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 return cpufreq_generic_init(policy, kirkwood_freq_table, 5000); 89 } 90 91 static struct cpufreq_driver kirkwood_cpufreq_driver = { 92 .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, 93 .get = kirkwood_cpufreq_get_cpu_frequency, 94 .verify = cpufreq_generic_frequency_table_verify, 95 .target_index = kirkwood_cpufreq_target, 96 .init = kirkwood_cpufreq_cpu_init, 97 .name = "kirkwood-cpufreq", 98 .attr = cpufreq_generic_attr, 99 }; 100 101 static int kirkwood_cpufreq_probe(struct platform_device *pdev) 102 { 103 struct device_node *np; 104 struct resource *res; 105 int err; 106 107 priv.dev = &pdev->dev; 108 109 res = platform_get_resource(pdev, IORESOURCE_MEM, 0); 110 priv.base = devm_ioremap_resource(&pdev->dev, res); 111 if (IS_ERR(priv.base)) 112 return PTR_ERR(priv.base); 113 114 np = of_cpu_device_node_get(0); 115 if (!np) { 116 dev_err(&pdev->dev, "failed to get cpu device node\n"); 117 return -ENODEV; 118 } 119 120 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk"); 121 if (IS_ERR(priv.cpu_clk)) { 122 dev_err(priv.dev, "Unable to get cpuclk\n"); 123 err = PTR_ERR(priv.cpu_clk); 124 goto out_node; 125 } 126 127 err = clk_prepare_enable(priv.cpu_clk); 128 if (err) { 129 dev_err(priv.dev, "Unable to prepare cpuclk\n"); 130 goto out_node; 131 } 132 133 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000; 134 135 priv.ddr_clk = of_clk_get_by_name(np, "ddrclk"); 136 if (IS_ERR(priv.ddr_clk)) { 137 dev_err(priv.dev, "Unable to get ddrclk\n"); 138 err = PTR_ERR(priv.ddr_clk); 139 goto out_cpu; 140 } 141 142 err = clk_prepare_enable(priv.ddr_clk); 143 if (err) { 144 dev_err(priv.dev, "Unable to prepare ddrclk\n"); 145 goto out_cpu; 146 } 147 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000; 148 149 priv.powersave_clk = of_clk_get_by_name(np, "powersave"); 150 if (IS_ERR(priv.powersave_clk)) { 151 dev_err(priv.dev, "Unable to get powersave\n"); 152 err = PTR_ERR(priv.powersave_clk); 153 goto out_ddr; 154 } 155 err = clk_prepare_enable(priv.powersave_clk); 156 if (err) { 157 dev_err(priv.dev, "Unable to prepare powersave clk\n"); 158 goto out_ddr; 159 } 160 161 err = cpufreq_register_driver(&kirkwood_cpufreq_driver); 162 if (err) { 163 dev_err(priv.dev, "Failed to register cpufreq driver\n"); 164 goto out_powersave; 165 } 166 167 of_node_put(np); 168 return 0; 169 170 out_powersave: 171 clk_disable_unprepare(priv.powersave_clk); 172 out_ddr: 173 clk_disable_unprepare(priv.ddr_clk); 174 out_cpu: 175 clk_disable_unprepare(priv.cpu_clk); 176 out_node: 177 of_node_put(np); 178 179 return err; 180 } 181 182 static int kirkwood_cpufreq_remove(struct platform_device *pdev) 183 { 184 cpufreq_unregister_driver(&kirkwood_cpufreq_driver); 185 186 clk_disable_unprepare(priv.powersave_clk); 187 clk_disable_unprepare(priv.ddr_clk); 188 clk_disable_unprepare(priv.cpu_clk); 189 190 return 0; 191 } 192 193 static struct platform_driver kirkwood_cpufreq_platform_driver = { 194 .probe = kirkwood_cpufreq_probe, 195 .remove = kirkwood_cpufreq_remove, 196 .driver = { 197 .name = "kirkwood-cpufreq", 198 }, 199 }; 200 201 module_platform_driver(kirkwood_cpufreq_platform_driver); 202 203 MODULE_LICENSE("GPL v2"); 204 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch"); 205 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU"); 206 MODULE_ALIAS("platform:kirkwood-cpufreq"); 207