1 /*
2 * CPU Frequency Scaling for Loongson 1 SoC
3 *
4 * Copyright (C) 2014-2016 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/io.h>
17 #include <linux/module.h>
18 #include <linux/platform_device.h>
19 #include <linux/slab.h>
20
21 #include <cpufreq.h>
22 #include <loongson1.h>
23
24 struct ls1x_cpufreq {
25 struct device *dev;
26 struct clk *clk; /* CPU clk */
27 struct clk *mux_clk; /* MUX of CPU clk */
28 struct clk *pll_clk; /* PLL clk */
29 struct clk *osc_clk; /* OSC clk */
30 unsigned int max_freq;
31 unsigned int min_freq;
32 };
33
34 static struct ls1x_cpufreq *cpufreq;
35
ls1x_cpufreq_notifier(struct notifier_block * nb,unsigned long val,void * data)36 static int ls1x_cpufreq_notifier(struct notifier_block *nb,
37 unsigned long val, void *data)
38 {
39 if (val == CPUFREQ_POSTCHANGE)
40 current_cpu_data.udelay_val = loops_per_jiffy;
41
42 return NOTIFY_OK;
43 }
44
45 static struct notifier_block ls1x_cpufreq_notifier_block = {
46 .notifier_call = ls1x_cpufreq_notifier
47 };
48
ls1x_cpufreq_target(struct cpufreq_policy * policy,unsigned int index)49 static int ls1x_cpufreq_target(struct cpufreq_policy *policy,
50 unsigned int index)
51 {
52 struct device *cpu_dev = get_cpu_device(policy->cpu);
53 unsigned int old_freq, new_freq;
54
55 old_freq = policy->cur;
56 new_freq = policy->freq_table[index].frequency;
57
58 /*
59 * The procedure of reconfiguring CPU clk is as below.
60 *
61 * - Reparent CPU clk to OSC clk
62 * - Reset CPU clock (very important)
63 * - Reconfigure CPU DIV
64 * - Reparent CPU clk back to CPU DIV clk
65 */
66
67 clk_set_parent(policy->clk, cpufreq->osc_clk);
68 __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU,
69 LS1X_CLK_PLL_DIV);
70 __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU),
71 LS1X_CLK_PLL_DIV);
72 clk_set_rate(cpufreq->mux_clk, new_freq * 1000);
73 clk_set_parent(policy->clk, cpufreq->mux_clk);
74 dev_dbg(cpu_dev, "%u KHz --> %u KHz\n", old_freq, new_freq);
75
76 return 0;
77 }
78
ls1x_cpufreq_init(struct cpufreq_policy * policy)79 static int ls1x_cpufreq_init(struct cpufreq_policy *policy)
80 {
81 struct device *cpu_dev = get_cpu_device(policy->cpu);
82 struct cpufreq_frequency_table *freq_tbl;
83 unsigned int pll_freq, freq;
84 int steps, i;
85
86 pll_freq = clk_get_rate(cpufreq->pll_clk) / 1000;
87
88 steps = 1 << DIV_CPU_WIDTH;
89 freq_tbl = kcalloc(steps, sizeof(*freq_tbl), GFP_KERNEL);
90 if (!freq_tbl)
91 return -ENOMEM;
92
93 for (i = 0; i < (steps - 1); i++) {
94 freq = pll_freq / (i + 1);
95 if ((freq < cpufreq->min_freq) || (freq > cpufreq->max_freq))
96 freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
97 else
98 freq_tbl[i].frequency = freq;
99 dev_dbg(cpu_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 = cpufreq->clk;
106 cpufreq_generic_init(policy, freq_tbl, 0);
107
108 return 0;
109 }
110
ls1x_cpufreq_exit(struct cpufreq_policy * policy)111 static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
112 {
113 kfree(policy->freq_table);
114 return 0;
115 }
116
117 static struct cpufreq_driver ls1x_cpufreq_driver = {
118 .name = "cpufreq-ls1x",
119 .flags = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
120 .verify = cpufreq_generic_frequency_table_verify,
121 .target_index = ls1x_cpufreq_target,
122 .get = cpufreq_generic_get,
123 .init = ls1x_cpufreq_init,
124 .exit = ls1x_cpufreq_exit,
125 .attr = cpufreq_generic_attr,
126 };
127
ls1x_cpufreq_remove(struct platform_device * pdev)128 static int ls1x_cpufreq_remove(struct platform_device *pdev)
129 {
130 cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block,
131 CPUFREQ_TRANSITION_NOTIFIER);
132 cpufreq_unregister_driver(&ls1x_cpufreq_driver);
133
134 return 0;
135 }
136
ls1x_cpufreq_probe(struct platform_device * pdev)137 static int ls1x_cpufreq_probe(struct platform_device *pdev)
138 {
139 struct plat_ls1x_cpufreq *pdata = dev_get_platdata(&pdev->dev);
140 struct clk *clk;
141 int ret;
142
143 if (!pdata || !pdata->clk_name || !pdata->osc_clk_name) {
144 dev_err(&pdev->dev, "platform data missing\n");
145 return -EINVAL;
146 }
147
148 cpufreq =
149 devm_kzalloc(&pdev->dev, sizeof(struct ls1x_cpufreq), GFP_KERNEL);
150 if (!cpufreq)
151 return -ENOMEM;
152
153 cpufreq->dev = &pdev->dev;
154
155 clk = devm_clk_get(&pdev->dev, pdata->clk_name);
156 if (IS_ERR(clk)) {
157 dev_err(&pdev->dev, "unable to get %s clock\n",
158 pdata->clk_name);
159 return PTR_ERR(clk);
160 }
161 cpufreq->clk = clk;
162
163 clk = clk_get_parent(clk);
164 if (IS_ERR(clk)) {
165 dev_err(&pdev->dev, "unable to get parent of %s clock\n",
166 __clk_get_name(cpufreq->clk));
167 return PTR_ERR(clk);
168 }
169 cpufreq->mux_clk = clk;
170
171 clk = clk_get_parent(clk);
172 if (IS_ERR(clk)) {
173 dev_err(&pdev->dev, "unable to get parent of %s clock\n",
174 __clk_get_name(cpufreq->mux_clk));
175 return PTR_ERR(clk);
176 }
177 cpufreq->pll_clk = clk;
178
179 clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
180 if (IS_ERR(clk)) {
181 dev_err(&pdev->dev, "unable to get %s clock\n",
182 pdata->osc_clk_name);
183 return PTR_ERR(clk);
184 }
185 cpufreq->osc_clk = clk;
186
187 cpufreq->max_freq = pdata->max_freq;
188 cpufreq->min_freq = pdata->min_freq;
189
190 ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
191 if (ret) {
192 dev_err(&pdev->dev,
193 "failed to register CPUFreq driver: %d\n", ret);
194 return ret;
195 }
196
197 ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
198 CPUFREQ_TRANSITION_NOTIFIER);
199
200 if (ret) {
201 dev_err(&pdev->dev,
202 "failed to register CPUFreq notifier: %d\n",ret);
203 cpufreq_unregister_driver(&ls1x_cpufreq_driver);
204 }
205
206 return ret;
207 }
208
209 static struct platform_driver ls1x_cpufreq_platdrv = {
210 .probe = ls1x_cpufreq_probe,
211 .remove = ls1x_cpufreq_remove,
212 .driver = {
213 .name = "ls1x-cpufreq",
214 },
215 };
216
217 module_platform_driver(ls1x_cpufreq_platdrv);
218
219 MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
220 MODULE_DESCRIPTION("Loongson1 CPUFreq driver");
221 MODULE_LICENSE("GPL");
222