1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2010 Google, Inc.
4 *
5 * Author:
6 * Colin Cross <ccross@google.com>
7 * Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
8 */
9
10 #include <linux/clk.h>
11 #include <linux/cpufreq.h>
12 #include <linux/err.h>
13 #include <linux/init.h>
14 #include <linux/module.h>
15 #include <linux/platform_device.h>
16 #include <linux/types.h>
17
18 static struct cpufreq_frequency_table freq_table[] = {
19 { .frequency = 216000 },
20 { .frequency = 312000 },
21 { .frequency = 456000 },
22 { .frequency = 608000 },
23 { .frequency = 760000 },
24 { .frequency = 816000 },
25 { .frequency = 912000 },
26 { .frequency = 1000000 },
27 { .frequency = CPUFREQ_TABLE_END },
28 };
29
30 struct tegra20_cpufreq {
31 struct device *dev;
32 struct cpufreq_driver driver;
33 struct clk *cpu_clk;
34 struct clk *pll_x_clk;
35 struct clk *pll_p_clk;
36 bool pll_x_prepared;
37 };
38
tegra_get_intermediate(struct cpufreq_policy * policy,unsigned int index)39 static unsigned int tegra_get_intermediate(struct cpufreq_policy *policy,
40 unsigned int index)
41 {
42 struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
43 unsigned int ifreq = clk_get_rate(cpufreq->pll_p_clk) / 1000;
44
45 /*
46 * Don't switch to intermediate freq if:
47 * - we are already at it, i.e. policy->cur == ifreq
48 * - index corresponds to ifreq
49 */
50 if (freq_table[index].frequency == ifreq || policy->cur == ifreq)
51 return 0;
52
53 return ifreq;
54 }
55
tegra_target_intermediate(struct cpufreq_policy * policy,unsigned int index)56 static int tegra_target_intermediate(struct cpufreq_policy *policy,
57 unsigned int index)
58 {
59 struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
60 int ret;
61
62 /*
63 * Take an extra reference to the main pll so it doesn't turn
64 * off when we move the cpu off of it as enabling it again while we
65 * switch to it from tegra_target() would take additional time.
66 *
67 * When target-freq is equal to intermediate freq we don't need to
68 * switch to an intermediate freq and so this routine isn't called.
69 * Also, we wouldn't be using pll_x anymore and must not take extra
70 * reference to it, as it can be disabled now to save some power.
71 */
72 clk_prepare_enable(cpufreq->pll_x_clk);
73
74 ret = clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_p_clk);
75 if (ret)
76 clk_disable_unprepare(cpufreq->pll_x_clk);
77 else
78 cpufreq->pll_x_prepared = true;
79
80 return ret;
81 }
82
tegra_target(struct cpufreq_policy * policy,unsigned int index)83 static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
84 {
85 struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
86 unsigned long rate = freq_table[index].frequency;
87 unsigned int ifreq = clk_get_rate(cpufreq->pll_p_clk) / 1000;
88 int ret;
89
90 /*
91 * target freq == pll_p, don't need to take extra reference to pll_x_clk
92 * as it isn't used anymore.
93 */
94 if (rate == ifreq)
95 return clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_p_clk);
96
97 ret = clk_set_rate(cpufreq->pll_x_clk, rate * 1000);
98 /* Restore to earlier frequency on error, i.e. pll_x */
99 if (ret)
100 dev_err(cpufreq->dev, "Failed to change pll_x to %lu\n", rate);
101
102 ret = clk_set_parent(cpufreq->cpu_clk, cpufreq->pll_x_clk);
103 /* This shouldn't fail while changing or restoring */
104 WARN_ON(ret);
105
106 /*
107 * Drop count to pll_x clock only if we switched to intermediate freq
108 * earlier while transitioning to a target frequency.
109 */
110 if (cpufreq->pll_x_prepared) {
111 clk_disable_unprepare(cpufreq->pll_x_clk);
112 cpufreq->pll_x_prepared = false;
113 }
114
115 return ret;
116 }
117
tegra_cpu_init(struct cpufreq_policy * policy)118 static int tegra_cpu_init(struct cpufreq_policy *policy)
119 {
120 struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
121
122 clk_prepare_enable(cpufreq->cpu_clk);
123
124 /* FIXME: what's the actual transition time? */
125 cpufreq_generic_init(policy, freq_table, 300 * 1000);
126 policy->clk = cpufreq->cpu_clk;
127 policy->suspend_freq = freq_table[0].frequency;
128 return 0;
129 }
130
tegra_cpu_exit(struct cpufreq_policy * policy)131 static int tegra_cpu_exit(struct cpufreq_policy *policy)
132 {
133 struct tegra20_cpufreq *cpufreq = cpufreq_get_driver_data();
134
135 clk_disable_unprepare(cpufreq->cpu_clk);
136 return 0;
137 }
138
tegra20_cpufreq_probe(struct platform_device * pdev)139 static int tegra20_cpufreq_probe(struct platform_device *pdev)
140 {
141 struct tegra20_cpufreq *cpufreq;
142 int err;
143
144 cpufreq = devm_kzalloc(&pdev->dev, sizeof(*cpufreq), GFP_KERNEL);
145 if (!cpufreq)
146 return -ENOMEM;
147
148 cpufreq->cpu_clk = clk_get_sys(NULL, "cclk");
149 if (IS_ERR(cpufreq->cpu_clk))
150 return PTR_ERR(cpufreq->cpu_clk);
151
152 cpufreq->pll_x_clk = clk_get_sys(NULL, "pll_x");
153 if (IS_ERR(cpufreq->pll_x_clk)) {
154 err = PTR_ERR(cpufreq->pll_x_clk);
155 goto put_cpu;
156 }
157
158 cpufreq->pll_p_clk = clk_get_sys(NULL, "pll_p");
159 if (IS_ERR(cpufreq->pll_p_clk)) {
160 err = PTR_ERR(cpufreq->pll_p_clk);
161 goto put_pll_x;
162 }
163
164 cpufreq->dev = &pdev->dev;
165 cpufreq->driver.get = cpufreq_generic_get;
166 cpufreq->driver.attr = cpufreq_generic_attr;
167 cpufreq->driver.init = tegra_cpu_init;
168 cpufreq->driver.exit = tegra_cpu_exit;
169 cpufreq->driver.flags = CPUFREQ_NEED_INITIAL_FREQ_CHECK;
170 cpufreq->driver.verify = cpufreq_generic_frequency_table_verify;
171 cpufreq->driver.suspend = cpufreq_generic_suspend;
172 cpufreq->driver.driver_data = cpufreq;
173 cpufreq->driver.target_index = tegra_target;
174 cpufreq->driver.get_intermediate = tegra_get_intermediate;
175 cpufreq->driver.target_intermediate = tegra_target_intermediate;
176 snprintf(cpufreq->driver.name, CPUFREQ_NAME_LEN, "tegra");
177
178 err = cpufreq_register_driver(&cpufreq->driver);
179 if (err)
180 goto put_pll_p;
181
182 platform_set_drvdata(pdev, cpufreq);
183
184 return 0;
185
186 put_pll_p:
187 clk_put(cpufreq->pll_p_clk);
188 put_pll_x:
189 clk_put(cpufreq->pll_x_clk);
190 put_cpu:
191 clk_put(cpufreq->cpu_clk);
192
193 return err;
194 }
195
tegra20_cpufreq_remove(struct platform_device * pdev)196 static int tegra20_cpufreq_remove(struct platform_device *pdev)
197 {
198 struct tegra20_cpufreq *cpufreq = platform_get_drvdata(pdev);
199
200 cpufreq_unregister_driver(&cpufreq->driver);
201
202 clk_put(cpufreq->pll_p_clk);
203 clk_put(cpufreq->pll_x_clk);
204 clk_put(cpufreq->cpu_clk);
205
206 return 0;
207 }
208
209 static struct platform_driver tegra20_cpufreq_driver = {
210 .probe = tegra20_cpufreq_probe,
211 .remove = tegra20_cpufreq_remove,
212 .driver = {
213 .name = "tegra20-cpufreq",
214 },
215 };
216 module_platform_driver(tegra20_cpufreq_driver);
217
218 MODULE_ALIAS("platform:tegra20-cpufreq");
219 MODULE_AUTHOR("Colin Cross <ccross@android.com>");
220 MODULE_DESCRIPTION("NVIDIA Tegra20 cpufreq driver");
221 MODULE_LICENSE("GPL");
222