1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * CPU frequency scaling for DaVinci
4  *
5  * Copyright (C) 2009 Texas Instruments Incorporated - http://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 
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 
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 	return cpufreq_generic_init(policy, freq_table, 2000 * 1000);
94 }
95 
96 static struct cpufreq_driver davinci_driver = {
97 	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
98 	.verify		= cpufreq_generic_frequency_table_verify,
99 	.target_index	= davinci_target,
100 	.get		= cpufreq_generic_get,
101 	.init		= davinci_cpu_init,
102 	.name		= "davinci",
103 	.attr		= cpufreq_generic_attr,
104 };
105 
106 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
107 {
108 	struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
109 	struct clk *asyncclk;
110 
111 	if (!pdata)
112 		return -EINVAL;
113 	if (!pdata->freq_table)
114 		return -EINVAL;
115 
116 	cpufreq.dev = &pdev->dev;
117 
118 	cpufreq.armclk = clk_get(NULL, "arm");
119 	if (IS_ERR(cpufreq.armclk)) {
120 		dev_err(cpufreq.dev, "Unable to get ARM clock\n");
121 		return PTR_ERR(cpufreq.armclk);
122 	}
123 
124 	asyncclk = clk_get(cpufreq.dev, "async");
125 	if (!IS_ERR(asyncclk)) {
126 		cpufreq.asyncclk = asyncclk;
127 		cpufreq.asyncrate = clk_get_rate(asyncclk);
128 	}
129 
130 	return cpufreq_register_driver(&davinci_driver);
131 }
132 
133 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
134 {
135 	clk_put(cpufreq.armclk);
136 
137 	if (cpufreq.asyncclk)
138 		clk_put(cpufreq.asyncclk);
139 
140 	return cpufreq_unregister_driver(&davinci_driver);
141 }
142 
143 static struct platform_driver davinci_cpufreq_driver = {
144 	.driver = {
145 		.name	 = "cpufreq-davinci",
146 	},
147 	.remove = __exit_p(davinci_cpufreq_remove),
148 };
149 
150 int __init davinci_cpufreq_init(void)
151 {
152 	return platform_driver_probe(&davinci_cpufreq_driver,
153 							davinci_cpufreq_probe);
154 }
155 
156