1 | /* |
2 | * CPU frequency scaling for Broadcom BMIPS SoCs |
3 | * |
4 | * Copyright (c) 2017 Broadcom |
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 as |
8 | * published by the Free Software Foundation version 2. |
9 | * |
10 | * This program is distributed "as is" WITHOUT ANY WARRANTY of any |
11 | * kind, whether express or implied; without even the implied warranty |
12 | * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
13 | * GNU General Public License for more details. |
14 | */ |
15 | |
16 | #include <linux/cpufreq.h> |
17 | #include <linux/module.h> |
18 | #include <linux/of_address.h> |
19 | #include <linux/slab.h> |
20 | |
21 | /* for mips_hpt_frequency */ |
22 | #include <asm/time.h> |
23 | |
24 | #define BMIPS_CPUFREQ_PREFIX "bmips" |
25 | #define BMIPS_CPUFREQ_NAME BMIPS_CPUFREQ_PREFIX "-cpufreq" |
26 | |
27 | #define TRANSITION_LATENCY (25 * 1000) /* 25 us */ |
28 | |
29 | #define BMIPS5_CLK_DIV_SET_SHIFT 0x7 |
30 | #define BMIPS5_CLK_DIV_SHIFT 0x4 |
31 | #define BMIPS5_CLK_DIV_MASK 0xf |
32 | |
33 | enum bmips_type { |
34 | BMIPS5000, |
35 | BMIPS5200, |
36 | }; |
37 | |
38 | struct cpufreq_compat { |
39 | const char *compatible; |
40 | unsigned int bmips_type; |
41 | unsigned int clk_mult; |
42 | unsigned int max_freqs; |
43 | }; |
44 | |
45 | #define BMIPS(c, t, m, f) { \ |
46 | .compatible = c, \ |
47 | .bmips_type = (t), \ |
48 | .clk_mult = (m), \ |
49 | .max_freqs = (f), \ |
50 | } |
51 | |
52 | static struct cpufreq_compat bmips_cpufreq_compat[] = { |
53 | BMIPS("brcm,bmips5000" , BMIPS5000, 8, 4), |
54 | BMIPS("brcm,bmips5200" , BMIPS5200, 8, 4), |
55 | { } |
56 | }; |
57 | |
58 | static struct cpufreq_compat *priv; |
59 | |
60 | static int htp_freq_to_cpu_freq(unsigned int clk_mult) |
61 | { |
62 | return mips_hpt_frequency * clk_mult / 1000; |
63 | } |
64 | |
65 | static struct cpufreq_frequency_table * |
66 | bmips_cpufreq_get_freq_table(const struct cpufreq_policy *policy) |
67 | { |
68 | struct cpufreq_frequency_table *table; |
69 | unsigned long cpu_freq; |
70 | int i; |
71 | |
72 | cpu_freq = htp_freq_to_cpu_freq(clk_mult: priv->clk_mult); |
73 | |
74 | table = kmalloc_array(n: priv->max_freqs + 1, size: sizeof(*table), GFP_KERNEL); |
75 | if (!table) |
76 | return ERR_PTR(error: -ENOMEM); |
77 | |
78 | for (i = 0; i < priv->max_freqs; i++) { |
79 | table[i].frequency = cpu_freq / (1 << i); |
80 | table[i].driver_data = i; |
81 | } |
82 | table[i].frequency = CPUFREQ_TABLE_END; |
83 | |
84 | return table; |
85 | } |
86 | |
87 | static unsigned int bmips_cpufreq_get(unsigned int cpu) |
88 | { |
89 | unsigned int div; |
90 | uint32_t mode; |
91 | |
92 | switch (priv->bmips_type) { |
93 | case BMIPS5200: |
94 | case BMIPS5000: |
95 | mode = read_c0_brcm_mode(); |
96 | div = ((mode >> BMIPS5_CLK_DIV_SHIFT) & BMIPS5_CLK_DIV_MASK); |
97 | break; |
98 | default: |
99 | div = 0; |
100 | } |
101 | |
102 | return htp_freq_to_cpu_freq(clk_mult: priv->clk_mult) / (1 << div); |
103 | } |
104 | |
105 | static int bmips_cpufreq_target_index(struct cpufreq_policy *policy, |
106 | unsigned int index) |
107 | { |
108 | unsigned int div = policy->freq_table[index].driver_data; |
109 | |
110 | switch (priv->bmips_type) { |
111 | case BMIPS5200: |
112 | case BMIPS5000: |
113 | change_c0_brcm_mode(BMIPS5_CLK_DIV_MASK << BMIPS5_CLK_DIV_SHIFT, |
114 | (1 << BMIPS5_CLK_DIV_SET_SHIFT) | |
115 | (div << BMIPS5_CLK_DIV_SHIFT)); |
116 | break; |
117 | default: |
118 | return -ENOTSUPP; |
119 | } |
120 | |
121 | return 0; |
122 | } |
123 | |
124 | static int bmips_cpufreq_exit(struct cpufreq_policy *policy) |
125 | { |
126 | kfree(objp: policy->freq_table); |
127 | |
128 | return 0; |
129 | } |
130 | |
131 | static int bmips_cpufreq_init(struct cpufreq_policy *policy) |
132 | { |
133 | struct cpufreq_frequency_table *freq_table; |
134 | |
135 | freq_table = bmips_cpufreq_get_freq_table(policy); |
136 | if (IS_ERR(ptr: freq_table)) { |
137 | pr_err("%s: couldn't determine frequency table (%ld).\n" , |
138 | BMIPS_CPUFREQ_NAME, PTR_ERR(freq_table)); |
139 | return PTR_ERR(ptr: freq_table); |
140 | } |
141 | |
142 | cpufreq_generic_init(policy, table: freq_table, TRANSITION_LATENCY); |
143 | pr_info("%s: registered\n" , BMIPS_CPUFREQ_NAME); |
144 | |
145 | return 0; |
146 | } |
147 | |
148 | static struct cpufreq_driver bmips_cpufreq_driver = { |
149 | .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, |
150 | .verify = cpufreq_generic_frequency_table_verify, |
151 | .target_index = bmips_cpufreq_target_index, |
152 | .get = bmips_cpufreq_get, |
153 | .init = bmips_cpufreq_init, |
154 | .exit = bmips_cpufreq_exit, |
155 | .attr = cpufreq_generic_attr, |
156 | .name = BMIPS_CPUFREQ_PREFIX, |
157 | }; |
158 | |
159 | static int __init bmips_cpufreq_driver_init(void) |
160 | { |
161 | struct cpufreq_compat *cc; |
162 | struct device_node *np; |
163 | |
164 | for (cc = bmips_cpufreq_compat; cc->compatible; cc++) { |
165 | np = of_find_compatible_node(NULL, type: "cpu" , compat: cc->compatible); |
166 | if (np) { |
167 | of_node_put(node: np); |
168 | priv = cc; |
169 | break; |
170 | } |
171 | } |
172 | |
173 | /* We hit the guard element of the array. No compatible CPU found. */ |
174 | if (!cc->compatible) |
175 | return -ENODEV; |
176 | |
177 | return cpufreq_register_driver(driver_data: &bmips_cpufreq_driver); |
178 | } |
179 | module_init(bmips_cpufreq_driver_init); |
180 | |
181 | static void __exit bmips_cpufreq_driver_exit(void) |
182 | { |
183 | cpufreq_unregister_driver(driver_data: &bmips_cpufreq_driver); |
184 | } |
185 | module_exit(bmips_cpufreq_driver_exit); |
186 | |
187 | MODULE_AUTHOR("Markus Mayer <mmayer@broadcom.com>" ); |
188 | MODULE_DESCRIPTION("CPUfreq driver for Broadcom BMIPS SoCs" ); |
189 | MODULE_LICENSE("GPL" ); |
190 | |