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