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
)
72 struct cpufreq_freqs freqs
;
73 struct davinci_cpufreq_config
*pdata
= cpufreq
.dev
->platform_data
;
74 struct clk
*armclk
= cpufreq
.armclk
;
76 freqs
.old
= davinci_getspeed(0);
77 freqs
.new = pdata
->freq_table
[idx
].frequency
;
79 dev_dbg(cpufreq
.dev
, "transition: %u --> %u\n", freqs
.old
, freqs
.new);
81 cpufreq_notify_transition(policy
, &freqs
, CPUFREQ_PRECHANGE
);
83 /* if moving to higher frequency, up the voltage beforehand */
84 if (pdata
->set_voltage
&& freqs
.new > freqs
.old
) {
85 ret
= pdata
->set_voltage(idx
);
90 ret
= clk_set_rate(armclk
, idx
);
94 if (cpufreq
.asyncclk
) {
95 ret
= clk_set_rate(cpufreq
.asyncclk
, cpufreq
.asyncrate
);
100 /* if moving to lower freq, lower the voltage after lowering freq */
101 if (pdata
->set_voltage
&& freqs
.new < freqs
.old
)
102 pdata
->set_voltage(idx
);
106 freqs
.new = freqs
.old
;
108 cpufreq_notify_transition(policy
, &freqs
, CPUFREQ_POSTCHANGE
);
113 static int davinci_cpu_init(struct cpufreq_policy
*policy
)
116 struct davinci_cpufreq_config
*pdata
= cpufreq
.dev
->platform_data
;
117 struct cpufreq_frequency_table
*freq_table
= pdata
->freq_table
;
119 if (policy
->cpu
!= 0)
122 /* Finish platform specific initialization */
124 result
= pdata
->init();
130 * Time measurement across the target() function yields ~1500-1800us
131 * time taken with no drivers on notification list.
132 * Setting the latency to 2000 us to accommodate addition of drivers
133 * to pre/post change notification list.
135 return cpufreq_generic_init(policy
, freq_table
, 2000 * 1000);
138 static struct cpufreq_driver davinci_driver
= {
139 .flags
= CPUFREQ_STICKY
,
140 .verify
= davinci_verify_speed
,
141 .target_index
= davinci_target
,
142 .get
= davinci_getspeed
,
143 .init
= davinci_cpu_init
,
144 .exit
= cpufreq_generic_exit
,
146 .attr
= cpufreq_generic_attr
,
149 static int __init
davinci_cpufreq_probe(struct platform_device
*pdev
)
151 struct davinci_cpufreq_config
*pdata
= pdev
->dev
.platform_data
;
152 struct clk
*asyncclk
;
156 if (!pdata
->freq_table
)
159 cpufreq
.dev
= &pdev
->dev
;
161 cpufreq
.armclk
= clk_get(NULL
, "arm");
162 if (IS_ERR(cpufreq
.armclk
)) {
163 dev_err(cpufreq
.dev
, "Unable to get ARM clock\n");
164 return PTR_ERR(cpufreq
.armclk
);
167 asyncclk
= clk_get(cpufreq
.dev
, "async");
168 if (!IS_ERR(asyncclk
)) {
169 cpufreq
.asyncclk
= asyncclk
;
170 cpufreq
.asyncrate
= clk_get_rate(asyncclk
);
173 return cpufreq_register_driver(&davinci_driver
);
176 static int __exit
davinci_cpufreq_remove(struct platform_device
*pdev
)
178 clk_put(cpufreq
.armclk
);
180 if (cpufreq
.asyncclk
)
181 clk_put(cpufreq
.asyncclk
);
183 return cpufreq_unregister_driver(&davinci_driver
);
186 static struct platform_driver davinci_cpufreq_driver
= {
188 .name
= "cpufreq-davinci",
189 .owner
= THIS_MODULE
,
191 .remove
= __exit_p(davinci_cpufreq_remove
),
194 int __init
davinci_cpufreq_init(void)
196 return platform_driver_probe(&davinci_cpufreq_driver
,
197 davinci_cpufreq_probe
);