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 static const struct of_device_id __maybe_unused hb_cpufreq_of_match[] = { 105 { .compatible = "calxeda,highbank" }, 106 { .compatible = "calxeda,ecx-2000" }, 107 { }, 108 }; 109 MODULE_DEVICE_TABLE(of, hb_cpufreq_of_match); 110 111 MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>"); 112 MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver"); 113 MODULE_LICENSE("GPL"); 114