GNU Linux-libre 4.4.289-gnu1
[releases.git] / drivers / cpufreq / ls1x-cpufreq.c
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
20 #include <cpufreq.h>
21 #include <loongson1.h>
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",
213         },
214         .probe          = ls1x_cpufreq_probe,
215         .remove         = ls1x_cpufreq_remove,
216 };
217
218 module_platform_driver(ls1x_cpufreq_platdrv);
219
220 MODULE_ALIAS("platform:ls1x-cpufreq");
221 MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
222 MODULE_DESCRIPTION("Loongson 1 CPUFreq driver");
223 MODULE_LICENSE("GPL");