drivers/cpufreq/kirkwood-cpufreq.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *  kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
0004  *
0005  *  Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
0006  */
0007
0008 #include <linux/kernel.h>
0009 #include <linux/module.h>
0010 #include <linux/clk.h>
0011 #include <linux/cpufreq.h>
0012 #include <linux/of_device.h>
0013 #include <linux/platform_device.h>
0014 #include <linux/io.h>
0015 #include <asm/proc-fns.h>
0016
0017 #define CPU_SW_INT_BLK BIT(28)
0018
0019 static struct priv
0020 {
0021     struct clk *cpu_clk;
0022     struct clk *ddr_clk;
0023     struct clk *powersave_clk;
0024     struct device *dev;
0025     void __iomem *base;
0026 } priv;
0027
0028 #define STATE_CPU_FREQ 0x01
0029 #define STATE_DDR_FREQ 0x02
0030
0031 /*
0032  * Kirkwood can swap the clock to the CPU between two clocks:
0033  *
0034  * - cpu clk
0035  * - ddr clk
0036  *
0037  * The frequencies are set at runtime before registering this table.
0038  */
0039 static struct cpufreq_frequency_table kirkwood_freq_table[] = {
0040     {0, STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */
0041     {0, STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */
0042     {0, 0,          CPUFREQ_TABLE_END},
0043 };
0044
0045 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
0046 {
0047     return clk_get_rate(priv.powersave_clk) / 1000;
0048 }
0049
0050 static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
0051                 unsigned int index)
0052 {
0053     unsigned int state = kirkwood_freq_table[index].driver_data;
0054     unsigned long reg;
0055
0056     local_irq_disable();
0057
0058     /* Disable interrupts to the CPU */
0059     reg = readl_relaxed(priv.base);
0060     reg |= CPU_SW_INT_BLK;
0061     writel_relaxed(reg, priv.base);
0062
0063     switch (state) {
0064     case STATE_CPU_FREQ:
0065         clk_set_parent(priv.powersave_clk, priv.cpu_clk);
0066         break;
0067     case STATE_DDR_FREQ:
0068         clk_set_parent(priv.powersave_clk, priv.ddr_clk);
0069         break;
0070     }
0071
0072     /* Wait-for-Interrupt, while the hardware changes frequency */
0073     cpu_do_idle();
0074
0075     /* Enable interrupts to the CPU */
0076     reg = readl_relaxed(priv.base);
0077     reg &= ~CPU_SW_INT_BLK;
0078     writel_relaxed(reg, priv.base);
0079
0080     local_irq_enable();
0081
0082     return 0;
0083 }
0084
0085 /* Module init and exit code */
0086 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
0087 {
0088     cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
0089     return 0;
0090 }
0091
0092 static struct cpufreq_driver kirkwood_cpufreq_driver = {
0093     .flags  = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
0094     .get    = kirkwood_cpufreq_get_cpu_frequency,
0095     .verify = cpufreq_generic_frequency_table_verify,
0096     .target_index = kirkwood_cpufreq_target,
0097     .init   = kirkwood_cpufreq_cpu_init,
0098     .name   = "kirkwood-cpufreq",
0099     .attr   = cpufreq_generic_attr,
0100 };
0101
0102 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
0103 {
0104     struct device_node *np;
0105     int err;
0106
0107     priv.dev = &pdev->dev;
0108
0109     priv.base = devm_platform_ioremap_resource(pdev, 0);
0110     if (IS_ERR(priv.base))
0111         return PTR_ERR(priv.base);
0112
0113     np = of_cpu_device_node_get(0);
0114     if (!np) {
0115         dev_err(&pdev->dev, "failed to get cpu device node\n");
0116         return -ENODEV;
0117     }
0118
0119     priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
0120     if (IS_ERR(priv.cpu_clk)) {
0121         dev_err(priv.dev, "Unable to get cpuclk\n");
0122         err = PTR_ERR(priv.cpu_clk);
0123         goto out_node;
0124     }
0125
0126     err = clk_prepare_enable(priv.cpu_clk);
0127     if (err) {
0128         dev_err(priv.dev, "Unable to prepare cpuclk\n");
0129         goto out_node;
0130     }
0131
0132     kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
0133
0134     priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
0135     if (IS_ERR(priv.ddr_clk)) {
0136         dev_err(priv.dev, "Unable to get ddrclk\n");
0137         err = PTR_ERR(priv.ddr_clk);
0138         goto out_cpu;
0139     }
0140
0141     err = clk_prepare_enable(priv.ddr_clk);
0142     if (err) {
0143         dev_err(priv.dev, "Unable to prepare ddrclk\n");
0144         goto out_cpu;
0145     }
0146     kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
0147
0148     priv.powersave_clk = of_clk_get_by_name(np, "powersave");
0149     if (IS_ERR(priv.powersave_clk)) {
0150         dev_err(priv.dev, "Unable to get powersave\n");
0151         err = PTR_ERR(priv.powersave_clk);
0152         goto out_ddr;
0153     }
0154     err = clk_prepare_enable(priv.powersave_clk);
0155     if (err) {
0156         dev_err(priv.dev, "Unable to prepare powersave clk\n");
0157         goto out_ddr;
0158     }
0159
0160     err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
0161     if (err) {
0162         dev_err(priv.dev, "Failed to register cpufreq driver\n");
0163         goto out_powersave;
0164     }
0165
0166     of_node_put(np);
0167     return 0;
0168
0169 out_powersave:
0170     clk_disable_unprepare(priv.powersave_clk);
0171 out_ddr:
0172     clk_disable_unprepare(priv.ddr_clk);
0173 out_cpu:
0174     clk_disable_unprepare(priv.cpu_clk);
0175 out_node:
0176     of_node_put(np);
0177
0178     return err;
0179 }
0180
0181 static int kirkwood_cpufreq_remove(struct platform_device *pdev)
0182 {
0183     cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
0184
0185     clk_disable_unprepare(priv.powersave_clk);
0186     clk_disable_unprepare(priv.ddr_clk);
0187     clk_disable_unprepare(priv.cpu_clk);
0188
0189     return 0;
0190 }
0191
0192 static struct platform_driver kirkwood_cpufreq_platform_driver = {
0193     .probe = kirkwood_cpufreq_probe,
0194     .remove = kirkwood_cpufreq_remove,
0195     .driver = {
0196         .name = "kirkwood-cpufreq",
0197     },
0198 };
0199
0200 module_platform_driver(kirkwood_cpufreq_platform_driver);
0201
0202 MODULE_LICENSE("GPL v2");
0203 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
0204 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
0205 MODULE_ALIAS("platform:kirkwood-cpufreq");