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.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 void kirkwood_cpufreq_set_cpu_state(struct cpufreq_policy *policy, 59 unsigned int index) 60 { 61 struct cpufreq_freqs freqs; 62 unsigned int state = kirkwood_freq_table[index].index; 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 }; 104 105 static int kirkwood_cpufreq_verify(struct cpufreq_policy *policy) 106 { 107 return cpufreq_frequency_table_verify(policy, kirkwood_freq_table); 108 } 109 110 static int kirkwood_cpufreq_target(struct cpufreq_policy *policy, 111 unsigned int target_freq, 112 unsigned int relation) 113 { 114 unsigned int index = 0; 115 116 if (cpufreq_frequency_table_target(policy, kirkwood_freq_table, 117 target_freq, relation, &index)) 118 return -EINVAL; 119 120 kirkwood_cpufreq_set_cpu_state(policy, index); 121 122 return 0; 123 } 124 125 /* Module init and exit code */ 126 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy) 127 { 128 int result; 129 130 /* cpuinfo and default policy values */ 131 policy->cpuinfo.transition_latency = 5000; /* 5uS */ 132 policy->cur = kirkwood_cpufreq_get_cpu_frequency(0); 133 134 result = cpufreq_frequency_table_cpuinfo(policy, kirkwood_freq_table); 135 if (result) 136 return result; 137 138 cpufreq_frequency_table_get_attr(kirkwood_freq_table, policy->cpu); 139 140 return 0; 141 } 142 143 static int kirkwood_cpufreq_cpu_exit(struct cpufreq_policy *policy) 144 { 145 cpufreq_frequency_table_put_attr(policy->cpu); 146 return 0; 147 } 148 149 static struct freq_attr *kirkwood_cpufreq_attr[] = { 150 &cpufreq_freq_attr_scaling_available_freqs, 151 NULL, 152 }; 153 154 static struct cpufreq_driver kirkwood_cpufreq_driver = { 155 .get = kirkwood_cpufreq_get_cpu_frequency, 156 .verify = kirkwood_cpufreq_verify, 157 .target = kirkwood_cpufreq_target, 158 .init = kirkwood_cpufreq_cpu_init, 159 .exit = kirkwood_cpufreq_cpu_exit, 160 .name = "kirkwood-cpufreq", 161 .owner = THIS_MODULE, 162 .attr = kirkwood_cpufreq_attr, 163 }; 164 165 static int kirkwood_cpufreq_probe(struct platform_device *pdev) 166 { 167 struct device_node *np; 168 struct resource *res; 169 int err; 170 171 priv.dev = &pdev->dev; 172 173 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 174 if (!res) { 175 dev_err(&pdev->dev, "Cannot get memory resource\n"); 176 return -ENODEV; 177 } 178 priv.base = devm_ioremap_resource(&pdev->dev, res); 179 if (IS_ERR(priv.base)) 180 return PTR_ERR(priv.base); 181 182 np = of_find_node_by_path("/cpus/cpu@0"); 183 if (!np) 184 return -ENODEV; 185 186 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk"); 187 if (IS_ERR(priv.cpu_clk)) { 188 dev_err(priv.dev, "Unable to get cpuclk"); 189 return PTR_ERR(priv.cpu_clk); 190 } 191 192 clk_prepare_enable(priv.cpu_clk); 193 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000; 194 195 priv.ddr_clk = of_clk_get_by_name(np, "ddrclk"); 196 if (IS_ERR(priv.ddr_clk)) { 197 dev_err(priv.dev, "Unable to get ddrclk"); 198 err = PTR_ERR(priv.ddr_clk); 199 goto out_cpu; 200 } 201 202 clk_prepare_enable(priv.ddr_clk); 203 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000; 204 205 priv.powersave_clk = of_clk_get_by_name(np, "powersave"); 206 if (IS_ERR(priv.powersave_clk)) { 207 dev_err(priv.dev, "Unable to get powersave"); 208 err = PTR_ERR(priv.powersave_clk); 209 goto out_ddr; 210 } 211 clk_prepare(priv.powersave_clk); 212 213 of_node_put(np); 214 np = NULL; 215 216 err = cpufreq_register_driver(&kirkwood_cpufreq_driver); 217 if (!err) 218 return 0; 219 220 dev_err(priv.dev, "Failed to register cpufreq driver"); 221 222 clk_disable_unprepare(priv.powersave_clk); 223 out_ddr: 224 clk_disable_unprepare(priv.ddr_clk); 225 out_cpu: 226 clk_disable_unprepare(priv.cpu_clk); 227 of_node_put(np); 228 229 return err; 230 } 231 232 static int kirkwood_cpufreq_remove(struct platform_device *pdev) 233 { 234 cpufreq_unregister_driver(&kirkwood_cpufreq_driver); 235 236 clk_disable_unprepare(priv.powersave_clk); 237 clk_disable_unprepare(priv.ddr_clk); 238 clk_disable_unprepare(priv.cpu_clk); 239 240 return 0; 241 } 242 243 static struct platform_driver kirkwood_cpufreq_platform_driver = { 244 .probe = kirkwood_cpufreq_probe, 245 .remove = kirkwood_cpufreq_remove, 246 .driver = { 247 .name = "kirkwood-cpufreq", 248 .owner = THIS_MODULE, 249 }, 250 }; 251 252 module_platform_driver(kirkwood_cpufreq_platform_driver); 253 254 MODULE_LICENSE("GPL v2"); 255 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch"); 256 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU"); 257 MODULE_ALIAS("platform:kirkwood-cpufreq"); 258