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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 | |
29 | static int hb_voltage_change(unsigned int freq) |
30 | { |
31 | u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000}; |
32 | |
33 | return pl320_ipc_transmit(msg); |
34 | } |
35 | |
36 | static int hb_cpufreq_clk_notify(struct notifier_block *nb, |
37 | unsigned long action, void *hclk) |
38 | { |
39 | struct clk_notifier_data *clk_data = hclk; |
40 | int i = 0; |
41 | |
42 | if (action == PRE_RATE_CHANGE) { |
43 | if (clk_data->new_rate > clk_data->old_rate) |
44 | while (hb_voltage_change(clk_data->new_rate)) |
45 | if (i++ > HB_CPUFREQ_VOLT_RETRIES) |
46 | return NOTIFY_BAD; |
47 | } else if (action == POST_RATE_CHANGE) { |
48 | if (clk_data->new_rate < clk_data->old_rate) |
49 | while (hb_voltage_change(clk_data->new_rate)) |
50 | if (i++ > HB_CPUFREQ_VOLT_RETRIES) |
51 | return NOTIFY_BAD; |
52 | } |
53 | |
54 | return NOTIFY_DONE; |
55 | } |
56 | |
57 | static struct notifier_block hb_cpufreq_clk_nb = { |
58 | .notifier_call = hb_cpufreq_clk_notify, |
59 | }; |
60 | |
61 | static int hb_cpufreq_driver_init(void) |
62 | { |
63 | struct platform_device_info devinfo = { .name = "cpufreq-cpu0", }; |
64 | struct device *cpu_dev; |
65 | struct clk *cpu_clk; |
66 | struct device_node *np; |
67 | int ret; |
68 | |
69 | if (!of_machine_is_compatible("calxeda,highbank")) |
70 | return -ENODEV; |
71 | |
72 | for_each_child_of_node(of_find_node_by_path("/cpus"), np) |
73 | if (of_get_property(np, "operating-points", NULL)) |
74 | break; |
75 | |
76 | if (!np) { |
77 | pr_err("failed to find highbank cpufreq node\n"); |
78 | return -ENOENT; |
79 | } |
80 | |
81 | cpu_dev = get_cpu_device(0); |
82 | if (!cpu_dev) { |
83 | pr_err("failed to get highbank cpufreq device\n"); |
84 | ret = -ENODEV; |
85 | goto out_put_node; |
86 | } |
87 | |
88 | cpu_dev->of_node = np; |
89 | |
90 | cpu_clk = clk_get(cpu_dev, NULL); |
91 | if (IS_ERR(cpu_clk)) { |
92 | ret = PTR_ERR(cpu_clk); |
93 | pr_err("failed to get cpu0 clock: %d\n", ret); |
94 | goto out_put_node; |
95 | } |
96 | |
97 | ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb); |
98 | if (ret) { |
99 | pr_err("failed to register clk notifier: %d\n", ret); |
100 | goto out_put_node; |
101 | } |
102 | |
103 | /* Instantiate cpufreq-cpu0 */ |
104 | platform_device_register_full(&devinfo); |
105 | |
106 | out_put_node: |
107 | of_node_put(np); |
108 | return ret; |
109 | } |
110 | module_init(hb_cpufreq_driver_init); |
111 | |
112 | MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>"); |
113 | MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver"); |
114 | MODULE_LICENSE("GPL"); |
115 |
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Tags:
od-2011-09-04
od-2011-09-18
v2.6.34-rc5
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