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