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_device.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 struct resource *res; 106 int err; 107 108 priv.dev = &pdev->dev; 109 110 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 111 priv.base = devm_ioremap_resource(&pdev->dev, res); 112 if (IS_ERR(priv.base)) 113 return PTR_ERR(priv.base); 114 115 np = of_cpu_device_node_get(0); 116 if (!np) { 117 dev_err(&pdev->dev, "failed to get cpu device node\n"); 118 return -ENODEV; 119 } 120 121 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk"); 122 if (IS_ERR(priv.cpu_clk)) { 123 dev_err(priv.dev, "Unable to get cpuclk\n"); 124 err = PTR_ERR(priv.cpu_clk); 125 goto out_node; 126 } 127 128 err = clk_prepare_enable(priv.cpu_clk); 129 if (err) { 130 dev_err(priv.dev, "Unable to prepare cpuclk\n"); 131 goto out_node; 132 } 133 134 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000; 135 136 priv.ddr_clk = of_clk_get_by_name(np, "ddrclk"); 137 if (IS_ERR(priv.ddr_clk)) { 138 dev_err(priv.dev, "Unable to get ddrclk\n"); 139 err = PTR_ERR(priv.ddr_clk); 140 goto out_cpu; 141 } 142 143 err = clk_prepare_enable(priv.ddr_clk); 144 if (err) { 145 dev_err(priv.dev, "Unable to prepare ddrclk\n"); 146 goto out_cpu; 147 } 148 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000; 149 150 priv.powersave_clk = of_clk_get_by_name(np, "powersave"); 151 if (IS_ERR(priv.powersave_clk)) { 152 dev_err(priv.dev, "Unable to get powersave\n"); 153 err = PTR_ERR(priv.powersave_clk); 154 goto out_ddr; 155 } 156 err = clk_prepare_enable(priv.powersave_clk); 157 if (err) { 158 dev_err(priv.dev, "Unable to prepare powersave clk\n"); 159 goto out_ddr; 160 } 161 162 err = cpufreq_register_driver(&kirkwood_cpufreq_driver); 163 if (err) { 164 dev_err(priv.dev, "Failed to register cpufreq driver\n"); 165 goto out_powersave; 166 } 167 168 of_node_put(np); 169 return 0; 170 171 out_powersave: 172 clk_disable_unprepare(priv.powersave_clk); 173 out_ddr: 174 clk_disable_unprepare(priv.ddr_clk); 175 out_cpu: 176 clk_disable_unprepare(priv.cpu_clk); 177 out_node: 178 of_node_put(np); 179 180 return err; 181 } 182 183 static int kirkwood_cpufreq_remove(struct platform_device *pdev) 184 { 185 cpufreq_unregister_driver(&kirkwood_cpufreq_driver); 186 187 clk_disable_unprepare(priv.powersave_clk); 188 clk_disable_unprepare(priv.ddr_clk); 189 clk_disable_unprepare(priv.cpu_clk); 190 191 return 0; 192 } 193 194 static struct platform_driver kirkwood_cpufreq_platform_driver = { 195 .probe = kirkwood_cpufreq_probe, 196 .remove = kirkwood_cpufreq_remove, 197 .driver = { 198 .name = "kirkwood-cpufreq", 199 }, 200 }; 201 202 module_platform_driver(kirkwood_cpufreq_platform_driver); 203 204 MODULE_LICENSE("GPL v2"); 205 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch"); 206 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU"); 207 MODULE_ALIAS("platform:kirkwood-cpufreq"); 208