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