1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
|
/*
* kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
*
* Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version
* 2 of the License, or (at your option) any later version.
*/
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/cpufreq.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <asm/proc-fns.h>
#define CPU_SW_INT_BLK BIT(28)
static struct priv
{
struct clk *cpu_clk;
struct clk *ddr_clk;
struct clk *powersave_clk;
struct device *dev;
void __iomem *base;
} priv;
#define STATE_CPU_FREQ 0x01
#define STATE_DDR_FREQ 0x02
/*
* Kirkwood can swap the clock to the CPU between two clocks:
*
* - cpu clk
* - ddr clk
*
* The frequencies are set at runtime before registering this *
* table.
*/
static struct cpufreq_frequency_table kirkwood_freq_table[] = {
{STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */
{STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */
{0, CPUFREQ_TABLE_END},
};
static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
{
if (__clk_is_enabled(priv.powersave_clk))
return kirkwood_freq_table[1].frequency;
return kirkwood_freq_table[0].frequency;
}
static void kirkwood_cpufreq_set_cpu_state(struct cpufreq_policy *policy,
unsigned int index)
{
struct cpufreq_freqs freqs;
unsigned int state = kirkwood_freq_table[index].index;
unsigned long reg;
freqs.old = kirkwood_cpufreq_get_cpu_frequency(0);
freqs.new = kirkwood_freq_table[index].frequency;
cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
dev_dbg(priv.dev, "Attempting to set frequency to %i KHz\n",
kirkwood_freq_table[index].frequency);
dev_dbg(priv.dev, "old frequency was %i KHz\n",
kirkwood_cpufreq_get_cpu_frequency(0));
if (freqs.old != freqs.new) {
local_irq_disable();
/* Disable interrupts to the CPU */
reg = readl_relaxed(priv.base);
reg |= CPU_SW_INT_BLK;
writel_relaxed(reg, priv.base);
switch (state) {
case STATE_CPU_FREQ:
clk_disable(priv.powersave_clk);
break;
case STATE_DDR_FREQ:
clk_enable(priv.powersave_clk);
break;
}
/* Wait-for-Interrupt, while the hardware changes frequency */
cpu_do_idle();
/* Enable interrupts to the CPU */
reg = readl_relaxed(priv.base);
reg &= ~CPU_SW_INT_BLK;
writel_relaxed(reg, priv.base);
local_irq_enable();
}
cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
};
static int kirkwood_cpufreq_verify(struct cpufreq_policy *policy)
{
return cpufreq_frequency_table_verify(policy, kirkwood_freq_table);
}
static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
unsigned int target_freq,
unsigned int relation)
{
unsigned int index = 0;
if (cpufreq_frequency_table_target(policy, kirkwood_freq_table,
target_freq, relation, &index))
return -EINVAL;
kirkwood_cpufreq_set_cpu_state(policy, index);
return 0;
}
/* Module init and exit code */
static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
{
int result;
/* cpuinfo and default policy values */
policy->cpuinfo.transition_latency = 5000; /* 5uS */
policy->cur = kirkwood_cpufreq_get_cpu_frequency(0);
result = cpufreq_frequency_table_cpuinfo(policy, kirkwood_freq_table);
if (result)
return result;
cpufreq_frequency_table_get_attr(kirkwood_freq_table, policy->cpu);
return 0;
}
static int kirkwood_cpufreq_cpu_exit(struct cpufreq_policy *policy)
{
cpufreq_frequency_table_put_attr(policy->cpu);
return 0;
}
static struct freq_attr *kirkwood_cpufreq_attr[] = {
&cpufreq_freq_attr_scaling_available_freqs,
NULL,
};
static struct cpufreq_driver kirkwood_cpufreq_driver = {
.get = kirkwood_cpufreq_get_cpu_frequency,
.verify = kirkwood_cpufreq_verify,
.target = kirkwood_cpufreq_target,
.init = kirkwood_cpufreq_cpu_init,
.exit = kirkwood_cpufreq_cpu_exit,
.name = "kirkwood-cpufreq",
.owner = THIS_MODULE,
.attr = kirkwood_cpufreq_attr,
};
static int kirkwood_cpufreq_probe(struct platform_device *pdev)
{
struct device_node *np;
struct resource *res;
int err;
priv.dev = &pdev->dev;
res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
priv.base = devm_ioremap_resource(&pdev->dev, res);
if (IS_ERR(priv.base))
return PTR_ERR(priv.base);
np = of_find_node_by_path("/cpus/cpu@0");
if (!np)
return -ENODEV;
priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
if (IS_ERR(priv.cpu_clk)) {
dev_err(priv.dev, "Unable to get cpuclk");
return PTR_ERR(priv.cpu_clk);
}
clk_prepare_enable(priv.cpu_clk);
kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
if (IS_ERR(priv.ddr_clk)) {
dev_err(priv.dev, "Unable to get ddrclk");
err = PTR_ERR(priv.ddr_clk);
goto out_cpu;
}
clk_prepare_enable(priv.ddr_clk);
kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
priv.powersave_clk = of_clk_get_by_name(np, "powersave");
if (IS_ERR(priv.powersave_clk)) {
dev_err(priv.dev, "Unable to get powersave");
err = PTR_ERR(priv.powersave_clk);
goto out_ddr;
}
clk_prepare(priv.powersave_clk);
of_node_put(np);
np = NULL;
err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
if (!err)
return 0;
dev_err(priv.dev, "Failed to register cpufreq driver");
clk_disable_unprepare(priv.powersave_clk);
out_ddr:
clk_disable_unprepare(priv.ddr_clk);
out_cpu:
clk_disable_unprepare(priv.cpu_clk);
of_node_put(np);
return err;
}
static int kirkwood_cpufreq_remove(struct platform_device *pdev)
{
cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
clk_disable_unprepare(priv.powersave_clk);
clk_disable_unprepare(priv.ddr_clk);
clk_disable_unprepare(priv.cpu_clk);
return 0;
}
static struct platform_driver kirkwood_cpufreq_platform_driver = {
.probe = kirkwood_cpufreq_probe,
.remove = kirkwood_cpufreq_remove,
.driver = {
.name = "kirkwood-cpufreq",
.owner = THIS_MODULE,
},
};
module_platform_driver(kirkwood_cpufreq_platform_driver);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
MODULE_ALIAS("platform:kirkwood-cpufreq");
|
