1/*
  2 * CPU Frequency Scaling for Loongson 1 SoC
  3 *
  4 * Copyright (C) 2014 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
 23static struct {
 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} ls1x_cpufreq;
 32
 33static int ls1x_cpufreq_notifier(struct notifier_block *nb,
 34				 unsigned long val, void *data)
 35{
 36	if (val == CPUFREQ_POSTCHANGE)
 37		current_cpu_data.udelay_val = loops_per_jiffy;
 38
 39	return NOTIFY_OK;
 40}
 41
 42static struct notifier_block ls1x_cpufreq_notifier_block = {
 43	.notifier_call = ls1x_cpufreq_notifier
 44};
 45
 46static int ls1x_cpufreq_target(struct cpufreq_policy *policy,
 47			       unsigned int index)
 48{
 49	unsigned int old_freq, new_freq;
 50
 51	old_freq = policy->cur;
 52	new_freq = policy->freq_table[index].frequency;
 53
 54	/*
 55	 * The procedure of reconfiguring CPU clk is as below.
 56	 *
 57	 *  - Reparent CPU clk to OSC clk
 58	 *  - Reset CPU clock (very important)
 59	 *  - Reconfigure CPU DIV
 60	 *  - Reparent CPU clk back to CPU DIV clk
 61	 */
 62
 63	dev_dbg(ls1x_cpufreq.dev, "%u KHz --> %u KHz\n", old_freq, new_freq);
 64	clk_set_parent(policy->clk, ls1x_cpufreq.osc_clk);
 65	__raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) | RST_CPU_EN | RST_CPU,
 66		     LS1X_CLK_PLL_DIV);
 67	__raw_writel(__raw_readl(LS1X_CLK_PLL_DIV) & ~(RST_CPU_EN | RST_CPU),
 68		     LS1X_CLK_PLL_DIV);
 69	clk_set_rate(ls1x_cpufreq.mux_clk, new_freq * 1000);
 70	clk_set_parent(policy->clk, ls1x_cpufreq.mux_clk);
 71
 72	return 0;
 73}
 74
 75static int ls1x_cpufreq_init(struct cpufreq_policy *policy)
 76{
 77	struct cpufreq_frequency_table *freq_tbl;
 78	unsigned int pll_freq, freq;
 79	int steps, i, ret;
 80
 81	pll_freq = clk_get_rate(ls1x_cpufreq.pll_clk) / 1000;
 82
 83	steps = 1 << DIV_CPU_WIDTH;
 84	freq_tbl = kzalloc(sizeof(*freq_tbl) * steps, GFP_KERNEL);
 85	if (!freq_tbl) {
 86		dev_err(ls1x_cpufreq.dev,
 87			"failed to alloc cpufreq_frequency_table\n");
 88		ret = -ENOMEM;
 89		goto out;
 90	}
 91
 92	for (i = 0; i < (steps - 1); i++) {
 93		freq = pll_freq / (i + 1);
 94		if ((freq < ls1x_cpufreq.min_freq) ||
 95		    (freq > ls1x_cpufreq.max_freq))
 96			freq_tbl[i].frequency = CPUFREQ_ENTRY_INVALID;
 97		else
 98			freq_tbl[i].frequency = freq;
 99		dev_dbg(ls1x_cpufreq.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 = ls1x_cpufreq.clk;
106	ret = cpufreq_generic_init(policy, freq_tbl, 0);
107	if (ret)
108		kfree(freq_tbl);
109out:
110	return ret;
111}
112
113static int ls1x_cpufreq_exit(struct cpufreq_policy *policy)
114{
115	kfree(policy->freq_table);
116	return 0;
117}
118
119static struct cpufreq_driver ls1x_cpufreq_driver = {
120	.name		= "cpufreq-ls1x",
121	.flags		= CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
122	.verify		= cpufreq_generic_frequency_table_verify,
123	.target_index	= ls1x_cpufreq_target,
124	.get		= cpufreq_generic_get,
125	.init		= ls1x_cpufreq_init,
126	.exit		= ls1x_cpufreq_exit,
127	.attr		= cpufreq_generic_attr,
128};
129
130static int ls1x_cpufreq_remove(struct platform_device *pdev)
131{
132	cpufreq_unregister_notifier(&ls1x_cpufreq_notifier_block,
133				    CPUFREQ_TRANSITION_NOTIFIER);
134	cpufreq_unregister_driver(&ls1x_cpufreq_driver);
135
136	return 0;
137}
138
139static int ls1x_cpufreq_probe(struct platform_device *pdev)
140{
141	struct plat_ls1x_cpufreq *pdata = pdev->dev.platform_data;
142	struct clk *clk;
143	int ret;
144
145	if (!pdata || !pdata->clk_name || !pdata->osc_clk_name)
146		return -EINVAL;
147
148	ls1x_cpufreq.dev = &pdev->dev;
149
150	clk = devm_clk_get(&pdev->dev, pdata->clk_name);
151	if (IS_ERR(clk)) {
152		dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n",
153			pdata->clk_name);
154		ret = PTR_ERR(clk);
155		goto out;
156	}
157	ls1x_cpufreq.clk = clk;
158
159	clk = clk_get_parent(clk);
160	if (IS_ERR(clk)) {
161		dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n",
162			__clk_get_name(ls1x_cpufreq.clk));
163		ret = PTR_ERR(clk);
164		goto out;
165	}
166	ls1x_cpufreq.mux_clk = clk;
167
168	clk = clk_get_parent(clk);
169	if (IS_ERR(clk)) {
170		dev_err(ls1x_cpufreq.dev, "unable to get parent of %s clock\n",
171			__clk_get_name(ls1x_cpufreq.mux_clk));
172		ret = PTR_ERR(clk);
173		goto out;
174	}
175	ls1x_cpufreq.pll_clk = clk;
176
177	clk = devm_clk_get(&pdev->dev, pdata->osc_clk_name);
178	if (IS_ERR(clk)) {
179		dev_err(ls1x_cpufreq.dev, "unable to get %s clock\n",
180			pdata->osc_clk_name);
181		ret = PTR_ERR(clk);
182		goto out;
183	}
184	ls1x_cpufreq.osc_clk = clk;
185
186	ls1x_cpufreq.max_freq = pdata->max_freq;
187	ls1x_cpufreq.min_freq = pdata->min_freq;
188
189	ret = cpufreq_register_driver(&ls1x_cpufreq_driver);
190	if (ret) {
191		dev_err(ls1x_cpufreq.dev,
192			"failed to register cpufreq driver: %d\n", ret);
193		goto out;
194	}
195
196	ret = cpufreq_register_notifier(&ls1x_cpufreq_notifier_block,
197					CPUFREQ_TRANSITION_NOTIFIER);
198
199	if (!ret)
200		goto out;
201
202	dev_err(ls1x_cpufreq.dev, "failed to register cpufreq notifier: %d\n",
203		ret);
204
205	cpufreq_unregister_driver(&ls1x_cpufreq_driver);
206out:
207	return ret;
208}
209
210static struct platform_driver ls1x_cpufreq_platdrv = {
211	.driver = {
212		.name	= "ls1x-cpufreq",
213	},
214	.probe		= ls1x_cpufreq_probe,
215	.remove		= ls1x_cpufreq_remove,
216};
217
218module_platform_driver(ls1x_cpufreq_platdrv);
219
220MODULE_AUTHOR("Kelvin Cheung <keguang.zhang@gmail.com>");
221MODULE_DESCRIPTION("Loongson 1 CPUFreq driver");
222MODULE_LICENSE("GPL");