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
 18static 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
 30struct 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
 39static 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
 56static 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
 83static 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
118static 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
131static 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
139static 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
186put_pll_p:
187	clk_put(cpufreq->pll_p_clk);
188put_pll_x:
189	clk_put(cpufreq->pll_x_clk);
190put_cpu:
191	clk_put(cpufreq->cpu_clk);
192
193	return err;
194}
195
196static 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
209static struct platform_driver tegra20_cpufreq_driver = {
210	.probe		= tegra20_cpufreq_probe,
211	.remove		= tegra20_cpufreq_remove,
212	.driver		= {
213		.name	= "tegra20-cpufreq",
214	},
215};
216module_platform_driver(tegra20_cpufreq_driver);
217
218MODULE_ALIAS("platform:tegra20-cpufreq");
219MODULE_AUTHOR("Colin Cross <ccross@android.com>");
220MODULE_DESCRIPTION("NVIDIA Tegra20 cpufreq driver");
221MODULE_LICENSE("GPL");