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-dt 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/pl320-ipc.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
29static 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
36static 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
57static struct notifier_block hb_cpufreq_clk_nb = {
58	.notifier_call = hb_cpufreq_clk_notify,
59};
60
61static int hb_cpufreq_driver_init(void)
62{
63	struct platform_device_info devinfo = { .name = "cpufreq-dt", };
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		(!of_machine_is_compatible("calxeda,ecx-2000")))
71		return -ENODEV;
72
73	cpu_dev = get_cpu_device(0);
74	if (!cpu_dev) {
75		pr_err("failed to get highbank cpufreq device\n");
76		return -ENODEV;
77	}
78
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	}
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
98	/* Instantiate cpufreq-dt */
99	platform_device_register_full(&devinfo);
100
101out_put_node:
102	of_node_put(np);
103	return ret;
104}
105module_init(hb_cpufreq_driver_init);
106
107MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
108MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
109MODULE_LICENSE("GPL");
110