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/cpufreq.h>
  16 #include <linux/of_device.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/io.h>
  19 #include <asm/proc-fns.h>
  20
  21 #define CPU_SW_INT_BLK BIT(28)
  22
  23 static struct priv
  24 {
  25         struct clk *cpu_clk;
  26         struct clk *ddr_clk;
  27         struct clk *powersave_clk;
  28         struct device *dev;
  29         void __iomem *base;
  30 } priv;
  31
  32 #define STATE_CPU_FREQ 0x01
  33 #define STATE_DDR_FREQ 0x02
  34
  35 /*
  36  * Kirkwood can swap the clock to the CPU between two clocks:
  37  *
  38  * - cpu clk
  39  * - ddr clk
  40  *
  41  * The frequencies are set at runtime before registering this table.
  42  */
  43 static struct cpufreq_frequency_table kirkwood_freq_table[] = {
  44         {0, STATE_CPU_FREQ,     0}, /* CPU uses cpuclk */
  45         {0, STATE_DDR_FREQ,     0}, /* CPU uses ddrclk */
  46         {0, 0,                  CPUFREQ_TABLE_END},
  47 };
  48
  49 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
  50 {
  51         return clk_get_rate(priv.powersave_clk) / 1000;
  52 }
  53
  54 static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
  55                             unsigned int index)
  56 {
  57         unsigned int state = kirkwood_freq_table[index].driver_data;
  58         unsigned long reg;
  59
  60         local_irq_disable();
  61
  62         /* Disable interrupts to the CPU */
  63         reg = readl_relaxed(priv.base);
  64         reg |= CPU_SW_INT_BLK;
  65         writel_relaxed(reg, priv.base);
  66
  67         switch (state) {
  68         case STATE_CPU_FREQ:
  69                 clk_set_parent(priv.powersave_clk, priv.cpu_clk);
  70                 break;
  71         case STATE_DDR_FREQ:
  72                 clk_set_parent(priv.powersave_clk, priv.ddr_clk);
  73                 break;
  74         }
  75
  76         /* Wait-for-Interrupt, while the hardware changes frequency */
  77         cpu_do_idle();
  78
  79         /* Enable interrupts to the CPU */
  80         reg = readl_relaxed(priv.base);
  81         reg &= ~CPU_SW_INT_BLK;
  82         writel_relaxed(reg, priv.base);
  83
  84         local_irq_enable();
  85
  86         return 0;
  87 }
  88
  89 /* Module init and exit code */
  90 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
  91 {
  92         return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
  93 }
  94
  95 static struct cpufreq_driver kirkwood_cpufreq_driver = {
  96         .flags  = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
  97         .get    = kirkwood_cpufreq_get_cpu_frequency,
  98         .verify = cpufreq_generic_frequency_table_verify,
  99         .target_index = kirkwood_cpufreq_target,
 100         .init   = kirkwood_cpufreq_cpu_init,
 101         .name   = "kirkwood-cpufreq",
 102         .attr   = cpufreq_generic_attr,
 103 };
 104
 105 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
 106 {
 107         struct device_node *np;
 108         struct resource *res;
 109         int err;
 110
 111         priv.dev = &pdev->dev;
 112
 113         res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 114         priv.base = devm_ioremap_resource(&pdev->dev, res);
 115         if (IS_ERR(priv.base))
 116                 return PTR_ERR(priv.base);
 117
 118         np = of_cpu_device_node_get(0);
 119         if (!np) {
 120                 dev_err(&pdev->dev, "failed to get cpu device node\n");
 121                 return -ENODEV;
 122         }
 123
 124         priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
 125         if (IS_ERR(priv.cpu_clk)) {
 126                 dev_err(priv.dev, "Unable to get cpuclk");
 127                 return PTR_ERR(priv.cpu_clk);
 128         }
 129
 130         clk_prepare_enable(priv.cpu_clk);
 131         kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
 132
 133         priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
 134         if (IS_ERR(priv.ddr_clk)) {
 135                 dev_err(priv.dev, "Unable to get ddrclk");
 136                 err = PTR_ERR(priv.ddr_clk);
 137                 goto out_cpu;
 138         }
 139
 140         clk_prepare_enable(priv.ddr_clk);
 141         kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
 142
 143         priv.powersave_clk = of_clk_get_by_name(np, "powersave");
 144         if (IS_ERR(priv.powersave_clk)) {
 145                 dev_err(priv.dev, "Unable to get powersave");
 146                 err = PTR_ERR(priv.powersave_clk);
 147                 goto out_ddr;
 148         }
 149         clk_prepare_enable(priv.powersave_clk);
 150
 151         of_node_put(np);
 152         np = NULL;
 153
 154         err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
 155         if (!err)
 156                 return 0;
 157
 158         dev_err(priv.dev, "Failed to register cpufreq driver");
 159
 160         clk_disable_unprepare(priv.powersave_clk);
 161 out_ddr:
 162         clk_disable_unprepare(priv.ddr_clk);
 163 out_cpu:
 164         clk_disable_unprepare(priv.cpu_clk);
 165         of_node_put(np);
 166
 167         return err;
 168 }
 169
 170 static int kirkwood_cpufreq_remove(struct platform_device *pdev)
 171 {
 172         cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
 173
 174         clk_disable_unprepare(priv.powersave_clk);
 175         clk_disable_unprepare(priv.ddr_clk);
 176         clk_disable_unprepare(priv.cpu_clk);
 177
 178         return 0;
 179 }
 180
 181 static struct platform_driver kirkwood_cpufreq_platform_driver = {
 182         .probe = kirkwood_cpufreq_probe,
 183         .remove = kirkwood_cpufreq_remove,
 184         .driver = {
 185                 .name = "kirkwood-cpufreq",
 186         },
 187 };
 188
 189 module_platform_driver(kirkwood_cpufreq_platform_driver);
 190
 191 MODULE_LICENSE("GPL v2");
 192 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
 193 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
 194 MODULE_ALIAS("platform:kirkwood-cpufreq");