drivers/cpufreq/highbank-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 2012 Calxeda, Inc.
   4  *
   5  * This driver provides the clk notifier callbacks that are used when
   6  * the cpufreq-dt driver changes to frequency to alert the highbank
   7  * EnergyCore Management Engine (ECME) about the need to change
   8  * voltage. The ECME interfaces with the actual voltage regulators.
   9  */
  10
  11 #define pr_fmt(fmt)     KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/kernel.h>
  14 #include <linux/module.h>
  15 #include <linux/clk.h>
  16 #include <linux/cpu.h>
  17 #include <linux/err.h>
  18 #include <linux/of.h>
  19 #include <linux/pl320-ipc.h>
  20 #include <linux/platform_device.h>
  21
  22 #define HB_CPUFREQ_CHANGE_NOTE  0x80000001
  23 #define HB_CPUFREQ_IPC_LEN      7
  24 #define HB_CPUFREQ_VOLT_RETRIES 15
  25
  26 static int hb_voltage_change(unsigned int freq)
  27 {
  28         u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};
  29
  30         return pl320_ipc_transmit(msg);
  31 }
  32
  33 static int hb_cpufreq_clk_notify(struct notifier_block *nb,
  34                                 unsigned long action, void *hclk)
  35 {
  36         struct clk_notifier_data *clk_data = hclk;
  37         int i = 0;
  38
  39         if (action == PRE_RATE_CHANGE) {
  40                 if (clk_data->new_rate > clk_data->old_rate)
  41                         while (hb_voltage_change(clk_data->new_rate))
  42                                 if (i++ > HB_CPUFREQ_VOLT_RETRIES)
  43                                         return NOTIFY_BAD;
  44         } else if (action == POST_RATE_CHANGE) {
  45                 if (clk_data->new_rate < clk_data->old_rate)
  46                         while (hb_voltage_change(clk_data->new_rate))
  47                                 if (i++ > HB_CPUFREQ_VOLT_RETRIES)
  48                                         return NOTIFY_BAD;
  49         }
  50
  51         return NOTIFY_DONE;
  52 }
  53
  54 static struct notifier_block hb_cpufreq_clk_nb = {
  55         .notifier_call = hb_cpufreq_clk_notify,
  56 };
  57
  58 static int hb_cpufreq_driver_init(void)
  59 {
  60         struct platform_device_info devinfo = { .name = "cpufreq-dt", };
  61         struct device *cpu_dev;
  62         struct clk *cpu_clk;
  63         struct device_node *np;
  64         int ret;
  65
  66         if ((!of_machine_is_compatible("calxeda,highbank")) &&
  67                 (!of_machine_is_compatible("calxeda,ecx-2000")))
  68                 return -ENODEV;
  69
  70         cpu_dev = get_cpu_device(0);
  71         if (!cpu_dev) {
  72                 pr_err("failed to get highbank cpufreq device\n");
  73                 return -ENODEV;
  74         }
  75
  76         np = of_node_get(cpu_dev->of_node);
  77         if (!np) {
  78                 pr_err("failed to find highbank cpufreq node\n");
  79                 return -ENOENT;
  80         }
  81
  82         cpu_clk = clk_get(cpu_dev, NULL);
  83         if (IS_ERR(cpu_clk)) {
  84                 ret = PTR_ERR(cpu_clk);
  85                 pr_err("failed to get cpu0 clock: %d\n", ret);
  86                 goto out_put_node;
  87         }
  88
  89         ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
  90         if (ret) {
  91                 pr_err("failed to register clk notifier: %d\n", ret);
  92                 goto out_put_node;
  93         }
  94
  95         /* Instantiate cpufreq-dt */
  96         platform_device_register_full(&devinfo);
  97
  98 out_put_node:
  99         of_node_put(np);
 100         return ret;
 101 }
 102 module_init(hb_cpufreq_driver_init);
 103
 104 MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
 105 MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
 106 MODULE_LICENSE("GPL");