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a0a22cf1 KC |
1 | /* |
2 | * CPU Frequency Scaling for Loongson 1 SoC | |
3 | * | |
4 | * Copyright (C) 2014 Zhang, Keguang <keguang.zhang@gmail.com> | |
5 | * | |
6 | * This file is licensed under the terms of the GNU General Public | |
7 | * License version 2. This program is licensed "as is" without any | |
8 | * warranty of any kind, whether express or implied. | |
9 | */ | |
10 | ||
11 | #include <linux/clk.h> | |
12 | #include <linux/clk-provider.h> | |
13 | #include <linux/cpu.h> | |
14 | #include <linux/cpufreq.h> | |
15 | #include <linux/delay.h> | |
16 | #include <linux/module.h> | |
17 | #include <linux/platform_device.h> | |
18 | #include <linux/slab.h> | |
19 | ||
30ad29bb HC |
20 | #include <cpufreq.h> |
21 | #include <loongson1.h> | |
a0a22cf1 KC |
22 | |
23 | static struct { | |
24 | struct device *dev; | |
25 | struct clk *clk; /* CPU clk */ | |
26 | struct clk *mux_clk; /* MUX of CPU clk */ | |
27 | struct clk *pll_clk; /* PLL clk */ | |
28 | struct clk *osc_clk; /* OSC clk */ | |
29 | unsigned int max_freq; | |
30 | unsigned int min_freq; | |
31 | } ls1x_cpufreq; | |
32 | ||
33 | static int ls1x_cpufreq_notifier(struct notifier_block *nb, | |
34 | unsigned long val, void *data) | |
35 | { | |
36 | if (val == CPUFREQ_POSTCHANGE) | |
37 | current_cpu_data.udelay_val = loops_per_jiffy; | |
38 | ||
39 | return NOTIFY_OK; | |
40 | } | |
41 | ||
42 | static struct notifier_block ls1x_cpufreq_notifier_block = { | |
43 | .notifier_call = ls1x_cpufreq_notifier | |
44 | }; | |
45 | ||
46 | static int ls1x_cpufreq_target(struct cpufreq_policy *policy, | |
47 | unsigned int index) | |
48 | { | |
49 | unsigned int old_freq, new_freq; | |
50 | ||
51 | old_freq = policy->cur; | |
52 | new_freq = policy->freq_table[index].frequency; | |
53 | ||
54 | /* | |
55 | * The procedure of reconfiguring CPU clk is as below. | |
56 | * | |
57 | * - Reparent CPU clk to OSC clk | |
58 | * - Reset CPU clock (very important) | |
59 | * - Reconfigure CPU DIV | |
60 | * - Reparent CPU clk back to CPU DIV clk | |
61 | */ | |
62 | ||
63 | dev_dbg(ls1x_cpufreq.dev, "%u KHz --> %u KHz\n", old_freq, new_freq); | |
64 | clk_set_parent(policy->clk, ls1x_cpufreq.osc_clk); | |
65 | __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU, | |
66 | LS1X_CLK_PLL_DIV); | |
67 | __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU), | |
68 | LS1X_CLK_PLL_DIV); | |
69 | clk_set_rate(ls1x_cpufreq.mux_clk, new_freq * 1000); | |
70 | clk_set_parent(policy->clk, ls1x_cpufreq.mux_clk); | |
71 | ||
72 | return 0; | |
73 | } | |
74 | ||
75 | static int ls1x_cpufreq_init(struct cpufreq_policy *policy) | |
76 | { | |
77 | struct cpufreq_frequency_table *freq_tbl; | |
78 | unsigned int pll_freq, freq; | |
79 | int steps, i, ret; | |
80 | ||
81 | pll_freq = clk_get_rate(ls1x_cpufreq.pll_clk) / 1000; | |
82 | ||
83 | steps = 1 << DIV_CPU_WIDTH; | |
84 | freq_tbl = kzalloc(sizeof(*freq_tbl) * steps, GFP_KERNEL); | |
85 | if (!freq_tbl) { | |
86 | dev_err(ls1x_cpufreq.dev, | |
87 | "failed to alloc cpufreq_frequency_table\n"); | |
88 | ret = -ENOMEM; | |
89 | goto out; | |
90 | } | |
91 | ||
92 | for (i = 0; i < (steps - 1); i++) { | |
93 | freq = pll_freq / (i + 1); | |
94 | if ((freq < ls1x_cpufreq.min_freq) || | |
95 | (freq > ls1x_cpufreq.max_freq)) | |
96 | freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID; | |
97 | else | |
98 | freq_tbl[i].frequency = freq; | |
99 | dev_dbg(ls1x_cpufreq.dev, | |
100 | "cpufreq table: index %d: frequency %d\n", i, | |
101 | freq_tbl[i].frequency); | |
102 | } | |
103 | freq_tbl[i].frequency = CPUFREQ_TABLE_END; | |
104 | ||
105 | policy->clk = ls1x_cpufreq.clk; | |
106 | ret = cpufreq_generic_init(policy, freq_tbl, 0); | |
107 | if (ret) | |
108 | kfree(freq_tbl); | |
109 | out: | |
110 | return ret; | |
111 | } | |
112 | ||
113 | static int ls1x_cpufreq_exit(struct cpufreq_policy *policy) | |
114 | { | |
115 | kfree(policy->freq_table); | |
116 | return 0; | |
117 | } | |
118 | ||
119 | static struct cpufreq_driver ls1x_cpufreq_driver = { | |
120 | .name = "cpufreq-ls1x", | |
121 | .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK, | |
122 | .verify = cpufreq_generic_frequency_table_verify, | |
123 | .target_index = ls1x_cpufreq_target, | |
124 | .get = cpufreq_generic_get, | |
125 | .init = ls1x_cpufreq_init, | |
126 | .exit = ls1x_cpufreq_exit, | |
127 | .attr = cpufreq_generic_attr, | |
128 | }; | |
129 | ||
130 | static int ls1x_cpufreq_remove(struct platform_device *pdev) | |
131 | { | |
132 | cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block, | |
133 | CPUFREQ_TRANSITION_NOTIFIER); | |
134 | cpufreq_unregister_driver(&ls1x_cpufreq_driver); | |
135 | ||
136 | return 0; | |
137 | } | |
138 | ||
139 | static int ls1x_cpufreq_probe(struct platform_device *pdev) | |
140 | { | |
141 | struct plat_ls1x_cpufreq *pdata = pdev->dev.platform_data; | |
142 | struct clk *clk; | |
143 | int ret; | |
144 | ||
145 | if (!pdata || !pdata->clk_name || !pdata->osc_clk_name) | |
146 | return -EINVAL; | |
147 | ||
148 | ls1x_cpufreq.dev = &pdev->dev; | |
149 | ||
150 | clk = devm_clk_get(&pdev->dev, pdata->clk_name); | |
151 | if (IS_ERR(clk)) { | |
152 | dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n", | |
153 | pdata->clk_name); | |
154 | ret = PTR_ERR(clk); | |
155 | goto out; | |
156 | } | |
157 | ls1x_cpufreq.clk = clk; | |
158 | ||
159 | clk = clk_get_parent(clk); | |
160 | if (IS_ERR(clk)) { | |
161 | dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n", | |
162 | __clk_get_name(ls1x_cpufreq.clk)); | |
163 | ret = PTR_ERR(clk); | |
164 | goto out; | |
165 | } | |
166 | ls1x_cpufreq.mux_clk = clk; | |
167 | ||
168 | clk = clk_get_parent(clk); | |
169 | if (IS_ERR(clk)) { | |
170 | dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n", | |
171 | __clk_get_name(ls1x_cpufreq.mux_clk)); | |
172 | ret = PTR_ERR(clk); | |
173 | goto out; | |
174 | } | |
175 | ls1x_cpufreq.pll_clk = clk; | |
176 | ||
177 | clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name); | |
178 | if (IS_ERR(clk)) { | |
179 | dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n", | |
180 | pdata->osc_clk_name); | |
181 | ret = PTR_ERR(clk); | |
182 | goto out; | |
183 | } | |
184 | ls1x_cpufreq.osc_clk = clk; | |
185 | ||
186 | ls1x_cpufreq.max_freq = pdata->max_freq; | |
187 | ls1x_cpufreq.min_freq = pdata->min_freq; | |
188 | ||
189 | ret = cpufreq_register_driver(&ls1x_cpufreq_driver); | |
190 | if (ret) { | |
191 | dev_err(ls1x_cpufreq.dev, | |
192 | "failed to register cpufreq driver: %d\n", ret); | |
193 | goto out; | |
194 | } | |
195 | ||
196 | ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block, | |
197 | CPUFREQ_TRANSITION_NOTIFIER); | |
198 | ||
199 | if (!ret) | |
200 | goto out; | |
201 | ||
202 | dev_err(ls1x_cpufreq.dev, "failed to register cpufreq notifier: %d\n", | |
203 | ret); | |
204 | ||
205 | cpufreq_unregister_driver(&ls1x_cpufreq_driver); | |
206 | out: | |
207 | return ret; | |
208 | } | |
209 | ||
210 | static struct platform_driver ls1x_cpufreq_platdrv = { | |
211 | .driver = { | |
212 | .name = "ls1x-cpufreq", | |
a0a22cf1 KC |
213 | }, |
214 | .probe = ls1x_cpufreq_probe, | |
215 | .remove = ls1x_cpufreq_remove, | |
216 | }; | |
217 | ||
218 | module_platform_driver(ls1x_cpufreq_platdrv); | |
219 | ||
220 | MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>"); | |
221 | MODULE_DESCRIPTION("Loongson 1 CPUFreq driver"); | |
222 | MODULE_LICENSE("GPL"); |