davinci-cpufreq.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * CPU frequency scaling for DaVinci
  4 *
  5 * Copyright (C) 2009 Texas Instruments Incorporated - https://www.ti.com/
  6 *
  7 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
  8 *
  9 *  Copyright (C) 2005 Nokia Corporation
 10 *  Written by Tony Lindgren <tony@atomide.com>
 11 *
 12 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
 13 *
 14 * Copyright (C) 2007-2008 Texas Instruments, Inc.
 15 * Updated to support OMAP3
 16 * Rajendra Nayak <rnayak@ti.com>
 17 */
 18#include <linux/types.h>
 19#include <linux/cpufreq.h>
 20#include <linux/init.h>
 21#include <linux/err.h>
 22#include <linux/clk.h>
 23#include <linux/platform_data/davinci-cpufreq.h>
 24#include <linux/platform_device.h>
 25#include <linux/export.h>
 26
 27struct davinci_cpufreq {
 28	struct device *dev;
 29	struct clk *armclk;
 30	struct clk *asyncclk;
 31	unsigned long asyncrate;
 32};
 33static struct davinci_cpufreq cpufreq;
 34
 35static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
 36{
 37	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 38	struct clk *armclk = cpufreq.armclk;
 39	unsigned int old_freq, new_freq;
 40	int ret = 0;
 41
 42	old_freq = policy->cur;
 43	new_freq = pdata->freq_table[idx].frequency;
 44
 45	/* if moving to higher frequency, up the voltage beforehand */
 46	if (pdata->set_voltage && new_freq > old_freq) {
 47		ret = pdata->set_voltage(idx);
 48		if (ret)
 49			return ret;
 50	}
 51
 52	ret = clk_set_rate(armclk, new_freq * 1000);
 53	if (ret)
 54		return ret;
 55
 56	if (cpufreq.asyncclk) {
 57		ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
 58		if (ret)
 59			return ret;
 60	}
 61
 62	/* if moving to lower freq, lower the voltage after lowering freq */
 63	if (pdata->set_voltage && new_freq < old_freq)
 64		pdata->set_voltage(idx);
 65
 66	return 0;
 67}
 68
 69static int davinci_cpu_init(struct cpufreq_policy *policy)
 70{
 71	int result = 0;
 72	struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 73	struct cpufreq_frequency_table *freq_table = pdata->freq_table;
 74
 75	if (policy->cpu != 0)
 76		return -EINVAL;
 77
 78	/* Finish platform specific initialization */
 79	if (pdata->init) {
 80		result = pdata->init();
 81		if (result)
 82			return result;
 83	}
 84
 85	policy->clk = cpufreq.armclk;
 86
 87	/*
 88	 * Time measurement across the target() function yields ~1500-1800us
 89	 * time taken with no drivers on notification list.
 90	 * Setting the latency to 2000 us to accommodate addition of drivers
 91	 * to pre/post change notification list.
 92	 */
 93	cpufreq_generic_init(policy, freq_table, 2000 * 1000);
 94	return 0;
 95}
 96
 97static struct cpufreq_driver davinci_driver = {
 98	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 99	.verify		= cpufreq_generic_frequency_table_verify,
100	.target_index	= davinci_target,
101	.get		= cpufreq_generic_get,
102	.init		= davinci_cpu_init,
103	.name		= "davinci",
104};
105
106static int __init davinci_cpufreq_probe(struct platform_device *pdev)
107{
108	struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
109	struct clk *asyncclk;
110
111	if (!pdata)
112		return -EINVAL;
113	if (!pdata->freq_table)
114		return -EINVAL;
115
116	cpufreq.dev = &pdev->dev;
117
118	cpufreq.armclk = clk_get(NULL, "arm");
119	if (IS_ERR(cpufreq.armclk)) {
120		dev_err(cpufreq.dev, "Unable to get ARM clock\n");
121		return PTR_ERR(cpufreq.armclk);
122	}
123
124	asyncclk = clk_get(cpufreq.dev, "async");
125	if (!IS_ERR(asyncclk)) {
126		cpufreq.asyncclk = asyncclk;
127		cpufreq.asyncrate = clk_get_rate(asyncclk);
128	}
129
130	return cpufreq_register_driver(&davinci_driver);
131}
132
133static void __exit davinci_cpufreq_remove(struct platform_device *pdev)
134{
135	cpufreq_unregister_driver(&davinci_driver);
136
137	clk_put(cpufreq.armclk);
138
139	if (cpufreq.asyncclk)
140		clk_put(cpufreq.asyncclk);
141}
142
143static struct platform_driver davinci_cpufreq_driver = {
144	.driver = {
145		.name	 = "cpufreq-davinci",
146	},
147	.remove = __exit_p(davinci_cpufreq_remove),
148};
149
150int __init davinci_cpufreq_init(void)
151{
152	return platform_driver_probe(&davinci_cpufreq_driver,
153							davinci_cpufreq_probe);
154}
155