xref: /kernel/linux/linux-5.10/drivers/clk/clk-scpi.c (revision 8c2ecf20) 
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * System Control and Power Interface (SCPI) Protocol based clock driver
4 *
5 * Copyright (C) 2015 ARM Ltd.
6 */
7
8#include <linux/clk-provider.h>
9#include <linux/device.h>
10#include <linux/err.h>
11#include <linux/of.h>
12#include <linux/module.h>
13#include <linux/of_platform.h>
14#include <linux/platform_device.h>
15#include <linux/scpi_protocol.h>
16
17struct scpi_clk {
18	u32 id;
19	struct clk_hw hw;
20	struct scpi_dvfs_info *info;
21	struct scpi_ops *scpi_ops;
22};
23
24#define to_scpi_clk(clk) container_of(clk, struct scpi_clk, hw)
25
26static struct platform_device *cpufreq_dev;
27
28static unsigned long scpi_clk_recalc_rate(struct clk_hw *hw,
29					  unsigned long parent_rate)
30{
31	struct scpi_clk *clk = to_scpi_clk(hw);
32
33	return clk->scpi_ops->clk_get_val(clk->id);
34}
35
36static long scpi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
37				unsigned long *parent_rate)
38{
39	/*
40	 * We can't figure out what rate it will be, so just return the
41	 * rate back to the caller. scpi_clk_recalc_rate() will be called
42	 * after the rate is set and we'll know what rate the clock is
43	 * running at then.
44	 */
45	return rate;
46}
47
48static int scpi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
49			     unsigned long parent_rate)
50{
51	struct scpi_clk *clk = to_scpi_clk(hw);
52
53	return clk->scpi_ops->clk_set_val(clk->id, rate);
54}
55
56static const struct clk_ops scpi_clk_ops = {
57	.recalc_rate = scpi_clk_recalc_rate,
58	.round_rate = scpi_clk_round_rate,
59	.set_rate = scpi_clk_set_rate,
60};
61
62/* find closest match to given frequency in OPP table */
63static long __scpi_dvfs_round_rate(struct scpi_clk *clk, unsigned long rate)
64{
65	int idx;
66	unsigned long fmin = 0, fmax = ~0, ftmp;
67	const struct scpi_opp *opp = clk->info->opps;
68
69	for (idx = 0; idx < clk->info->count; idx++, opp++) {
70		ftmp = opp->freq;
71		if (ftmp >= rate) {
72			if (ftmp <= fmax)
73				fmax = ftmp;
74			break;
75		} else if (ftmp >= fmin) {
76			fmin = ftmp;
77		}
78	}
79	return fmax != ~0 ? fmax : fmin;
80}
81
82static unsigned long scpi_dvfs_recalc_rate(struct clk_hw *hw,
83					   unsigned long parent_rate)
84{
85	struct scpi_clk *clk = to_scpi_clk(hw);
86	int idx = clk->scpi_ops->dvfs_get_idx(clk->id);
87	const struct scpi_opp *opp;
88
89	if (idx < 0)
90		return 0;
91
92	opp = clk->info->opps + idx;
93	return opp->freq;
94}
95
96static long scpi_dvfs_round_rate(struct clk_hw *hw, unsigned long rate,
97				 unsigned long *parent_rate)
98{
99	struct scpi_clk *clk = to_scpi_clk(hw);
100
101	return __scpi_dvfs_round_rate(clk, rate);
102}
103
104static int __scpi_find_dvfs_index(struct scpi_clk *clk, unsigned long rate)
105{
106	int idx, max_opp = clk->info->count;
107	const struct scpi_opp *opp = clk->info->opps;
108
109	for (idx = 0; idx < max_opp; idx++, opp++)
110		if (opp->freq == rate)
111			return idx;
112	return -EINVAL;
113}
114
115static int scpi_dvfs_set_rate(struct clk_hw *hw, unsigned long rate,
116			      unsigned long parent_rate)
117{
118	struct scpi_clk *clk = to_scpi_clk(hw);
119	int ret = __scpi_find_dvfs_index(clk, rate);
120
121	if (ret < 0)
122		return ret;
123	return clk->scpi_ops->dvfs_set_idx(clk->id, (u8)ret);
124}
125
126static const struct clk_ops scpi_dvfs_ops = {
127	.recalc_rate = scpi_dvfs_recalc_rate,
128	.round_rate = scpi_dvfs_round_rate,
129	.set_rate = scpi_dvfs_set_rate,
130};
131
132static const struct of_device_id scpi_clk_match[] = {
133	{ .compatible = "arm,scpi-dvfs-clocks", .data = &scpi_dvfs_ops, },
134	{ .compatible = "arm,scpi-variable-clocks", .data = &scpi_clk_ops, },
135	{}
136};
137
138static int
139scpi_clk_ops_init(struct device *dev, const struct of_device_id *match,
140		  struct scpi_clk *sclk, const char *name)
141{
142	struct clk_init_data init;
143	unsigned long min = 0, max = 0;
144	int ret;
145
146	init.name = name;
147	init.flags = 0;
148	init.num_parents = 0;
149	init.ops = match->data;
150	sclk->hw.init = &init;
151	sclk->scpi_ops = get_scpi_ops();
152
153	if (init.ops == &scpi_dvfs_ops) {
154		sclk->info = sclk->scpi_ops->dvfs_get_info(sclk->id);
155		if (IS_ERR(sclk->info))
156			return PTR_ERR(sclk->info);
157	} else if (init.ops == &scpi_clk_ops) {
158		if (sclk->scpi_ops->clk_get_range(sclk->id, &min, &max) || !max)
159			return -EINVAL;
160	} else {
161		return -EINVAL;
162	}
163
164	ret = devm_clk_hw_register(dev, &sclk->hw);
165	if (!ret && max)
166		clk_hw_set_rate_range(&sclk->hw, min, max);
167	return ret;
168}
169
170struct scpi_clk_data {
171	struct scpi_clk **clk;
172	unsigned int clk_num;
173};
174
175static struct clk_hw *
176scpi_of_clk_src_get(struct of_phandle_args *clkspec, void *data)
177{
178	struct scpi_clk *sclk;
179	struct scpi_clk_data *clk_data = data;
180	unsigned int idx = clkspec->args[0], count;
181
182	for (count = 0; count < clk_data->clk_num; count++) {
183		sclk = clk_data->clk[count];
184		if (idx == sclk->id)
185			return &sclk->hw;
186	}
187
188	return ERR_PTR(-EINVAL);
189}
190
191static int scpi_clk_add(struct device *dev, struct device_node *np,
192			const struct of_device_id *match)
193{
194	int idx, count, err;
195	struct scpi_clk_data *clk_data;
196
197	count = of_property_count_strings(np, "clock-output-names");
198	if (count < 0) {
199		dev_err(dev, "%pOFn: invalid clock output count\n", np);
200		return -EINVAL;
201	}
202
203	clk_data = devm_kmalloc(dev, sizeof(*clk_data), GFP_KERNEL);
204	if (!clk_data)
205		return -ENOMEM;
206
207	clk_data->clk_num = count;
208	clk_data->clk = devm_kcalloc(dev, count, sizeof(*clk_data->clk),
209				     GFP_KERNEL);
210	if (!clk_data->clk)
211		return -ENOMEM;
212
213	for (idx = 0; idx < count; idx++) {
214		struct scpi_clk *sclk;
215		const char *name;
216		u32 val;
217
218		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
219		if (!sclk)
220			return -ENOMEM;
221
222		if (of_property_read_string_index(np, "clock-output-names",
223						  idx, &name)) {
224			dev_err(dev, "invalid clock name @ %pOFn\n", np);
225			return -EINVAL;
226		}
227
228		if (of_property_read_u32_index(np, "clock-indices",
229					       idx, &val)) {
230			dev_err(dev, "invalid clock index @ %pOFn\n", np);
231			return -EINVAL;
232		}
233
234		sclk->id = val;
235
236		err = scpi_clk_ops_init(dev, match, sclk, name);
237		if (err) {
238			dev_err(dev, "failed to register clock '%s'\n", name);
239			return err;
240		}
241
242		dev_dbg(dev, "Registered clock '%s'\n", name);
243		clk_data->clk[idx] = sclk;
244	}
245
246	return of_clk_add_hw_provider(np, scpi_of_clk_src_get, clk_data);
247}
248
249static int scpi_clocks_remove(struct platform_device *pdev)
250{
251	struct device *dev = &pdev->dev;
252	struct device_node *child, *np = dev->of_node;
253
254	if (cpufreq_dev) {
255		platform_device_unregister(cpufreq_dev);
256		cpufreq_dev = NULL;
257	}
258
259	for_each_available_child_of_node(np, child)
260		of_clk_del_provider(np);
261	return 0;
262}
263
264static int scpi_clocks_probe(struct platform_device *pdev)
265{
266	int ret;
267	struct device *dev = &pdev->dev;
268	struct device_node *child, *np = dev->of_node;
269	const struct of_device_id *match;
270
271	if (!get_scpi_ops())
272		return -ENXIO;
273
274	for_each_available_child_of_node(np, child) {
275		match = of_match_node(scpi_clk_match, child);
276		if (!match)
277			continue;
278		ret = scpi_clk_add(dev, child, match);
279		if (ret) {
280			scpi_clocks_remove(pdev);
281			of_node_put(child);
282			return ret;
283		}
284
285		if (match->data != &scpi_dvfs_ops)
286			continue;
287		/* Add the virtual cpufreq device if it's DVFS clock provider */
288		cpufreq_dev = platform_device_register_simple("scpi-cpufreq",
289							      -1, NULL, 0);
290		if (IS_ERR(cpufreq_dev))
291			pr_warn("unable to register cpufreq device");
292	}
293	return 0;
294}
295
296static const struct of_device_id scpi_clocks_ids[] = {
297	{ .compatible = "arm,scpi-clocks", },
298	{}
299};
300MODULE_DEVICE_TABLE(of, scpi_clocks_ids);
301
302static struct platform_driver scpi_clocks_driver = {
303	.driver	= {
304		.name = "scpi_clocks",
305		.of_match_table = scpi_clocks_ids,
306	},
307	.probe = scpi_clocks_probe,
308	.remove = scpi_clocks_remove,
309};
310module_platform_driver(scpi_clocks_driver);
311
312MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
313MODULE_DESCRIPTION("ARM SCPI clock driver");
314MODULE_LICENSE("GPL v2");
315