1 /* 2 * kirkwood_freq.c: cpufreq driver for the Marvell kirkwood 3 * 4 * Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch> 5 * 6 * This program is free software; you can redistribute it and/or 7 * modify it under the terms of the GNU General Public License 8 * as published by the Free Software Foundation; either version 9 * 2 of the License, or (at your option) any later version. 10 */ 11 12 #include <linux/kernel.h> 13 #include <linux/module.h> 14 #include <linux/clk.h> 15 #include <linux/clk-provider.h> 16 #include <linux/cpufreq.h> 17 #include <linux/of_device.h> 18 #include <linux/platform_device.h> 19 #include <linux/io.h> 20 #include <asm/proc-fns.h> 21 22 #define CPU_SW_INT_BLK BIT(28) 23 24 static struct priv 25 { 26 struct clk *cpu_clk; 27 struct clk *ddr_clk; 28 struct clk *powersave_clk; 29 struct device *dev; 30 void __iomem *base; 31 } priv; 32 33 #define STATE_CPU_FREQ 0x01 34 #define STATE_DDR_FREQ 0x02 35 36 /* 37 * Kirkwood can swap the clock to the CPU between two clocks: 38 * 39 * - cpu clk 40 * - ddr clk 41 * 42 * The frequencies are set at runtime before registering this * 43 * table. 44 */ 45 static struct cpufreq_frequency_table kirkwood_freq_table[] = { 46 {STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */ 47 {STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */ 48 {0, CPUFREQ_TABLE_END}, 49 }; 50 51 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu) 52 { 53 if (__clk_is_enabled(priv.powersave_clk)) 54 return kirkwood_freq_table[1].frequency; 55 return kirkwood_freq_table[0].frequency; 56 } 57 58 static int kirkwood_cpufreq_target(struct cpufreq_policy *policy, 59 unsigned int index) 60 { 61 struct cpufreq_freqs freqs; 62 unsigned int state = kirkwood_freq_table[index].driver_data; 63 unsigned long reg; 64 65 freqs.old = kirkwood_cpufreq_get_cpu_frequency(0); 66 freqs.new = kirkwood_freq_table[index].frequency; 67 68 cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE); 69 70 dev_dbg(priv.dev, "Attempting to set frequency to %i KHz\n", 71 kirkwood_freq_table[index].frequency); 72 dev_dbg(priv.dev, "old frequency was %i KHz\n", 73 kirkwood_cpufreq_get_cpu_frequency(0)); 74 75 if (freqs.old != freqs.new) { 76 local_irq_disable(); 77 78 /* Disable interrupts to the CPU */ 79 reg = readl_relaxed(priv.base); 80 reg |= CPU_SW_INT_BLK; 81 writel_relaxed(reg, priv.base); 82 83 switch (state) { 84 case STATE_CPU_FREQ: 85 clk_disable(priv.powersave_clk); 86 break; 87 case STATE_DDR_FREQ: 88 clk_enable(priv.powersave_clk); 89 break; 90 } 91 92 /* Wait-for-Interrupt, while the hardware changes frequency */ 93 cpu_do_idle(); 94 95 /* Enable interrupts to the CPU */ 96 reg = readl_relaxed(priv.base); 97 reg &= ~CPU_SW_INT_BLK; 98 writel_relaxed(reg, priv.base); 99 100 local_irq_enable(); 101 } 102 cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE); 103 104 return 0; 105 } 106 107 /* Module init and exit code */ 108 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy) 109 { 110 return cpufreq_generic_init(policy, kirkwood_freq_table, 5000); 111 } 112 113 static struct cpufreq_driver kirkwood_cpufreq_driver = { 114 .get = kirkwood_cpufreq_get_cpu_frequency, 115 .verify = cpufreq_generic_frequency_table_verify, 116 .target_index = kirkwood_cpufreq_target, 117 .init = kirkwood_cpufreq_cpu_init, 118 .exit = cpufreq_generic_exit, 119 .name = "kirkwood-cpufreq", 120 .attr = cpufreq_generic_attr, 121 }; 122 123 static int kirkwood_cpufreq_probe(struct platform_device *pdev) 124 { 125 struct device_node *np; 126 struct resource *res; 127 int err; 128 129 priv.dev = &pdev->dev; 130 131 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 132 priv.base = devm_ioremap_resource(&pdev->dev, res); 133 if (IS_ERR(priv.base)) 134 return PTR_ERR(priv.base); 135 136 np = of_cpu_device_node_get(0); 137 if (!np) { 138 dev_err(&pdev->dev, "failed to get cpu device node\n"); 139 return -ENODEV; 140 } 141 142 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk"); 143 if (IS_ERR(priv.cpu_clk)) { 144 dev_err(priv.dev, "Unable to get cpuclk"); 145 return PTR_ERR(priv.cpu_clk); 146 } 147 148 clk_prepare_enable(priv.cpu_clk); 149 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000; 150 151 priv.ddr_clk = of_clk_get_by_name(np, "ddrclk"); 152 if (IS_ERR(priv.ddr_clk)) { 153 dev_err(priv.dev, "Unable to get ddrclk"); 154 err = PTR_ERR(priv.ddr_clk); 155 goto out_cpu; 156 } 157 158 clk_prepare_enable(priv.ddr_clk); 159 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000; 160 161 priv.powersave_clk = of_clk_get_by_name(np, "powersave"); 162 if (IS_ERR(priv.powersave_clk)) { 163 dev_err(priv.dev, "Unable to get powersave"); 164 err = PTR_ERR(priv.powersave_clk); 165 goto out_ddr; 166 } 167 clk_prepare(priv.powersave_clk); 168 169 of_node_put(np); 170 np = NULL; 171 172 err = cpufreq_register_driver(&kirkwood_cpufreq_driver); 173 if (!err) 174 return 0; 175 176 dev_err(priv.dev, "Failed to register cpufreq driver"); 177 178 clk_disable_unprepare(priv.powersave_clk); 179 out_ddr: 180 clk_disable_unprepare(priv.ddr_clk); 181 out_cpu: 182 clk_disable_unprepare(priv.cpu_clk); 183 of_node_put(np); 184 185 return err; 186 } 187 188 static int kirkwood_cpufreq_remove(struct platform_device *pdev) 189 { 190 cpufreq_unregister_driver(&kirkwood_cpufreq_driver); 191 192 clk_disable_unprepare(priv.powersave_clk); 193 clk_disable_unprepare(priv.ddr_clk); 194 clk_disable_unprepare(priv.cpu_clk); 195 196 return 0; 197 } 198 199 static struct platform_driver kirkwood_cpufreq_platform_driver = { 200 .probe = kirkwood_cpufreq_probe, 201 .remove = kirkwood_cpufreq_remove, 202 .driver = { 203 .name = "kirkwood-cpufreq", 204 .owner = THIS_MODULE, 205 }, 206 }; 207 208 module_platform_driver(kirkwood_cpufreq_platform_driver); 209 210 MODULE_LICENSE("GPL v2"); 211 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch"); 212 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU"); 213 MODULE_ALIAS("platform:kirkwood-cpufreq"); 214