kirkwood-cpufreq.c (4890B)
1// SPDX-License-Identifier: GPL-2.0-or-later 2/* 3 * kirkwood_freq.c: cpufreq driver for the Marvell kirkwood 4 * 5 * Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch> 6 */ 7 8#include <linux/kernel.h> 9#include <linux/module.h> 10#include <linux/clk.h> 11#include <linux/cpufreq.h> 12#include <linux/of_device.h> 13#include <linux/platform_device.h> 14#include <linux/io.h> 15#include <asm/proc-fns.h> 16 17#define CPU_SW_INT_BLK BIT(28) 18 19static struct priv 20{ 21 struct clk *cpu_clk; 22 struct clk *ddr_clk; 23 struct clk *powersave_clk; 24 struct device *dev; 25 void __iomem *base; 26} priv; 27 28#define STATE_CPU_FREQ 0x01 29#define STATE_DDR_FREQ 0x02 30 31/* 32 * Kirkwood can swap the clock to the CPU between two clocks: 33 * 34 * - cpu clk 35 * - ddr clk 36 * 37 * The frequencies are set at runtime before registering this table. 38 */ 39static struct cpufreq_frequency_table kirkwood_freq_table[] = { 40 {0, STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */ 41 {0, STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */ 42 {0, 0, CPUFREQ_TABLE_END}, 43}; 44 45static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu) 46{ 47 return clk_get_rate(priv.powersave_clk) / 1000; 48} 49 50static int kirkwood_cpufreq_target(struct cpufreq_policy *policy, 51 unsigned int index) 52{ 53 unsigned int state = kirkwood_freq_table[index].driver_data; 54 unsigned long reg; 55 56 local_irq_disable(); 57 58 /* Disable interrupts to the CPU */ 59 reg = readl_relaxed(priv.base); 60 reg |= CPU_SW_INT_BLK; 61 writel_relaxed(reg, priv.base); 62 63 switch (state) { 64 case STATE_CPU_FREQ: 65 clk_set_parent(priv.powersave_clk, priv.cpu_clk); 66 break; 67 case STATE_DDR_FREQ: 68 clk_set_parent(priv.powersave_clk, priv.ddr_clk); 69 break; 70 } 71 72 /* Wait-for-Interrupt, while the hardware changes frequency */ 73 cpu_do_idle(); 74 75 /* Enable interrupts to the CPU */ 76 reg = readl_relaxed(priv.base); 77 reg &= ~CPU_SW_INT_BLK; 78 writel_relaxed(reg, priv.base); 79 80 local_irq_enable(); 81 82 return 0; 83} 84 85/* Module init and exit code */ 86static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy) 87{ 88 cpufreq_generic_init(policy, kirkwood_freq_table, 5000); 89 return 0; 90} 91 92static struct cpufreq_driver kirkwood_cpufreq_driver = { 93 .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, 94 .get = kirkwood_cpufreq_get_cpu_frequency, 95 .verify = cpufreq_generic_frequency_table_verify, 96 .target_index = kirkwood_cpufreq_target, 97 .init = kirkwood_cpufreq_cpu_init, 98 .name = "kirkwood-cpufreq", 99 .attr = cpufreq_generic_attr, 100}; 101 102static int kirkwood_cpufreq_probe(struct platform_device *pdev) 103{ 104 struct device_node *np; 105 int err; 106 107 priv.dev = &pdev->dev; 108 109 priv.base = devm_platform_ioremap_resource(pdev, 0); 110 if (IS_ERR(priv.base)) 111 return PTR_ERR(priv.base); 112 113 np = of_cpu_device_node_get(0); 114 if (!np) { 115 dev_err(&pdev->dev, "failed to get cpu device node\n"); 116 return -ENODEV; 117 } 118 119 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk"); 120 if (IS_ERR(priv.cpu_clk)) { 121 dev_err(priv.dev, "Unable to get cpuclk\n"); 122 err = PTR_ERR(priv.cpu_clk); 123 goto out_node; 124 } 125 126 err = clk_prepare_enable(priv.cpu_clk); 127 if (err) { 128 dev_err(priv.dev, "Unable to prepare cpuclk\n"); 129 goto out_node; 130 } 131 132 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000; 133 134 priv.ddr_clk = of_clk_get_by_name(np, "ddrclk"); 135 if (IS_ERR(priv.ddr_clk)) { 136 dev_err(priv.dev, "Unable to get ddrclk\n"); 137 err = PTR_ERR(priv.ddr_clk); 138 goto out_cpu; 139 } 140 141 err = clk_prepare_enable(priv.ddr_clk); 142 if (err) { 143 dev_err(priv.dev, "Unable to prepare ddrclk\n"); 144 goto out_cpu; 145 } 146 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000; 147 148 priv.powersave_clk = of_clk_get_by_name(np, "powersave"); 149 if (IS_ERR(priv.powersave_clk)) { 150 dev_err(priv.dev, "Unable to get powersave\n"); 151 err = PTR_ERR(priv.powersave_clk); 152 goto out_ddr; 153 } 154 err = clk_prepare_enable(priv.powersave_clk); 155 if (err) { 156 dev_err(priv.dev, "Unable to prepare powersave clk\n"); 157 goto out_ddr; 158 } 159 160 err = cpufreq_register_driver(&kirkwood_cpufreq_driver); 161 if (err) { 162 dev_err(priv.dev, "Failed to register cpufreq driver\n"); 163 goto out_powersave; 164 } 165 166 of_node_put(np); 167 return 0; 168 169out_powersave: 170 clk_disable_unprepare(priv.powersave_clk); 171out_ddr: 172 clk_disable_unprepare(priv.ddr_clk); 173out_cpu: 174 clk_disable_unprepare(priv.cpu_clk); 175out_node: 176 of_node_put(np); 177 178 return err; 179} 180 181static int kirkwood_cpufreq_remove(struct platform_device *pdev) 182{ 183 cpufreq_unregister_driver(&kirkwood_cpufreq_driver); 184 185 clk_disable_unprepare(priv.powersave_clk); 186 clk_disable_unprepare(priv.ddr_clk); 187 clk_disable_unprepare(priv.cpu_clk); 188 189 return 0; 190} 191 192static struct platform_driver kirkwood_cpufreq_platform_driver = { 193 .probe = kirkwood_cpufreq_probe, 194 .remove = kirkwood_cpufreq_remove, 195 .driver = { 196 .name = "kirkwood-cpufreq", 197 }, 198}; 199 200module_platform_driver(kirkwood_cpufreq_platform_driver); 201 202MODULE_LICENSE("GPL v2"); 203MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch"); 204MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU"); 205MODULE_ALIAS("platform:kirkwood-cpufreq");