drivers/cpufreq/loongson1-cpufreq.c

   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/module.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/slab.h>
  19
  20 #include <cpufreq.h>
  21 #include <loongson1.h>
  22
  23 static struct {
  24         struct device *dev;
  25         struct clk *clk;        /* CPU clk */
  26         struct clk *mux_clk;    /* MUX of CPU clk */
  27         struct clk *pll_clk;    /* PLL clk */
  28         struct clk *osc_clk;    /* OSC clk */
  29         unsigned int max_freq;
  30         unsigned int min_freq;
  31 } ls1x_cpufreq;
  32
  33 static int ls1x_cpufreq_notifier(struct notifier_block *nb,
  34                                  unsigned long val, void *data)
  35 {
  36         if (val == CPUFREQ_POSTCHANGE)
  37                 current_cpu_data.udelay_val = loops_per_jiffy;
  38
  39         return NOTIFY_OK;
  40 }
  41
  42 static struct notifier_block ls1x_cpufreq_notifier_block = {
  43         .notifier_call = ls1x_cpufreq_notifier
  44 };
  45
  46 static int ls1x_cpufreq_target(struct cpufreq_policy *policy,
  47                                unsigned int index)
  48 {
  49         unsigned int old_freq, new_freq;
  50
  51         old_freq = policy->cur;
  52         new_freq = policy->freq_table[index].frequency;
  53
  54         /*
  55          * The procedure of reconfiguring CPU clk is as below.
  56          *
  57          *  - Reparent CPU clk to OSC clk
  58          *  - Reset CPU clock (very important)
  59          *  - Reconfigure CPU DIV
  60          *  - Reparent CPU clk back to CPU DIV clk
  61          */
  62
  63         dev_dbg(ls1x_cpufreq.dev, "%u KHz --> %u KHz\n", old_freq, new_freq);
  64         clk_set_parent(policy->clk, ls1x_cpufreq.osc_clk);
  65         __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU,
  66                      LS1X_CLK_PLL_DIV);
  67         __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU),
  68                      LS1X_CLK_PLL_DIV);
  69         clk_set_rate(ls1x_cpufreq.mux_clk, new_freq * 1000);
  70         clk_set_parent(policy->clk, ls1x_cpufreq.mux_clk);
  71
  72         return 0;
  73 }
  74
  75 static int ls1x_cpufreq_init(struct cpufreq_policy *policy)
  76 {
  77         struct cpufreq_frequency_table *freq_tbl;
  78         unsigned int pll_freq, freq;
  79         int steps, i, ret;
  80
  81         pll_freq = clk_get_rate(ls1x_cpufreq.pll_clk) / 1000;
  82
  83         steps = 1 << DIV_CPU_WIDTH;
  84         freq_tbl = kcalloc(steps, sizeof(*freq_tbl), GFP_KERNEL);
  85         if (!freq_tbl)
  86                 return -ENOMEM;
  87
  88         for (i = 0; i < (steps - 1); i++) {
  89                 freq = pll_freq / (i + 1);
  90                 if ((freq < ls1x_cpufreq.min_freq) ||
  91                     (freq > ls1x_cpufreq.max_freq))
  92                         freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
  93                 else
  94                         freq_tbl[i].frequency = freq;
  95                 dev_dbg(ls1x_cpufreq.dev,
  96                         "cpufreq table: index %d: frequency %d\n", i,
  97                         freq_tbl[i].frequency);
  98         }
  99         freq_tbl[i].frequency = CPUFREQ_TABLE_END;
 100
 101         policy->clk = ls1x_cpufreq.clk;
 102         ret = cpufreq_generic_init(policy, freq_tbl, 0);
 103         if (ret)
 104                 kfree(freq_tbl);
 105
 106         return ret;
 107 }
 108
 109 static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
 110 {
 111         kfree(policy->freq_table);
 112         return 0;
 113 }
 114
 115 static struct cpufreq_driver ls1x_cpufreq_driver = {
 116         .name           = "cpufreq-ls1x",
 117         .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 118         .verify         = cpufreq_generic_frequency_table_verify,
 119         .target_index   = ls1x_cpufreq_target,
 120         .get            = cpufreq_generic_get,
 121         .init           = ls1x_cpufreq_init,
 122         .exit           = ls1x_cpufreq_exit,
 123         .attr           = cpufreq_generic_attr,
 124 };
 125
 126 static int ls1x_cpufreq_remove(struct platform_device *pdev)
 127 {
 128         cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block,
 129                                     CPUFREQ_TRANSITION_NOTIFIER);
 130         cpufreq_unregister_driver(&ls1x_cpufreq_driver);
 131
 132         return 0;
 133 }
 134
 135 static int ls1x_cpufreq_probe(struct platform_device *pdev)
 136 {
 137         struct plat_ls1x_cpufreq *pdata = dev_get_platdata(&pdev->dev);
 138         struct clk *clk;
 139         int ret;
 140
 141         if (!pdata || !pdata->clk_name || !pdata->osc_clk_name)
 142                 return -EINVAL;
 143
 144         ls1x_cpufreq.dev = &pdev->dev;
 145
 146         clk = devm_clk_get(&pdev->dev, pdata->clk_name);
 147         if (IS_ERR(clk)) {
 148                 dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n",
 149                         pdata->clk_name);
 150                 ret = PTR_ERR(clk);
 151                 goto out;
 152         }
 153         ls1x_cpufreq.clk = clk;
 154
 155         clk = clk_get_parent(clk);
 156         if (IS_ERR(clk)) {
 157                 dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n",
 158                         __clk_get_name(ls1x_cpufreq.clk));
 159                 ret = PTR_ERR(clk);
 160                 goto out;
 161         }
 162         ls1x_cpufreq.mux_clk = clk;
 163
 164         clk = clk_get_parent(clk);
 165         if (IS_ERR(clk)) {
 166                 dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n",
 167                         __clk_get_name(ls1x_cpufreq.mux_clk));
 168                 ret = PTR_ERR(clk);
 169                 goto out;
 170         }
 171         ls1x_cpufreq.pll_clk = clk;
 172
 173         clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
 174         if (IS_ERR(clk)) {
 175                 dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n",
 176                         pdata->osc_clk_name);
 177                 ret = PTR_ERR(clk);
 178                 goto out;
 179         }
 180         ls1x_cpufreq.osc_clk = clk;
 181
 182         ls1x_cpufreq.max_freq = pdata->max_freq;
 183         ls1x_cpufreq.min_freq = pdata->min_freq;
 184
 185         ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
 186         if (ret) {
 187                 dev_err(ls1x_cpufreq.dev,
 188                         "failed to register cpufreq driver: %d\n", ret);
 189                 goto out;
 190         }
 191
 192         ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
 193                                         CPUFREQ_TRANSITION_NOTIFIER);
 194
 195         if (!ret)
 196                 goto out;
 197
 198         dev_err(ls1x_cpufreq.dev, "failed to register cpufreq notifier: %d\n",
 199                 ret);
 200
 201         cpufreq_unregister_driver(&ls1x_cpufreq_driver);
 202 out:
 203         return ret;
 204 }
 205
 206 static struct platform_driver ls1x_cpufreq_platdrv = {
 207         .probe  = ls1x_cpufreq_probe,
 208         .remove = ls1x_cpufreq_remove,
 209         .driver = {
 210                 .name   = "ls1x-cpufreq",
 211         },
 212 };
 213
 214 module_platform_driver(ls1x_cpufreq_platdrv);
 215
 216 MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
 217 MODULE_DESCRIPTION("Loongson1 CPUFreq driver");
 218 MODULE_LICENSE("GPL");