1 /*
2  * CPUFreq support for Armada 370/XP platforms.
3  *
4  * Copyright (C) 2012-2016 Marvell
5  *
6  * Yehuda Yitschak <yehuday@marvell.com>
7  * Gregory Clement <gregory.clement@free-electrons.com>
8  * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
9  *
10  * This file is licensed under the terms of the GNU General Public
11  * License version 2.  This program is licensed "as is" without any
12  * warranty of any kind, whether express or implied.
13  */
14 
15 #define pr_fmt(fmt) "mvebu-pmsu: " fmt
16 
17 #include <linux/clk.h>
18 #include <linux/cpu.h>
19 #include <linux/init.h>
20 #include <linux/kernel.h>
21 #include <linux/of_address.h>
22 #include <linux/platform_device.h>
23 #include <linux/pm_opp.h>
24 #include <linux/resource.h>
25 
armada_xp_pmsu_cpufreq_init(void)26 static int __init armada_xp_pmsu_cpufreq_init(void)
27 {
28 	struct device_node *np;
29 	struct resource res;
30 	int ret, cpu;
31 
32 	if (!of_machine_is_compatible("marvell,armadaxp"))
33 		return 0;
34 
35 	/*
36 	 * In order to have proper cpufreq handling, we need to ensure
37 	 * that the Device Tree description of the CPU clock includes
38 	 * the definition of the PMU DFS registers. If not, we do not
39 	 * register the clock notifier and the cpufreq driver. This
40 	 * piece of code is only for compatibility with old Device
41 	 * Trees.
42 	 */
43 	np = of_find_compatible_node(NULL, NULL, "marvell,armada-xp-cpu-clock");
44 	if (!np)
45 		return 0;
46 
47 	ret = of_address_to_resource(np, 1, &res);
48 	if (ret) {
49 		pr_warn(FW_WARN "not enabling cpufreq, deprecated armada-xp-cpu-clock binding\n");
50 		of_node_put(np);
51 		return 0;
52 	}
53 
54 	of_node_put(np);
55 
56 	/*
57 	 * For each CPU, this loop registers the operating points
58 	 * supported (which are the nominal CPU frequency and half of
59 	 * it), and registers the clock notifier that will take care
60 	 * of doing the PMSU part of a frequency transition.
61 	 */
62 	for_each_possible_cpu(cpu) {
63 		struct device *cpu_dev;
64 		struct clk *clk;
65 		int ret;
66 
67 		cpu_dev = get_cpu_device(cpu);
68 		if (!cpu_dev) {
69 			pr_err("Cannot get CPU %d\n", cpu);
70 			continue;
71 		}
72 
73 		clk = clk_get(cpu_dev, NULL);
74 		if (IS_ERR(clk)) {
75 			pr_err("Cannot get clock for CPU %d\n", cpu);
76 			return PTR_ERR(clk);
77 		}
78 
79 		ret = dev_pm_opp_add(cpu_dev, clk_get_rate(clk), 0);
80 		if (ret) {
81 			clk_put(clk);
82 			return ret;
83 		}
84 
85 		ret = dev_pm_opp_add(cpu_dev, clk_get_rate(clk) / 2, 0);
86 		if (ret) {
87 			clk_put(clk);
88 			dev_err(cpu_dev, "Failed to register OPPs\n");
89 			goto opp_register_failed;
90 		}
91 
92 		ret = dev_pm_opp_set_sharing_cpus(cpu_dev,
93 						  cpumask_of(cpu_dev->id));
94 		if (ret)
95 			dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
96 				__func__, ret);
97 		clk_put(clk);
98 	}
99 
100 	platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
101 	return 0;
102 
103 opp_register_failed:
104 	/* As registering has failed remove all the opp for all cpus */
105 	dev_pm_opp_cpumask_remove_table(cpu_possible_mask);
106 
107 	return ret;
108 }
109 device_initcall(armada_xp_pmsu_cpufreq_init);
110