drivers/cpufreq/tegra20-cpufreq.c

   1 /*
   2  * Copyright (C) 2010 Google, Inc.
   3  *
   4  * Author:
   5  *      Colin Cross <ccross@google.com>
   6  *      Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
   7  *
   8  * This software is licensed under the terms of the GNU General Public
   9  * License version 2, as published by the Free Software Foundation, and
  10  * may be copied, distributed, and modified under those terms.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  */
  18
  19 #include <linux/clk.h>
  20 #include <linux/cpufreq.h>
  21 #include <linux/err.h>
  22 #include <linux/init.h>
  23 #include <linux/module.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/types.h>
  26
  27 static struct cpufreq_frequency_table freq_table[] = {
  28         { .frequency = 216000 },
  29         { .frequency = 312000 },
  30         { .frequency = 456000 },
  31         { .frequency = 608000 },
  32         { .frequency = 760000 },
  33         { .frequency = 816000 },
  34         { .frequency = 912000 },
  35         { .frequency = 1000000 },
  36         { .frequency = CPUFREQ_TABLE_END },
  37 };
  38
  39 struct tegra20_cpufreq {
  40         struct device *dev;
  41         struct cpufreq_driver driver;
  42         struct clk *cpu_clk;
  43         struct clk *pll_x_clk;
  44         struct clk *pll_p_clk;
  45         bool pll_x_prepared;
  46 };
  47
  48 static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
  49                                            unsigned int index)
  50 {
  51         struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
  52         unsigned int ifreq = clk_get_rate(cpufreq->pll_p_clk) / 1000;
  53
  54         /*
  55          * Don't switch to intermediate freq if:
  56          * - we are already at it, i.e. policy->cur == ifreq
  57          * - index corresponds to ifreq
  58          */
  59         if (freq_table[index].frequency == ifreq || policy->cur == ifreq)
  60                 return 0;
  61
  62         return ifreq;
  63 }
  64
  65 static int tegra_target_intermediate(struct cpufreq_policy *policy,
  66                                      unsigned int index)
  67 {
  68         struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
  69         int ret;
  70
  71         /*
  72          * Take an extra reference to the main pll so it doesn't turn
  73          * off when we move the cpu off of it as enabling it again while we
  74          * switch to it from tegra_target() would take additional time.
  75          *
  76          * When target-freq is equal to intermediate freq we don't need to
  77          * switch to an intermediate freq and so this routine isn't called.
  78          * Also, we wouldn't be using pll_x anymore and must not take extra
  79          * reference to it, as it can be disabled now to save some power.
  80          */
  81         clk_prepare_enable(cpufreq->pll_x_clk);
  82
  83         ret = clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_p_clk);
  84         if (ret)
  85                 clk_disable_unprepare(cpufreq->pll_x_clk);
  86         else
  87                 cpufreq->pll_x_prepared = true;
  88
  89         return ret;
  90 }
  91
  92 static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
  93 {
  94         struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
  95         unsigned long rate = freq_table[index].frequency;
  96         unsigned int ifreq = clk_get_rate(cpufreq->pll_p_clk) / 1000;
  97         int ret;
  98
  99         /*
 100          * target freq == pll_p, don't need to take extra reference to pll_x_clk
 101          * as it isn't used anymore.
 102          */
 103         if (rate == ifreq)
 104                 return clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_p_clk);
 105
 106         ret = clk_set_rate(cpufreq->pll_x_clk, rate * 1000);
 107         /* Restore to earlier frequency on error, i.e. pll_x */
 108         if (ret)
 109                 dev_err(cpufreq->dev, "Failed to change pll_x to %lu\n", rate);
 110
 111         ret = clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_x_clk);
 112         /* This shouldn't fail while changing or restoring */
 113         WARN_ON(ret);
 114
 115         /*
 116          * Drop count to pll_x clock only if we switched to intermediate freq
 117          * earlier while transitioning to a target frequency.
 118          */
 119         if (cpufreq->pll_x_prepared) {
 120                 clk_disable_unprepare(cpufreq->pll_x_clk);
 121                 cpufreq->pll_x_prepared = false;
 122         }
 123
 124         return ret;
 125 }
 126
 127 static int tegra_cpu_init(struct cpufreq_policy *policy)
 128 {
 129         struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
 130         int ret;
 131
 132         clk_prepare_enable(cpufreq->cpu_clk);
 133
 134         /* FIXME: what's the actual transition time? */
 135         ret = cpufreq_generic_init(policy, freq_table, 300 * 1000);
 136         if (ret) {
 137                 clk_disable_unprepare(cpufreq->cpu_clk);
 138                 return ret;
 139         }
 140
 141         policy->clk = cpufreq->cpu_clk;
 142         policy->suspend_freq = freq_table[0].frequency;
 143         return 0;
 144 }
 145
 146 static int tegra_cpu_exit(struct cpufreq_policy *policy)
 147 {
 148         struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
 149
 150         clk_disable_unprepare(cpufreq->cpu_clk);
 151         return 0;
 152 }
 153
 154 static int tegra20_cpufreq_probe(struct platform_device *pdev)
 155 {
 156         struct tegra20_cpufreq *cpufreq;
 157         int err;
 158
 159         cpufreq = devm_kzalloc(&pdev->dev, sizeof(*cpufreq), GFP_KERNEL);
 160         if (!cpufreq)
 161                 return -ENOMEM;
 162
 163         cpufreq->cpu_clk = clk_get_sys(NULL, "cclk");
 164         if (IS_ERR(cpufreq->cpu_clk))
 165                 return PTR_ERR(cpufreq->cpu_clk);
 166
 167         cpufreq->pll_x_clk = clk_get_sys(NULL, "pll_x");
 168         if (IS_ERR(cpufreq->pll_x_clk)) {
 169                 err = PTR_ERR(cpufreq->pll_x_clk);
 170                 goto put_cpu;
 171         }
 172
 173         cpufreq->pll_p_clk = clk_get_sys(NULL, "pll_p");
 174         if (IS_ERR(cpufreq->pll_p_clk)) {
 175                 err = PTR_ERR(cpufreq->pll_p_clk);
 176                 goto put_pll_x;
 177         }
 178
 179         cpufreq->dev = &pdev->dev;
 180         cpufreq->driver.get = cpufreq_generic_get;
 181         cpufreq->driver.attr = cpufreq_generic_attr;
 182         cpufreq->driver.init = tegra_cpu_init;
 183         cpufreq->driver.exit = tegra_cpu_exit;
 184         cpufreq->driver.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK;
 185         cpufreq->driver.verify = cpufreq_generic_frequency_table_verify;
 186         cpufreq->driver.suspend = cpufreq_generic_suspend;
 187         cpufreq->driver.driver_data = cpufreq;
 188         cpufreq->driver.target_index = tegra_target;
 189         cpufreq->driver.get_intermediate = tegra_get_intermediate;
 190         cpufreq->driver.target_intermediate = tegra_target_intermediate;
 191         snprintf(cpufreq->driver.name, CPUFREQ_NAME_LEN, "tegra");
 192
 193         err = cpufreq_register_driver(&cpufreq->driver);
 194         if (err)
 195                 goto put_pll_p;
 196
 197         platform_set_drvdata(pdev, cpufreq);
 198
 199         return 0;
 200
 201 put_pll_p:
 202         clk_put(cpufreq->pll_p_clk);
 203 put_pll_x:
 204         clk_put(cpufreq->pll_x_clk);
 205 put_cpu:
 206         clk_put(cpufreq->cpu_clk);
 207
 208         return err;
 209 }
 210
 211 static int tegra20_cpufreq_remove(struct platform_device *pdev)
 212 {
 213         struct tegra20_cpufreq *cpufreq = platform_get_drvdata(pdev);
 214
 215         cpufreq_unregister_driver(&cpufreq->driver);
 216
 217         clk_put(cpufreq->pll_p_clk);
 218         clk_put(cpufreq->pll_x_clk);
 219         clk_put(cpufreq->cpu_clk);
 220
 221         return 0;
 222 }
 223
 224 static struct platform_driver tegra20_cpufreq_driver = {
 225         .probe          = tegra20_cpufreq_probe,
 226         .remove         = tegra20_cpufreq_remove,
 227         .driver         = {
 228                 .name   = "tegra20-cpufreq",
 229         },
 230 };
 231 module_platform_driver(tegra20_cpufreq_driver);
 232
 233 MODULE_ALIAS("platform:tegra20-cpufreq");
 234 MODULE_AUTHOR("Colin Cross <ccross@android.com>");
 235 MODULE_DESCRIPTION("NVIDIA Tegra20 cpufreq driver");
 236 MODULE_LICENSE("GPL");