kirkwood-cpufreq.c

  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
 19static 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 */
 39static 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
 45static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
 46{
 47	return clk_get_rate(priv.powersave_clk) / 1000;
 48}
 49
 50static 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 */
 86static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
 87{
 88	cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
 89	return 0;
 90}
 91
 92static 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};
100
101static int kirkwood_cpufreq_probe(struct platform_device *pdev)
102{
103	struct device_node *np;
104	int err;
105
106	priv.dev = &pdev->dev;
107
108	priv.base = devm_platform_ioremap_resource(pdev, 0);
109	if (IS_ERR(priv.base))
110		return PTR_ERR(priv.base);
111
112	np = of_cpu_device_node_get(0);
113	if (!np) {
114		dev_err(&pdev->dev, "failed to get cpu device node\n");
115		return -ENODEV;
116	}
117
118	priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
119	if (IS_ERR(priv.cpu_clk)) {
120		dev_err(priv.dev, "Unable to get cpuclk\n");
121		err = PTR_ERR(priv.cpu_clk);
122		goto out_node;
123	}
124
125	err = clk_prepare_enable(priv.cpu_clk);
126	if (err) {
127		dev_err(priv.dev, "Unable to prepare cpuclk\n");
128		goto out_node;
129	}
130
131	kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
132
133	priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
134	if (IS_ERR(priv.ddr_clk)) {
135		dev_err(priv.dev, "Unable to get ddrclk\n");
136		err = PTR_ERR(priv.ddr_clk);
137		goto out_cpu;
138	}
139
140	err = clk_prepare_enable(priv.ddr_clk);
141	if (err) {
142		dev_err(priv.dev, "Unable to prepare ddrclk\n");
143		goto out_cpu;
144	}
145	kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
146
147	priv.powersave_clk = of_clk_get_by_name(np, "powersave");
148	if (IS_ERR(priv.powersave_clk)) {
149		dev_err(priv.dev, "Unable to get powersave\n");
150		err = PTR_ERR(priv.powersave_clk);
151		goto out_ddr;
152	}
153	err = clk_prepare_enable(priv.powersave_clk);
154	if (err) {
155		dev_err(priv.dev, "Unable to prepare powersave clk\n");
156		goto out_ddr;
157	}
158
159	err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
160	if (err) {
161		dev_err(priv.dev, "Failed to register cpufreq driver\n");
162		goto out_powersave;
163	}
164
165	of_node_put(np);
166	return 0;
167
168out_powersave:
169	clk_disable_unprepare(priv.powersave_clk);
170out_ddr:
171	clk_disable_unprepare(priv.ddr_clk);
172out_cpu:
173	clk_disable_unprepare(priv.cpu_clk);
174out_node:
175	of_node_put(np);
176
177	return err;
178}
179
180static void kirkwood_cpufreq_remove(struct platform_device *pdev)
181{
182	cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
183
184	clk_disable_unprepare(priv.powersave_clk);
185	clk_disable_unprepare(priv.ddr_clk);
186	clk_disable_unprepare(priv.cpu_clk);
187}
188
189static struct platform_driver kirkwood_cpufreq_platform_driver = {
190	.probe = kirkwood_cpufreq_probe,
191	.remove = kirkwood_cpufreq_remove,
192	.driver = {
193		.name = "kirkwood-cpufreq",
194	},
195};
196
197module_platform_driver(kirkwood_cpufreq_platform_driver);
198
199MODULE_LICENSE("GPL v2");
200MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
201MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
202MODULE_ALIAS("platform:kirkwood-cpufreq");