/* * Copyright (C) 2012 Calxeda, Inc. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 as * published by the Free Software Foundation. * * This driver provides the clk notifier callbacks that are used when * the cpufreq-cpu0 driver changes to frequency to alert the highbank * EnergyCore Management Engine (ECME) about the need to change * voltage. The ECME interfaces with the actual voltage regulators. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/kernel.h> #include <linux/module.h> #include <linux/clk.h> #include <linux/cpu.h> #include <linux/err.h> #include <linux/of.h> #include <linux/mailbox.h> #include <linux/platform_device.h> #define HB_CPUFREQ_CHANGE_NOTE 0x80000001 #define HB_CPUFREQ_IPC_LEN 7 #define HB_CPUFREQ_VOLT_RETRIES 15 static int hb_voltage_change(unsigned int freq) { u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000}; return pl320_ipc_transmit(msg); } static int hb_cpufreq_clk_notify(struct notifier_block *nb, unsigned long action, void *hclk) { struct clk_notifier_data *clk_data = hclk; int i = 0; if (action == PRE_RATE_CHANGE) { if (clk_data->new_rate > clk_data->old_rate) while (hb_voltage_change(clk_data->new_rate)) if (i++ > HB_CPUFREQ_VOLT_RETRIES) return NOTIFY_BAD; } else if (action == POST_RATE_CHANGE) { if (clk_data->new_rate < clk_data->old_rate) while (hb_voltage_change(clk_data->new_rate)) if (i++ > HB_CPUFREQ_VOLT_RETRIES) return NOTIFY_BAD; } return NOTIFY_DONE; } static struct notifier_block hb_cpufreq_clk_nb = { .notifier_call = hb_cpufreq_clk_notify, }; static int hb_cpufreq_driver_init(void) { struct platform_device_info devinfo = { .name = "cpufreq-cpu0", }; struct device *cpu_dev; struct clk *cpu_clk; struct device_node *np; int ret; if ((!of_machine_is_compatible("calxeda,highbank")) && (!of_machine_is_compatible("calxeda,ecx-2000"))) return -ENODEV; cpu_dev = get_cpu_device(0); if (!cpu_dev) { pr_err("failed to get highbank cpufreq device\n"); return -ENODEV; } np = of_node_get(cpu_dev->of_node); if (!np) { pr_err("failed to find highbank cpufreq node\n"); return -ENOENT; } cpu_clk = clk_get(cpu_dev, NULL); if (IS_ERR(cpu_clk)) { ret = PTR_ERR(cpu_clk); pr_err("failed to get cpu0 clock: %d\n", ret); goto out_put_node; } ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb); if (ret) { pr_err("failed to register clk notifier: %d\n", ret); goto out_put_node; } /* Instantiate cpufreq-cpu0 */ platform_device_register_full(&devinfo); out_put_node: of_node_put(np); return ret; } module_init(hb_cpufreq_driver_init); MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>"); MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver"); MODULE_LICENSE("GPL");