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 | |
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(clk: armclk, rate: new_freq * 1000); |
53 | if (ret) |
54 | return ret; |
55 | |
56 | if (cpufreq.asyncclk) { |
57 | ret = clk_set_rate(clk: cpufreq.asyncclk, rate: 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 | cpufreq_generic_init(policy, table: freq_table, transition_latency: 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 | |
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, id: "arm" ); |
120 | if (IS_ERR(ptr: cpufreq.armclk)) { |
121 | dev_err(cpufreq.dev, "Unable to get ARM clock\n" ); |
122 | return PTR_ERR(ptr: cpufreq.armclk); |
123 | } |
124 | |
125 | asyncclk = clk_get(dev: cpufreq.dev, id: "async" ); |
126 | if (!IS_ERR(ptr: asyncclk)) { |
127 | cpufreq.asyncclk = asyncclk; |
128 | cpufreq.asyncrate = clk_get_rate(clk: asyncclk); |
129 | } |
130 | |
131 | return cpufreq_register_driver(driver_data: &davinci_driver); |
132 | } |
133 | |
134 | static void __exit davinci_cpufreq_remove(struct platform_device *pdev) |
135 | { |
136 | cpufreq_unregister_driver(driver_data: &davinci_driver); |
137 | |
138 | clk_put(clk: cpufreq.armclk); |
139 | |
140 | if (cpufreq.asyncclk) |
141 | clk_put(clk: 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 | |
151 | int __init davinci_cpufreq_init(void) |
152 | { |
153 | return platform_driver_probe(&davinci_cpufreq_driver, |
154 | davinci_cpufreq_probe); |
155 | } |
156 | |
157 | |