drivers/cpufreq/kirkwood-cpufreq.c

   1 /*
   2  *      kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
   3  *
   4  *      Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
   5  *
   6  *      This program is free software; you can redistribute it and/or
   7  *      modify it under the terms of the GNU General Public License
   8  *      as published by the Free Software Foundation; either version
   9  *      2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/kernel.h>
  13 #include <linux/module.h>
  14 #include <linux/clk.h>
  15 #include <linux/clk-provider.h>
  16 #include <linux/cpufreq.h>
  17 #include <linux/of.h>
  18 #include <linux/platform_device.h>
  19 #include <linux/io.h>
  20 #include <asm/proc-fns.h>
  21
  22 #define CPU_SW_INT_BLK BIT(28)
  23
  24 static struct priv
  25 {
  26         struct clk *cpu_clk;
  27         struct clk *ddr_clk;
  28         struct clk *powersave_clk;
  29         struct device *dev;
  30         void __iomem *base;
  31 } priv;
  32
  33 #define STATE_CPU_FREQ 0x01
  34 #define STATE_DDR_FREQ 0x02
  35
  36 /*
  37  * Kirkwood can swap the clock to the CPU between two clocks:
  38  *
  39  * - cpu clk
  40  * - ddr clk
  41  *
  42  * The frequencies are set at runtime before registering this *
  43  * table.
  44  */
  45 static struct cpufreq_frequency_table kirkwood_freq_table[] = {
  46         {STATE_CPU_FREQ,        0}, /* CPU uses cpuclk */
  47         {STATE_DDR_FREQ,        0}, /* CPU uses ddrclk */
  48         {0,                     CPUFREQ_TABLE_END},
  49 };
  50
  51 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
  52 {
  53         if (__clk_is_enabled(priv.powersave_clk))
  54                 return kirkwood_freq_table[1].frequency;
  55         return kirkwood_freq_table[0].frequency;
  56 }
  57
  58 static void kirkwood_cpufreq_set_cpu_state(struct cpufreq_policy *policy,
  59                 unsigned int index)
  60 {
  61         struct cpufreq_freqs freqs;
  62         unsigned int state = kirkwood_freq_table[index].index;
  63         unsigned long reg;
  64
  65         freqs.old = kirkwood_cpufreq_get_cpu_frequency(0);
  66         freqs.new = kirkwood_freq_table[index].frequency;
  67
  68         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  69
  70         dev_dbg(priv.dev, "Attempting to set frequency to %i KHz\n",
  71                 kirkwood_freq_table[index].frequency);
  72         dev_dbg(priv.dev, "old frequency was %i KHz\n",
  73                 kirkwood_cpufreq_get_cpu_frequency(0));
  74
  75         if (freqs.old != freqs.new) {
  76                 local_irq_disable();
  77
  78                 /* Disable interrupts to the CPU */
  79                 reg = readl_relaxed(priv.base);
  80                 reg |= CPU_SW_INT_BLK;
  81                 writel_relaxed(reg, priv.base);
  82
  83                 switch (state) {
  84                 case STATE_CPU_FREQ:
  85                         clk_disable(priv.powersave_clk);
  86                         break;
  87                 case STATE_DDR_FREQ:
  88                         clk_enable(priv.powersave_clk);
  89                         break;
  90                 }
  91
  92                 /* Wait-for-Interrupt, while the hardware changes frequency */
  93                 cpu_do_idle();
  94
  95                 /* Enable interrupts to the CPU */
  96                 reg = readl_relaxed(priv.base);
  97                 reg &= ~CPU_SW_INT_BLK;
  98                 writel_relaxed(reg, priv.base);
  99
 100                 local_irq_enable();
 101         }
 102         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 103 };
 104
 105 static int kirkwood_cpufreq_verify(struct cpufreq_policy *policy)
 106 {
 107         return cpufreq_frequency_table_verify(policy, kirkwood_freq_table);
 108 }
 109
 110 static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
 111                             unsigned int target_freq,
 112                             unsigned int relation)
 113 {
 114         unsigned int index = 0;
 115
 116         if (cpufreq_frequency_table_target(policy, kirkwood_freq_table,
 117                                 target_freq, relation, &index))
 118                 return -EINVAL;
 119
 120         kirkwood_cpufreq_set_cpu_state(policy, index);
 121
 122         return 0;
 123 }
 124
 125 /* Module init and exit code */
 126 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
 127 {
 128         int result;
 129
 130         /* cpuinfo and default policy values */
 131         policy->cpuinfo.transition_latency = 5000; /* 5uS */
 132         policy->cur = kirkwood_cpufreq_get_cpu_frequency(0);
 133
 134         result = cpufreq_frequency_table_cpuinfo(policy, kirkwood_freq_table);
 135         if (result)
 136                 return result;
 137
 138         cpufreq_frequency_table_get_attr(kirkwood_freq_table, policy->cpu);
 139
 140         return 0;
 141 }
 142
 143 static int kirkwood_cpufreq_cpu_exit(struct cpufreq_policy *policy)
 144 {
 145         cpufreq_frequency_table_put_attr(policy->cpu);
 146         return 0;
 147 }
 148
 149 static struct freq_attr *kirkwood_cpufreq_attr[] = {
 150         &cpufreq_freq_attr_scaling_available_freqs,
 151         NULL,
 152 };
 153
 154 static struct cpufreq_driver kirkwood_cpufreq_driver = {
 155         .get    = kirkwood_cpufreq_get_cpu_frequency,
 156         .verify = kirkwood_cpufreq_verify,
 157         .target = kirkwood_cpufreq_target,
 158         .init   = kirkwood_cpufreq_cpu_init,
 159         .exit   = kirkwood_cpufreq_cpu_exit,
 160         .name   = "kirkwood-cpufreq",
 161         .owner  = THIS_MODULE,
 162         .attr   = kirkwood_cpufreq_attr,
 163 };
 164
 165 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
 166 {
 167         struct device_node *np;
 168         struct resource *res;
 169         int err;
 170
 171         priv.dev = &pdev->dev;
 172
 173         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 174         priv.base = devm_ioremap_resource(&pdev->dev, res);
 175         if (IS_ERR(priv.base))
 176                 return PTR_ERR(priv.base);
 177
 178         np = of_find_node_by_path("/cpus/cpu@0");
 179         if (!np)
 180                 return -ENODEV;
 181
 182         priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
 183         if (IS_ERR(priv.cpu_clk)) {
 184                 dev_err(priv.dev, "Unable to get cpuclk");
 185                 return PTR_ERR(priv.cpu_clk);
 186         }
 187
 188         clk_prepare_enable(priv.cpu_clk);
 189         kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
 190
 191         priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
 192         if (IS_ERR(priv.ddr_clk)) {
 193                 dev_err(priv.dev, "Unable to get ddrclk");
 194                 err = PTR_ERR(priv.ddr_clk);
 195                 goto out_cpu;
 196         }
 197
 198         clk_prepare_enable(priv.ddr_clk);
 199         kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
 200
 201         priv.powersave_clk = of_clk_get_by_name(np, "powersave");
 202         if (IS_ERR(priv.powersave_clk)) {
 203                 dev_err(priv.dev, "Unable to get powersave");
 204                 err = PTR_ERR(priv.powersave_clk);
 205                 goto out_ddr;
 206         }
 207         clk_prepare(priv.powersave_clk);
 208
 209         of_node_put(np);
 210         np = NULL;
 211
 212         err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
 213         if (!err)
 214                 return 0;
 215
 216         dev_err(priv.dev, "Failed to register cpufreq driver");
 217
 218         clk_disable_unprepare(priv.powersave_clk);
 219 out_ddr:
 220         clk_disable_unprepare(priv.ddr_clk);
 221 out_cpu:
 222         clk_disable_unprepare(priv.cpu_clk);
 223         of_node_put(np);
 224
 225         return err;
 226 }
 227
 228 static int kirkwood_cpufreq_remove(struct platform_device *pdev)
 229 {
 230         cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
 231
 232         clk_disable_unprepare(priv.powersave_clk);
 233         clk_disable_unprepare(priv.ddr_clk);
 234         clk_disable_unprepare(priv.cpu_clk);
 235
 236         return 0;
 237 }
 238
 239 static struct platform_driver kirkwood_cpufreq_platform_driver = {
 240         .probe = kirkwood_cpufreq_probe,
 241         .remove = kirkwood_cpufreq_remove,
 242         .driver = {
 243                 .name = "kirkwood-cpufreq",
 244                 .owner = THIS_MODULE,
 245         },
 246 };
 247
 248 module_platform_driver(kirkwood_cpufreq_platform_driver);
 249
 250 MODULE_LICENSE("GPL v2");
 251 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
 252 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
 253 MODULE_ALIAS("platform:kirkwood-cpufreq");