1/*
  2 * CPU Frequency Scaling for Loongson 1 SoC
  3 *
  4 * Copyright (C) 2014-2016 Zhang, Keguang <keguang.zhang@gmail.com>
  5 *
  6 * This file is licensed under the terms of the GNU General Public
  7 * License version 2. This program is licensed "as is" without any
  8 * warranty of any kind, whether express or implied.
  9 */
 10
 11#include <linux/clk.h>
 12#include <linux/clk-provider.h>
 13#include <linux/cpu.h>
 14#include <linux/cpufreq.h>
 15#include <linux/delay.h>
 16#include <linux/io.h>
 17#include <linux/module.h>
 18#include <linux/platform_device.h>
 19#include <linux/slab.h>
 20
 21#include <cpufreq.h>
 22#include <loongson1.h>
 23
 24struct ls1x_cpufreq {
 25	struct device *dev;
 26	struct clk *clk;	/* CPU clk */
 27	struct clk *mux_clk;	/* MUX of CPU clk */
 28	struct clk *pll_clk;	/* PLL clk */
 29	struct clk *osc_clk;	/* OSC clk */
 30	unsigned int max_freq;
 31	unsigned int min_freq;
 32};
 33
 34static struct ls1x_cpufreq *cpufreq;
 35
 36static int ls1x_cpufreq_notifier(struct notifier_block *nb,
 37				 unsigned long val, void *data)
 38{
 39	if (val == CPUFREQ_POSTCHANGE)
 40		current_cpu_data.udelay_val = loops_per_jiffy;
 41
 42	return NOTIFY_OK;
 43}
 44
 45static struct notifier_block ls1x_cpufreq_notifier_block = {
 46	.notifier_call = ls1x_cpufreq_notifier
 47};
 48
 49static int ls1x_cpufreq_target(struct cpufreq_policy *policy,
 50			       unsigned int index)
 51{
 52	struct device *cpu_dev = get_cpu_device(policy->cpu);
 53	unsigned int old_freq, new_freq;
 54
 55	old_freq = policy->cur;
 56	new_freq = policy->freq_table[index].frequency;
 57
 58	/*
 59	 * The procedure of reconfiguring CPU clk is as below.
 60	 *
 61	 *  - Reparent CPU clk to OSC clk
 62	 *  - Reset CPU clock (very important)
 63	 *  - Reconfigure CPU DIV
 64	 *  - Reparent CPU clk back to CPU DIV clk
 65	 */
 66
 67	clk_set_parent(policy->clk, cpufreq->osc_clk);
 68	__raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU,
 69		     LS1X_CLK_PLL_DIV);
 70	__raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU),
 71		     LS1X_CLK_PLL_DIV);
 72	clk_set_rate(cpufreq->mux_clk, new_freq * 1000);
 73	clk_set_parent(policy->clk, cpufreq->mux_clk);
 74	dev_dbg(cpu_dev, "%u KHz --> %u KHz\n", old_freq, new_freq);
 75
 76	return 0;
 77}
 78
 79static int ls1x_cpufreq_init(struct cpufreq_policy *policy)
 80{
 81	struct device *cpu_dev = get_cpu_device(policy->cpu);
 82	struct cpufreq_frequency_table *freq_tbl;
 83	unsigned int pll_freq, freq;
 84	int steps, i;
 85
 86	pll_freq = clk_get_rate(cpufreq->pll_clk) / 1000;
 87
 88	steps = 1 << DIV_CPU_WIDTH;
 89	freq_tbl = kcalloc(steps, sizeof(*freq_tbl), GFP_KERNEL);
 90	if (!freq_tbl)
 91		return -ENOMEM;
 92
 93	for (i = 0; i < (steps - 1); i++) {
 94		freq = pll_freq / (i + 1);
 95		if ((freq < cpufreq->min_freq) || (freq > cpufreq->max_freq))
 96			freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
 97		else
 98			freq_tbl[i].frequency = freq;
 99		dev_dbg(cpu_dev,
100			"cpufreq table: index %d: frequency %d\n", i,
101			freq_tbl[i].frequency);
102	}
103	freq_tbl[i].frequency = CPUFREQ_TABLE_END;
104
105	policy->clk = cpufreq->clk;
106	cpufreq_generic_init(policy, freq_tbl, 0);
107
108	return 0;
109}
110
111static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
112{
113	kfree(policy->freq_table);
114	return 0;
115}
116
117static struct cpufreq_driver ls1x_cpufreq_driver = {
118	.name		= "cpufreq-ls1x",
119	.flags		= CPUFREQ_NEED_INITIAL_FREQ_CHECK,
120	.verify		= cpufreq_generic_frequency_table_verify,
121	.target_index	= ls1x_cpufreq_target,
122	.get		= cpufreq_generic_get,
123	.init		= ls1x_cpufreq_init,
124	.exit		= ls1x_cpufreq_exit,
125	.attr		= cpufreq_generic_attr,
126};
127
128static int ls1x_cpufreq_remove(struct platform_device *pdev)
129{
130	cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block,
131				    CPUFREQ_TRANSITION_NOTIFIER);
132	cpufreq_unregister_driver(&ls1x_cpufreq_driver);
133
134	return 0;
135}
136
137static int ls1x_cpufreq_probe(struct platform_device *pdev)
138{
139	struct plat_ls1x_cpufreq *pdata = dev_get_platdata(&pdev->dev);
140	struct clk *clk;
141	int ret;
142
143	if (!pdata || !pdata->clk_name || !pdata->osc_clk_name) {
144		dev_err(&pdev->dev, "platform data missing\n");
145		return -EINVAL;
146	}
147
148	cpufreq =
149	    devm_kzalloc(&pdev->dev, sizeof(struct ls1x_cpufreq), GFP_KERNEL);
150	if (!cpufreq)
151		return -ENOMEM;
152
153	cpufreq->dev = &pdev->dev;
154
155	clk = devm_clk_get(&pdev->dev, pdata->clk_name);
156	if (IS_ERR(clk)) {
157		dev_err(&pdev->dev, "unable to get %s clock\n",
158			pdata->clk_name);
159		return PTR_ERR(clk);
160	}
161	cpufreq->clk = clk;
162
163	clk = clk_get_parent(clk);
164	if (IS_ERR(clk)) {
165		dev_err(&pdev->dev, "unable to get parent of %s clock\n",
166			__clk_get_name(cpufreq->clk));
167		return PTR_ERR(clk);
168	}
169	cpufreq->mux_clk = clk;
170
171	clk = clk_get_parent(clk);
172	if (IS_ERR(clk)) {
173		dev_err(&pdev->dev, "unable to get parent of %s clock\n",
174			__clk_get_name(cpufreq->mux_clk));
175		return PTR_ERR(clk);
176	}
177	cpufreq->pll_clk = clk;
178
179	clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
180	if (IS_ERR(clk)) {
181		dev_err(&pdev->dev, "unable to get %s clock\n",
182			pdata->osc_clk_name);
183		return PTR_ERR(clk);
184	}
185	cpufreq->osc_clk = clk;
186
187	cpufreq->max_freq = pdata->max_freq;
188	cpufreq->min_freq = pdata->min_freq;
189
190	ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
191	if (ret) {
192		dev_err(&pdev->dev,
193			"failed to register CPUFreq driver: %d\n", ret);
194		return ret;
195	}
196
197	ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
198					CPUFREQ_TRANSITION_NOTIFIER);
199
200	if (ret) {
201		dev_err(&pdev->dev,
202			"failed to register CPUFreq notifier: %d\n",ret);
203		cpufreq_unregister_driver(&ls1x_cpufreq_driver);
204	}
205
206	return ret;
207}
208
209static struct platform_driver ls1x_cpufreq_platdrv = {
210	.probe	= ls1x_cpufreq_probe,
211	.remove	= ls1x_cpufreq_remove,
212	.driver	= {
213		.name	= "ls1x-cpufreq",
214	},
215};
216
217module_platform_driver(ls1x_cpufreq_platdrv);
218
219MODULE_ALIAS("platform:ls1x-cpufreq");
220MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
221MODULE_DESCRIPTION("Loongson1 CPUFreq driver");
222MODULE_LICENSE("GPL");