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.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 19 static 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 */ 39 static 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 45 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu) 46 { 47 return clk_get_rate(priv.powersave_clk) / 1000; 48 } 49 50 static 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 */ 86 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy) 87 { 88 cpufreq_generic_init(policy, kirkwood_freq_table, 5000); 89 return 0; 90 } 91 92 static 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 }; 100 101 static int kirkwood_cpufreq_probe(struct platform_device *pdev) 102 { 103 struct device_node *np; 104 int err; 105 106 priv.dev = &pdev->dev; 107 108 priv.base = devm_platform_ioremap_resource(pdev, 0); 109 if (IS_ERR(priv.base)) 110 return PTR_ERR(priv.base); 111 112 np = of_cpu_device_node_get(0); 113 if (!np) { 114 dev_err(&pdev->dev, "failed to get cpu device node\n"); 115 return -ENODEV; 116 } 117 118 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk"); 119 if (IS_ERR(priv.cpu_clk)) { 120 dev_err(priv.dev, "Unable to get cpuclk\n"); 121 err = PTR_ERR(priv.cpu_clk); 122 goto out_node; 123 } 124 125 err = clk_prepare_enable(priv.cpu_clk); 126 if (err) { 127 dev_err(priv.dev, "Unable to prepare cpuclk\n"); 128 goto out_node; 129 } 130 131 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\n"); 136 err = PTR_ERR(priv.ddr_clk); 137 goto out_cpu; 138 } 139 140 err = clk_prepare_enable(priv.ddr_clk); 141 if (err) { 142 dev_err(priv.dev, "Unable to prepare ddrclk\n"); 143 goto out_cpu; 144 } 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\n"); 150 err = PTR_ERR(priv.powersave_clk); 151 goto out_ddr; 152 } 153 err = clk_prepare_enable(priv.powersave_clk); 154 if (err) { 155 dev_err(priv.dev, "Unable to prepare powersave clk\n"); 156 goto out_ddr; 157 } 158 159 err = cpufreq_register_driver(&kirkwood_cpufreq_driver); 160 if (err) { 161 dev_err(priv.dev, "Failed to register cpufreq driver\n"); 162 goto out_powersave; 163 } 164 165 of_node_put(np); 166 return 0; 167 168 out_powersave: 169 clk_disable_unprepare(priv.powersave_clk); 170 out_ddr: 171 clk_disable_unprepare(priv.ddr_clk); 172 out_cpu: 173 clk_disable_unprepare(priv.cpu_clk); 174 out_node: 175 of_node_put(np); 176 177 return err; 178 } 179 180 static void kirkwood_cpufreq_remove(struct platform_device *pdev) 181 { 182 cpufreq_unregister_driver(&kirkwood_cpufreq_driver); 183 184 clk_disable_unprepare(priv.powersave_clk); 185 clk_disable_unprepare(priv.ddr_clk); 186 clk_disable_unprepare(priv.cpu_clk); 187 } 188 189 static struct platform_driver kirkwood_cpufreq_platform_driver = { 190 .probe = kirkwood_cpufreq_probe, 191 .remove = kirkwood_cpufreq_remove, 192 .driver = { 193 .name = "kirkwood-cpufreq", 194 }, 195 }; 196 197 module_platform_driver(kirkwood_cpufreq_platform_driver); 198 199 MODULE_LICENSE("GPL v2"); 200 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch"); 201 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU"); 202 MODULE_ALIAS("platform:kirkwood-cpufreq"); 203