1 /* 2 * Copyright (C) 2012 Calxeda, Inc. 3 * 4 * This program is free software; you can redistribute it and/or modify 5 * it under the terms of the GNU General Public License version 2 as 6 * published by the Free Software Foundation. 7 * 8 * This driver provides the clk notifier callbacks that are used when 9 * the cpufreq-dt driver changes to frequency to alert the highbank 10 * EnergyCore Management Engine (ECME) about the need to change 11 * voltage. The ECME interfaces with the actual voltage regulators. 12 */ 13 14 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt 15 16 #include <linux/kernel.h> 17 #include <linux/module.h> 18 #include <linux/clk.h> 19 #include <linux/cpu.h> 20 #include <linux/err.h> 21 #include <linux/of.h> 22 #include <linux/pl320-ipc.h> 23 #include <linux/platform_device.h> 24 25 #define HB_CPUFREQ_CHANGE_NOTE 0x80000001 26 #define HB_CPUFREQ_IPC_LEN 7 27 #define HB_CPUFREQ_VOLT_RETRIES 15 28 29 static int hb_voltage_change(unsigned int freq) 30 { 31 u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000}; 32 33 return pl320_ipc_transmit(msg); 34 } 35 36 static int hb_cpufreq_clk_notify(struct notifier_block *nb, 37 unsigned long action, void *hclk) 38 { 39 struct clk_notifier_data *clk_data = hclk; 40 int i = 0; 41 42 if (action == PRE_RATE_CHANGE) { 43 if (clk_data->new_rate > clk_data->old_rate) 44 while (hb_voltage_change(clk_data->new_rate)) 45 if (i++ > HB_CPUFREQ_VOLT_RETRIES) 46 return NOTIFY_BAD; 47 } else if (action == POST_RATE_CHANGE) { 48 if (clk_data->new_rate < clk_data->old_rate) 49 while (hb_voltage_change(clk_data->new_rate)) 50 if (i++ > HB_CPUFREQ_VOLT_RETRIES) 51 return NOTIFY_BAD; 52 } 53 54 return NOTIFY_DONE; 55 } 56 57 static struct notifier_block hb_cpufreq_clk_nb = { 58 .notifier_call = hb_cpufreq_clk_notify, 59 }; 60 61 static int hb_cpufreq_driver_init(void) 62 { 63 struct platform_device_info devinfo = { .name = "cpufreq-dt", }; 64 struct device *cpu_dev; 65 struct clk *cpu_clk; 66 struct device_node *np; 67 int ret; 68 69 if ((!of_machine_is_compatible("calxeda,highbank")) && 70 (!of_machine_is_compatible("calxeda,ecx-2000"))) 71 return -ENODEV; 72 73 cpu_dev = get_cpu_device(0); 74 if (!cpu_dev) { 75 pr_err("failed to get highbank cpufreq device\n"); 76 return -ENODEV; 77 } 78 79 np = of_node_get(cpu_dev->of_node); 80 if (!np) { 81 pr_err("failed to find highbank cpufreq node\n"); 82 return -ENOENT; 83 } 84 85 cpu_clk = clk_get(cpu_dev, NULL); 86 if (IS_ERR(cpu_clk)) { 87 ret = PTR_ERR(cpu_clk); 88 pr_err("failed to get cpu0 clock: %d\n", ret); 89 goto out_put_node; 90 } 91 92 ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb); 93 if (ret) { 94 pr_err("failed to register clk notifier: %d\n", ret); 95 goto out_put_node; 96 } 97 98 /* Instantiate cpufreq-dt */ 99 platform_device_register_full(&devinfo); 100 101 out_put_node: 102 of_node_put(np); 103 return ret; 104 } 105 module_init(hb_cpufreq_driver_init); 106 107 MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>"); 108 MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver"); 109 MODULE_LICENSE("GPL"); 110