1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * CPU frequency scaling for DaVinci
4 *
5 * Copyright (C) 2009 Texas Instruments Incorporated - https://www.ti.com/
6 *
7 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
8 *
9 * Copyright (C) 2005 Nokia Corporation
10 * Written by Tony Lindgren <tony@atomide.com>
11 *
12 * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
13 *
14 * Copyright (C) 2007-2008 Texas Instruments, Inc.
15 * Updated to support OMAP3
16 * Rajendra Nayak <rnayak@ti.com>
17 */
18 #include <linux/types.h>
19 #include <linux/cpufreq.h>
20 #include <linux/init.h>
21 #include <linux/err.h>
22 #include <linux/clk.h>
23 #include <linux/platform_data/davinci-cpufreq.h>
24 #include <linux/platform_device.h>
25 #include <linux/export.h>
26
27 struct davinci_cpufreq {
28 struct device *dev;
29 struct clk *armclk;
30 struct clk *asyncclk;
31 unsigned long asyncrate;
32 };
33 static struct davinci_cpufreq cpufreq;
34
davinci_target(struct cpufreq_policy * policy,unsigned int idx)35 static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
36 {
37 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
38 struct clk *armclk = cpufreq.armclk;
39 unsigned int old_freq, new_freq;
40 int ret = 0;
41
42 old_freq = policy->cur;
43 new_freq = pdata->freq_table[idx].frequency;
44
45 /* if moving to higher frequency, up the voltage beforehand */
46 if (pdata->set_voltage && new_freq > old_freq) {
47 ret = pdata->set_voltage(idx);
48 if (ret)
49 return ret;
50 }
51
52 ret = clk_set_rate(armclk, new_freq * 1000);
53 if (ret)
54 return ret;
55
56 if (cpufreq.asyncclk) {
57 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
58 if (ret)
59 return ret;
60 }
61
62 /* if moving to lower freq, lower the voltage after lowering freq */
63 if (pdata->set_voltage && new_freq < old_freq)
64 pdata->set_voltage(idx);
65
66 return 0;
67 }
68
davinci_cpu_init(struct cpufreq_policy * policy)69 static int davinci_cpu_init(struct cpufreq_policy *policy)
70 {
71 int result = 0;
72 struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
73 struct cpufreq_frequency_table *freq_table = pdata->freq_table;
74
75 if (policy->cpu != 0)
76 return -EINVAL;
77
78 /* Finish platform specific initialization */
79 if (pdata->init) {
80 result = pdata->init();
81 if (result)
82 return result;
83 }
84
85 policy->clk = cpufreq.armclk;
86
87 /*
88 * Time measurement across the target() function yields ~1500-1800us
89 * time taken with no drivers on notification list.
90 * Setting the latency to 2000 us to accommodate addition of drivers
91 * to pre/post change notification list.
92 */
93 cpufreq_generic_init(policy, freq_table, 2000 * 1000);
94 return 0;
95 }
96
97 static struct cpufreq_driver davinci_driver = {
98 .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
99 .verify = cpufreq_generic_frequency_table_verify,
100 .target_index = davinci_target,
101 .get = cpufreq_generic_get,
102 .init = davinci_cpu_init,
103 .name = "davinci",
104 .attr = cpufreq_generic_attr,
105 };
106
davinci_cpufreq_probe(struct platform_device * pdev)107 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
108 {
109 struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
110 struct clk *asyncclk;
111
112 if (!pdata)
113 return -EINVAL;
114 if (!pdata->freq_table)
115 return -EINVAL;
116
117 cpufreq.dev = &pdev->dev;
118
119 cpufreq.armclk = clk_get(NULL, "arm");
120 if (IS_ERR(cpufreq.armclk)) {
121 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
122 return PTR_ERR(cpufreq.armclk);
123 }
124
125 asyncclk = clk_get(cpufreq.dev, "async");
126 if (!IS_ERR(asyncclk)) {
127 cpufreq.asyncclk = asyncclk;
128 cpufreq.asyncrate = clk_get_rate(asyncclk);
129 }
130
131 return cpufreq_register_driver(&davinci_driver);
132 }
133
davinci_cpufreq_remove(struct platform_device * pdev)134 static void __exit davinci_cpufreq_remove(struct platform_device *pdev)
135 {
136 cpufreq_unregister_driver(&davinci_driver);
137
138 clk_put(cpufreq.armclk);
139
140 if (cpufreq.asyncclk)
141 clk_put(cpufreq.asyncclk);
142 }
143
144 static struct platform_driver davinci_cpufreq_driver = {
145 .driver = {
146 .name = "cpufreq-davinci",
147 },
148 .remove_new = __exit_p(davinci_cpufreq_remove),
149 };
150
davinci_cpufreq_init(void)151 int __init davinci_cpufreq_init(void)
152 {
153 return platform_driver_probe(&davinci_cpufreq_driver,
154 davinci_cpufreq_probe);
155 }
156
157