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6754f556 ML |
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> | |
5553f9e2 | 23 | #include <linux/platform_device.h> |
6754f556 ML |
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 | { | |
f5f43dcf | 31 | u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000}; |
6754f556 ML |
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 | { | |
5553f9e2 | 63 | struct platform_device_info devinfo = { .name = "cpufreq-cpu0", }; |
6754f556 ML |
64 | struct device *cpu_dev; |
65 | struct clk *cpu_clk; | |
66 | struct device_node *np; | |
67 | int ret; | |
68 | ||
fbbc5bfb ML |
69 | if ((!of_machine_is_compatible("calxeda,highbank")) && |
70 | (!of_machine_is_compatible("calxeda,ecx-2000"))) | |
6754f556 ML |
71 | return -ENODEV; |
72 | ||
6754f556 ML |
73 | cpu_dev = get_cpu_device(0); |
74 | if (!cpu_dev) { | |
75 | pr_err("failed to get highbank cpufreq device\n"); | |
5de6e94a | 76 | return -ENODEV; |
6754f556 ML |
77 | } |
78 | ||
5de6e94a SK |
79 | np = of_node_get(cpu_dev->of_node); |
80 | if (!np) { | |
81 | pr_err("failed to find highbank cpufreq node\n"); | |
82 | return -ENOENT; | |
83 | } | |
6754f556 ML |
84 | |
85 | cpu_clk = clk_get(cpu_dev, NULL); | |
86 | if (IS_ERR(cpu_clk)) { | |
87 | ret = PTR_ERR(cpu_clk); | |
88 | pr_err("failed to get cpu0 clock: %d\n", ret); | |
89 | goto out_put_node; | |
90 | } | |
91 | ||
92 | ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb); | |
93 | if (ret) { | |
94 | pr_err("failed to register clk notifier: %d\n", ret); | |
95 | goto out_put_node; | |
96 | } | |
97 | ||
5553f9e2 SG |
98 | /* Instantiate cpufreq-cpu0 */ |
99 | platform_device_register_full(&devinfo); | |
100 | ||
6754f556 ML |
101 | out_put_node: |
102 | of_node_put(np); | |
103 | return ret; | |
104 | } | |
105 | module_init(hb_cpufreq_driver_init); | |
106 | ||
107 | MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>"); | |
108 | MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver"); | |
109 | MODULE_LICENSE("GPL"); |