drivers/cpufreq/highbank-cpufreq.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (C) 2012 Calxeda, Inc.
0004  *
0005  * This driver provides the clk notifier callbacks that are used when
0006  * the cpufreq-dt driver changes to frequency to alert the highbank
0007  * EnergyCore Management Engine (ECME) about the need to change
0008  * voltage. The ECME interfaces with the actual voltage regulators.
0009  */
0010
0011 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0012
0013 #include <linux/kernel.h>
0014 #include <linux/module.h>
0015 #include <linux/clk.h>
0016 #include <linux/cpu.h>
0017 #include <linux/err.h>
0018 #include <linux/of.h>
0019 #include <linux/pl320-ipc.h>
0020 #include <linux/platform_device.h>
0021
0022 #define HB_CPUFREQ_CHANGE_NOTE  0x80000001
0023 #define HB_CPUFREQ_IPC_LEN  7
0024 #define HB_CPUFREQ_VOLT_RETRIES 15
0025
0026 static int hb_voltage_change(unsigned int freq)
0027 {
0028     u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};
0029
0030     return pl320_ipc_transmit(msg);
0031 }
0032
0033 static int hb_cpufreq_clk_notify(struct notifier_block *nb,
0034                 unsigned long action, void *hclk)
0035 {
0036     struct clk_notifier_data *clk_data = hclk;
0037     int i = 0;
0038
0039     if (action == PRE_RATE_CHANGE) {
0040         if (clk_data->new_rate > clk_data->old_rate)
0041             while (hb_voltage_change(clk_data->new_rate))
0042                 if (i++ > HB_CPUFREQ_VOLT_RETRIES)
0043                     return NOTIFY_BAD;
0044     } else if (action == POST_RATE_CHANGE) {
0045         if (clk_data->new_rate < clk_data->old_rate)
0046             while (hb_voltage_change(clk_data->new_rate))
0047                 if (i++ > HB_CPUFREQ_VOLT_RETRIES)
0048                     return NOTIFY_BAD;
0049     }
0050
0051     return NOTIFY_DONE;
0052 }
0053
0054 static struct notifier_block hb_cpufreq_clk_nb = {
0055     .notifier_call = hb_cpufreq_clk_notify,
0056 };
0057
0058 static int hb_cpufreq_driver_init(void)
0059 {
0060     struct platform_device_info devinfo = { .name = "cpufreq-dt", };
0061     struct device *cpu_dev;
0062     struct clk *cpu_clk;
0063     struct device_node *np;
0064     int ret;
0065
0066     if ((!of_machine_is_compatible("calxeda,highbank")) &&
0067         (!of_machine_is_compatible("calxeda,ecx-2000")))
0068         return -ENODEV;
0069
0070     cpu_dev = get_cpu_device(0);
0071     if (!cpu_dev) {
0072         pr_err("failed to get highbank cpufreq device\n");
0073         return -ENODEV;
0074     }
0075
0076     np = of_node_get(cpu_dev->of_node);
0077     if (!np) {
0078         pr_err("failed to find highbank cpufreq node\n");
0079         return -ENOENT;
0080     }
0081
0082     cpu_clk = clk_get(cpu_dev, NULL);
0083     if (IS_ERR(cpu_clk)) {
0084         ret = PTR_ERR(cpu_clk);
0085         pr_err("failed to get cpu0 clock: %d\n", ret);
0086         goto out_put_node;
0087     }
0088
0089     ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
0090     if (ret) {
0091         pr_err("failed to register clk notifier: %d\n", ret);
0092         goto out_put_node;
0093     }
0094
0095     /* Instantiate cpufreq-dt */
0096     platform_device_register_full(&devinfo);
0097
0098 out_put_node:
0099     of_node_put(np);
0100     return ret;
0101 }
0102 module_init(hb_cpufreq_driver_init);
0103
0104 static const struct of_device_id __maybe_unused hb_cpufreq_of_match[] = {
0105     { .compatible = "calxeda,highbank" },
0106     { .compatible = "calxeda,ecx-2000" },
0107     { },
0108 };
0109 MODULE_DEVICE_TABLE(of, hb_cpufreq_of_match);
0110
0111 MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
0112 MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
0113 MODULE_LICENSE("GPL");