| /* |
| * 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; |
| |
| for_each_child_of_node(of_find_node_by_path("/cpus"), np) |
| if (of_get_property(np, "operating-points", NULL)) |
| break; |
| |
| if (!np) { |
| pr_err("failed to find highbank cpufreq node\n"); |
| return -ENOENT; |
| } |
| |
| cpu_dev = get_cpu_device(0); |
| if (!cpu_dev) { |
| pr_err("failed to get highbank cpufreq device\n"); |
| ret = -ENODEV; |
| goto out_put_node; |
| } |
| |
| cpu_dev->of_node = np; |
| |
| 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"); |