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 .attr = cpufreq_generic_attr, 100 }; 101 102 static int kirkwood_cpufreq_probe(struct platform_device *pdev) 103 { 104 struct device_node *np; 105 int err; 106 107 priv.dev = &pdev->dev; 108 109 priv.base = devm_platform_ioremap_resource(pdev, 0); 110 if (IS_ERR(priv.base)) 111 return PTR_ERR(priv.base); 112 113 np = of_cpu_device_node_get(0); 114 if (!np) { 115 dev_err(&pdev->dev, "failed to get cpu device node\n"); 116 return -ENODEV; 117 } 118 119 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk"); 120 if (IS_ERR(priv.cpu_clk)) { 121 dev_err(priv.dev, "Unable to get cpuclk\n"); 122 err = PTR_ERR(priv.cpu_clk); 123 goto out_node; 124 } 125 126 err = clk_prepare_enable(priv.cpu_clk); 127 if (err) { 128 dev_err(priv.dev, "Unable to prepare cpuclk\n"); 129 goto out_node; 130 } 131 132 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000; 133 134 priv.ddr_clk = of_clk_get_by_name(np, "ddrclk"); 135 if (IS_ERR(priv.ddr_clk)) { 136 dev_err(priv.dev, "Unable to get ddrclk\n"); 137 err = PTR_ERR(priv.ddr_clk); 138 goto out_cpu; 139 } 140 141 err = clk_prepare_enable(priv.ddr_clk); 142 if (err) { 143 dev_err(priv.dev, "Unable to prepare ddrclk\n"); 144 goto out_cpu; 145 } 146 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000; 147 148 priv.powersave_clk = of_clk_get_by_name(np, "powersave"); 149 if (IS_ERR(priv.powersave_clk)) { 150 dev_err(priv.dev, "Unable to get powersave\n"); 151 err = PTR_ERR(priv.powersave_clk); 152 goto out_ddr; 153 } 154 err = clk_prepare_enable(priv.powersave_clk); 155 if (err) { 156 dev_err(priv.dev, "Unable to prepare powersave clk\n"); 157 goto out_ddr; 158 } 159 160 err = cpufreq_register_driver(&kirkwood_cpufreq_driver); 161 if (err) { 162 dev_err(priv.dev, "Failed to register cpufreq driver\n"); 163 goto out_powersave; 164 } 165 166 of_node_put(np); 167 return 0; 168 169 out_powersave: 170 clk_disable_unprepare(priv.powersave_clk); 171 out_ddr: 172 clk_disable_unprepare(priv.ddr_clk); 173 out_cpu: 174 clk_disable_unprepare(priv.cpu_clk); 175 out_node: 176 of_node_put(np); 177 178 return err; 179 } 180 181 static void kirkwood_cpufreq_remove(struct platform_device *pdev) 182 { 183 cpufreq_unregister_driver(&kirkwood_cpufreq_driver); 184 185 clk_disable_unprepare(priv.powersave_clk); 186 clk_disable_unprepare(priv.ddr_clk); 187 clk_disable_unprepare(priv.cpu_clk); 188 } 189 190 static struct platform_driver kirkwood_cpufreq_platform_driver = { 191 .probe = kirkwood_cpufreq_probe, 192 .remove_new = kirkwood_cpufreq_remove, 193 .driver = { 194 .name = "kirkwood-cpufreq", 195 }, 196 }; 197 198 module_platform_driver(kirkwood_cpufreq_platform_driver); 199 200 MODULE_LICENSE("GPL v2"); 201 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch"); 202 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU"); 203 MODULE_ALIAS("platform:kirkwood-cpufreq"); 204