1 /*
2 * Copyright (C) 2010 Freescale Semiconductor, Inc. All Rights Reserved.
3 */
4
5 /*
6 * The code contained herein is licensed under the GNU General Public
7 * License. You may obtain a copy of the GNU General Public License
8 * Version 2 or later at the following locations:
9 *
10 * http://www.opensource.org/licenses/gpl-license.html
11 * http://www.gnu.org/copyleft/gpl.html
12 */
13
14 /*
15 * A driver for the Freescale Semiconductor i.MXC CPUfreq module.
16 * The CPUFREQ driver is for controlling CPU frequency. It allows you to change
17 * the CPU clock speed on the fly.
18 */
19
20 #include <linux/cpufreq.h>
21 #include <linux/clk.h>
22 #include <linux/err.h>
23 #include <linux/slab.h>
24 #include <mach/hardware.h>
25 #include <mach/clock.h>
26
27 #define CLK32_FREQ 32768
28 #define NANOSECOND (1000 * 1000 * 1000)
29
30 struct cpu_op *(*get_cpu_op)(int *op);
31
32 static int cpu_freq_khz_min;
33 static int cpu_freq_khz_max;
34
35 static struct clk *cpu_clk;
36 static struct cpufreq_frequency_table *imx_freq_table;
37
38 static int cpu_op_nr;
39 static struct cpu_op *cpu_op_tbl;
40
set_cpu_freq(int freq)41 static int set_cpu_freq(int freq)
42 {
43 int ret = 0;
44 int org_cpu_rate;
45
46 org_cpu_rate = clk_get_rate(cpu_clk);
47 if (org_cpu_rate == freq)
48 return ret;
49
50 ret = clk_set_rate(cpu_clk, freq);
51 if (ret != 0) {
52 printk(KERN_DEBUG "cannot set CPU clock rate\n");
53 return ret;
54 }
55
56 return ret;
57 }
58
mxc_verify_speed(struct cpufreq_policy * policy)59 static int mxc_verify_speed(struct cpufreq_policy *policy)
60 {
61 if (policy->cpu != 0)
62 return -EINVAL;
63
64 return cpufreq_frequency_table_verify(policy, imx_freq_table);
65 }
66
mxc_get_speed(unsigned int cpu)67 static unsigned int mxc_get_speed(unsigned int cpu)
68 {
69 if (cpu)
70 return 0;
71
72 return clk_get_rate(cpu_clk) / 1000;
73 }
74
mxc_set_target(struct cpufreq_policy * policy,unsigned int target_freq,unsigned int relation)75 static int mxc_set_target(struct cpufreq_policy *policy,
76 unsigned int target_freq, unsigned int relation)
77 {
78 struct cpufreq_freqs freqs;
79 int freq_Hz;
80 int ret = 0;
81 unsigned int index;
82
83 cpufreq_frequency_table_target(policy, imx_freq_table,
84 target_freq, relation, &index);
85 freq_Hz = imx_freq_table[index].frequency * 1000;
86
87 freqs.old = clk_get_rate(cpu_clk) / 1000;
88 freqs.new = freq_Hz / 1000;
89 freqs.cpu = 0;
90 freqs.flags = 0;
91 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
92
93 ret = set_cpu_freq(freq_Hz);
94
95 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
96
97 return ret;
98 }
99
mxc_cpufreq_init(struct cpufreq_policy * policy)100 static int __init mxc_cpufreq_init(struct cpufreq_policy *policy)
101 {
102 int ret;
103 int i;
104
105 printk(KERN_INFO "i.MXC CPU frequency driver\n");
106
107 if (policy->cpu != 0)
108 return -EINVAL;
109
110 if (!get_cpu_op)
111 return -EINVAL;
112
113 cpu_clk = clk_get(NULL, "cpu_clk");
114 if (IS_ERR(cpu_clk)) {
115 printk(KERN_ERR "%s: failed to get cpu clock\n", __func__);
116 return PTR_ERR(cpu_clk);
117 }
118
119 cpu_op_tbl = get_cpu_op(&cpu_op_nr);
120
121 cpu_freq_khz_min = cpu_op_tbl[0].cpu_rate / 1000;
122 cpu_freq_khz_max = cpu_op_tbl[0].cpu_rate / 1000;
123
124 imx_freq_table = kmalloc(
125 sizeof(struct cpufreq_frequency_table) * (cpu_op_nr + 1),
126 GFP_KERNEL);
127 if (!imx_freq_table) {
128 ret = -ENOMEM;
129 goto err1;
130 }
131
132 for (i = 0; i < cpu_op_nr; i++) {
133 imx_freq_table[i].index = i;
134 imx_freq_table[i].frequency = cpu_op_tbl[i].cpu_rate / 1000;
135
136 if ((cpu_op_tbl[i].cpu_rate / 1000) < cpu_freq_khz_min)
137 cpu_freq_khz_min = cpu_op_tbl[i].cpu_rate / 1000;
138
139 if ((cpu_op_tbl[i].cpu_rate / 1000) > cpu_freq_khz_max)
140 cpu_freq_khz_max = cpu_op_tbl[i].cpu_rate / 1000;
141 }
142
143 imx_freq_table[i].index = i;
144 imx_freq_table[i].frequency = CPUFREQ_TABLE_END;
145
146 policy->cur = clk_get_rate(cpu_clk) / 1000;
147 policy->min = policy->cpuinfo.min_freq = cpu_freq_khz_min;
148 policy->max = policy->cpuinfo.max_freq = cpu_freq_khz_max;
149
150 /* Manual states, that PLL stabilizes in two CLK32 periods */
151 policy->cpuinfo.transition_latency = 2 * NANOSECOND / CLK32_FREQ;
152
153 ret = cpufreq_frequency_table_cpuinfo(policy, imx_freq_table);
154
155 if (ret < 0) {
156 printk(KERN_ERR "%s: failed to register i.MXC CPUfreq \
157 with error code %d\n", __func__, ret);
158 goto err;
159 }
160
161 cpufreq_frequency_table_get_attr(imx_freq_table, policy->cpu);
162 return 0;
163 err:
164 kfree(imx_freq_table);
165 err1:
166 clk_put(cpu_clk);
167 return ret;
168 }
169
mxc_cpufreq_exit(struct cpufreq_policy * policy)170 static int mxc_cpufreq_exit(struct cpufreq_policy *policy)
171 {
172 cpufreq_frequency_table_put_attr(policy->cpu);
173
174 set_cpu_freq(cpu_freq_khz_max * 1000);
175 clk_put(cpu_clk);
176 kfree(imx_freq_table);
177 return 0;
178 }
179
180 static struct cpufreq_driver mxc_driver = {
181 .flags = CPUFREQ_STICKY,
182 .verify = mxc_verify_speed,
183 .target = mxc_set_target,
184 .get = mxc_get_speed,
185 .init = mxc_cpufreq_init,
186 .exit = mxc_cpufreq_exit,
187 .name = "imx",
188 };
189
mxc_cpufreq_driver_init(void)190 static int __devinit mxc_cpufreq_driver_init(void)
191 {
192 return cpufreq_register_driver(&mxc_driver);
193 }
194
mxc_cpufreq_driver_exit(void)195 static void mxc_cpufreq_driver_exit(void)
196 {
197 cpufreq_unregister_driver(&mxc_driver);
198 }
199
200 module_init(mxc_cpufreq_driver_init);
201 module_exit(mxc_cpufreq_driver_exit);
202
203 MODULE_AUTHOR("Freescale Semiconductor Inc. Yong Shen <yong.shen@linaro.org>");
204 MODULE_DESCRIPTION("CPUfreq driver for i.MX");
205 MODULE_LICENSE("GPL");
206