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Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/linville/wirel...
[karo-tx-linux.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/clk-provider.h>
16 #include <linux/cpufreq.h>
17 #include <linux/of.h>
18 #include <linux/platform_device.h>
19 #include <linux/io.h>
20 #include <asm/proc-fns.h>
21
22 #define CPU_SW_INT_BLK BIT(28)
23
24 static struct priv
25 {
26         struct clk *cpu_clk;
27         struct clk *ddr_clk;
28         struct clk *powersave_clk;
29         struct device *dev;
30         void __iomem *base;
31 } priv;
32
33 #define STATE_CPU_FREQ 0x01
34 #define STATE_DDR_FREQ 0x02
35
36 /*
37  * Kirkwood can swap the clock to the CPU between two clocks:
38  *
39  * - cpu clk
40  * - ddr clk
41  *
42  * The frequencies are set at runtime before registering this *
43  * table.
44  */
45 static struct cpufreq_frequency_table kirkwood_freq_table[] = {
46         {STATE_CPU_FREQ,        0}, /* CPU uses cpuclk */
47         {STATE_DDR_FREQ,        0}, /* CPU uses ddrclk */
48         {0,                     CPUFREQ_TABLE_END},
49 };
50
51 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
52 {
53         if (__clk_is_enabled(priv.powersave_clk))
54                 return kirkwood_freq_table[1].frequency;
55         return kirkwood_freq_table[0].frequency;
56 }
57
58 static void kirkwood_cpufreq_set_cpu_state(unsigned int index)
59 {
60         struct cpufreq_freqs freqs;
61         unsigned int state = kirkwood_freq_table[index].index;
62         unsigned long reg;
63
64         freqs.old = kirkwood_cpufreq_get_cpu_frequency(0);
65         freqs.new = kirkwood_freq_table[index].frequency;
66         freqs.cpu = 0; /* Kirkwood is UP */
67
68         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
69
70         dev_dbg(priv.dev, "Attempting to set frequency to %i KHz\n",
71                 kirkwood_freq_table[index].frequency);
72         dev_dbg(priv.dev, "old frequency was %i KHz\n",
73                 kirkwood_cpufreq_get_cpu_frequency(0));
74
75         if (freqs.old != freqs.new) {
76                 local_irq_disable();
77
78                 /* Disable interrupts to the CPU */
79                 reg = readl_relaxed(priv.base);
80                 reg |= CPU_SW_INT_BLK;
81                 writel_relaxed(reg, priv.base);
82
83                 switch (state) {
84                 case STATE_CPU_FREQ:
85                         clk_disable(priv.powersave_clk);
86                         break;
87                 case STATE_DDR_FREQ:
88                         clk_enable(priv.powersave_clk);
89                         break;
90                 }
91
92                 /* Wait-for-Interrupt, while the hardware changes frequency */
93                 cpu_do_idle();
94
95                 /* Enable interrupts to the CPU */
96                 reg = readl_relaxed(priv.base);
97                 reg &= ~CPU_SW_INT_BLK;
98                 writel_relaxed(reg, priv.base);
99
100                 local_irq_enable();
101         }
102         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
103 };
104
105 static int kirkwood_cpufreq_verify(struct cpufreq_policy *policy)
106 {
107         return cpufreq_frequency_table_verify(policy, kirkwood_freq_table);
108 }
109
110 static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
111                             unsigned int target_freq,
112                             unsigned int relation)
113 {
114         unsigned int index = 0;
115
116         if (cpufreq_frequency_table_target(policy, kirkwood_freq_table,
117                                 target_freq, relation, &index))
118                 return -EINVAL;
119
120         kirkwood_cpufreq_set_cpu_state(index);
121
122         return 0;
123 }
124
125 /* Module init and exit code */
126 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
127 {
128         int result;
129
130         /* cpuinfo and default policy values */
131         policy->cpuinfo.transition_latency = 5000; /* 5uS */
132         policy->cur = kirkwood_cpufreq_get_cpu_frequency(0);
133
134         result = cpufreq_frequency_table_cpuinfo(policy, kirkwood_freq_table);
135         if (result)
136                 return result;
137
138         cpufreq_frequency_table_get_attr(kirkwood_freq_table, policy->cpu);
139
140         return 0;
141 }
142
143 static int kirkwood_cpufreq_cpu_exit(struct cpufreq_policy *policy)
144 {
145         cpufreq_frequency_table_put_attr(policy->cpu);
146         return 0;
147 }
148
149 static struct freq_attr *kirkwood_cpufreq_attr[] = {
150         &cpufreq_freq_attr_scaling_available_freqs,
151         NULL,
152 };
153
154 static struct cpufreq_driver kirkwood_cpufreq_driver = {
155         .get    = kirkwood_cpufreq_get_cpu_frequency,
156         .verify = kirkwood_cpufreq_verify,
157         .target = kirkwood_cpufreq_target,
158         .init   = kirkwood_cpufreq_cpu_init,
159         .exit   = kirkwood_cpufreq_cpu_exit,
160         .name   = "kirkwood-cpufreq",
161         .owner  = THIS_MODULE,
162         .attr   = kirkwood_cpufreq_attr,
163 };
164
165 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
166 {
167         struct device_node *np;
168         struct resource *res;
169         int err;
170
171         priv.dev = &pdev->dev;
172
173         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
174         if (!res) {
175                 dev_err(&pdev->dev, "Cannot get memory resource\n");
176                 return -ENODEV;
177         }
178         priv.base = devm_request_and_ioremap(&pdev->dev, res);
179         if (!priv.base) {
180                 dev_err(&pdev->dev, "Cannot ioremap\n");
181                 return -EADDRNOTAVAIL;
182         }
183
184         np = of_find_node_by_path("/cpus/cpu@0");
185         if (!np)
186                 return -ENODEV;
187
188         priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
189         if (IS_ERR(priv.cpu_clk)) {
190                 dev_err(priv.dev, "Unable to get cpuclk");
191                 return PTR_ERR(priv.cpu_clk);
192         }
193
194         clk_prepare_enable(priv.cpu_clk);
195         kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
196
197         priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
198         if (IS_ERR(priv.ddr_clk)) {
199                 dev_err(priv.dev, "Unable to get ddrclk");
200                 err = PTR_ERR(priv.ddr_clk);
201                 goto out_cpu;
202         }
203
204         clk_prepare_enable(priv.ddr_clk);
205         kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
206
207         priv.powersave_clk = of_clk_get_by_name(np, "powersave");
208         if (IS_ERR(priv.powersave_clk)) {
209                 dev_err(priv.dev, "Unable to get powersave");
210                 err = PTR_ERR(priv.powersave_clk);
211                 goto out_ddr;
212         }
213         clk_prepare(priv.powersave_clk);
214
215         of_node_put(np);
216         np = NULL;
217
218         err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
219         if (!err)
220                 return 0;
221
222         dev_err(priv.dev, "Failed to register cpufreq driver");
223
224         clk_disable_unprepare(priv.powersave_clk);
225 out_ddr:
226         clk_disable_unprepare(priv.ddr_clk);
227 out_cpu:
228         clk_disable_unprepare(priv.cpu_clk);
229         of_node_put(np);
230
231         return err;
232 }
233
234 static int kirkwood_cpufreq_remove(struct platform_device *pdev)
235 {
236         cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
237
238         clk_disable_unprepare(priv.powersave_clk);
239         clk_disable_unprepare(priv.ddr_clk);
240         clk_disable_unprepare(priv.cpu_clk);
241
242         return 0;
243 }
244
245 static struct platform_driver kirkwood_cpufreq_platform_driver = {
246         .probe = kirkwood_cpufreq_probe,
247         .remove = kirkwood_cpufreq_remove,
248         .driver = {
249                 .name = "kirkwood-cpufreq",
250                 .owner = THIS_MODULE,
251         },
252 };
253
254 module_platform_driver(kirkwood_cpufreq_platform_driver);
255
256 MODULE_LICENSE("GPL v2");
257 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
258 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
259 MODULE_ALIAS("platform:kirkwood-cpufreq");