2 * CPU frequency scaling for DaVinci
4 * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
6 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
8 * Copyright (C) 2005 Nokia Corporation
9 * Written by Tony Lindgren <tony@atomide.com>
11 * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
13 * Copyright (C) 2007-2008 Texas Instruments, Inc.
14 * Updated to support OMAP3
15 * Rajendra Nayak <rnayak@ti.com>
17 * This program is free software; you can redistribute it and/or modify
18 * it under the terms of the GNU General Public License version 2 as
19 * published by the Free Software Foundation.
21 #include <linux/types.h>
22 #include <linux/cpufreq.h>
23 #include <linux/init.h>
24 #include <linux/err.h>
25 #include <linux/clk.h>
26 #include <linux/platform_data/davinci-cpufreq.h>
27 #include <linux/platform_device.h>
28 #include <linux/export.h>
30 struct davinci_cpufreq
{
34 unsigned long asyncrate
;
36 static struct davinci_cpufreq cpufreq
;
38 static int davinci_target(struct cpufreq_policy
*policy
, unsigned int idx
)
40 struct davinci_cpufreq_config
*pdata
= cpufreq
.dev
->platform_data
;
41 struct clk
*armclk
= cpufreq
.armclk
;
42 unsigned int old_freq
, new_freq
;
45 old_freq
= policy
->cur
;
46 new_freq
= pdata
->freq_table
[idx
].frequency
;
48 /* if moving to higher frequency, up the voltage beforehand */
49 if (pdata
->set_voltage
&& new_freq
> old_freq
) {
50 ret
= pdata
->set_voltage(idx
);
55 ret
= clk_set_rate(armclk
, new_freq
* 1000);
59 if (cpufreq
.asyncclk
) {
60 ret
= clk_set_rate(cpufreq
.asyncclk
, cpufreq
.asyncrate
);
65 /* if moving to lower freq, lower the voltage after lowering freq */
66 if (pdata
->set_voltage
&& new_freq
< old_freq
)
67 pdata
->set_voltage(idx
);
72 static int davinci_cpu_init(struct cpufreq_policy
*policy
)
75 struct davinci_cpufreq_config
*pdata
= cpufreq
.dev
->platform_data
;
76 struct cpufreq_frequency_table
*freq_table
= pdata
->freq_table
;
81 /* Finish platform specific initialization */
83 result
= pdata
->init();
88 policy
->clk
= cpufreq
.armclk
;
91 * Time measurement across the target() function yields ~1500-1800us
92 * time taken with no drivers on notification list.
93 * Setting the latency to 2000 us to accommodate addition of drivers
94 * to pre/post change notification list.
96 return cpufreq_generic_init(policy
, freq_table
, 2000 * 1000);
99 static struct cpufreq_driver davinci_driver
= {
100 .flags
= CPUFREQ_STICKY
| CPUFREQ_NEED_INITIAL_FREQ_CHECK
,
101 .verify
= cpufreq_generic_frequency_table_verify
,
102 .target_index
= davinci_target
,
103 .get
= cpufreq_generic_get
,
104 .init
= davinci_cpu_init
,
106 .attr
= cpufreq_generic_attr
,
109 static int __init
davinci_cpufreq_probe(struct platform_device
*pdev
)
111 struct davinci_cpufreq_config
*pdata
= pdev
->dev
.platform_data
;
112 struct clk
*asyncclk
;
116 if (!pdata
->freq_table
)
119 cpufreq
.dev
= &pdev
->dev
;
121 cpufreq
.armclk
= clk_get(NULL
, "arm");
122 if (IS_ERR(cpufreq
.armclk
)) {
123 dev_err(cpufreq
.dev
, "Unable to get ARM clock\n");
124 return PTR_ERR(cpufreq
.armclk
);
127 asyncclk
= clk_get(cpufreq
.dev
, "async");
128 if (!IS_ERR(asyncclk
)) {
129 cpufreq
.asyncclk
= asyncclk
;
130 cpufreq
.asyncrate
= clk_get_rate(asyncclk
);
133 return cpufreq_register_driver(&davinci_driver
);
136 static int __exit
davinci_cpufreq_remove(struct platform_device
*pdev
)
138 clk_put(cpufreq
.armclk
);
140 if (cpufreq
.asyncclk
)
141 clk_put(cpufreq
.asyncclk
);
143 return cpufreq_unregister_driver(&davinci_driver
);
146 static struct platform_driver davinci_cpufreq_driver
= {
148 .name
= "cpufreq-davinci",
150 .remove
= __exit_p(davinci_cpufreq_remove
),
153 int __init
davinci_cpufreq_init(void)
155 return platform_driver_probe(&davinci_cpufreq_driver
,
156 davinci_cpufreq_probe
);