1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2012 Calxeda, Inc.
4 *
5 * This driver provides the clk notifier callbacks that are used when
6 * the cpufreq-dt driver changes to frequency to alert the highbank
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>
19 #include <linux/pl320-ipc.h>
20 #include <linux/platform_device.h>
21
22 #define HB_CPUFREQ_CHANGE_NOTE 0x80000001
23 #define HB_CPUFREQ_IPC_LEN 7
24 #define HB_CPUFREQ_VOLT_RETRIES 15
25
hb_voltage_change(unsigned int freq)26 static int hb_voltage_change(unsigned int freq)
27 {
28 u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};
29
30 return pl320_ipc_transmit(msg);
31 }
32
hb_cpufreq_clk_notify(struct notifier_block * nb,unsigned long action,void * hclk)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
hb_cpufreq_driver_init(void)58 static int __init hb_cpufreq_driver_init(void)
59 {
60 struct platform_device_info devinfo = { .name = "cpufreq-dt", };
61 struct device *cpu_dev;
62 struct clk *cpu_clk;
63 struct device_node *np;
64 int ret;
65
66 if ((!of_machine_is_compatible("calxeda,highbank")) &&
67 (!of_machine_is_compatible("calxeda,ecx-2000")))
68 return -ENODEV;
69
70 cpu_dev = get_cpu_device(0);
71 if (!cpu_dev) {
72 pr_err("failed to get highbank cpufreq device\n");
73 return -ENODEV;
74 }
75
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 }
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
95 /* Instantiate cpufreq-dt */
96 platform_device_register_full(&devinfo);
97
98 out_put_node:
99 of_node_put(np);
100 return ret;
101 }
102 module_init(hb_cpufreq_driver_init);
103
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
111 MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
112 MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
113 MODULE_LICENSE("GPL");
114