clk-scpi.c

  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/platform_device.h>
 14#include <linux/scpi_protocol.h>
 15
 16struct scpi_clk {
 17	u32 id;
 18	struct clk_hw hw;
 19	struct scpi_dvfs_info *info;
 20	struct scpi_ops *scpi_ops;
 21};
 22
 23#define to_scpi_clk(clk) container_of(clk, struct scpi_clk, hw)
 24
 25static struct platform_device *cpufreq_dev;
 26
 27static unsigned long scpi_clk_recalc_rate(struct clk_hw *hw,
 28					  unsigned long parent_rate)
 29{
 30	struct scpi_clk *clk = to_scpi_clk(hw);
 31
 32	return clk->scpi_ops->clk_get_val(clk->id);
 33}
 34
 35static int scpi_clk_determine_rate(struct clk_hw *hw,
 36				   struct clk_rate_request *req)
 37{
 38	/*
 39	 * We can't figure out what rate it will be, so just return the
 40	 * rate back to the caller. scpi_clk_recalc_rate() will be called
 41	 * after the rate is set and we'll know what rate the clock is
 42	 * running at then.
 43	 */
 44	return 0;
 45}
 46
 47static int scpi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
 48			     unsigned long parent_rate)
 49{
 50	struct scpi_clk *clk = to_scpi_clk(hw);
 51
 52	return clk->scpi_ops->clk_set_val(clk->id, rate);
 53}
 54
 55static const struct clk_ops scpi_clk_ops = {
 56	.recalc_rate = scpi_clk_recalc_rate,
 57	.determine_rate = scpi_clk_determine_rate,
 58	.set_rate = scpi_clk_set_rate,
 59};
 60
 61/* find closest match to given frequency in OPP table */
 62static long __scpi_dvfs_round_rate(struct scpi_clk *clk, unsigned long rate)
 63{
 64	int idx;
 65	unsigned long fmin = 0, fmax = ~0, ftmp;
 66	const struct scpi_opp *opp = clk->info->opps;
 67
 68	for (idx = 0; idx < clk->info->count; idx++, opp++) {
 69		ftmp = opp->freq;
 70		if (ftmp >= rate) {
 71			if (ftmp <= fmax)
 72				fmax = ftmp;
 73			break;
 74		} else if (ftmp >= fmin) {
 75			fmin = ftmp;
 76		}
 77	}
 78	return fmax != ~0 ? fmax : fmin;
 79}
 80
 81static unsigned long scpi_dvfs_recalc_rate(struct clk_hw *hw,
 82					   unsigned long parent_rate)
 83{
 84	struct scpi_clk *clk = to_scpi_clk(hw);
 85	int idx = clk->scpi_ops->dvfs_get_idx(clk->id);
 86	const struct scpi_opp *opp;
 87
 88	if (idx < 0)
 89		return 0;
 90
 91	opp = clk->info->opps + idx;
 92	return opp->freq;
 93}
 94
 95static int scpi_dvfs_determine_rate(struct clk_hw *hw,
 96				    struct clk_rate_request *req)
 97{
 98	struct scpi_clk *clk = to_scpi_clk(hw);
 99
100	req->rate = __scpi_dvfs_round_rate(clk, req->rate);
101
102	return 0;
103}
104
105static int __scpi_find_dvfs_index(struct scpi_clk *clk, unsigned long rate)
106{
107	int idx, max_opp = clk->info->count;
108	const struct scpi_opp *opp = clk->info->opps;
109
110	for (idx = 0; idx < max_opp; idx++, opp++)
111		if (opp->freq == rate)
112			return idx;
113	return -EINVAL;
114}
115
116static int scpi_dvfs_set_rate(struct clk_hw *hw, unsigned long rate,
117			      unsigned long parent_rate)
118{
119	struct scpi_clk *clk = to_scpi_clk(hw);
120	int ret = __scpi_find_dvfs_index(clk, rate);
121
122	if (ret < 0)
123		return ret;
124	return clk->scpi_ops->dvfs_set_idx(clk->id, (u8)ret);
125}
126
127static const struct clk_ops scpi_dvfs_ops = {
128	.recalc_rate = scpi_dvfs_recalc_rate,
129	.determine_rate = scpi_dvfs_determine_rate,
130	.set_rate = scpi_dvfs_set_rate,
131};
132
133static const struct of_device_id scpi_clk_match[] __maybe_unused = {
134	{ .compatible = "arm,scpi-dvfs-clocks", .data = &scpi_dvfs_ops, },
135	{ .compatible = "arm,scpi-variable-clocks", .data = &scpi_clk_ops, },
136	{}
137};
138
139static int
140scpi_clk_ops_init(struct device *dev, const struct of_device_id *match,
141		  struct scpi_clk *sclk, const char *name)
142{
143	struct clk_init_data init;
144	unsigned long min = 0, max = 0;
145	int ret;
146
147	init.name = name;
148	init.flags = 0;
149	init.num_parents = 0;
150	init.ops = match->data;
151	sclk->hw.init = &init;
152	sclk->scpi_ops = get_scpi_ops();
153
154	if (init.ops == &scpi_dvfs_ops) {
155		sclk->info = sclk->scpi_ops->dvfs_get_info(sclk->id);
156		if (IS_ERR(sclk->info))
157			return PTR_ERR(sclk->info);
158	} else if (init.ops == &scpi_clk_ops) {
159		if (sclk->scpi_ops->clk_get_range(sclk->id, &min, &max) || !max)
160			return -EINVAL;
161	} else {
162		return -EINVAL;
163	}
164
165	ret = devm_clk_hw_register(dev, &sclk->hw);
166	if (!ret && max)
167		clk_hw_set_rate_range(&sclk->hw, min, max);
168	return ret;
169}
170
171struct scpi_clk_data {
172	struct scpi_clk **clk;
173	unsigned int clk_num;
174};
175
176static struct clk_hw *
177scpi_of_clk_src_get(struct of_phandle_args *clkspec, void *data)
178{
179	struct scpi_clk *sclk;
180	struct scpi_clk_data *clk_data = data;
181	unsigned int idx = clkspec->args[0], count;
182
183	for (count = 0; count < clk_data->clk_num; count++) {
184		sclk = clk_data->clk[count];
185		if (idx == sclk->id)
186			return &sclk->hw;
187	}
188
189	return ERR_PTR(-EINVAL);
190}
191
192static int scpi_clk_add(struct device *dev, struct device_node *np,
193			const struct of_device_id *match)
194{
195	int idx, count, err;
196	struct scpi_clk_data *clk_data;
197
198	count = of_property_count_strings(np, "clock-output-names");
199	if (count < 0) {
200		dev_err(dev, "%pOFn: invalid clock output count\n", np);
201		return -EINVAL;
202	}
203
204	clk_data = devm_kmalloc(dev, sizeof(*clk_data), GFP_KERNEL);
205	if (!clk_data)
206		return -ENOMEM;
207
208	clk_data->clk_num = count;
209	clk_data->clk = devm_kcalloc(dev, count, sizeof(*clk_data->clk),
210				     GFP_KERNEL);
211	if (!clk_data->clk)
212		return -ENOMEM;
213
214	for (idx = 0; idx < count; idx++) {
215		struct scpi_clk *sclk;
216		const char *name;
217		u32 val;
218
219		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
220		if (!sclk)
221			return -ENOMEM;
222
223		if (of_property_read_string_index(np, "clock-output-names",
224						  idx, &name)) {
225			dev_err(dev, "invalid clock name @ %pOFn\n", np);
226			return -EINVAL;
227		}
228
229		if (of_property_read_u32_index(np, "clock-indices",
230					       idx, &val)) {
231			dev_err(dev, "invalid clock index @ %pOFn\n", np);
232			return -EINVAL;
233		}
234
235		sclk->id = val;
236
237		err = scpi_clk_ops_init(dev, match, sclk, name);
238		if (err) {
239			dev_err(dev, "failed to register clock '%s'\n", name);
240			return err;
241		}
242
243		dev_dbg(dev, "Registered clock '%s'\n", name);
244		clk_data->clk[idx] = sclk;
245	}
246
247	return of_clk_add_hw_provider(np, scpi_of_clk_src_get, clk_data);
248}
249
250static void scpi_clocks_remove(struct platform_device *pdev)
251{
252	struct device *dev = &pdev->dev;
253	struct device_node *child, *np = dev->of_node;
254
255	if (cpufreq_dev) {
256		platform_device_unregister(cpufreq_dev);
257		cpufreq_dev = NULL;
258	}
259
260	for_each_available_child_of_node(np, child)
261		of_clk_del_provider(np);
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");