1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *	kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
4 *
5 *	Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
6 */
7
8#include <linux/kernel.h>
9#include <linux/module.h>
10#include <linux/clk.h>
11#include <linux/cpufreq.h>
12#include <linux/of.h>
13#include <linux/platform_device.h>
14#include <linux/io.h>
15#include <asm/proc-fns.h>
16
17#define CPU_SW_INT_BLK BIT(28)
18
19static struct priv
20{
21	struct clk *cpu_clk;
22	struct clk *ddr_clk;
23	struct clk *powersave_clk;
24	struct device *dev;
25	void __iomem *base;
26} priv;
27
28#define STATE_CPU_FREQ 0x01
29#define STATE_DDR_FREQ 0x02
30
31/*
32 * Kirkwood can swap the clock to the CPU between two clocks:
33 *
34 * - cpu clk
35 * - ddr clk
36 *
37 * The frequencies are set at runtime before registering this table.
38 */
39static struct cpufreq_frequency_table kirkwood_freq_table[] = {
40	{0, STATE_CPU_FREQ,	0}, /* CPU uses cpuclk */
41	{0, STATE_DDR_FREQ,	0}, /* CPU uses ddrclk */
42	{0, 0,			CPUFREQ_TABLE_END},
43};
44
45static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
46{
47	return clk_get_rate(priv.powersave_clk) / 1000;
48}
49
50static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
51			    unsigned int index)
52{
53	unsigned int state = kirkwood_freq_table[index].driver_data;
54	unsigned long reg;
55
56	local_irq_disable();
57
58	/* Disable interrupts to the CPU */
59	reg = readl_relaxed(priv.base);
60	reg |= CPU_SW_INT_BLK;
61	writel_relaxed(reg, priv.base);
62
63	switch (state) {
64	case STATE_CPU_FREQ:
65		clk_set_parent(priv.powersave_clk, priv.cpu_clk);
66		break;
67	case STATE_DDR_FREQ:
68		clk_set_parent(priv.powersave_clk, priv.ddr_clk);
69		break;
70	}
71
72	/* Wait-for-Interrupt, while the hardware changes frequency */
73	cpu_do_idle();
74
75	/* Enable interrupts to the CPU */
76	reg = readl_relaxed(priv.base);
77	reg &= ~CPU_SW_INT_BLK;
78	writel_relaxed(reg, priv.base);
79
80	local_irq_enable();
81
82	return 0;
83}
84
85/* Module init and exit code */
86static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
87{
88	cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
89	return 0;
90}
91
92static struct cpufreq_driver kirkwood_cpufreq_driver = {
93	.flags	= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
94	.get	= kirkwood_cpufreq_get_cpu_frequency,
95	.verify	= cpufreq_generic_frequency_table_verify,
96	.target_index = kirkwood_cpufreq_target,
97	.init	= kirkwood_cpufreq_cpu_init,
98	.name	= "kirkwood-cpufreq",
99	.attr	= cpufreq_generic_attr,
100};
101
102static int kirkwood_cpufreq_probe(struct platform_device *pdev)
103{
104	struct device_node *np;
105	int err;
106
107	priv.dev = &pdev->dev;
108
109	priv.base = devm_platform_ioremap_resource(pdev, 0);
110	if (IS_ERR(priv.base))
111		return PTR_ERR(priv.base);
112
113	np = of_cpu_device_node_get(0);
114	if (!np) {
115		dev_err(&pdev->dev, "failed to get cpu device node\n");
116		return -ENODEV;
117	}
118
119	priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
120	if (IS_ERR(priv.cpu_clk)) {
121		dev_err(priv.dev, "Unable to get cpuclk\n");
122		err = PTR_ERR(priv.cpu_clk);
123		goto out_node;
124	}
125
126	err = clk_prepare_enable(priv.cpu_clk);
127	if (err) {
128		dev_err(priv.dev, "Unable to prepare cpuclk\n");
129		goto out_node;
130	}
131
132	kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
133
134	priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
135	if (IS_ERR(priv.ddr_clk)) {
136		dev_err(priv.dev, "Unable to get ddrclk\n");
137		err = PTR_ERR(priv.ddr_clk);
138		goto out_cpu;
139	}
140
141	err = clk_prepare_enable(priv.ddr_clk);
142	if (err) {
143		dev_err(priv.dev, "Unable to prepare ddrclk\n");
144		goto out_cpu;
145	}
146	kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
147
148	priv.powersave_clk = of_clk_get_by_name(np, "powersave");
149	if (IS_ERR(priv.powersave_clk)) {
150		dev_err(priv.dev, "Unable to get powersave\n");
151		err = PTR_ERR(priv.powersave_clk);
152		goto out_ddr;
153	}
154	err = clk_prepare_enable(priv.powersave_clk);
155	if (err) {
156		dev_err(priv.dev, "Unable to prepare powersave clk\n");
157		goto out_ddr;
158	}
159
160	err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
161	if (err) {
162		dev_err(priv.dev, "Failed to register cpufreq driver\n");
163		goto out_powersave;
164	}
165
166	of_node_put(np);
167	return 0;
168
169out_powersave:
170	clk_disable_unprepare(priv.powersave_clk);
171out_ddr:
172	clk_disable_unprepare(priv.ddr_clk);
173out_cpu:
174	clk_disable_unprepare(priv.cpu_clk);
175out_node:
176	of_node_put(np);
177
178	return err;
179}
180
181static void kirkwood_cpufreq_remove(struct platform_device *pdev)
182{
183	cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
184
185	clk_disable_unprepare(priv.powersave_clk);
186	clk_disable_unprepare(priv.ddr_clk);
187	clk_disable_unprepare(priv.cpu_clk);
188}
189
190static struct platform_driver kirkwood_cpufreq_platform_driver = {
191	.probe = kirkwood_cpufreq_probe,
192	.remove_new = kirkwood_cpufreq_remove,
193	.driver = {
194		.name = "kirkwood-cpufreq",
195	},
196};
197
198module_platform_driver(kirkwood_cpufreq_platform_driver);
199
200MODULE_LICENSE("GPL v2");
201MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
202MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
203MODULE_ALIAS("platform:kirkwood-cpufreq");
204