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 int scpi_get_transition_latency(struct device *cpu_dev)
34 {
35 	return scpi_ops->get_transition_latency(cpu_dev);
36 }
37 
38 static int scpi_init_opp_table(const struct cpumask *cpumask)
39 {
40 	int ret;
41 	struct device *cpu_dev = get_cpu_device(cpumask_first(cpumask));
42 
43 	ret = scpi_ops->add_opps_to_device(cpu_dev);
44 	if (ret) {
45 		dev_warn(cpu_dev, "failed to add opps to the device\n");
46 		return ret;
47 	}
48 
49 	ret = dev_pm_opp_set_sharing_cpus(cpu_dev, cpumask);
50 	if (ret)
51 		dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
52 			__func__, ret);
53 	return ret;
54 }
55 
56 static struct cpufreq_arm_bL_ops scpi_cpufreq_ops = {
57 	.name	= "scpi",
58 	.get_transition_latency = scpi_get_transition_latency,
59 	.init_opp_table = scpi_init_opp_table,
60 	.free_opp_table = dev_pm_opp_cpumask_remove_table,
61 };
62 
63 static int scpi_cpufreq_probe(struct platform_device *pdev)
64 {
65 	scpi_ops = get_scpi_ops();
66 	if (!scpi_ops)
67 		return -EIO;
68 
69 	return bL_cpufreq_register(&scpi_cpufreq_ops);
70 }
71 
72 static int scpi_cpufreq_remove(struct platform_device *pdev)
73 {
74 	bL_cpufreq_unregister(&scpi_cpufreq_ops);
75 	scpi_ops = NULL;
76 	return 0;
77 }
78 
79 static struct platform_driver scpi_cpufreq_platdrv = {
80 	.driver = {
81 		.name	= "scpi-cpufreq",
82 	},
83 	.probe		= scpi_cpufreq_probe,
84 	.remove		= scpi_cpufreq_remove,
85 };
86 module_platform_driver(scpi_cpufreq_platdrv);
87 
88 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
89 MODULE_DESCRIPTION("ARM SCPI CPUFreq interface driver");
90 MODULE_LICENSE("GPL v2");
91