110 lines
2.8 KiB
C
110 lines
2.8 KiB
C
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/*
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* Copyright (C) 2012 Calxeda, Inc.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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* This driver provides the clk notifier callbacks that are used when
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* the cpufreq-dt driver changes to frequency to alert the highbank
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* EnergyCore Management Engine (ECME) about the need to change
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* voltage. The ECME interfaces with the actual voltage regulators.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/clk.h>
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#include <linux/cpu.h>
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#include <linux/err.h>
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#include <linux/of.h>
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#include <linux/pl320-ipc.h>
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#include <linux/platform_device.h>
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#define HB_CPUFREQ_CHANGE_NOTE 0x80000001
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#define HB_CPUFREQ_IPC_LEN 7
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#define HB_CPUFREQ_VOLT_RETRIES 15
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static int hb_voltage_change(unsigned int freq)
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{
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u32 msg[HB_CPUFREQ_IPC_LEN] = {HB_CPUFREQ_CHANGE_NOTE, freq / 1000000};
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return pl320_ipc_transmit(msg);
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}
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static int hb_cpufreq_clk_notify(struct notifier_block *nb,
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unsigned long action, void *hclk)
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{
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struct clk_notifier_data *clk_data = hclk;
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int i = 0;
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if (action == PRE_RATE_CHANGE) {
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if (clk_data->new_rate > clk_data->old_rate)
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while (hb_voltage_change(clk_data->new_rate))
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if (i++ > HB_CPUFREQ_VOLT_RETRIES)
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return NOTIFY_BAD;
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} else if (action == POST_RATE_CHANGE) {
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if (clk_data->new_rate < clk_data->old_rate)
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while (hb_voltage_change(clk_data->new_rate))
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if (i++ > HB_CPUFREQ_VOLT_RETRIES)
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return NOTIFY_BAD;
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}
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return NOTIFY_DONE;
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}
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static struct notifier_block hb_cpufreq_clk_nb = {
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.notifier_call = hb_cpufreq_clk_notify,
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};
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static int hb_cpufreq_driver_init(void)
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{
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struct platform_device_info devinfo = { .name = "cpufreq-dt", };
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struct device *cpu_dev;
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struct clk *cpu_clk;
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struct device_node *np;
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int ret;
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if ((!of_machine_is_compatible("calxeda,highbank")) &&
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(!of_machine_is_compatible("calxeda,ecx-2000")))
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return -ENODEV;
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cpu_dev = get_cpu_device(0);
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if (!cpu_dev) {
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pr_err("failed to get highbank cpufreq device\n");
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return -ENODEV;
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}
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np = of_node_get(cpu_dev->of_node);
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if (!np) {
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pr_err("failed to find highbank cpufreq node\n");
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return -ENOENT;
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}
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cpu_clk = clk_get(cpu_dev, NULL);
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if (IS_ERR(cpu_clk)) {
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ret = PTR_ERR(cpu_clk);
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pr_err("failed to get cpu0 clock: %d\n", ret);
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goto out_put_node;
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}
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ret = clk_notifier_register(cpu_clk, &hb_cpufreq_clk_nb);
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if (ret) {
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pr_err("failed to register clk notifier: %d\n", ret);
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goto out_put_node;
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}
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/* Instantiate cpufreq-dt */
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platform_device_register_full(&devinfo);
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out_put_node:
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of_node_put(np);
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return ret;
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}
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module_init(hb_cpufreq_driver_init);
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MODULE_AUTHOR("Mark Langsdorf <mark.langsdorf@calxeda.com>");
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MODULE_DESCRIPTION("Calxeda Highbank cpufreq driver");
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MODULE_LICENSE("GPL");
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