tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * Copyright (C) 2012 Calxeda, Inc.
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License version 2 as
6 * published by the Free Software Foundation.
7 *
8 * This driver provides the clk notifier callbacks that are used when
9 * the cpufreq-cpu0 driver changes to frequency to alert the highbank
10 * EnergyCore Management Engine (ECME) about the need to change
11 * voltage. The ECME interfaces with the actual voltage regulators.
12 */
13
14#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
15
16#include <linux/kernel.h>
17#include <linux/module.h>
18#include <linux/clk.h>
19#include <linux/cpu.h>
20#include <linux/err.h>
21#include <linux/of.h>
22#include <linux/mailbox.h>
23#include <linux/platform_device.h>
24
25#define HB_CPUFREQ_CHANGE_NOTE 0x80000001
26#define HB_CPUFREQ_IPC_LEN 7
27#define HB_CPUFREQ_VOLT_RETRIES 15
28
29static int hb_voltage_change(unsigned int freq)
30{
31 int i;
32 u32 msg[HB_CPUFREQ_IPC_LEN];
33
34 msg[0] = HB_CPUFREQ_CHANGE_NOTE;
35 msg[1] = freq / 1000000;
36 for (i = 2; i < HB_CPUFREQ_IPC_LEN; i++)
37 msg[i] = 0;
38
39 return pl320_ipc_transmit(msg);
40}
41
42static int hb_cpufreq_clk_notify(struct notifier_block *nb,
43 unsigned long action, void *hclk)
44{
45 struct clk_notifier_data *clk_data = hclk;
46 int i = 0;
47
48 if (action == PRE_RATE_CHANGE) {
49 if (clk_data->new_rate > clk_data->old_rate)
50 while (hb_voltage_change(clk_data->new_rate))
51 if (i++ > HB_CPUFREQ_VOLT_RETRIES)
52 return NOTIFY_BAD;
53 } else if (action == POST_RATE_CHANGE) {
54 if (clk_data->new_rate < clk_data->old_rate)
55 while (hb_voltage_change(clk_data->new_rate))
56 if (i++ > HB_CPUFREQ_VOLT_RETRIES)
57 return NOTIFY_BAD;
58 }
59
60 return NOTIFY_DONE;
61}
62
63static struct notifier_block hb_cpufreq_clk_nb = {
64 .notifier_call = hb_cpufreq_clk_notify,
65};
66
67static int hb_cpufreq_driver_init(void)
68{
69 struct platform_device_info devinfo = { .name = "cpufreq-cpu0", };
70 struct device *cpu_dev;
71 struct clk *cpu_clk;
72 struct device_node *np;
73 int ret;
74
75 if (!of_machine_is_compatible("calxeda,highbank"))
76 return -ENODEV;
77
78 for_each_child_of_node(of_find_node_by_path("/cpus"), np)
79 if (of_get_property(np, "operating-points", NULL))
80 break;
81
82 if (!np) {
83 pr_err("failed to find highbank cpufreq node\n");
84 return -ENOENT;
85 }
86
87 cpu_dev = get_cpu_device(0);
88 if (!cpu_dev) {
89 pr_err("failed to get highbank cpufreq device\n");
90 ret = -ENODEV;
91 goto out_put_node;
92 }
93
94 cpu_dev->of_node = np;
95
96 cpu_clk = clk_get(cpu_dev, NULL);
97 if (IS_ERR(cpu_clk)) {
98 ret = PTR_ERR(cpu_clk);
99 pr_err("failed to get cpu0 clock: %d\n", ret);
100 goto out_put_node;
101 }
102
103 ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
104 if (ret) {
105 pr_err("failed to register clk notifier: %d\n", ret);
106 goto out_put_node;
107 }
108
109 /* Instantiate cpufreq-cpu0 */
110 platform_device_register_full(&devinfo);
111
112out_put_node:
113 of_node_put(np);
114 return ret;
115}
116module_init(hb_cpufreq_driver_init);
117
118MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
119MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
120MODULE_LICENSE("GPL");