int scpi_opp_table_ops(struct device *cpu_dev, bool remove)
42 {
43 	int idx, ret = 0;
44 	struct scpi_opp *opp;
45 	struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
46 
47 	if (IS_ERR(info))
48 		return PTR_ERR(info);
49 
50 	if (!info->opps)
51 		return -EIO;
52 
53 	for (opp = info->opps, idx = 0; idx < info->count; idx++, opp++) {
54 		if (remove)
55 			dev_pm_opp_remove(cpu_dev, opp->freq);
56 		else
57 			ret = dev_pm_opp_add(cpu_dev, opp->freq,
58 					     opp->m_volt * 1000);
59 		if (ret) {
60 			dev_warn(cpu_dev, "failed to add opp %uHz %umV\n",
61 				 opp->freq, opp->m_volt);
62 			while (idx-- > 0)
63 				dev_pm_opp_remove(cpu_dev, (--opp)->freq);
64 			return ret;
65 		}
66 	}
67 	return ret;
68 }
69 
70 static int scpi_get_transition_latency(struct device *cpu_dev)
71 {
72 	struct scpi_dvfs_info *info = scpi_get_dvfs_info(cpu_dev);
73 
74 	if (IS_ERR(info))
75 		return PTR_ERR(info);
76 	return info->latency;
77 }
78 
79 static int scpi_init_opp_table(struct device *cpu_dev)
80 {
81 	return scpi_opp_table_ops(cpu_dev, false);
82 }
83 
84 static void scpi_free_opp_table(struct device *cpu_dev)
85 {
86 	scpi_opp_table_ops(cpu_dev, true);
87 }
88 
89 static struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
90 	.name	= "scpi",
91 	.get_transition_latency = scpi_get_transition_latency,
92 	.init_opp_table = scpi_init_opp_table,
93 	.free_opp_table = scpi_free_opp_table,
94 };
95 
96 static int scpi_cpufreq_probe(struct platform_device *pdev)
97 {
98 	scpi_ops = get_scpi_ops();
99 	if (!scpi_ops)
100 		return -EIO;
101 
102 	return bL_cpufreq_register(&scpi_cpufreq_ops);
103 }
104 
105 static int scpi_cpufreq_remove(struct platform_device *pdev)
106 {
107 	bL_cpufreq_unregister(&scpi_cpufreq_ops);
108 	scpi_ops = NULL;
109 	return 0;
110 }
111 
112 static struct platform_driver scpi_cpufreq_platdrv = {
113 	.driver = {
114 		.name	= "scpi-cpufreq",
115 		.owner	= THIS_MODULE,
116 	},
117 	.probe		= scpi_cpufreq_probe,
118 	.remove		= scpi_cpufreq_remove,
119 };
120 module_platform_driver(scpi_cpufreq_platdrv);
121 
122 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
123 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
124 MODULE_LICENSE("GPL v2");
125