GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / cpufreq / kirkwood-cpufreq.c
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
23 static 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  */
43 static 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
49 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
50 {
51         return clk_get_rate(priv.powersave_clk) / 1000;
52 }
53
54 static 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 */
90 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
91 {
92         return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
93 }
94
95 static 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
105 static 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);
161 out_ddr:
162         clk_disable_unprepare(priv.ddr_clk);
163 out_cpu:
164         clk_disable_unprepare(priv.cpu_clk);
165         of_node_put(np);
166
167         return err;
168 }
169
170 static 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
181 static 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
189 module_platform_driver(kirkwood_cpufreq_platform_driver);
190
191 MODULE_LICENSE("GPL v2");
192 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
193 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
194 MODULE_ALIAS("platform:kirkwood-cpufreq");