1/*
2 *	kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
3 *
4 *	Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
5 *
6 *	This program is free software; you can redistribute it and/or
7 *	modify it under the terms of the GNU General Public License
8 *	as published by the Free Software Foundation; either version
9 *	2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/clk.h>
15#include <linux/cpufreq.h>
16#include <linux/of_device.h>
17#include <linux/platform_device.h>
18#include <linux/io.h>
19#include <asm/proc-fns.h>
20
21#define CPU_SW_INT_BLK BIT(28)
22
23static struct priv
24{
25	struct clk *cpu_clk;
26	struct clk *ddr_clk;
27	struct clk *powersave_clk;
28	struct device *dev;
29	void __iomem *base;
30} priv;
31
32#define STATE_CPU_FREQ 0x01
33#define STATE_DDR_FREQ 0x02
34
35/*
36 * Kirkwood can swap the clock to the CPU between two clocks:
37 *
38 * - cpu clk
39 * - ddr clk
40 *
41 * The frequencies are set at runtime before registering this table.
42 */
43static struct cpufreq_frequency_table kirkwood_freq_table[] = {
44	{0, STATE_CPU_FREQ,	0}, /* CPU uses cpuclk */
45	{0, STATE_DDR_FREQ,	0}, /* CPU uses ddrclk */
46	{0, 0,			CPUFREQ_TABLE_END},
47};
48
49static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
50{
51	return clk_get_rate(priv.powersave_clk) / 1000;
52}
53
54static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
55			    unsigned int index)
56{
57	unsigned int state = kirkwood_freq_table[index].driver_data;
58	unsigned long reg;
59
60	local_irq_disable();
61
62	/* Disable interrupts to the CPU */
63	reg = readl_relaxed(priv.base);
64	reg |= CPU_SW_INT_BLK;
65	writel_relaxed(reg, priv.base);
66
67	switch (state) {
68	case STATE_CPU_FREQ:
69		clk_set_parent(priv.powersave_clk, priv.cpu_clk);
70		break;
71	case STATE_DDR_FREQ:
72		clk_set_parent(priv.powersave_clk, priv.ddr_clk);
73		break;
74	}
75
76	/* Wait-for-Interrupt, while the hardware changes frequency */
77	cpu_do_idle();
78
79	/* Enable interrupts to the CPU */
80	reg = readl_relaxed(priv.base);
81	reg &= ~CPU_SW_INT_BLK;
82	writel_relaxed(reg, priv.base);
83
84	local_irq_enable();
85
86	return 0;
87}
88
89/* Module init and exit code */
90static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
91{
92	return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
93}
94
95static struct cpufreq_driver kirkwood_cpufreq_driver = {
96	.flags	= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
97	.get	= kirkwood_cpufreq_get_cpu_frequency,
98	.verify	= cpufreq_generic_frequency_table_verify,
99	.target_index = kirkwood_cpufreq_target,
100	.init	= kirkwood_cpufreq_cpu_init,
101	.name	= "kirkwood-cpufreq",
102	.attr	= cpufreq_generic_attr,
103};
104
105static int kirkwood_cpufreq_probe(struct platform_device *pdev)
106{
107	struct device_node *np;
108	struct resource *res;
109	int err;
110
111	priv.dev = &pdev->dev;
112
113	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
114	priv.base = devm_ioremap_resource(&pdev->dev, res);
115	if (IS_ERR(priv.base))
116		return PTR_ERR(priv.base);
117
118	np = of_cpu_device_node_get(0);
119	if (!np) {
120		dev_err(&pdev->dev, "failed to get cpu device node\n");
121		return -ENODEV;
122	}
123
124	priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
125	if (IS_ERR(priv.cpu_clk)) {
126		dev_err(priv.dev, "Unable to get cpuclk");
127		return PTR_ERR(priv.cpu_clk);
128	}
129
130	clk_prepare_enable(priv.cpu_clk);
131	kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
132
133	priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
134	if (IS_ERR(priv.ddr_clk)) {
135		dev_err(priv.dev, "Unable to get ddrclk");
136		err = PTR_ERR(priv.ddr_clk);
137		goto out_cpu;
138	}
139
140	clk_prepare_enable(priv.ddr_clk);
141	kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
142
143	priv.powersave_clk = of_clk_get_by_name(np, "powersave");
144	if (IS_ERR(priv.powersave_clk)) {
145		dev_err(priv.dev, "Unable to get powersave");
146		err = PTR_ERR(priv.powersave_clk);
147		goto out_ddr;
148	}
149	clk_prepare_enable(priv.powersave_clk);
150
151	of_node_put(np);
152	np = NULL;
153
154	err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
155	if (!err)
156		return 0;
157
158	dev_err(priv.dev, "Failed to register cpufreq driver");
159
160	clk_disable_unprepare(priv.powersave_clk);
161out_ddr:
162	clk_disable_unprepare(priv.ddr_clk);
163out_cpu:
164	clk_disable_unprepare(priv.cpu_clk);
165	of_node_put(np);
166
167	return err;
168}
169
170static int kirkwood_cpufreq_remove(struct platform_device *pdev)
171{
172	cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
173
174	clk_disable_unprepare(priv.powersave_clk);
175	clk_disable_unprepare(priv.ddr_clk);
176	clk_disable_unprepare(priv.cpu_clk);
177
178	return 0;
179}
180
181static struct platform_driver kirkwood_cpufreq_platform_driver = {
182	.probe = kirkwood_cpufreq_probe,
183	.remove = kirkwood_cpufreq_remove,
184	.driver = {
185		.name = "kirkwood-cpufreq",
186	},
187};
188
189module_platform_driver(kirkwood_cpufreq_platform_driver);
190
191MODULE_LICENSE("GPL v2");
192MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
193MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
194MODULE_ALIAS("platform:kirkwood-cpufreq");
195