drivers/cpufreq/ls1x-cpufreq.c

   1 /*
   2  * CPU Frequency Scaling for Loongson 1 SoC
   3  *
   4  * Copyright (C) 2014 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 = kzalloc(sizeof(*freq_tbl) * steps, GFP_KERNEL);
  85         if (!freq_tbl) {
  86                 dev_err(ls1x_cpufreq.dev,
  87                         "failed to alloc cpufreq_frequency_table\n");
  88                 ret = -ENOMEM;
  89                 goto out;
  90         }
  91
  92         for (i = 0; i < (steps - 1); i++) {
  93                 freq = pll_freq / (i + 1);
  94                 if ((freq < ls1x_cpufreq.min_freq) ||
  95                     (freq > ls1x_cpufreq.max_freq))
  96                         freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
  97                 else
  98                         freq_tbl[i].frequency = freq;
  99                 dev_dbg(ls1x_cpufreq.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 = ls1x_cpufreq.clk;
 106         ret = cpufreq_generic_init(policy, freq_tbl, 0);
 107         if (ret)
 108                 kfree(freq_tbl);
 109 out:
 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 = pdev->dev.platform_data;
 142         struct clk *clk;
 143         int ret;
 144
 145         if (!pdata || !pdata->clk_name || !pdata->osc_clk_name)
 146                 return -EINVAL;
 147
 148         ls1x_cpufreq.dev = &pdev->dev;
 149
 150         clk = devm_clk_get(&pdev->dev, pdata->clk_name);
 151         if (IS_ERR(clk)) {
 152                 dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n",
 153                         pdata->clk_name);
 154                 ret = PTR_ERR(clk);
 155                 goto out;
 156         }
 157         ls1x_cpufreq.clk = clk;
 158
 159         clk = clk_get_parent(clk);
 160         if (IS_ERR(clk)) {
 161                 dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n",
 162                         __clk_get_name(ls1x_cpufreq.clk));
 163                 ret = PTR_ERR(clk);
 164                 goto out;
 165         }
 166         ls1x_cpufreq.mux_clk = clk;
 167
 168         clk = clk_get_parent(clk);
 169         if (IS_ERR(clk)) {
 170                 dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n",
 171                         __clk_get_name(ls1x_cpufreq.mux_clk));
 172                 ret = PTR_ERR(clk);
 173                 goto out;
 174         }
 175         ls1x_cpufreq.pll_clk = clk;
 176
 177         clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
 178         if (IS_ERR(clk)) {
 179                 dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n",
 180                         pdata->osc_clk_name);
 181                 ret = PTR_ERR(clk);
 182                 goto out;
 183         }
 184         ls1x_cpufreq.osc_clk = clk;
 185
 186         ls1x_cpufreq.max_freq = pdata->max_freq;
 187         ls1x_cpufreq.min_freq = pdata->min_freq;
 188
 189         ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
 190         if (ret) {
 191                 dev_err(ls1x_cpufreq.dev,
 192                         "failed to register cpufreq driver: %d\n", ret);
 193                 goto out;
 194         }
 195
 196         ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
 197                                         CPUFREQ_TRANSITION_NOTIFIER);
 198
 199         if (!ret)
 200                 goto out;
 201
 202         dev_err(ls1x_cpufreq.dev, "failed to register cpufreq notifier: %d\n",
 203                 ret);
 204
 205         cpufreq_unregister_driver(&ls1x_cpufreq_driver);
 206 out:
 207         return ret;
 208 }
 209
 210 static struct platform_driver ls1x_cpufreq_platdrv = {
 211         .driver = {
 212                 .name   = "ls1x-cpufreq",
 213         },
 214         .probe          = ls1x_cpufreq_probe,
 215         .remove         = ls1x_cpufreq_remove,
 216 };
 217
 218 module_platform_driver(ls1x_cpufreq_platdrv);
 219
 220 MODULE_ALIAS("platform:ls1x-cpufreq");
 221 MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
 222 MODULE_DESCRIPTION("Loongson 1 CPUFreq driver");
 223 MODULE_LICENSE("GPL");