1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
5 * Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
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>
15 #include <asm/proc-fns.h>
17 #define CPU_SW_INT_BLK BIT(28)
23 struct clk *powersave_clk;
28 #define STATE_CPU_FREQ 0x01
29 #define STATE_DDR_FREQ 0x02
32 * Kirkwood can swap the clock to the CPU between two clocks:
37 * The frequencies are set at runtime before registering this table.
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},
45 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
47 return clk_get_rate(priv.powersave_clk) / 1000;
50 static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
53 unsigned int state = kirkwood_freq_table[index].driver_data;
58 /* Disable interrupts to the CPU */
59 reg = readl_relaxed(priv.base);
60 reg |= CPU_SW_INT_BLK;
61 writel_relaxed(reg, priv.base);
65 clk_set_parent(priv.powersave_clk, priv.cpu_clk);
68 clk_set_parent(priv.powersave_clk, priv.ddr_clk);
72 /* Wait-for-Interrupt, while the hardware changes frequency */
75 /* Enable interrupts to the CPU */
76 reg = readl_relaxed(priv.base);
77 reg &= ~CPU_SW_INT_BLK;
78 writel_relaxed(reg, priv.base);
85 /* Module init and exit code */
86 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
88 return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
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,
101 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
103 struct device_node *np;
104 struct resource *res;
107 priv.dev = &pdev->dev;
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);
114 np = of_cpu_device_node_get(0);
116 dev_err(&pdev->dev, "failed to get cpu device node\n");
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);
127 err = clk_prepare_enable(priv.cpu_clk);
129 dev_err(priv.dev, "Unable to prepare cpuclk\n");
133 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
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);
142 err = clk_prepare_enable(priv.ddr_clk);
144 dev_err(priv.dev, "Unable to prepare ddrclk\n");
147 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
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);
155 err = clk_prepare_enable(priv.powersave_clk);
157 dev_err(priv.dev, "Unable to prepare powersave clk\n");
161 err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
163 dev_err(priv.dev, "Failed to register cpufreq driver\n");
171 clk_disable_unprepare(priv.powersave_clk);
173 clk_disable_unprepare(priv.ddr_clk);
175 clk_disable_unprepare(priv.cpu_clk);
182 static int kirkwood_cpufreq_remove(struct platform_device *pdev)
184 cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
186 clk_disable_unprepare(priv.powersave_clk);
187 clk_disable_unprepare(priv.ddr_clk);
188 clk_disable_unprepare(priv.cpu_clk);
193 static struct platform_driver kirkwood_cpufreq_platform_driver = {
194 .probe = kirkwood_cpufreq_probe,
195 .remove = kirkwood_cpufreq_remove,
197 .name = "kirkwood-cpufreq",
201 module_platform_driver(kirkwood_cpufreq_platform_driver);
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");