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/module.h>
 17#include <linux/platform_device.h>
 18#include <linux/slab.h>
 19
 20#include <cpufreq.h>
 21#include <loongson1.h>
 22
 23struct ls1x_cpufreq {
 24	struct device *dev;
 25	struct clk *clk;	/* CPU clk */
 26	struct clk *mux_clk;	/* MUX of CPU clk */
 27	struct clk *pll_clk;	/* PLL clk */
 28	struct clk *osc_clk;	/* OSC clk */
 29	unsigned int max_freq;
 30	unsigned int min_freq;
 31};
 32
 33static struct ls1x_cpufreq *cpufreq;
 34
 35static int ls1x_cpufreq_notifier(struct notifier_block *nb,
 36				 unsigned long val, void *data)
 37{
 38	if (val == CPUFREQ_POSTCHANGE)
 39		current_cpu_data.udelay_val = loops_per_jiffy;
 40
 41	return NOTIFY_OK;
 42}
 43
 44static struct notifier_block ls1x_cpufreq_notifier_block = {
 45	.notifier_call = ls1x_cpufreq_notifier
 46};
 47
 48static int ls1x_cpufreq_target(struct cpufreq_policy *policy,
 49			       unsigned int index)
 50{
 51	struct device *cpu_dev = get_cpu_device(policy->cpu);
 52	unsigned int old_freq, new_freq;
 53
 54	old_freq = policy->cur;
 55	new_freq = policy->freq_table[index].frequency;
 56
 57	/*
 58	 * The procedure of reconfiguring CPU clk is as below.
 59	 *
 60	 *  - Reparent CPU clk to OSC clk
 61	 *  - Reset CPU clock (very important)
 62	 *  - Reconfigure CPU DIV
 63	 *  - Reparent CPU clk back to CPU DIV clk
 64	 */
 65
 66	clk_set_parent(policy->clk, cpufreq->osc_clk);
 67	__raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU,
 68		     LS1X_CLK_PLL_DIV);
 69	__raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU),
 70		     LS1X_CLK_PLL_DIV);
 71	clk_set_rate(cpufreq->mux_clk, new_freq * 1000);
 72	clk_set_parent(policy->clk, cpufreq->mux_clk);
 73	dev_dbg(cpu_dev, "%u KHz --> %u KHz\n", old_freq, new_freq);
 74
 75	return 0;
 76}
 77
 78static int ls1x_cpufreq_init(struct cpufreq_policy *policy)
 79{
 80	struct device *cpu_dev = get_cpu_device(policy->cpu);
 81	struct cpufreq_frequency_table *freq_tbl;
 82	unsigned int pll_freq, freq;
 83	int steps, i, ret;
 84
 85	pll_freq = clk_get_rate(cpufreq->pll_clk) / 1000;
 86
 87	steps = 1 << DIV_CPU_WIDTH;
 88	freq_tbl = kcalloc(steps, sizeof(*freq_tbl), GFP_KERNEL);
 89	if (!freq_tbl)
 90		return -ENOMEM;
 91
 92	for (i = 0; i < (steps - 1); i++) {
 93		freq = pll_freq / (i + 1);
 94		if ((freq < cpufreq->min_freq) || (freq > cpufreq->max_freq))
 95			freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
 96		else
 97			freq_tbl[i].frequency = freq;
 98		dev_dbg(cpu_dev,
 99			"cpufreq table: index %d: frequency %d\n", i,
100			freq_tbl[i].frequency);
101	}
102	freq_tbl[i].frequency = CPUFREQ_TABLE_END;
103
104	policy->clk = cpufreq->clk;
105	ret = cpufreq_generic_init(policy, freq_tbl, 0);
106	if (ret)
107		kfree(freq_tbl);
108
109	return ret;
110}
111
112static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
113{
114	kfree(policy->freq_table);
115	return 0;
116}
117
118static struct cpufreq_driver ls1x_cpufreq_driver = {
119	.name		= "cpufreq-ls1x",
120	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
121	.verify		= cpufreq_generic_frequency_table_verify,
122	.target_index	= ls1x_cpufreq_target,
123	.get		= cpufreq_generic_get,
124	.init		= ls1x_cpufreq_init,
125	.exit		= ls1x_cpufreq_exit,
126	.attr		= cpufreq_generic_attr,
127};
128
129static int ls1x_cpufreq_remove(struct platform_device *pdev)
130{
131	cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block,
132				    CPUFREQ_TRANSITION_NOTIFIER);
133	cpufreq_unregister_driver(&ls1x_cpufreq_driver);
134
135	return 0;
136}
137
138static int ls1x_cpufreq_probe(struct platform_device *pdev)
139{
140	struct plat_ls1x_cpufreq *pdata = dev_get_platdata(&pdev->dev);
141	struct clk *clk;
142	int ret;
143
144	if (!pdata || !pdata->clk_name || !pdata->osc_clk_name) {
145		dev_err(&pdev->dev, "platform data missing\n");
146		return -EINVAL;
147	}
148
149	cpufreq =
150	    devm_kzalloc(&pdev->dev, sizeof(struct ls1x_cpufreq), GFP_KERNEL);
151	if (!cpufreq)
152		return -ENOMEM;
153
154	cpufreq->dev = &pdev->dev;
155
156	clk = devm_clk_get(&pdev->dev, pdata->clk_name);
157	if (IS_ERR(clk)) {
158		dev_err(&pdev->dev, "unable to get %s clock\n",
159			pdata->clk_name);
160		return PTR_ERR(clk);
161	}
162	cpufreq->clk = clk;
163
164	clk = clk_get_parent(clk);
165	if (IS_ERR(clk)) {
166		dev_err(&pdev->dev, "unable to get parent of %s clock\n",
167			__clk_get_name(cpufreq->clk));
168		return PTR_ERR(clk);
169	}
170	cpufreq->mux_clk = clk;
171
172	clk = clk_get_parent(clk);
173	if (IS_ERR(clk)) {
174		dev_err(&pdev->dev, "unable to get parent of %s clock\n",
175			__clk_get_name(cpufreq->mux_clk));
176		return PTR_ERR(clk);
177	}
178	cpufreq->pll_clk = clk;
179
180	clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
181	if (IS_ERR(clk)) {
182		dev_err(&pdev->dev, "unable to get %s clock\n",
183			pdata->osc_clk_name);
184		return PTR_ERR(clk);
185	}
186	cpufreq->osc_clk = clk;
187
188	cpufreq->max_freq = pdata->max_freq;
189	cpufreq->min_freq = pdata->min_freq;
190
191	ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
192	if (ret) {
193		dev_err(&pdev->dev,
194			"failed to register CPUFreq driver: %d\n", ret);
195		return ret;
196	}
197
198	ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
199					CPUFREQ_TRANSITION_NOTIFIER);
200
201	if (ret) {
202		dev_err(&pdev->dev,
203			"failed to register CPUFreq notifier: %d\n",ret);
204		cpufreq_unregister_driver(&ls1x_cpufreq_driver);
205	}
206
207	return ret;
208}
209
210static struct platform_driver ls1x_cpufreq_platdrv = {
211	.probe	= ls1x_cpufreq_probe,
212	.remove	= ls1x_cpufreq_remove,
213	.driver	= {
214		.name	= "ls1x-cpufreq",
215	},
216};
217
218module_platform_driver(ls1x_cpufreq_platdrv);
219
220MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
221MODULE_DESCRIPTION("Loongson1 CPUFreq driver");
222MODULE_LICENSE("GPL");