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 | |
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 | |
45 | static unsigned int kirkwood_cpufreq_get_cpu_frequency(unsigned int cpu) |
46 | { |
47 | return clk_get_rate(clk: priv.powersave_clk) / 1000; |
48 | } |
49 | |
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(clk: priv.powersave_clk, parent: priv.cpu_clk); |
66 | break; |
67 | case STATE_DDR_FREQ: |
68 | clk_set_parent(clk: priv.powersave_clk, parent: 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 */ |
86 | static int kirkwood_cpufreq_cpu_init(struct cpufreq_policy *policy) |
87 | { |
88 | cpufreq_generic_init(policy, table: kirkwood_freq_table, transition_latency: 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 | |
102 | static int kirkwood_cpufreq_probe(struct platform_device *pdev) |
103 | { |
104 | struct device_node *np; |
105 | int err; |
106 | |
107 | priv.dev = &pdev->dev; |
108 | |
109 | priv.base = devm_platform_ioremap_resource(pdev, index: 0); |
110 | if (IS_ERR(ptr: priv.base)) |
111 | return PTR_ERR(ptr: priv.base); |
112 | |
113 | np = of_cpu_device_node_get(cpu: 0); |
114 | if (!np) { |
115 | dev_err(&pdev->dev, "failed to get cpu device node\n" ); |
116 | return -ENODEV; |
117 | } |
118 | |
119 | priv.cpu_clk = of_clk_get_by_name(np, name: "cpu_clk" ); |
120 | if (IS_ERR(ptr: priv.cpu_clk)) { |
121 | dev_err(priv.dev, "Unable to get cpuclk\n" ); |
122 | err = PTR_ERR(ptr: priv.cpu_clk); |
123 | goto out_node; |
124 | } |
125 | |
126 | err = clk_prepare_enable(clk: priv.cpu_clk); |
127 | if (err) { |
128 | dev_err(priv.dev, "Unable to prepare cpuclk\n" ); |
129 | goto out_node; |
130 | } |
131 | |
132 | kirkwood_freq_table[0].frequency = clk_get_rate(clk: priv.cpu_clk) / 1000; |
133 | |
134 | priv.ddr_clk = of_clk_get_by_name(np, name: "ddrclk" ); |
135 | if (IS_ERR(ptr: priv.ddr_clk)) { |
136 | dev_err(priv.dev, "Unable to get ddrclk\n" ); |
137 | err = PTR_ERR(ptr: priv.ddr_clk); |
138 | goto out_cpu; |
139 | } |
140 | |
141 | err = clk_prepare_enable(clk: priv.ddr_clk); |
142 | if (err) { |
143 | dev_err(priv.dev, "Unable to prepare ddrclk\n" ); |
144 | goto out_cpu; |
145 | } |
146 | kirkwood_freq_table[1].frequency = clk_get_rate(clk: priv.ddr_clk) / 1000; |
147 | |
148 | priv.powersave_clk = of_clk_get_by_name(np, name: "powersave" ); |
149 | if (IS_ERR(ptr: priv.powersave_clk)) { |
150 | dev_err(priv.dev, "Unable to get powersave\n" ); |
151 | err = PTR_ERR(ptr: priv.powersave_clk); |
152 | goto out_ddr; |
153 | } |
154 | err = clk_prepare_enable(clk: priv.powersave_clk); |
155 | if (err) { |
156 | dev_err(priv.dev, "Unable to prepare powersave clk\n" ); |
157 | goto out_ddr; |
158 | } |
159 | |
160 | err = cpufreq_register_driver(driver_data: &kirkwood_cpufreq_driver); |
161 | if (err) { |
162 | dev_err(priv.dev, "Failed to register cpufreq driver\n" ); |
163 | goto out_powersave; |
164 | } |
165 | |
166 | of_node_put(node: np); |
167 | return 0; |
168 | |
169 | out_powersave: |
170 | clk_disable_unprepare(clk: priv.powersave_clk); |
171 | out_ddr: |
172 | clk_disable_unprepare(clk: priv.ddr_clk); |
173 | out_cpu: |
174 | clk_disable_unprepare(clk: priv.cpu_clk); |
175 | out_node: |
176 | of_node_put(node: np); |
177 | |
178 | return err; |
179 | } |
180 | |
181 | static void kirkwood_cpufreq_remove(struct platform_device *pdev) |
182 | { |
183 | cpufreq_unregister_driver(driver_data: &kirkwood_cpufreq_driver); |
184 | |
185 | clk_disable_unprepare(clk: priv.powersave_clk); |
186 | clk_disable_unprepare(clk: priv.ddr_clk); |
187 | clk_disable_unprepare(clk: priv.cpu_clk); |
188 | } |
189 | |
190 | static struct platform_driver kirkwood_cpufreq_platform_driver = { |
191 | .probe = kirkwood_cpufreq_probe, |
192 | .remove_new = kirkwood_cpufreq_remove, |
193 | .driver = { |
194 | .name = "kirkwood-cpufreq" , |
195 | }, |
196 | }; |
197 | |
198 | module_platform_driver(kirkwood_cpufreq_platform_driver); |
199 | |
200 | MODULE_LICENSE("GPL v2" ); |
201 | MODULE_AUTHOR("Andrew Lunn <andrew@lunn.ch" ); |
202 | MODULE_DESCRIPTION("cpufreq driver for Marvell's kirkwood CPU" ); |
203 | MODULE_ALIAS("platform:kirkwood-cpufreq" ); |
204 | |