tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * kirkwood_freq.c: cpufreq driver for the Marvell kirkwood
3 *
4 * Copyright (C) 2013 Andrew Lunn <andrew@lunn.ch>
5 *
6 * This program is free software; you can redistribute it and/or
7 * modify it under the terms of the GNU General Public License
8 * as published by the Free Software Foundation; either version
9 * 2 of the License, or (at your option) any later version.
10 */
11
12#include <linux/kernel.h>
13#include <linux/module.h>
14#include <linux/clk.h>
15#include <linux/clk-provider.h>
16#include <linux/cpufreq.h>
17#include <linux/of_device.h>
18#include <linux/platform_device.h>
19#include <linux/io.h>
20#include <asm/proc-fns.h>
21
22#define CPU_SW_INT_BLK BIT(28)
23
24static struct priv
25{
26 struct clk *cpu_clk;
27 struct clk *ddr_clk;
28 struct clk *powersave_clk;
29 struct device *dev;
30 void __iomem *base;
31} priv;
32
33#define STATE_CPU_FREQ 0x01
34#define STATE_DDR_FREQ 0x02
35
36/*
37 * Kirkwood can swap the clock to the CPU between two clocks:
38 *
39 * - cpu clk
40 * - ddr clk
41 *
42 * The frequencies are set at runtime before registering this *
43 * table.
44 */
45static struct cpufreq_frequency_table kirkwood_freq_table[] = {
46 {0, STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */
47 {0, STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */
48 {0, 0, CPUFREQ_TABLE_END},
49};
50
51static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
52{
53 if (__clk_is_enabled(priv.powersave_clk))
54 return kirkwood_freq_table[1].frequency;
55 return kirkwood_freq_table[0].frequency;
56}
57
58static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
59 unsigned int index)
60{
61 unsigned int state = kirkwood_freq_table[index].driver_data;
62 unsigned long reg;
63
64 local_irq_disable();
65
66 /* Disable interrupts to the CPU */
67 reg = readl_relaxed(priv.base);
68 reg |= CPU_SW_INT_BLK;
69 writel_relaxed(reg, priv.base);
70
71 switch (state) {
72 case STATE_CPU_FREQ:
73 clk_disable(priv.powersave_clk);
74 break;
75 case STATE_DDR_FREQ:
76 clk_enable(priv.powersave_clk);
77 break;
78 }
79
80 /* Wait-for-Interrupt, while the hardware changes frequency */
81 cpu_do_idle();
82
83 /* Enable interrupts to the CPU */
84 reg = readl_relaxed(priv.base);
85 reg &= ~CPU_SW_INT_BLK;
86 writel_relaxed(reg, priv.base);
87
88 local_irq_enable();
89
90 return 0;
91}
92
93/* Module init and exit code */
94static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
95{
96 return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
97}
98
99static struct cpufreq_driver kirkwood_cpufreq_driver = {
100 .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
101 .get = kirkwood_cpufreq_get_cpu_frequency,
102 .verify = cpufreq_generic_frequency_table_verify,
103 .target_index = kirkwood_cpufreq_target,
104 .init = kirkwood_cpufreq_cpu_init,
105 .name = "kirkwood-cpufreq",
106 .attr = cpufreq_generic_attr,
107};
108
109static int kirkwood_cpufreq_probe(struct platform_device *pdev)
110{
111 struct device_node *np;
112 struct resource *res;
113 int err;
114
115 priv.dev = &pdev->dev;
116
117 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
118 priv.base = devm_ioremap_resource(&pdev->dev, res);
119 if (IS_ERR(priv.base))
120 return PTR_ERR(priv.base);
121
122 np = of_cpu_device_node_get(0);
123 if (!np) {
124 dev_err(&pdev->dev, "failed to get cpu device node\n");
125 return -ENODEV;
126 }
127
128 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
129 if (IS_ERR(priv.cpu_clk)) {
130 dev_err(priv.dev, "Unable to get cpuclk");
131 return PTR_ERR(priv.cpu_clk);
132 }
133
134 clk_prepare_enable(priv.cpu_clk);
135 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
136
137 priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
138 if (IS_ERR(priv.ddr_clk)) {
139 dev_err(priv.dev, "Unable to get ddrclk");
140 err = PTR_ERR(priv.ddr_clk);
141 goto out_cpu;
142 }
143
144 clk_prepare_enable(priv.ddr_clk);
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");
150 err = PTR_ERR(priv.powersave_clk);
151 goto out_ddr;
152 }
153 clk_prepare(priv.powersave_clk);
154
155 of_node_put(np);
156 np = NULL;
157
158 err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
159 if (!err)
160 return 0;
161
162 dev_err(priv.dev, "Failed to register cpufreq driver");
163
164 clk_disable_unprepare(priv.powersave_clk);
165out_ddr:
166 clk_disable_unprepare(priv.ddr_clk);
167out_cpu:
168 clk_disable_unprepare(priv.cpu_clk);
169 of_node_put(np);
170
171 return err;
172}
173
174static int kirkwood_cpufreq_remove(struct platform_device *pdev)
175{
176 cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
177
178 clk_disable_unprepare(priv.powersave_clk);
179 clk_disable_unprepare(priv.ddr_clk);
180 clk_disable_unprepare(priv.cpu_clk);
181
182 return 0;
183}
184
185static struct platform_driver kirkwood_cpufreq_platform_driver = {
186 .probe = kirkwood_cpufreq_probe,
187 .remove = kirkwood_cpufreq_remove,
188 .driver = {
189 .name = "kirkwood-cpufreq",
190 .owner = THIS_MODULE,
191 },
192};
193
194module_platform_driver(kirkwood_cpufreq_platform_driver);
195
196MODULE_LICENSE("GPL v2");
197MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
198MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
199MODULE_ALIAS("platform:kirkwood-cpufreq");