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/cpufreq.h>
16 #include <linux/of_device.h>
17 #include <linux/platform_device.h>
18 #include <linux/io.h>
19 #include <asm/proc-fns.h>
20
21 #define CPU_SW_INT_BLK BIT(28)
22
23 static struct priv
24 {
25 struct clk *cpu_clk;
26 struct clk *ddr_clk;
27 struct clk *powersave_clk;
28 struct device *dev;
29 void __iomem *base;
30 } priv;
31
32 #define STATE_CPU_FREQ 0x01
33 #define STATE_DDR_FREQ 0x02
34
35 /*
36 * Kirkwood can swap the clock to the CPU between two clocks:
37 *
38 * - cpu clk
39 * - ddr clk
40 *
41 * The frequencies are set at runtime before registering this table.
42 */
43 static struct cpufreq_frequency_table kirkwood_freq_table[] = {
44 {0, STATE_CPU_FREQ, 0}, /* CPU uses cpuclk */
45 {0, STATE_DDR_FREQ, 0}, /* CPU uses ddrclk */
46 {0, 0, CPUFREQ_TABLE_END},
47 };
48
kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)49 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
50 {
51 return clk_get_rate(priv.powersave_clk) / 1000;
52 }
53
kirkwood_cpufreq_target(struct cpufreq_policy * policy,unsigned int index)54 static int kirkwood_cpufreq_target(struct cpufreq_policy *policy,
55 unsigned int index)
56 {
57 unsigned int state = kirkwood_freq_table[index].driver_data;
58 unsigned long reg;
59
60 local_irq_disable();
61
62 /* Disable interrupts to the CPU */
63 reg = readl_relaxed(priv.base);
64 reg |= CPU_SW_INT_BLK;
65 writel_relaxed(reg, priv.base);
66
67 switch (state) {
68 case STATE_CPU_FREQ:
69 clk_set_parent(priv.powersave_clk, priv.cpu_clk);
70 break;
71 case STATE_DDR_FREQ:
72 clk_set_parent(priv.powersave_clk, priv.ddr_clk);
73 break;
74 }
75
76 /* Wait-for-Interrupt, while the hardware changes frequency */
77 cpu_do_idle();
78
79 /* Enable interrupts to the CPU */
80 reg = readl_relaxed(priv.base);
81 reg &= ~CPU_SW_INT_BLK;
82 writel_relaxed(reg, priv.base);
83
84 local_irq_enable();
85
86 return 0;
87 }
88
89 /* Module init and exit code */
kirkwood_cpufreq_cpu_init(struct cpufreq_policy * policy)90 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
91 {
92 return cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
93 }
94
95 static struct cpufreq_driver kirkwood_cpufreq_driver = {
96 .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
97 .get = kirkwood_cpufreq_get_cpu_frequency,
98 .verify = cpufreq_generic_frequency_table_verify,
99 .target_index = kirkwood_cpufreq_target,
100 .init = kirkwood_cpufreq_cpu_init,
101 .name = "kirkwood-cpufreq",
102 .attr = cpufreq_generic_attr,
103 };
104
kirkwood_cpufreq_probe(struct platform_device * pdev)105 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
106 {
107 struct device_node *np;
108 struct resource *res;
109 int err;
110
111 priv.dev = &pdev->dev;
112
113 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
114 priv.base = devm_ioremap_resource(&pdev->dev, res);
115 if (IS_ERR(priv.base))
116 return PTR_ERR(priv.base);
117
118 np = of_cpu_device_node_get(0);
119 if (!np) {
120 dev_err(&pdev->dev, "failed to get cpu device node\n");
121 return -ENODEV;
122 }
123
124 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
125 if (IS_ERR(priv.cpu_clk)) {
126 dev_err(priv.dev, "Unable to get cpuclk\n");
127 return PTR_ERR(priv.cpu_clk);
128 }
129
130 err = clk_prepare_enable(priv.cpu_clk);
131 if (err) {
132 dev_err(priv.dev, "Unable to prepare cpuclk\n");
133 return err;
134 }
135
136 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
137
138 priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
139 if (IS_ERR(priv.ddr_clk)) {
140 dev_err(priv.dev, "Unable to get ddrclk\n");
141 err = PTR_ERR(priv.ddr_clk);
142 goto out_cpu;
143 }
144
145 err = clk_prepare_enable(priv.ddr_clk);
146 if (err) {
147 dev_err(priv.dev, "Unable to prepare ddrclk\n");
148 goto out_cpu;
149 }
150 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
151
152 priv.powersave_clk = of_clk_get_by_name(np, "powersave");
153 if (IS_ERR(priv.powersave_clk)) {
154 dev_err(priv.dev, "Unable to get powersave\n");
155 err = PTR_ERR(priv.powersave_clk);
156 goto out_ddr;
157 }
158 err = clk_prepare_enable(priv.powersave_clk);
159 if (err) {
160 dev_err(priv.dev, "Unable to prepare powersave clk\n");
161 goto out_ddr;
162 }
163
164 of_node_put(np);
165 np = NULL;
166
167 err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
168 if (!err)
169 return 0;
170
171 dev_err(priv.dev, "Failed to register cpufreq driver\n");
172
173 clk_disable_unprepare(priv.powersave_clk);
174 out_ddr:
175 clk_disable_unprepare(priv.ddr_clk);
176 out_cpu:
177 clk_disable_unprepare(priv.cpu_clk);
178 of_node_put(np);
179
180 return err;
181 }
182
kirkwood_cpufreq_remove(struct platform_device * pdev)183 static int kirkwood_cpufreq_remove(struct platform_device *pdev)
184 {
185 cpufreq_unregister_driver(&kirkwood_cpufreq_driver);
186
187 clk_disable_unprepare(priv.powersave_clk);
188 clk_disable_unprepare(priv.ddr_clk);
189 clk_disable_unprepare(priv.cpu_clk);
190
191 return 0;
192 }
193
194 static struct platform_driver kirkwood_cpufreq_platform_driver = {
195 .probe = kirkwood_cpufreq_probe,
196 .remove = kirkwood_cpufreq_remove,
197 .driver = {
198 .name = "kirkwood-cpufreq",
199 },
200 };
201
202 module_platform_driver(kirkwood_cpufreq_platform_driver);
203
204 MODULE_LICENSE("GPL v2");
205 MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch");
206 MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU");
207 MODULE_ALIAS("platform:kirkwood-cpufreq");
208
