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2a4bd9f0 AL |
1 | /* |
2 | * kirkwood_freq.c: cpufreq driver for the Marvell kirkwood | |
3 | * | |
4 | * Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch> | |
5 | * | |
6 | * This program is free software; you can redistribute it and/or | |
7 | * modify it under the terms of the GNU General Public License | |
8 | * as published by the Free Software Foundation; either version | |
9 | * 2 of the License, or (at your option) any later version. | |
10 | */ | |
11 | ||
12 | #include <linux/kernel.h> | |
13 | #include <linux/module.h> | |
14 | #include <linux/clk.h> | |
15 | #include <linux/clk-provider.h> | |
16 | #include <linux/cpufreq.h> | |
17 | #include <linux/of.h> | |
18 | #include <linux/platform_device.h> | |
19 | #include <linux/io.h> | |
20 | #include <asm/proc-fns.h> | |
21 | ||
22 | #define CPU_SW_INT_BLK BIT(28) | |
23 | ||
24 | static struct priv | |
25 | { | |
26 | struct clk *cpu_clk; | |
27 | struct clk *ddr_clk; | |
28 | struct clk *powersave_clk; | |
29 | struct device *dev; | |
30 | void __iomem *base; | |
31 | } priv; | |
32 | ||
33 | #define STATE_CPU_FREQ 0x01 | |
34 | #define STATE_DDR_FREQ 0x02 | |
35 | ||
36 | /* | |
37 | * Kirkwood can swap the clock to the CPU between two clocks: | |
38 | * | |
39 | * - cpu clk | |
40 | * - ddr clk | |
41 | * | |
42 | * The frequencies are set at runtime before registering this * | |
43 | * table. | |
44 | */ | |
45 | static struct cpufreq_frequency_table kirkwood_freq_table[] = { | |
46 | {STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */ | |
47 | {STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */ | |
48 | {0, CPUFREQ_TABLE_END}, | |
49 | }; | |
50 | ||
51 | static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu) | |
52 | { | |
53 | if (__clk_is_enabled(priv.powersave_clk)) | |
54 | return kirkwood_freq_table[1].frequency; | |
55 | return kirkwood_freq_table[0].frequency; | |
56 | } | |
57 | ||
58 | static void kirkwood_cpufreq_set_cpu_state(unsigned int index) | |
59 | { | |
60 | struct cpufreq_freqs freqs; | |
61 | unsigned int state = kirkwood_freq_table[index].index; | |
62 | unsigned long reg; | |
63 | ||
64 | freqs.old = kirkwood_cpufreq_get_cpu_frequency(0); | |
65 | freqs.new = kirkwood_freq_table[index].frequency; | |
66 | freqs.cpu = 0; /* Kirkwood is UP */ | |
67 | ||
68 | cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE); | |
69 | ||
70 | dev_dbg(priv.dev, "Attempting to set frequency to %i KHz\n", | |
71 | kirkwood_freq_table[index].frequency); | |
72 | dev_dbg(priv.dev, "old frequency was %i KHz\n", | |
73 | kirkwood_cpufreq_get_cpu_frequency(0)); | |
74 | ||
75 | if (freqs.old != freqs.new) { | |
76 | local_irq_disable(); | |
77 | ||
78 | /* Disable interrupts to the CPU */ | |
79 | reg = readl_relaxed(priv.base); | |
80 | reg |= CPU_SW_INT_BLK; | |
81 | writel_relaxed(reg, priv.base); | |
82 | ||
83 | switch (state) { | |
84 | case STATE_CPU_FREQ: | |
85 | clk_disable(priv.powersave_clk); | |
86 | break; | |
87 | case STATE_DDR_FREQ: | |
88 | clk_enable(priv.powersave_clk); | |
89 | break; | |
90 | } | |
91 | ||
92 | /* Wait-for-Interrupt, while the hardware changes frequency */ | |
93 | cpu_do_idle(); | |
94 | ||
95 | /* Enable interrupts to the CPU */ | |
96 | reg = readl_relaxed(priv.base); | |
97 | reg &= ~CPU_SW_INT_BLK; | |
98 | writel_relaxed(reg, priv.base); | |
99 | ||
100 | local_irq_enable(); | |
101 | } | |
102 | cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE); | |
103 | }; | |
104 | ||
105 | static int kirkwood_cpufreq_verify(struct cpufreq_policy *policy) | |
106 | { | |
107 | return cpufreq_frequency_table_verify(policy, kirkwood_freq_table); | |
108 | } | |
109 | ||
110 | static int kirkwood_cpufreq_target(struct cpufreq_policy *policy, | |
111 | unsigned int target_freq, | |
112 | unsigned int relation) | |
113 | { | |
114 | unsigned int index = 0; | |
115 | ||
116 | if (cpufreq_frequency_table_target(policy, kirkwood_freq_table, | |
117 | target_freq, relation, &index)) | |
118 | return -EINVAL; | |
119 | ||
120 | kirkwood_cpufreq_set_cpu_state(index); | |
121 | ||
122 | return 0; | |
123 | } | |
124 | ||
125 | /* Module init and exit code */ | |
126 | static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy) | |
127 | { | |
128 | int result; | |
129 | ||
130 | /* cpuinfo and default policy values */ | |
131 | policy->cpuinfo.transition_latency = 5000; /* 5uS */ | |
132 | policy->cur = kirkwood_cpufreq_get_cpu_frequency(0); | |
133 | ||
134 | result = cpufreq_frequency_table_cpuinfo(policy, kirkwood_freq_table); | |
135 | if (result) | |
136 | return result; | |
137 | ||
138 | cpufreq_frequency_table_get_attr(kirkwood_freq_table, policy->cpu); | |
139 | ||
140 | return 0; | |
141 | } | |
142 | ||
143 | static int kirkwood_cpufreq_cpu_exit(struct cpufreq_policy *policy) | |
144 | { | |
145 | cpufreq_frequency_table_put_attr(policy->cpu); | |
146 | return 0; | |
147 | } | |
148 | ||
149 | static struct freq_attr *kirkwood_cpufreq_attr[] = { | |
150 | &cpufreq_freq_attr_scaling_available_freqs, | |
151 | NULL, | |
152 | }; | |
153 | ||
154 | static struct cpufreq_driver kirkwood_cpufreq_driver = { | |
155 | .get = kirkwood_cpufreq_get_cpu_frequency, | |
156 | .verify = kirkwood_cpufreq_verify, | |
157 | .target = kirkwood_cpufreq_target, | |
158 | .init = kirkwood_cpufreq_cpu_init, | |
159 | .exit = kirkwood_cpufreq_cpu_exit, | |
160 | .name = "kirkwood-cpufreq", | |
161 | .owner = THIS_MODULE, | |
162 | .attr = kirkwood_cpufreq_attr, | |
163 | }; | |
164 | ||
165 | static int kirkwood_cpufreq_probe(struct platform_device *pdev) | |
166 | { | |
167 | struct device_node *np; | |
168 | struct resource *res; | |
169 | int err; | |
170 | ||
171 | priv.dev = &pdev->dev; | |
172 | ||
173 | res = platform_get_resource(pdev, IORESOURCE_MEM, 0); | |
174 | if (!res) { | |
175 | dev_err(&pdev->dev, "Cannot get memory resource\n"); | |
176 | return -ENODEV; | |
177 | } | |
178 | priv.base = devm_request_and_ioremap(&pdev->dev, res); | |
179 | if (!priv.base) { | |
180 | dev_err(&pdev->dev, "Cannot ioremap\n"); | |
181 | return -EADDRNOTAVAIL; | |
182 | } | |
183 | ||
184 | np = of_find_node_by_path("/cpus/cpu@0"); | |
185 | if (!np) | |
186 | return -ENODEV; | |
187 | ||
188 | priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk"); | |
189 | if (IS_ERR(priv.cpu_clk)) { | |
190 | dev_err(priv.dev, "Unable to get cpuclk"); | |
191 | return PTR_ERR(priv.cpu_clk); | |
192 | } | |
193 | ||
194 | clk_prepare_enable(priv.cpu_clk); | |
195 | kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000; | |
196 | ||
197 | priv.ddr_clk = of_clk_get_by_name(np, "ddrclk"); | |
198 | if (IS_ERR(priv.ddr_clk)) { | |
199 | dev_err(priv.dev, "Unable to get ddrclk"); | |
200 | err = PTR_ERR(priv.ddr_clk); | |
201 | goto out_cpu; | |
202 | } | |
203 | ||
204 | clk_prepare_enable(priv.ddr_clk); | |
205 | kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000; | |
206 | ||
207 | priv.powersave_clk = of_clk_get_by_name(np, "powersave"); | |
208 | if (IS_ERR(priv.powersave_clk)) { | |
209 | dev_err(priv.dev, "Unable to get powersave"); | |
210 | err = PTR_ERR(priv.powersave_clk); | |
211 | goto out_ddr; | |
212 | } | |
213 | clk_prepare(priv.powersave_clk); | |
214 | ||
215 | of_node_put(np); | |
216 | np = NULL; | |
217 | ||
218 | err = cpufreq_register_driver(&kirkwood_cpufreq_driver); | |
219 | if (!err) | |
220 | return 0; | |
221 | ||
222 | dev_err(priv.dev, "Failed to register cpufreq driver"); | |
223 | ||
224 | clk_disable_unprepare(priv.powersave_clk); | |
225 | out_ddr: | |
226 | clk_disable_unprepare(priv.ddr_clk); | |
227 | out_cpu: | |
228 | clk_disable_unprepare(priv.cpu_clk); | |
229 | of_node_put(np); | |
230 | ||
231 | return err; | |
232 | } | |
233 | ||
234 | static int kirkwood_cpufreq_remove(struct platform_device *pdev) | |
235 | { | |
236 | cpufreq_unregister_driver(&kirkwood_cpufreq_driver); | |
237 | ||
238 | clk_disable_unprepare(priv.powersave_clk); | |
239 | clk_disable_unprepare(priv.ddr_clk); | |
240 | clk_disable_unprepare(priv.cpu_clk); | |
241 | ||
242 | return 0; | |
243 | } | |
244 | ||
245 | static struct platform_driver kirkwood_cpufreq_platform_driver = { | |
246 | .probe = kirkwood_cpufreq_probe, | |
247 | .remove = kirkwood_cpufreq_remove, | |
248 | .driver = { | |
249 | .name = "kirkwood-cpufreq", | |
250 | .owner = THIS_MODULE, | |
251 | }, | |
252 | }; | |
253 | ||
254 | module_platform_driver(kirkwood_cpufreq_platform_driver); | |
255 | ||
256 | MODULE_LICENSE("GPL v2"); | |
257 | MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch"); | |
258 | MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU"); | |
259 | MODULE_ALIAS("platform:kirkwood-cpufreq"); |