xref: /openbmc/linux/drivers/clk/clk-scpi.c (revision a96cbb14)
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 
16 struct 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 
25 static struct platform_device *cpufreq_dev;
26 
scpi_clk_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)27 static 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 
scpi_clk_round_rate(struct clk_hw * hw,unsigned long rate,unsigned long * parent_rate)35 static long scpi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
36 				unsigned long *parent_rate)
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 rate;
45 }
46 
scpi_clk_set_rate(struct clk_hw * hw,unsigned long rate,unsigned long parent_rate)47 static 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 
55 static const struct clk_ops scpi_clk_ops = {
56 	.recalc_rate = scpi_clk_recalc_rate,
57 	.round_rate = scpi_clk_round_rate,
58 	.set_rate = scpi_clk_set_rate,
59 };
60 
61 /* find closest match to given frequency in OPP table */
__scpi_dvfs_round_rate(struct scpi_clk * clk,unsigned long rate)62 static 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 
scpi_dvfs_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)81 static 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 
scpi_dvfs_round_rate(struct clk_hw * hw,unsigned long rate,unsigned long * parent_rate)95 static long scpi_dvfs_round_rate(struct clk_hw *hw, unsigned long rate,
96 				 unsigned long *parent_rate)
97 {
98 	struct scpi_clk *clk = to_scpi_clk(hw);
99 
100 	return __scpi_dvfs_round_rate(clk, rate);
101 }
102 
__scpi_find_dvfs_index(struct scpi_clk * clk,unsigned long rate)103 static int __scpi_find_dvfs_index(struct scpi_clk *clk, unsigned long rate)
104 {
105 	int idx, max_opp = clk->info->count;
106 	const struct scpi_opp *opp = clk->info->opps;
107 
108 	for (idx = 0; idx < max_opp; idx++, opp++)
109 		if (opp->freq == rate)
110 			return idx;
111 	return -EINVAL;
112 }
113 
scpi_dvfs_set_rate(struct clk_hw * hw,unsigned long rate,unsigned long parent_rate)114 static int scpi_dvfs_set_rate(struct clk_hw *hw, unsigned long rate,
115 			      unsigned long parent_rate)
116 {
117 	struct scpi_clk *clk = to_scpi_clk(hw);
118 	int ret = __scpi_find_dvfs_index(clk, rate);
119 
120 	if (ret < 0)
121 		return ret;
122 	return clk->scpi_ops->dvfs_set_idx(clk->id, (u8)ret);
123 }
124 
125 static const struct clk_ops scpi_dvfs_ops = {
126 	.recalc_rate = scpi_dvfs_recalc_rate,
127 	.round_rate = scpi_dvfs_round_rate,
128 	.set_rate = scpi_dvfs_set_rate,
129 };
130 
131 static const struct of_device_id scpi_clk_match[] __maybe_unused = {
132 	{ .compatible = "arm,scpi-dvfs-clocks", .data = &scpi_dvfs_ops, },
133 	{ .compatible = "arm,scpi-variable-clocks", .data = &scpi_clk_ops, },
134 	{}
135 };
136 
137 static int
scpi_clk_ops_init(struct device * dev,const struct of_device_id * match,struct scpi_clk * sclk,const char * name)138 scpi_clk_ops_init(struct device *dev, const struct of_device_id *match,
139 		  struct scpi_clk *sclk, const char *name)
140 {
141 	struct clk_init_data init;
142 	unsigned long min = 0, max = 0;
143 	int ret;
144 
145 	init.name = name;
146 	init.flags = 0;
147 	init.num_parents = 0;
148 	init.ops = match->data;
149 	sclk->hw.init = &init;
150 	sclk->scpi_ops = get_scpi_ops();
151 
152 	if (init.ops == &scpi_dvfs_ops) {
153 		sclk->info = sclk->scpi_ops->dvfs_get_info(sclk->id);
154 		if (IS_ERR(sclk->info))
155 			return PTR_ERR(sclk->info);
156 	} else if (init.ops == &scpi_clk_ops) {
157 		if (sclk->scpi_ops->clk_get_range(sclk->id, &min, &max) || !max)
158 			return -EINVAL;
159 	} else {
160 		return -EINVAL;
161 	}
162 
163 	ret = devm_clk_hw_register(dev, &sclk->hw);
164 	if (!ret && max)
165 		clk_hw_set_rate_range(&sclk->hw, min, max);
166 	return ret;
167 }
168 
169 struct scpi_clk_data {
170 	struct scpi_clk **clk;
171 	unsigned int clk_num;
172 };
173 
174 static struct clk_hw *
scpi_of_clk_src_get(struct of_phandle_args * clkspec,void * data)175 scpi_of_clk_src_get(struct of_phandle_args *clkspec, void *data)
176 {
177 	struct scpi_clk *sclk;
178 	struct scpi_clk_data *clk_data = data;
179 	unsigned int idx = clkspec->args[0], count;
180 
181 	for (count = 0; count < clk_data->clk_num; count++) {
182 		sclk = clk_data->clk[count];
183 		if (idx == sclk->id)
184 			return &sclk->hw;
185 	}
186 
187 	return ERR_PTR(-EINVAL);
188 }
189 
scpi_clk_add(struct device * dev,struct device_node * np,const struct of_device_id * match)190 static int scpi_clk_add(struct device *dev, struct device_node *np,
191 			const struct of_device_id *match)
192 {
193 	int idx, count, err;
194 	struct scpi_clk_data *clk_data;
195 
196 	count = of_property_count_strings(np, "clock-output-names");
197 	if (count < 0) {
198 		dev_err(dev, "%pOFn: invalid clock output count\n", np);
199 		return -EINVAL;
200 	}
201 
202 	clk_data = devm_kmalloc(dev, sizeof(*clk_data), GFP_KERNEL);
203 	if (!clk_data)
204 		return -ENOMEM;
205 
206 	clk_data->clk_num = count;
207 	clk_data->clk = devm_kcalloc(dev, count, sizeof(*clk_data->clk),
208 				     GFP_KERNEL);
209 	if (!clk_data->clk)
210 		return -ENOMEM;
211 
212 	for (idx = 0; idx < count; idx++) {
213 		struct scpi_clk *sclk;
214 		const char *name;
215 		u32 val;
216 
217 		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
218 		if (!sclk)
219 			return -ENOMEM;
220 
221 		if (of_property_read_string_index(np, "clock-output-names",
222 						  idx, &name)) {
223 			dev_err(dev, "invalid clock name @ %pOFn\n", np);
224 			return -EINVAL;
225 		}
226 
227 		if (of_property_read_u32_index(np, "clock-indices",
228 					       idx, &val)) {
229 			dev_err(dev, "invalid clock index @ %pOFn\n", np);
230 			return -EINVAL;
231 		}
232 
233 		sclk->id = val;
234 
235 		err = scpi_clk_ops_init(dev, match, sclk, name);
236 		if (err) {
237 			dev_err(dev, "failed to register clock '%s'\n", name);
238 			return err;
239 		}
240 
241 		dev_dbg(dev, "Registered clock '%s'\n", name);
242 		clk_data->clk[idx] = sclk;
243 	}
244 
245 	return of_clk_add_hw_provider(np, scpi_of_clk_src_get, clk_data);
246 }
247 
scpi_clocks_remove(struct platform_device * pdev)248 static void scpi_clocks_remove(struct platform_device *pdev)
249 {
250 	struct device *dev = &pdev->dev;
251 	struct device_node *child, *np = dev->of_node;
252 
253 	if (cpufreq_dev) {
254 		platform_device_unregister(cpufreq_dev);
255 		cpufreq_dev = NULL;
256 	}
257 
258 	for_each_available_child_of_node(np, child)
259 		of_clk_del_provider(np);
260 }
261 
scpi_clocks_probe(struct platform_device * pdev)262 static int scpi_clocks_probe(struct platform_device *pdev)
263 {
264 	int ret;
265 	struct device *dev = &pdev->dev;
266 	struct device_node *child, *np = dev->of_node;
267 	const struct of_device_id *match;
268 
269 	if (!get_scpi_ops())
270 		return -ENXIO;
271 
272 	for_each_available_child_of_node(np, child) {
273 		match = of_match_node(scpi_clk_match, child);
274 		if (!match)
275 			continue;
276 		ret = scpi_clk_add(dev, child, match);
277 		if (ret) {
278 			scpi_clocks_remove(pdev);
279 			of_node_put(child);
280 			return ret;
281 		}
282 
283 		if (match->data != &scpi_dvfs_ops)
284 			continue;
285 		/* Add the virtual cpufreq device if it's DVFS clock provider */
286 		cpufreq_dev = platform_device_register_simple("scpi-cpufreq",
287 							      -1, NULL, 0);
288 		if (IS_ERR(cpufreq_dev))
289 			pr_warn("unable to register cpufreq device");
290 	}
291 	return 0;
292 }
293 
294 static const struct of_device_id scpi_clocks_ids[] = {
295 	{ .compatible = "arm,scpi-clocks", },
296 	{}
297 };
298 MODULE_DEVICE_TABLE(of, scpi_clocks_ids);
299 
300 static struct platform_driver scpi_clocks_driver = {
301 	.driver	= {
302 		.name = "scpi_clocks",
303 		.of_match_table = scpi_clocks_ids,
304 	},
305 	.probe = scpi_clocks_probe,
306 	.remove_new = scpi_clocks_remove,
307 };
308 module_platform_driver(scpi_clocks_driver);
309 
310 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
311 MODULE_DESCRIPTION("ARM SCPI clock driver");
312 MODULE_LICENSE("GPL v2");
313