drivers/cpufreq/kirkwood-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  *      kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
   4  *
   5  *      Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
   6  */
   7
   8 #include <linux/kernel.h>
   9 #include <linux/module.h>
  10 #include <linux/clk.h>
  11 #include <linux/cpufreq.h>
  12 #include <linux/of_device.h>
  13 #include <linux/platform_device.h>
  14 #include <linux/io.h>
  15 #include <asm/proc-fns.h>
  16
  17 #define CPU_SW_INT_BLK BIT(28)
  18
  19 static struct priv
  20 {
  21         struct clk *cpu_clk;
  22         struct clk *ddr_clk;
  23         struct clk *powersave_clk;
  24         struct device *dev;
  25         void __iomem *base;
  26 } priv;
  27
  28 #define STATE_CPU_FREQ 0x01
  29 #define STATE_DDR_FREQ 0x02
  30
  31 /*
  32  * Kirkwood can swap the clock to the CPU between two clocks:
  33  *
  34  * - cpu clk
  35  * - ddr clk
  36  *
  37  * The frequencies are set at runtime before registering this table.
  38  */
  39 static struct cpufreq_frequency_table kirkwood_freq_table[] = {
  40         {0, STATE_CPU_FREQ,     0}, /* CPU uses cpuclk */
  41         {0, STATE_DDR_FREQ,     0}, /* CPU uses ddrclk */
  42         {0, 0,                  CPUFREQ_TABLE_END},
  43 };
  44
  45 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
  46 {
  47         return clk_get_rate(priv.powersave_clk) / 1000;
  48 }
  49
  50 static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
  51                             unsigned int index)
  52 {
  53         unsigned int state = kirkwood_freq_table[index].driver_data;
  54         unsigned long reg;
  55
  56         local_irq_disable();
  57
  58         /* Disable interrupts to the CPU */
  59         reg = readl_relaxed(priv.base);
  60         reg |= CPU_SW_INT_BLK;
  61         writel_relaxed(reg, priv.base);
  62
  63         switch (state) {
  64         case STATE_CPU_FREQ:
  65                 clk_set_parent(priv.powersave_clk, priv.cpu_clk);
  66                 break;
  67         case STATE_DDR_FREQ:
  68                 clk_set_parent(priv.powersave_clk, priv.ddr_clk);
  69                 break;
  70         }
  71
  72         /* Wait-for-Interrupt, while the hardware changes frequency */
  73         cpu_do_idle();
  74
  75         /* Enable interrupts to the CPU */
  76         reg = readl_relaxed(priv.base);
  77         reg &= ~CPU_SW_INT_BLK;
  78         writel_relaxed(reg, priv.base);
  79
  80         local_irq_enable();
  81
  82         return 0;
  83 }
  84
  85 /* Module init and exit code */
  86 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
  87 {
  88         cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
  89         return 0;
  90 }
  91
  92 static struct cpufreq_driver kirkwood_cpufreq_driver = {
  93         .flags  = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
  94         .get    = kirkwood_cpufreq_get_cpu_frequency,
  95         .verify = cpufreq_generic_frequency_table_verify,
  96         .target_index = kirkwood_cpufreq_target,
  97         .init   = kirkwood_cpufreq_cpu_init,
  98         .name   = "kirkwood-cpufreq",
  99         .attr   = cpufreq_generic_attr,
 100 };
 101
 102 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
 103 {
 104         struct device_node *np;
 105         int err;
 106
 107         priv.dev = &pdev->dev;
 108
 109         priv.base = devm_platform_ioremap_resource(pdev, 0);
 110         if (IS_ERR(priv.base))
 111                 return PTR_ERR(priv.base);
 112
 113         np = of_cpu_device_node_get(0);
 114         if (!np) {
 115                 dev_err(&pdev->dev, "failed to get cpu device node\n");
 116                 return -ENODEV;
 117         }
 118
 119         priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
 120         if (IS_ERR(priv.cpu_clk)) {
 121                 dev_err(priv.dev, "Unable to get cpuclk\n");
 122                 err = PTR_ERR(priv.cpu_clk);
 123                 goto out_node;
 124         }
 125
 126         err = clk_prepare_enable(priv.cpu_clk);
 127         if (err) {
 128                 dev_err(priv.dev, "Unable to prepare cpuclk\n");
 129                 goto out_node;
 130         }
 131
 132         kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
 133
 134         priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
 135         if (IS_ERR(priv.ddr_clk)) {
 136                 dev_err(priv.dev, "Unable to get ddrclk\n");
 137                 err = PTR_ERR(priv.ddr_clk);
 138                 goto out_cpu;
 139         }
 140
 141         err = clk_prepare_enable(priv.ddr_clk);
 142         if (err) {
 143                 dev_err(priv.dev, "Unable to prepare ddrclk\n");
 144                 goto out_cpu;
 145         }
 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\n");
 151                 err = PTR_ERR(priv.powersave_clk);
 152                 goto out_ddr;
 153         }
 154         err = clk_prepare_enable(priv.powersave_clk);
 155         if (err) {
 156                 dev_err(priv.dev, "Unable to prepare powersave clk\n");
 157                 goto out_ddr;
 158         }
 159
 160         err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
 161         if (err) {
 162                 dev_err(priv.dev, "Failed to register cpufreq driver\n");
 163                 goto out_powersave;
 164         }
 165
 166         of_node_put(np);
 167         return 0;
 168
 169 out_powersave:
 170         clk_disable_unprepare(priv.powersave_clk);
 171 out_ddr:
 172         clk_disable_unprepare(priv.ddr_clk);
 173 out_cpu:
 174         clk_disable_unprepare(priv.cpu_clk);
 175 out_node:
 176         of_node_put(np);
 177
 178         return err;
 179 }
 180
 181 static int kirkwood_cpufreq_remove(struct platform_device *pdev)
 182 {
 183         cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
 184
 185         clk_disable_unprepare(priv.powersave_clk);
 186         clk_disable_unprepare(priv.ddr_clk);
 187         clk_disable_unprepare(priv.cpu_clk);
 188
 189         return 0;
 190 }
 191
 192 static struct platform_driver kirkwood_cpufreq_platform_driver = {
 193         .probe = kirkwood_cpufreq_probe,
 194         .remove = kirkwood_cpufreq_remove,
 195         .driver = {
 196                 .name = "kirkwood-cpufreq",
 197         },
 198 };
 199
 200 module_platform_driver(kirkwood_cpufreq_platform_driver);
 201
 202 MODULE_LICENSE("GPL v2");
 203 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
 204 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
 205 MODULE_ALIAS("platform:kirkwood-cpufreq");