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/io.h>
  17 #include <linux/module.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/slab.h>
  20
  21 #include <cpufreq.h>
  22 #include <loongson1.h>
  23
  24 struct ls1x_cpufreq {
  25         struct device *dev;
  26         struct clk *clk;        /* CPU clk */
  27         struct clk *mux_clk;    /* MUX of CPU clk */
  28         struct clk *pll_clk;    /* PLL clk */
  29         struct clk *osc_clk;    /* OSC clk */
  30         unsigned int max_freq;
  31         unsigned int min_freq;
  32 };
  33
  34 static struct ls1x_cpufreq *cpufreq;
  35
  36 static int ls1x_cpufreq_notifier(struct notifier_block *nb,
  37                                  unsigned long val, void *data)
  38 {
  39         if (val == CPUFREQ_POSTCHANGE)
  40                 current_cpu_data.udelay_val = loops_per_jiffy;
  41
  42         return NOTIFY_OK;
  43 }
  44
  45 static struct notifier_block ls1x_cpufreq_notifier_block = {
  46         .notifier_call = ls1x_cpufreq_notifier
  47 };
  48
  49 static int ls1x_cpufreq_target(struct cpufreq_policy *policy,
  50                                unsigned int index)
  51 {
  52         struct device *cpu_dev = get_cpu_device(policy->cpu);
  53         unsigned int old_freq, new_freq;
  54
  55         old_freq = policy->cur;
  56         new_freq = policy->freq_table[index].frequency;
  57
  58         /*
  59          * The procedure of reconfiguring CPU clk is as below.
  60          *
  61          *  - Reparent CPU clk to OSC clk
  62          *  - Reset CPU clock (very important)
  63          *  - Reconfigure CPU DIV
  64          *  - Reparent CPU clk back to CPU DIV clk
  65          */
  66
  67         clk_set_parent(policy->clk, cpufreq->osc_clk);
  68         __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU,
  69                      LS1X_CLK_PLL_DIV);
  70         __raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU),
  71                      LS1X_CLK_PLL_DIV);
  72         clk_set_rate(cpufreq->mux_clk, new_freq * 1000);
  73         clk_set_parent(policy->clk, cpufreq->mux_clk);
  74         dev_dbg(cpu_dev, "%u KHz --> %u KHz\n", old_freq, new_freq);
  75
  76         return 0;
  77 }
  78
  79 static int ls1x_cpufreq_init(struct cpufreq_policy *policy)
  80 {
  81         struct device *cpu_dev = get_cpu_device(policy->cpu);
  82         struct cpufreq_frequency_table *freq_tbl;
  83         unsigned int pll_freq, freq;
  84         int steps, i, ret;
  85
  86         pll_freq = clk_get_rate(cpufreq->pll_clk) / 1000;
  87
  88         steps = 1 << DIV_CPU_WIDTH;
  89         freq_tbl = kcalloc(steps, sizeof(*freq_tbl), GFP_KERNEL);
  90         if (!freq_tbl)
  91                 return -ENOMEM;
  92
  93         for (i = 0; i < (steps - 1); i++) {
  94                 freq = pll_freq / (i + 1);
  95                 if ((freq < cpufreq->min_freq) || (freq > cpufreq->max_freq))
  96                         freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
  97                 else
  98                         freq_tbl[i].frequency = freq;
  99                 dev_dbg(cpu_dev,
 100                         "cpufreq table: index %d: frequency %d\n", i,
 101                         freq_tbl[i].frequency);
 102         }
 103         freq_tbl[i].frequency = CPUFREQ_TABLE_END;
 104
 105         policy->clk = cpufreq->clk;
 106         ret = cpufreq_generic_init(policy, freq_tbl, 0);
 107         if (ret)
 108                 kfree(freq_tbl);
 109
 110         return ret;
 111 }
 112
 113 static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
 114 {
 115         kfree(policy->freq_table);
 116         return 0;
 117 }
 118
 119 static struct cpufreq_driver ls1x_cpufreq_driver = {
 120         .name           = "cpufreq-ls1x",
 121         .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 122         .verify         = cpufreq_generic_frequency_table_verify,
 123         .target_index   = ls1x_cpufreq_target,
 124         .get            = cpufreq_generic_get,
 125         .init           = ls1x_cpufreq_init,
 126         .exit           = ls1x_cpufreq_exit,
 127         .attr           = cpufreq_generic_attr,
 128 };
 129
 130 static int ls1x_cpufreq_remove(struct platform_device *pdev)
 131 {
 132         cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block,
 133                                     CPUFREQ_TRANSITION_NOTIFIER);
 134         cpufreq_unregister_driver(&ls1x_cpufreq_driver);
 135
 136         return 0;
 137 }
 138
 139 static int ls1x_cpufreq_probe(struct platform_device *pdev)
 140 {
 141         struct plat_ls1x_cpufreq *pdata = dev_get_platdata(&pdev->dev);
 142         struct clk *clk;
 143         int ret;
 144
 145         if (!pdata || !pdata->clk_name || !pdata->osc_clk_name) {
 146                 dev_err(&pdev->dev, "platform data missing\n");
 147                 return -EINVAL;
 148         }
 149
 150         cpufreq =
 151             devm_kzalloc(&pdev->dev, sizeof(struct ls1x_cpufreq), GFP_KERNEL);
 152         if (!cpufreq)
 153                 return -ENOMEM;
 154
 155         cpufreq->dev = &pdev->dev;
 156
 157         clk = devm_clk_get(&pdev->dev, pdata->clk_name);
 158         if (IS_ERR(clk)) {
 159                 dev_err(&pdev->dev, "unable to get %s clock\n",
 160                         pdata->clk_name);
 161                 return PTR_ERR(clk);
 162         }
 163         cpufreq->clk = clk;
 164
 165         clk = clk_get_parent(clk);
 166         if (IS_ERR(clk)) {
 167                 dev_err(&pdev->dev, "unable to get parent of %s clock\n",
 168                         __clk_get_name(cpufreq->clk));
 169                 return PTR_ERR(clk);
 170         }
 171         cpufreq->mux_clk = clk;
 172
 173         clk = clk_get_parent(clk);
 174         if (IS_ERR(clk)) {
 175                 dev_err(&pdev->dev, "unable to get parent of %s clock\n",
 176                         __clk_get_name(cpufreq->mux_clk));
 177                 return PTR_ERR(clk);
 178         }
 179         cpufreq->pll_clk = clk;
 180
 181         clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
 182         if (IS_ERR(clk)) {
 183                 dev_err(&pdev->dev, "unable to get %s clock\n",
 184                         pdata->osc_clk_name);
 185                 return PTR_ERR(clk);
 186         }
 187         cpufreq->osc_clk = clk;
 188
 189         cpufreq->max_freq = pdata->max_freq;
 190         cpufreq->min_freq = pdata->min_freq;
 191
 192         ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
 193         if (ret) {
 194                 dev_err(&pdev->dev,
 195                         "failed to register CPUFreq driver: %d\n", ret);
 196                 return ret;
 197         }
 198
 199         ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
 200                                         CPUFREQ_TRANSITION_NOTIFIER);
 201
 202         if (ret) {
 203                 dev_err(&pdev->dev,
 204                         "failed to register CPUFreq notifier: %d\n",ret);
 205                 cpufreq_unregister_driver(&ls1x_cpufreq_driver);
 206         }
 207
 208         return ret;
 209 }
 210
 211 static struct platform_driver ls1x_cpufreq_platdrv = {
 212         .probe  = ls1x_cpufreq_probe,
 213         .remove = ls1x_cpufreq_remove,
 214         .driver = {
 215                 .name   = "ls1x-cpufreq",
 216         },
 217 };
 218
 219 module_platform_driver(ls1x_cpufreq_platdrv);
 220
 221 MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
 222 MODULE_DESCRIPTION("Loongson1 CPUFreq driver");
 223 MODULE_LICENSE("GPL");