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 
19 static 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  */
39 static 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 
45 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
46 {
47 	return clk_get_rate(priv.powersave_clk) / 1000;
48 }
49 
50 static 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 */
86 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
87 {
88 	cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
89 	return 0;
90 }
91 
92 static 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 
102 static 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 
169 out_powersave:
170 	clk_disable_unprepare(priv.powersave_clk);
171 out_ddr:
172 	clk_disable_unprepare(priv.ddr_clk);
173 out_cpu:
174 	clk_disable_unprepare(priv.cpu_clk);
175 out_node:
176 	of_node_put(np);
177 
178 	return err;
179 }
180 
181 static int 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 	return 0;
190 }
191 
192 static struct platform_driver kirkwood_cpufreq_platform_driver = {
193 	.probe = kirkwood_cpufreq_probe,
194 	.remove = kirkwood_cpufreq_remove,
195 	.driver = {
196 		.name = "kirkwood-cpufreq",
197 	},
198 };
199 
200 module_platform_driver(kirkwood_cpufreq_platform_driver);
201 
202 MODULE_LICENSE("GPL v2");
203 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
204 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
205 MODULE_ALIAS("platform:kirkwood-cpufreq");
206