xref: /openbmc/linux/drivers/clk/clk-scpi.c (revision 6de298ff) 
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 
17 struct 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 
26 static struct platform_device *cpufreq_dev;
27 
28 static 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 
36 static 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 
48 static 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 
56 static 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 */
63 static 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 
82 static 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 
96 static 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 
104 static 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 
115 static 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 
126 static 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 
132 static const struct of_device_id scpi_clk_match[] __maybe_unused = {
133 	{ .compatible = "arm,scpi-dvfs-clocks", .data = &scpi_dvfs_ops, },
134 	{ .compatible = "arm,scpi-variable-clocks", .data = &scpi_clk_ops, },
135 	{}
136 };
137 
138 static int
139 scpi_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 
170 struct scpi_clk_data {
171 	struct scpi_clk **clk;
172 	unsigned int clk_num;
173 };
174 
175 static struct clk_hw *
176 scpi_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 
191 static 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 
249 static void 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 }
262 
263 static int scpi_clocks_probe(struct platform_device *pdev)
264 {
265 	int ret;
266 	struct device *dev = &pdev->dev;
267 	struct device_node *child, *np = dev->of_node;
268 	const struct of_device_id *match;
269 
270 	if (!get_scpi_ops())
271 		return -ENXIO;
272 
273 	for_each_available_child_of_node(np, child) {
274 		match = of_match_node(scpi_clk_match, child);
275 		if (!match)
276 			continue;
277 		ret = scpi_clk_add(dev, child, match);
278 		if (ret) {
279 			scpi_clocks_remove(pdev);
280 			of_node_put(child);
281 			return ret;
282 		}
283 
284 		if (match->data != &scpi_dvfs_ops)
285 			continue;
286 		/* Add the virtual cpufreq device if it's DVFS clock provider */
287 		cpufreq_dev = platform_device_register_simple("scpi-cpufreq",
288 							      -1, NULL, 0);
289 		if (IS_ERR(cpufreq_dev))
290 			pr_warn("unable to register cpufreq device");
291 	}
292 	return 0;
293 }
294 
295 static const struct of_device_id scpi_clocks_ids[] = {
296 	{ .compatible = "arm,scpi-clocks", },
297 	{}
298 };
299 MODULE_DEVICE_TABLE(of, scpi_clocks_ids);
300 
301 static struct platform_driver scpi_clocks_driver = {
302 	.driver	= {
303 		.name = "scpi_clocks",
304 		.of_match_table = scpi_clocks_ids,
305 	},
306 	.probe = scpi_clocks_probe,
307 	.remove_new = scpi_clocks_remove,
308 };
309 module_platform_driver(scpi_clocks_driver);
310 
311 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
312 MODULE_DESCRIPTION("ARM SCPI clock driver");
313 MODULE_LICENSE("GPL v2");
314