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_device.h>
27 #include <linux/export.h>
29 #include <mach/hardware.h>
30 #include <mach/cpufreq.h>
31 #include <mach/common.h>
33 struct davinci_cpufreq
{
37 unsigned long asyncrate
;
39 static struct davinci_cpufreq cpufreq
;
41 static int davinci_verify_speed(struct cpufreq_policy
*policy
)
43 struct davinci_cpufreq_config
*pdata
= cpufreq
.dev
->platform_data
;
44 struct cpufreq_frequency_table
*freq_table
= pdata
->freq_table
;
45 struct clk
*armclk
= cpufreq
.armclk
;
48 return cpufreq_frequency_table_verify(policy
, freq_table
);
53 cpufreq_verify_within_cpu_limits(policy
);
54 policy
->min
= clk_round_rate(armclk
, policy
->min
* 1000) / 1000;
55 policy
->max
= clk_round_rate(armclk
, policy
->max
* 1000) / 1000;
56 cpufreq_verify_within_limits(policy
, policy
->cpuinfo
.min_freq
,
57 policy
->cpuinfo
.max_freq
);
61 static unsigned int davinci_getspeed(unsigned int cpu
)
66 return clk_get_rate(cpufreq
.armclk
) / 1000;
69 static int davinci_target(struct cpufreq_policy
*policy
, unsigned int idx
)
71 struct davinci_cpufreq_config
*pdata
= cpufreq
.dev
->platform_data
;
72 struct clk
*armclk
= cpufreq
.armclk
;
73 unsigned int old_freq
, new_freq
;
76 old_freq
= davinci_getspeed(0);
77 new_freq
= pdata
->freq_table
[idx
].frequency
;
79 /* if moving to higher frequency, up the voltage beforehand */
80 if (pdata
->set_voltage
&& new_freq
> old_freq
) {
81 ret
= pdata
->set_voltage(idx
);
86 ret
= clk_set_rate(armclk
, idx
);
90 if (cpufreq
.asyncclk
) {
91 ret
= clk_set_rate(cpufreq
.asyncclk
, cpufreq
.asyncrate
);
96 /* if moving to lower freq, lower the voltage after lowering freq */
97 if (pdata
->set_voltage
&& new_freq
< old_freq
)
98 pdata
->set_voltage(idx
);
103 static int davinci_cpu_init(struct cpufreq_policy
*policy
)
106 struct davinci_cpufreq_config
*pdata
= cpufreq
.dev
->platform_data
;
107 struct cpufreq_frequency_table
*freq_table
= pdata
->freq_table
;
109 if (policy
->cpu
!= 0)
112 /* Finish platform specific initialization */
114 result
= pdata
->init();
120 * Time measurement across the target() function yields ~1500-1800us
121 * time taken with no drivers on notification list.
122 * Setting the latency to 2000 us to accommodate addition of drivers
123 * to pre/post change notification list.
125 return cpufreq_generic_init(policy
, freq_table
, 2000 * 1000);
128 static struct cpufreq_driver davinci_driver
= {
129 .flags
= CPUFREQ_STICKY
,
130 .verify
= davinci_verify_speed
,
131 .target_index
= davinci_target
,
132 .get
= davinci_getspeed
,
133 .init
= davinci_cpu_init
,
134 .exit
= cpufreq_generic_exit
,
136 .attr
= cpufreq_generic_attr
,
139 static int __init
davinci_cpufreq_probe(struct platform_device
*pdev
)
141 struct davinci_cpufreq_config
*pdata
= pdev
->dev
.platform_data
;
142 struct clk
*asyncclk
;
146 if (!pdata
->freq_table
)
149 cpufreq
.dev
= &pdev
->dev
;
151 cpufreq
.armclk
= clk_get(NULL
, "arm");
152 if (IS_ERR(cpufreq
.armclk
)) {
153 dev_err(cpufreq
.dev
, "Unable to get ARM clock\n");
154 return PTR_ERR(cpufreq
.armclk
);
157 asyncclk
= clk_get(cpufreq
.dev
, "async");
158 if (!IS_ERR(asyncclk
)) {
159 cpufreq
.asyncclk
= asyncclk
;
160 cpufreq
.asyncrate
= clk_get_rate(asyncclk
);
163 return cpufreq_register_driver(&davinci_driver
);
166 static int __exit
davinci_cpufreq_remove(struct platform_device
*pdev
)
168 clk_put(cpufreq
.armclk
);
170 if (cpufreq
.asyncclk
)
171 clk_put(cpufreq
.asyncclk
);
173 return cpufreq_unregister_driver(&davinci_driver
);
176 static struct platform_driver davinci_cpufreq_driver
= {
178 .name
= "cpufreq-davinci",
179 .owner
= THIS_MODULE
,
181 .remove
= __exit_p(davinci_cpufreq_remove
),
184 int __init
davinci_cpufreq_init(void)
186 return platform_driver_probe(&davinci_cpufreq_driver
,
187 davinci_cpufreq_probe
);