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_device.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 int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
  59                             unsigned int index)
  60 {
  61         struct cpufreq_freqs freqs;
  62         unsigned int state = kirkwood_freq_table[index].driver_data;
  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         return 0;
 105 }
 106
 107 /* Module init and exit code */
 108 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
 109 {
 110         return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
 111 }
 112
 113 static struct cpufreq_driver kirkwood_cpufreq_driver = {
 114         .get    = kirkwood_cpufreq_get_cpu_frequency,
 115         .verify = cpufreq_generic_frequency_table_verify,
 116         .target_index = kirkwood_cpufreq_target,
 117         .init   = kirkwood_cpufreq_cpu_init,
 118         .exit   = cpufreq_generic_exit,
 119         .name   = "kirkwood-cpufreq",
 120         .attr   = cpufreq_generic_attr,
 121 };
 122
 123 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
 124 {
 125         struct device_node *np;
 126         struct resource *res;
 127         int err;
 128
 129         priv.dev = &pdev->dev;
 130
 131         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 132         priv.base = devm_ioremap_resource(&pdev->dev, res);
 133         if (IS_ERR(priv.base))
 134                 return PTR_ERR(priv.base);
 135
 136         np = of_cpu_device_node_get(0);
 137         if (!np) {
 138                 dev_err(&pdev->dev, "failed to get cpu device node\n");
 139                 return -ENODEV;
 140         }
 141
 142         priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
 143         if (IS_ERR(priv.cpu_clk)) {
 144                 dev_err(priv.dev, "Unable to get cpuclk");
 145                 return PTR_ERR(priv.cpu_clk);
 146         }
 147
 148         clk_prepare_enable(priv.cpu_clk);
 149         kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
 150
 151         priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
 152         if (IS_ERR(priv.ddr_clk)) {
 153                 dev_err(priv.dev, "Unable to get ddrclk");
 154                 err = PTR_ERR(priv.ddr_clk);
 155                 goto out_cpu;
 156         }
 157
 158         clk_prepare_enable(priv.ddr_clk);
 159         kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
 160
 161         priv.powersave_clk = of_clk_get_by_name(np, "powersave");
 162         if (IS_ERR(priv.powersave_clk)) {
 163                 dev_err(priv.dev, "Unable to get powersave");
 164                 err = PTR_ERR(priv.powersave_clk);
 165                 goto out_ddr;
 166         }
 167         clk_prepare(priv.powersave_clk);
 168
 169         of_node_put(np);
 170         np = NULL;
 171
 172         err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
 173         if (!err)
 174                 return 0;
 175
 176         dev_err(priv.dev, "Failed to register cpufreq driver");
 177
 178         clk_disable_unprepare(priv.powersave_clk);
 179 out_ddr:
 180         clk_disable_unprepare(priv.ddr_clk);
 181 out_cpu:
 182         clk_disable_unprepare(priv.cpu_clk);
 183         of_node_put(np);
 184
 185         return err;
 186 }
 187
 188 static int kirkwood_cpufreq_remove(struct platform_device *pdev)
 189 {
 190         cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
 191
 192         clk_disable_unprepare(priv.powersave_clk);
 193         clk_disable_unprepare(priv.ddr_clk);
 194         clk_disable_unprepare(priv.cpu_clk);
 195
 196         return 0;
 197 }
 198
 199 static struct platform_driver kirkwood_cpufreq_platform_driver = {
 200         .probe = kirkwood_cpufreq_probe,
 201         .remove = kirkwood_cpufreq_remove,
 202         .driver = {
 203                 .name = "kirkwood-cpufreq",
 204                 .owner = THIS_MODULE,
 205         },
 206 };
 207
 208 module_platform_driver(kirkwood_cpufreq_platform_driver);
 209
 210 MODULE_LICENSE("GPL v2");
 211 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
 212 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
 213 MODULE_ALIAS("platform:kirkwood-cpufreq");