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         unsigned int state = kirkwood_freq_table[index].driver_data;
  62         unsigned long reg;
  63
  64         local_irq_disable();
  65
  66         /* Disable interrupts to the CPU */
  67         reg = readl_relaxed(priv.base);
  68         reg |= CPU_SW_INT_BLK;
  69         writel_relaxed(reg, priv.base);
  70
  71         switch (state) {
  72         case STATE_CPU_FREQ:
  73                 clk_disable(priv.powersave_clk);
  74                 break;
  75         case STATE_DDR_FREQ:
  76                 clk_enable(priv.powersave_clk);
  77                 break;
  78         }
  79
  80         /* Wait-for-Interrupt, while the hardware changes frequency */
  81         cpu_do_idle();
  82
  83         /* Enable interrupts to the CPU */
  84         reg = readl_relaxed(priv.base);
  85         reg &= ~CPU_SW_INT_BLK;
  86         writel_relaxed(reg, priv.base);
  87
  88         local_irq_enable();
  89
  90         return 0;
  91 }
  92
  93 /* Module init and exit code */
  94 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
  95 {
  96         return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
  97 }
  98
  99 static struct cpufreq_driver kirkwood_cpufreq_driver = {
 100         .flags  = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 101         .get    = kirkwood_cpufreq_get_cpu_frequency,
 102         .verify = cpufreq_generic_frequency_table_verify,
 103         .target_index = kirkwood_cpufreq_target,
 104         .init   = kirkwood_cpufreq_cpu_init,
 105         .exit   = cpufreq_generic_exit,
 106         .name   = "kirkwood-cpufreq",
 107         .attr   = cpufreq_generic_attr,
 108 };
 109
 110 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
 111 {
 112         struct device_node *np;
 113         struct resource *res;
 114         int err;
 115
 116         priv.dev = &pdev->dev;
 117
 118         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 119         priv.base = devm_ioremap_resource(&pdev->dev, res);
 120         if (IS_ERR(priv.base))
 121                 return PTR_ERR(priv.base);
 122
 123         np = of_cpu_device_node_get(0);
 124         if (!np) {
 125                 dev_err(&pdev->dev, "failed to get cpu device node\n");
 126                 return -ENODEV;
 127         }
 128
 129         priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
 130         if (IS_ERR(priv.cpu_clk)) {
 131                 dev_err(priv.dev, "Unable to get cpuclk");
 132                 return PTR_ERR(priv.cpu_clk);
 133         }
 134
 135         clk_prepare_enable(priv.cpu_clk);
 136         kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
 137
 138         priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
 139         if (IS_ERR(priv.ddr_clk)) {
 140                 dev_err(priv.dev, "Unable to get ddrclk");
 141                 err = PTR_ERR(priv.ddr_clk);
 142                 goto out_cpu;
 143         }
 144
 145         clk_prepare_enable(priv.ddr_clk);
 146         kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
 147
 148         priv.powersave_clk = of_clk_get_by_name(np, "powersave");
 149         if (IS_ERR(priv.powersave_clk)) {
 150                 dev_err(priv.dev, "Unable to get powersave");
 151                 err = PTR_ERR(priv.powersave_clk);
 152                 goto out_ddr;
 153         }
 154         clk_prepare(priv.powersave_clk);
 155
 156         of_node_put(np);
 157         np = NULL;
 158
 159         err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
 160         if (!err)
 161                 return 0;
 162
 163         dev_err(priv.dev, "Failed to register cpufreq driver");
 164
 165         clk_disable_unprepare(priv.powersave_clk);
 166 out_ddr:
 167         clk_disable_unprepare(priv.ddr_clk);
 168 out_cpu:
 169         clk_disable_unprepare(priv.cpu_clk);
 170         of_node_put(np);
 171
 172         return err;
 173 }
 174
 175 static int kirkwood_cpufreq_remove(struct platform_device *pdev)
 176 {
 177         cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
 178
 179         clk_disable_unprepare(priv.powersave_clk);
 180         clk_disable_unprepare(priv.ddr_clk);
 181         clk_disable_unprepare(priv.cpu_clk);
 182
 183         return 0;
 184 }
 185
 186 static struct platform_driver kirkwood_cpufreq_platform_driver = {
 187         .probe = kirkwood_cpufreq_probe,
 188         .remove = kirkwood_cpufreq_remove,
 189         .driver = {
 190                 .name = "kirkwood-cpufreq",
 191                 .owner = THIS_MODULE,
 192         },
 193 };
 194
 195 module_platform_driver(kirkwood_cpufreq_platform_driver);
 196
 197 MODULE_LICENSE("GPL v2");
 198 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
 199 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
 200 MODULE_ALIAS("platform:kirkwood-cpufreq");