arch/arm/plat-mxc/cpufreq.c

   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/module.h>
  21 #include <linux/cpufreq.h>
  22 #include <linux/clk.h>
  23 #include <linux/err.h>
  24 #include <linux/slab.h>
  25 #include <mach/hardware.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
  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
  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
  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
  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
 100 static int 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 with error code %d\n",
 157                        __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
 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
 190 static int __devinit mxc_cpufreq_driver_init(void)
 191 {
 192         return cpufreq_register_driver(&mxc_driver);
 193 }
 194
 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");