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
26static 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
33static 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
54static struct notifier_block hb_cpufreq_clk_nb = {
55	.notifier_call = hb_cpufreq_clk_notify,
56};
57
58static int 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
98out_put_node:
99	of_node_put(np);
100	return ret;
101}
102module_init(hb_cpufreq_driver_init);
103
104static const struct of_device_id __maybe_unused hb_cpufreq_of_match[] = {
105	{ .compatible = "calxeda,highbank" },
106	{ .compatible = "calxeda,ecx-2000" },
107	{ },
108};
109MODULE_DEVICE_TABLE(of, hb_cpufreq_of_match);
110
111MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
112MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
113MODULE_LICENSE("GPL");
114