/* * kirkwood_freq.c: cpufreq driver for the Marvell kirkwood * * Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch> * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public License * as published by the Free Software Foundation; either version * 2 of the License, or (at your option) any later version. */ #include <linux/kernel.h> #include <linux/module.h> #include <linux/clk.h> #include <linux/clk-provider.h> #include <linux/cpufreq.h> #include <linux/of_device.h> #include <linux/platform_device.h> #include <linux/io.h> #include <asm/proc-fns.h> #define CPU_SW_INT_BLK BIT(28) static struct priv { struct clk *cpu_clk; struct clk *ddr_clk; struct clk *powersave_clk; struct device *dev; void __iomem *base; } priv; #define STATE_CPU_FREQ 0x01 #define STATE_DDR_FREQ 0x02 /* * Kirkwood can swap the clock to the CPU between two clocks: * * - cpu clk * - ddr clk * * The frequencies are set at runtime before registering this * * table. */ static struct cpufreq_frequency_table kirkwood_freq_table[] = { {STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */ {STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */ {0, CPUFREQ_TABLE_END}, }; static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu) { if (__clk_is_enabled(priv.powersave_clk)) return kirkwood_freq_table[1].frequency; return kirkwood_freq_table[0].frequency; } static void kirkwood_cpufreq_set_cpu_state(struct cpufreq_policy *policy, unsigned int index) { struct cpufreq_freqs freqs; unsigned int state = kirkwood_freq_table[index].driver_data; unsigned long reg; freqs.old = kirkwood_cpufreq_get_cpu_frequency(0); freqs.new = kirkwood_freq_table[index].frequency; cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); dev_dbg(priv.dev, "Attempting to set frequency to %i KHz\n", kirkwood_freq_table[index].frequency); dev_dbg(priv.dev, "old frequency was %i KHz\n", kirkwood_cpufreq_get_cpu_frequency(0)); if (freqs.old != freqs.new) { local_irq_disable(); /* Disable interrupts to the CPU */ reg = readl_relaxed(priv.base); reg |= CPU_SW_INT_BLK; writel_relaxed(reg, priv.base); switch (state) { case STATE_CPU_FREQ: clk_disable(priv.powersave_clk); break; case STATE_DDR_FREQ: clk_enable(priv.powersave_clk); break; } /* Wait-for-Interrupt, while the hardware changes frequency */ cpu_do_idle(); /* Enable interrupts to the CPU */ reg = readl_relaxed(priv.base); reg &= ~CPU_SW_INT_BLK; writel_relaxed(reg, priv.base); local_irq_enable(); } cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); }; static int kirkwood_cpufreq_verify(struct cpufreq_policy *policy) { return cpufreq_frequency_table_verify(policy, kirkwood_freq_table); } static int kirkwood_cpufreq_target(struct cpufreq_policy *policy, unsigned int target_freq, unsigned int relation) { unsigned int index = 0; if (cpufreq_frequency_table_target(policy, kirkwood_freq_table, target_freq, relation, &index)) return -EINVAL; kirkwood_cpufreq_set_cpu_state(policy, index); return 0; } /* Module init and exit code */ static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy) { int result; /* cpuinfo and default policy values */ policy->cpuinfo.transition_latency = 5000; /* 5uS */ policy->cur = kirkwood_cpufreq_get_cpu_frequency(0); result = cpufreq_frequency_table_cpuinfo(policy, kirkwood_freq_table); if (result) return result; cpufreq_frequency_table_get_attr(kirkwood_freq_table, policy->cpu); return 0; } static int kirkwood_cpufreq_cpu_exit(struct cpufreq_policy *policy) { cpufreq_frequency_table_put_attr(policy->cpu); return 0; } static struct freq_attr *kirkwood_cpufreq_attr[] = { &cpufreq_freq_attr_scaling_available_freqs, NULL, }; static struct cpufreq_driver kirkwood_cpufreq_driver = { .get = kirkwood_cpufreq_get_cpu_frequency, .verify = kirkwood_cpufreq_verify, .target = kirkwood_cpufreq_target, .init = kirkwood_cpufreq_cpu_init, .exit = kirkwood_cpufreq_cpu_exit, .name = "kirkwood-cpufreq", .attr = kirkwood_cpufreq_attr, }; static int kirkwood_cpufreq_probe(struct platform_device *pdev) { struct device_node *np; struct resource *res; int err; priv.dev = &pdev->dev; res = platform_get_resource(pdev, IORESOURCE_MEM, 0); priv.base = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(priv.base)) return PTR_ERR(priv.base); np = of_cpu_device_node_get(0); if (!np) { dev_err(&pdev->dev, "failed to get cpu device node\n"); return -ENODEV; } priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk"); if (IS_ERR(priv.cpu_clk)) { dev_err(priv.dev, "Unable to get cpuclk"); return PTR_ERR(priv.cpu_clk); } clk_prepare_enable(priv.cpu_clk); kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000; priv.ddr_clk = of_clk_get_by_name(np, "ddrclk"); if (IS_ERR(priv.ddr_clk)) { dev_err(priv.dev, "Unable to get ddrclk"); err = PTR_ERR(priv.ddr_clk); goto out_cpu; } clk_prepare_enable(priv.ddr_clk); kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000; priv.powersave_clk = of_clk_get_by_name(np, "powersave"); if (IS_ERR(priv.powersave_clk)) { dev_err(priv.dev, "Unable to get powersave"); err = PTR_ERR(priv.powersave_clk); goto out_ddr; } clk_prepare(priv.powersave_clk); of_node_put(np); np = NULL; err = cpufreq_register_driver(&kirkwood_cpufreq_driver); if (!err) return 0; dev_err(priv.dev, "Failed to register cpufreq driver"); clk_disable_unprepare(priv.powersave_clk); out_ddr: clk_disable_unprepare(priv.ddr_clk); out_cpu: clk_disable_unprepare(priv.cpu_clk); of_node_put(np); return err; } static int kirkwood_cpufreq_remove(struct platform_device *pdev) { cpufreq_unregister_driver(&kirkwood_cpufreq_driver); clk_disable_unprepare(priv.powersave_clk); clk_disable_unprepare(priv.ddr_clk); clk_disable_unprepare(priv.cpu_clk); return 0; } static struct platform_driver kirkwood_cpufreq_platform_driver = { .probe = kirkwood_cpufreq_probe, .remove = kirkwood_cpufreq_remove, .driver = { .name = "kirkwood-cpufreq", .owner = THIS_MODULE, }, }; module_platform_driver(kirkwood_cpufreq_platform_driver); MODULE_LICENSE("GPL v2"); MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch"); MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU"); MODULE_ALIAS("platform:kirkwood-cpufreq");