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d2912cb1 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
6754f556 ML |
2 | /* |
3 | * Copyright (C) 2012 Calxeda, Inc. | |
4 | * | |
6754f556 | 5 | * This driver provides the clk notifier callbacks that are used when |
bbcf0719 | 6 | * the cpufreq-dt driver changes to frequency to alert the highbank |
6754f556 ML |
7 | * EnergyCore Management Engine (ECME) about the need to change |
8 | * voltage. The ECME interfaces with the actual voltage regulators. | |
9 | */ | |
10 | ||
11 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt | |
12 | ||
13 | #include <linux/kernel.h> | |
14 | #include <linux/module.h> | |
15 | #include <linux/clk.h> | |
16 | #include <linux/cpu.h> | |
17 | #include <linux/err.h> | |
18 | #include <linux/of.h> | |
f2fc42b6 | 19 | #include <linux/pl320-ipc.h> |
5553f9e2 | 20 | #include <linux/platform_device.h> |
6754f556 ML |
21 | |
22 | #define HB_CPUFREQ_CHANGE_NOTE 0x80000001 | |
23 | #define HB_CPUFREQ_IPC_LEN 7 | |
24 | #define HB_CPUFREQ_VOLT_RETRIES 15 | |
25 | ||
26 | static int hb_voltage_change(unsigned int freq) | |
27 | { | |
f5f43dcf | 28 | u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000}; |
6754f556 ML |
29 | |
30 | return pl320_ipc_transmit(msg); | |
31 | } | |
32 | ||
33 | static int hb_cpufreq_clk_notify(struct notifier_block *nb, | |
34 | unsigned long action, void *hclk) | |
35 | { | |
36 | struct clk_notifier_data *clk_data = hclk; | |
37 | int i = 0; | |
38 | ||
39 | if (action == PRE_RATE_CHANGE) { | |
40 | if (clk_data->new_rate > clk_data->old_rate) | |
41 | while (hb_voltage_change(clk_data->new_rate)) | |
42 | if (i++ > HB_CPUFREQ_VOLT_RETRIES) | |
43 | return NOTIFY_BAD; | |
44 | } else if (action == POST_RATE_CHANGE) { | |
45 | if (clk_data->new_rate < clk_data->old_rate) | |
46 | while (hb_voltage_change(clk_data->new_rate)) | |
47 | if (i++ > HB_CPUFREQ_VOLT_RETRIES) | |
48 | return NOTIFY_BAD; | |
49 | } | |
50 | ||
51 | return NOTIFY_DONE; | |
52 | } | |
53 | ||
54 | static struct notifier_block hb_cpufreq_clk_nb = { | |
55 | .notifier_call = hb_cpufreq_clk_notify, | |
56 | }; | |
57 | ||
f7968c22 | 58 | static int __init hb_cpufreq_driver_init(void) |
6754f556 | 59 | { |
bbcf0719 | 60 | struct platform_device_info devinfo = { .name = "cpufreq-dt", }; |
6754f556 ML |
61 | struct device *cpu_dev; |
62 | struct clk *cpu_clk; | |
63 | struct device_node *np; | |
64 | int ret; | |
65 | ||
fbbc5bfb ML |
66 | if ((!of_machine_is_compatible("calxeda,highbank")) && |
67 | (!of_machine_is_compatible("calxeda,ecx-2000"))) | |
6754f556 ML |
68 | return -ENODEV; |
69 | ||
6754f556 ML |
70 | cpu_dev = get_cpu_device(0); |
71 | if (!cpu_dev) { | |
72 | pr_err("failed to get highbank cpufreq device\n"); | |
5de6e94a | 73 | return -ENODEV; |
6754f556 ML |
74 | } |
75 | ||
5de6e94a SK |
76 | np = of_node_get(cpu_dev->of_node); |
77 | if (!np) { | |
78 | pr_err("failed to find highbank cpufreq node\n"); | |
79 | return -ENOENT; | |
80 | } | |
6754f556 ML |
81 | |
82 | cpu_clk = clk_get(cpu_dev, NULL); | |
83 | if (IS_ERR(cpu_clk)) { | |
84 | ret = PTR_ERR(cpu_clk); | |
85 | pr_err("failed to get cpu0 clock: %d\n", ret); | |
86 | goto out_put_node; | |
87 | } | |
88 | ||
89 | ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb); | |
90 | if (ret) { | |
91 | pr_err("failed to register clk notifier: %d\n", ret); | |
92 | goto out_put_node; | |
93 | } | |
94 | ||
bbcf0719 | 95 | /* Instantiate cpufreq-dt */ |
5553f9e2 SG |
96 | platform_device_register_full(&devinfo); |
97 | ||
6754f556 ML |
98 | out_put_node: |
99 | of_node_put(np); | |
100 | return ret; | |
101 | } | |
102 | module_init(hb_cpufreq_driver_init); | |
103 | ||
9433777a PR |
104 | static const struct of_device_id __maybe_unused hb_cpufreq_of_match[] = { |
105 | { .compatible = "calxeda,highbank" }, | |
106 | { .compatible = "calxeda,ecx-2000" }, | |
107 | { }, | |
108 | }; | |
109 | MODULE_DEVICE_TABLE(of, hb_cpufreq_of_match); | |
110 | ||
6754f556 ML |
111 | MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>"); |
112 | MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver"); | |
113 | MODULE_LICENSE("GPL"); |