summaryrefslogtreecommitdiffstats
path: root/kernel/drivers/cpufreq/ls1x-cpufreq.c
blob: f0913eee2f5007a2ba8ca5ee7b1adea21bfc8215 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
/*
 * CPU Frequency Scaling for Loongson 1 SoC
 *
 * Copyright (C) 2014 Zhang, Keguang <keguang.zhang@gmail.com>
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/cpu.h>
#include <linux/cpufreq.h>
#include <linux/delay.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>

#include <asm/mach-loongson1/cpufreq.h>
#include <asm/mach-loongson1/loongson1.h>

static struct {
	struct device *dev;
	struct clk *clk;	/* CPU clk */
	struct clk *mux_clk;	/* MUX of CPU clk */
	struct clk *pll_clk;	/* PLL clk */
	struct clk *osc_clk;	/* OSC clk */
	unsigned int max_freq;
	unsigned int min_freq;
} ls1x_cpufreq;

static int ls1x_cpufreq_notifier(struct notifier_block *nb,
				 unsigned long val, void *data)
{
	if (val == CPUFREQ_POSTCHANGE)
		current_cpu_data.udelay_val = loops_per_jiffy;

	return NOTIFY_OK;
}

static struct notifier_block ls1x_cpufreq_notifier_block = {
	.notifier_call = ls1x_cpufreq_notifier
};

static int ls1x_cpufreq_target(struct cpufreq_policy *policy,
			       unsigned int index)
{
	unsigned int old_freq, new_freq;

	old_freq = policy->cur;
	new_freq = policy->freq_table[index].frequency;

	/*
	 * The procedure of reconfiguring CPU clk is as below.
	 *
	 *  - Reparent CPU clk to OSC clk
	 *  - Reset CPU clock (very important)
	 *  - Reconfigure CPU DIV
	 *  - Reparent CPU clk back to CPU DIV clk
	 */

	dev_dbg(ls1x_cpufreq.dev, "%u KHz --> %u KHz\n", old_freq, new_freq);
	clk_set_parent(policy->clk, ls1x_cpufreq.osc_clk);
	__raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU,
		     LS1X_CLK_PLL_DIV);
	__raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU),
		     LS1X_CLK_PLL_DIV);
	clk_set_rate(ls1x_cpufreq.mux_clk, new_freq * 1000);
	clk_set_parent(policy->clk, ls1x_cpufreq.mux_clk);

	return 0;
}

static int ls1x_cpufreq_init(struct cpufreq_policy *policy)
{
	struct cpufreq_frequency_table *freq_tbl;
	unsigned int pll_freq, freq;
	int steps, i, ret;

	pll_freq = clk_get_rate(ls1x_cpufreq.pll_clk) / 1000;

	steps = 1 << DIV_CPU_WIDTH;
	freq_tbl = kzalloc(sizeof(*freq_tbl) * steps, GFP_KERNEL);
	if (!freq_tbl) {
		dev_err(ls1x_cpufreq.dev,
			"failed to alloc cpufreq_frequency_table\n");
		ret = -ENOMEM;
		goto out;
	}

	for (i = 0; i < (steps - 1); i++) {
		freq = pll_freq / (i + 1);
		if ((freq < ls1x_cpufreq.min_freq) ||
		    (freq > ls1x_cpufreq.max_freq))
			freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
		else
			freq_tbl[i].frequency = freq;
		dev_dbg(ls1x_cpufreq.dev,
			"cpufreq table: index %d: frequency %d\n", i,
			freq_tbl[i].frequency);
	}
	freq_tbl[i].frequency = CPUFREQ_TABLE_END;

	policy->clk = ls1x_cpufreq.clk;
	ret = cpufreq_generic_init(policy, freq_tbl, 0);
	if (ret)
		kfree(freq_tbl);
out:
	return ret;
}

static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
{
	kfree(policy->freq_table);
	return 0;
}

static struct cpufreq_driver ls1x_cpufreq_driver = {
	.name		= "cpufreq-ls1x",
	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
	.verify		= cpufreq_generic_frequency_table_verify,
	.target_index	= ls1x_cpufreq_target,
	.get		= cpufreq_generic_get,
	.init		= ls1x_cpufreq_init,
	.exit		= ls1x_cpufreq_exit,
	.attr		= cpufreq_generic_attr,
};

static int ls1x_cpufreq_remove(struct platform_device *pdev)
{
	cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block,
				    CPUFREQ_TRANSITION_NOTIFIER);
	cpufreq_unregister_driver(&ls1x_cpufreq_driver);

	return 0;
}

static int ls1x_cpufreq_probe(struct platform_device *pdev)
{
	struct plat_ls1x_cpufreq *pdata = pdev->dev.platform_data;
	struct clk *clk;
	int ret;

	if (!pdata || !pdata->clk_name || !pdata->osc_clk_name)
		return -EINVAL;

	ls1x_cpufreq.dev = &pdev->dev;

	clk = devm_clk_get(&pdev->dev, pdata->clk_name);
	if (IS_ERR(clk)) {
		dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n",
			pdata->clk_name);
		ret = PTR_ERR(clk);
		goto out;
	}
	ls1x_cpufreq.clk = clk;

	clk = clk_get_parent(clk);
	if (IS_ERR(clk)) {
		dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n",
			__clk_get_name(ls1x_cpufreq.clk));
		ret = PTR_ERR(clk);
		goto out;
	}
	ls1x_cpufreq.mux_clk = clk;

	clk = clk_get_parent(clk);
	if (IS_ERR(clk)) {
		dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n",
			__clk_get_name(ls1x_cpufreq.mux_clk));
		ret = PTR_ERR(clk);
		goto out;
	}
	ls1x_cpufreq.pll_clk = clk;

	clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
	if (IS_ERR(clk)) {
		dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n",
			pdata->osc_clk_name);
		ret = PTR_ERR(clk);
		goto out;
	}
	ls1x_cpufreq.osc_clk = clk;

	ls1x_cpufreq.max_freq = pdata->max_freq;
	ls1x_cpufreq.min_freq = pdata->min_freq;

	ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
	if (ret) {
		dev_err(ls1x_cpufreq.dev,
			"failed to register cpufreq driver: %d\n", ret);
		goto out;
	}

	ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
					CPUFREQ_TRANSITION_NOTIFIER);

	if (!ret)
		goto out;

	dev_err(ls1x_cpufreq.dev, "failed to register cpufreq notifier: %d\n",
		ret);

	cpufreq_unregister_driver(&ls1x_cpufreq_driver);
out:
	return ret;
}

static struct platform_driver ls1x_cpufreq_platdrv = {
	.driver = {
		.name	= "ls1x-cpufreq",
	},
	.probe		= ls1x_cpufreq_probe,
	.remove		= ls1x_cpufreq_remove,
};

module_platform_driver(ls1x_cpufreq_platdrv);

MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
MODULE_DESCRIPTION("Loongson 1 CPUFreq driver");
MODULE_LICENSE("GPL");