1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * CPU frequency scaling for OMAP using OPP information |
4 | * |
5 | * Copyright (C) 2005 Nokia Corporation |
6 | * Written by Tony Lindgren <tony@atomide.com> |
7 | * |
8 | * Based on cpu-sa1110.c, Copyright (C) 2001 Russell King |
9 | * |
10 | * Copyright (C) 2007-2011 Texas Instruments, Inc. |
11 | * - OMAP3/4 support by Rajendra Nayak, Santosh Shilimkar |
12 | */ |
13 | |
14 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
15 | |
16 | #include <linux/types.h> |
17 | #include <linux/kernel.h> |
18 | #include <linux/sched.h> |
19 | #include <linux/cpufreq.h> |
20 | #include <linux/delay.h> |
21 | #include <linux/init.h> |
22 | #include <linux/err.h> |
23 | #include <linux/clk.h> |
24 | #include <linux/io.h> |
25 | #include <linux/pm_opp.h> |
26 | #include <linux/cpu.h> |
27 | #include <linux/module.h> |
28 | #include <linux/platform_device.h> |
29 | #include <linux/regulator/consumer.h> |
30 | |
31 | #include <asm/smp_plat.h> |
32 | #include <asm/cpu.h> |
33 | |
34 | /* OPP tolerance in percentage */ |
35 | #define OPP_TOLERANCE 4 |
36 | |
37 | static struct cpufreq_frequency_table *freq_table; |
38 | static atomic_t freq_table_users = ATOMIC_INIT(0); |
39 | static struct device *mpu_dev; |
40 | static struct regulator *mpu_reg; |
41 | |
42 | static int omap_target(struct cpufreq_policy *policy, unsigned int index) |
43 | { |
44 | int r, ret; |
45 | struct dev_pm_opp *opp; |
46 | unsigned long freq, volt = 0, volt_old = 0, tol = 0; |
47 | unsigned int old_freq, new_freq; |
48 | |
49 | old_freq = policy->cur; |
50 | new_freq = freq_table[index].frequency; |
51 | |
52 | freq = new_freq * 1000; |
53 | ret = clk_round_rate(clk: policy->clk, rate: freq); |
54 | if (ret < 0) { |
55 | dev_warn(mpu_dev, |
56 | "CPUfreq: Cannot find matching frequency for %lu\n" , |
57 | freq); |
58 | return ret; |
59 | } |
60 | freq = ret; |
61 | |
62 | if (mpu_reg) { |
63 | opp = dev_pm_opp_find_freq_ceil(dev: mpu_dev, freq: &freq); |
64 | if (IS_ERR(ptr: opp)) { |
65 | dev_err(mpu_dev, "%s: unable to find MPU OPP for %d\n" , |
66 | __func__, new_freq); |
67 | return -EINVAL; |
68 | } |
69 | volt = dev_pm_opp_get_voltage(opp); |
70 | dev_pm_opp_put(opp); |
71 | tol = volt * OPP_TOLERANCE / 100; |
72 | volt_old = regulator_get_voltage(regulator: mpu_reg); |
73 | } |
74 | |
75 | dev_dbg(mpu_dev, "cpufreq-omap: %u MHz, %ld mV --> %u MHz, %ld mV\n" , |
76 | old_freq / 1000, volt_old ? volt_old / 1000 : -1, |
77 | new_freq / 1000, volt ? volt / 1000 : -1); |
78 | |
79 | /* scaling up? scale voltage before frequency */ |
80 | if (mpu_reg && (new_freq > old_freq)) { |
81 | r = regulator_set_voltage(regulator: mpu_reg, min_uV: volt - tol, max_uV: volt + tol); |
82 | if (r < 0) { |
83 | dev_warn(mpu_dev, "%s: unable to scale voltage up.\n" , |
84 | __func__); |
85 | return r; |
86 | } |
87 | } |
88 | |
89 | ret = clk_set_rate(clk: policy->clk, rate: new_freq * 1000); |
90 | |
91 | /* scaling down? scale voltage after frequency */ |
92 | if (mpu_reg && (new_freq < old_freq)) { |
93 | r = regulator_set_voltage(regulator: mpu_reg, min_uV: volt - tol, max_uV: volt + tol); |
94 | if (r < 0) { |
95 | dev_warn(mpu_dev, "%s: unable to scale voltage down.\n" , |
96 | __func__); |
97 | clk_set_rate(clk: policy->clk, rate: old_freq * 1000); |
98 | return r; |
99 | } |
100 | } |
101 | |
102 | return ret; |
103 | } |
104 | |
105 | static inline void freq_table_free(void) |
106 | { |
107 | if (atomic_dec_and_test(v: &freq_table_users)) |
108 | dev_pm_opp_free_cpufreq_table(dev: mpu_dev, table: &freq_table); |
109 | } |
110 | |
111 | static int omap_cpu_init(struct cpufreq_policy *policy) |
112 | { |
113 | int result; |
114 | |
115 | policy->clk = clk_get(NULL, id: "cpufreq_ck" ); |
116 | if (IS_ERR(ptr: policy->clk)) |
117 | return PTR_ERR(ptr: policy->clk); |
118 | |
119 | if (!freq_table) { |
120 | result = dev_pm_opp_init_cpufreq_table(dev: mpu_dev, table: &freq_table); |
121 | if (result) { |
122 | dev_err(mpu_dev, |
123 | "%s: cpu%d: failed creating freq table[%d]\n" , |
124 | __func__, policy->cpu, result); |
125 | clk_put(clk: policy->clk); |
126 | return result; |
127 | } |
128 | } |
129 | |
130 | atomic_inc_return(v: &freq_table_users); |
131 | |
132 | /* FIXME: what's the actual transition time? */ |
133 | cpufreq_generic_init(policy, table: freq_table, transition_latency: 300 * 1000); |
134 | |
135 | return 0; |
136 | } |
137 | |
138 | static int omap_cpu_exit(struct cpufreq_policy *policy) |
139 | { |
140 | freq_table_free(); |
141 | clk_put(clk: policy->clk); |
142 | return 0; |
143 | } |
144 | |
145 | static struct cpufreq_driver omap_driver = { |
146 | .flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK, |
147 | .verify = cpufreq_generic_frequency_table_verify, |
148 | .target_index = omap_target, |
149 | .get = cpufreq_generic_get, |
150 | .init = omap_cpu_init, |
151 | .exit = omap_cpu_exit, |
152 | .register_em = cpufreq_register_em_with_opp, |
153 | .name = "omap" , |
154 | .attr = cpufreq_generic_attr, |
155 | }; |
156 | |
157 | static int omap_cpufreq_probe(struct platform_device *pdev) |
158 | { |
159 | mpu_dev = get_cpu_device(cpu: 0); |
160 | if (!mpu_dev) { |
161 | pr_warn("%s: unable to get the MPU device\n" , __func__); |
162 | return -EINVAL; |
163 | } |
164 | |
165 | mpu_reg = regulator_get(dev: mpu_dev, id: "vcc" ); |
166 | if (IS_ERR(ptr: mpu_reg)) { |
167 | pr_warn("%s: unable to get MPU regulator\n" , __func__); |
168 | mpu_reg = NULL; |
169 | } else { |
170 | /* |
171 | * Ensure physical regulator is present. |
172 | * (e.g. could be dummy regulator.) |
173 | */ |
174 | if (regulator_get_voltage(regulator: mpu_reg) < 0) { |
175 | pr_warn("%s: physical regulator not present for MPU\n" , |
176 | __func__); |
177 | regulator_put(regulator: mpu_reg); |
178 | mpu_reg = NULL; |
179 | } |
180 | } |
181 | |
182 | return cpufreq_register_driver(driver_data: &omap_driver); |
183 | } |
184 | |
185 | static void omap_cpufreq_remove(struct platform_device *pdev) |
186 | { |
187 | cpufreq_unregister_driver(driver_data: &omap_driver); |
188 | } |
189 | |
190 | static struct platform_driver omap_cpufreq_platdrv = { |
191 | .driver = { |
192 | .name = "omap-cpufreq" , |
193 | }, |
194 | .probe = omap_cpufreq_probe, |
195 | .remove_new = omap_cpufreq_remove, |
196 | }; |
197 | module_platform_driver(omap_cpufreq_platdrv); |
198 | |
199 | MODULE_DESCRIPTION("cpufreq driver for OMAP SoCs" ); |
200 | MODULE_LICENSE("GPL" ); |
201 | |