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 unsigned int state = kirkwood_freq_table[index].driver_data; 62 unsigned long reg; 63 64 local_irq_disable(); 65 66 /* Disable interrupts to the CPU */ 67 reg = readl_relaxed(priv.base); 68 reg |= CPU_SW_INT_BLK; 69 writel_relaxed(reg, priv.base); 70 71 switch (state) { 72 case STATE_CPU_FREQ: 73 clk_disable(priv.powersave_clk); 74 break; 75 case STATE_DDR_FREQ: 76 clk_enable(priv.powersave_clk); 77 break; 78 } 79 80 /* Wait-for-Interrupt, while the hardware changes frequency */ 81 cpu_do_idle(); 82 83 /* Enable interrupts to the CPU */ 84 reg = readl_relaxed(priv.base); 85 reg &= ~CPU_SW_INT_BLK; 86 writel_relaxed(reg, priv.base); 87 88 local_irq_enable(); 89 90 return 0; 91 } 92 93 /* Module init and exit code */ 94 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy) 95 { 96 return cpufreq_generic_init(policy, kirkwood_freq_table, 5000); 97 } 98 99 static struct cpufreq_driver kirkwood_cpufreq_driver = { 100 .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, 101 .get = kirkwood_cpufreq_get_cpu_frequency, 102 .verify = cpufreq_generic_frequency_table_verify, 103 .target_index = kirkwood_cpufreq_target, 104 .init = kirkwood_cpufreq_cpu_init, 105 .name = "kirkwood-cpufreq", 106 .attr = cpufreq_generic_attr, 107 }; 108 109 static int kirkwood_cpufreq_probe(struct platform_device *pdev) 110 { 111 struct device_node *np; 112 struct resource *res; 113 int err; 114 115 priv.dev = &pdev->dev; 116 117 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 118 priv.base = devm_ioremap_resource(&pdev->dev, res); 119 if (IS_ERR(priv.base)) 120 return PTR_ERR(priv.base); 121 122 np = of_cpu_device_node_get(0); 123 if (!np) { 124 dev_err(&pdev->dev, "failed to get cpu device node\n"); 125 return -ENODEV; 126 } 127 128 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk"); 129 if (IS_ERR(priv.cpu_clk)) { 130 dev_err(priv.dev, "Unable to get cpuclk"); 131 return PTR_ERR(priv.cpu_clk); 132 } 133 134 clk_prepare_enable(priv.cpu_clk); 135 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000; 136 137 priv.ddr_clk = of_clk_get_by_name(np, "ddrclk"); 138 if (IS_ERR(priv.ddr_clk)) { 139 dev_err(priv.dev, "Unable to get ddrclk"); 140 err = PTR_ERR(priv.ddr_clk); 141 goto out_cpu; 142 } 143 144 clk_prepare_enable(priv.ddr_clk); 145 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000; 146 147 priv.powersave_clk = of_clk_get_by_name(np, "powersave"); 148 if (IS_ERR(priv.powersave_clk)) { 149 dev_err(priv.dev, "Unable to get powersave"); 150 err = PTR_ERR(priv.powersave_clk); 151 goto out_ddr; 152 } 153 clk_prepare(priv.powersave_clk); 154 155 of_node_put(np); 156 np = NULL; 157 158 err = cpufreq_register_driver(&kirkwood_cpufreq_driver); 159 if (!err) 160 return 0; 161 162 dev_err(priv.dev, "Failed to register cpufreq driver"); 163 164 clk_disable_unprepare(priv.powersave_clk); 165 out_ddr: 166 clk_disable_unprepare(priv.ddr_clk); 167 out_cpu: 168 clk_disable_unprepare(priv.cpu_clk); 169 of_node_put(np); 170 171 return err; 172 } 173 174 static int kirkwood_cpufreq_remove(struct platform_device *pdev) 175 { 176 cpufreq_unregister_driver(&kirkwood_cpufreq_driver); 177 178 clk_disable_unprepare(priv.powersave_clk); 179 clk_disable_unprepare(priv.ddr_clk); 180 clk_disable_unprepare(priv.cpu_clk); 181 182 return 0; 183 } 184 185 static struct platform_driver kirkwood_cpufreq_platform_driver = { 186 .probe = kirkwood_cpufreq_probe, 187 .remove = kirkwood_cpufreq_remove, 188 .driver = { 189 .name = "kirkwood-cpufreq", 190 .owner = THIS_MODULE, 191 }, 192 }; 193 194 module_platform_driver(kirkwood_cpufreq_platform_driver); 195 196 MODULE_LICENSE("GPL v2"); 197 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch"); 198 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU"); 199 MODULE_ALIAS("platform:kirkwood-cpufreq"); 200