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
kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)45 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
46 {
47 return clk_get_rate(priv.powersave_clk) / 1000;
48 }
49
kirkwood_cpufreq_target(struct cpufreq_policy * policy,unsigned int index)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 */
kirkwood_cpufreq_cpu_init(struct cpufreq_policy * policy)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 };
100
kirkwood_cpufreq_probe(struct platform_device * pdev)101 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
102 {
103 struct device_node *np;
104 int err;
105
106 priv.dev = &pdev->dev;
107
108 priv.base = devm_platform_ioremap_resource(pdev, 0);
109 if (IS_ERR(priv.base))
110 return PTR_ERR(priv.base);
111
112 np = of_cpu_device_node_get(0);
113 if (!np) {
114 dev_err(&pdev->dev, "failed to get cpu device node\n");
115 return -ENODEV;
116 }
117
118 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
119 if (IS_ERR(priv.cpu_clk)) {
120 dev_err(priv.dev, "Unable to get cpuclk\n");
121 err = PTR_ERR(priv.cpu_clk);
122 goto out_node;
123 }
124
125 err = clk_prepare_enable(priv.cpu_clk);
126 if (err) {
127 dev_err(priv.dev, "Unable to prepare cpuclk\n");
128 goto out_node;
129 }
130
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\n");
136 err = PTR_ERR(priv.ddr_clk);
137 goto out_cpu;
138 }
139
140 err = clk_prepare_enable(priv.ddr_clk);
141 if (err) {
142 dev_err(priv.dev, "Unable to prepare ddrclk\n");
143 goto out_cpu;
144 }
145 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
146
147 priv.powersave_clk = of_clk_get_by_name(np, "powersave");
148 if (IS_ERR(priv.powersave_clk)) {
149 dev_err(priv.dev, "Unable to get powersave\n");
150 err = PTR_ERR(priv.powersave_clk);
151 goto out_ddr;
152 }
153 err = clk_prepare_enable(priv.powersave_clk);
154 if (err) {
155 dev_err(priv.dev, "Unable to prepare powersave clk\n");
156 goto out_ddr;
157 }
158
159 err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
160 if (err) {
161 dev_err(priv.dev, "Failed to register cpufreq driver\n");
162 goto out_powersave;
163 }
164
165 of_node_put(np);
166 return 0;
167
168 out_powersave:
169 clk_disable_unprepare(priv.powersave_clk);
170 out_ddr:
171 clk_disable_unprepare(priv.ddr_clk);
172 out_cpu:
173 clk_disable_unprepare(priv.cpu_clk);
174 out_node:
175 of_node_put(np);
176
177 return err;
178 }
179
kirkwood_cpufreq_remove(struct platform_device * pdev)180 static void kirkwood_cpufreq_remove(struct platform_device *pdev)
181 {
182 cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
183
184 clk_disable_unprepare(priv.powersave_clk);
185 clk_disable_unprepare(priv.ddr_clk);
186 clk_disable_unprepare(priv.cpu_clk);
187 }
188
189 static struct platform_driver kirkwood_cpufreq_platform_driver = {
190 .probe = kirkwood_cpufreq_probe,
191 .remove = kirkwood_cpufreq_remove,
192 .driver = {
193 .name = "kirkwood-cpufreq",
194 },
195 };
196
197 module_platform_driver(kirkwood_cpufreq_platform_driver);
198
199 MODULE_LICENSE("GPL v2");
200 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
201 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
202 MODULE_ALIAS("platform:kirkwood-cpufreq");
203