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_device.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
19 static 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 */
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},
43 };
44
kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)45 static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu)
46 {
47 return clk_get_rate(priv.powersave_clk) / 1000;
48 }
49
kirkwood_cpufreq_target(struct cpufreq_policy * policy,unsigned int index)50 static 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 */
kirkwood_cpufreq_cpu_init(struct cpufreq_policy * policy)86 static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy)
87 {
88 cpufreq_generic_init(policy, kirkwood_freq_table, 5000);
89 return 0;
90 }
91
92 static 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 .attr = cpufreq_generic_attr,
100 };
101
kirkwood_cpufreq_probe(struct platform_device * pdev)102 static int kirkwood_cpufreq_probe(struct platform_device *pdev)
103 {
104 struct device_node *np;
105 struct resource *res;
106 int err;
107
108 priv.dev = &pdev->dev;
109
110 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
111 priv.base = devm_ioremap_resource(&pdev->dev, res);
112 if (IS_ERR(priv.base))
113 return PTR_ERR(priv.base);
114
115 np = of_cpu_device_node_get(0);
116 if (!np) {
117 dev_err(&pdev->dev, "failed to get cpu device node\n");
118 return -ENODEV;
119 }
120
121 priv.cpu_clk = of_clk_get_by_name(np, "cpu_clk");
122 if (IS_ERR(priv.cpu_clk)) {
123 dev_err(priv.dev, "Unable to get cpuclk\n");
124 err = PTR_ERR(priv.cpu_clk);
125 goto out_node;
126 }
127
128 err = clk_prepare_enable(priv.cpu_clk);
129 if (err) {
130 dev_err(priv.dev, "Unable to prepare cpuclk\n");
131 goto out_node;
132 }
133
134 kirkwood_freq_table[0].frequency = clk_get_rate(priv.cpu_clk) / 1000;
135
136 priv.ddr_clk = of_clk_get_by_name(np, "ddrclk");
137 if (IS_ERR(priv.ddr_clk)) {
138 dev_err(priv.dev, "Unable to get ddrclk\n");
139 err = PTR_ERR(priv.ddr_clk);
140 goto out_cpu;
141 }
142
143 err = clk_prepare_enable(priv.ddr_clk);
144 if (err) {
145 dev_err(priv.dev, "Unable to prepare ddrclk\n");
146 goto out_cpu;
147 }
148 kirkwood_freq_table[1].frequency = clk_get_rate(priv.ddr_clk) / 1000;
149
150 priv.powersave_clk = of_clk_get_by_name(np, "powersave");
151 if (IS_ERR(priv.powersave_clk)) {
152 dev_err(priv.dev, "Unable to get powersave\n");
153 err = PTR_ERR(priv.powersave_clk);
154 goto out_ddr;
155 }
156 err = clk_prepare_enable(priv.powersave_clk);
157 if (err) {
158 dev_err(priv.dev, "Unable to prepare powersave clk\n");
159 goto out_ddr;
160 }
161
162 err = cpufreq_register_driver(&kirkwood_cpufreq_driver);
163 if (err) {
164 dev_err(priv.dev, "Failed to register cpufreq driver\n");
165 goto out_powersave;
166 }
167
168 of_node_put(np);
169 return 0;
170
171 out_powersave:
172 clk_disable_unprepare(priv.powersave_clk);
173 out_ddr:
174 clk_disable_unprepare(priv.ddr_clk);
175 out_cpu:
176 clk_disable_unprepare(priv.cpu_clk);
177 out_node:
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