1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * System Control and Power Interface (SCMI) Protocol based clock driver
4 *
5 * Copyright (C) 2018-2022 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/scmi_protocol.h>
14 #include <asm/div64.h>
15
16 static const struct scmi_clk_proto_ops *scmi_proto_clk_ops;
17
18 struct scmi_clk {
19 u32 id;
20 struct clk_hw hw;
21 const struct scmi_clock_info *info;
22 const struct scmi_protocol_handle *ph;
23 };
24
25 #define to_scmi_clk(clk) container_of(clk, struct scmi_clk, hw)
26
scmi_clk_recalc_rate(struct clk_hw * hw,unsigned long parent_rate)27 static unsigned long scmi_clk_recalc_rate(struct clk_hw *hw,
28 unsigned long parent_rate)
29 {
30 int ret;
31 u64 rate;
32 struct scmi_clk *clk = to_scmi_clk(hw);
33
34 ret = scmi_proto_clk_ops->rate_get(clk->ph, clk->id, &rate);
35 if (ret)
36 return 0;
37 return rate;
38 }
39
scmi_clk_round_rate(struct clk_hw * hw,unsigned long rate,unsigned long * parent_rate)40 static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
41 unsigned long *parent_rate)
42 {
43 u64 fmin, fmax, ftmp;
44 struct scmi_clk *clk = to_scmi_clk(hw);
45
46 /*
47 * We can't figure out what rate it will be, so just return the
48 * rate back to the caller. scmi_clk_recalc_rate() will be called
49 * after the rate is set and we'll know what rate the clock is
50 * running at then.
51 */
52 if (clk->info->rate_discrete)
53 return rate;
54
55 fmin = clk->info->range.min_rate;
56 fmax = clk->info->range.max_rate;
57 if (rate <= fmin)
58 return fmin;
59 else if (rate >= fmax)
60 return fmax;
61
62 ftmp = rate - fmin;
63 ftmp += clk->info->range.step_size - 1; /* to round up */
64 do_div(ftmp, clk->info->range.step_size);
65
66 return ftmp * clk->info->range.step_size + fmin;
67 }
68
scmi_clk_set_rate(struct clk_hw * hw,unsigned long rate,unsigned long parent_rate)69 static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
70 unsigned long parent_rate)
71 {
72 struct scmi_clk *clk = to_scmi_clk(hw);
73
74 return scmi_proto_clk_ops->rate_set(clk->ph, clk->id, rate);
75 }
76
scmi_clk_enable(struct clk_hw * hw)77 static int scmi_clk_enable(struct clk_hw *hw)
78 {
79 struct scmi_clk *clk = to_scmi_clk(hw);
80
81 return scmi_proto_clk_ops->enable(clk->ph, clk->id);
82 }
83
scmi_clk_disable(struct clk_hw * hw)84 static void scmi_clk_disable(struct clk_hw *hw)
85 {
86 struct scmi_clk *clk = to_scmi_clk(hw);
87
88 scmi_proto_clk_ops->disable(clk->ph, clk->id);
89 }
90
scmi_clk_atomic_enable(struct clk_hw * hw)91 static int scmi_clk_atomic_enable(struct clk_hw *hw)
92 {
93 struct scmi_clk *clk = to_scmi_clk(hw);
94
95 return scmi_proto_clk_ops->enable_atomic(clk->ph, clk->id);
96 }
97
scmi_clk_atomic_disable(struct clk_hw * hw)98 static void scmi_clk_atomic_disable(struct clk_hw *hw)
99 {
100 struct scmi_clk *clk = to_scmi_clk(hw);
101
102 scmi_proto_clk_ops->disable_atomic(clk->ph, clk->id);
103 }
104
105 /*
106 * We can provide enable/disable atomic callbacks only if the underlying SCMI
107 * transport for an SCMI instance is configured to handle SCMI commands in an
108 * atomic manner.
109 *
110 * When no SCMI atomic transport support is available we instead provide only
111 * the prepare/unprepare API, as allowed by the clock framework when atomic
112 * calls are not available.
113 *
114 * Two distinct sets of clk_ops are provided since we could have multiple SCMI
115 * instances with different underlying transport quality, so they cannot be
116 * shared.
117 */
118 static const struct clk_ops scmi_clk_ops = {
119 .recalc_rate = scmi_clk_recalc_rate,
120 .round_rate = scmi_clk_round_rate,
121 .set_rate = scmi_clk_set_rate,
122 .prepare = scmi_clk_enable,
123 .unprepare = scmi_clk_disable,
124 };
125
126 static const struct clk_ops scmi_atomic_clk_ops = {
127 .recalc_rate = scmi_clk_recalc_rate,
128 .round_rate = scmi_clk_round_rate,
129 .set_rate = scmi_clk_set_rate,
130 .enable = scmi_clk_atomic_enable,
131 .disable = scmi_clk_atomic_disable,
132 };
133
scmi_clk_ops_init(struct device * dev,struct scmi_clk * sclk,const struct clk_ops * scmi_ops)134 static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk,
135 const struct clk_ops *scmi_ops)
136 {
137 int ret;
138 unsigned long min_rate, max_rate;
139
140 struct clk_init_data init = {
141 .flags = CLK_GET_RATE_NOCACHE,
142 .num_parents = 0,
143 .ops = scmi_ops,
144 .name = sclk->info->name,
145 };
146
147 sclk->hw.init = &init;
148 ret = devm_clk_hw_register(dev, &sclk->hw);
149 if (ret)
150 return ret;
151
152 if (sclk->info->rate_discrete) {
153 int num_rates = sclk->info->list.num_rates;
154
155 if (num_rates <= 0)
156 return -EINVAL;
157
158 min_rate = sclk->info->list.rates[0];
159 max_rate = sclk->info->list.rates[num_rates - 1];
160 } else {
161 min_rate = sclk->info->range.min_rate;
162 max_rate = sclk->info->range.max_rate;
163 }
164
165 clk_hw_set_rate_range(&sclk->hw, min_rate, max_rate);
166 return ret;
167 }
168
scmi_clocks_probe(struct scmi_device * sdev)169 static int scmi_clocks_probe(struct scmi_device *sdev)
170 {
171 int idx, count, err;
172 unsigned int atomic_threshold;
173 bool is_atomic;
174 struct clk_hw **hws;
175 struct clk_hw_onecell_data *clk_data;
176 struct device *dev = &sdev->dev;
177 struct device_node *np = dev->of_node;
178 const struct scmi_handle *handle = sdev->handle;
179 struct scmi_protocol_handle *ph;
180
181 if (!handle)
182 return -ENODEV;
183
184 scmi_proto_clk_ops =
185 handle->devm_protocol_get(sdev, SCMI_PROTOCOL_CLOCK, &ph);
186 if (IS_ERR(scmi_proto_clk_ops))
187 return PTR_ERR(scmi_proto_clk_ops);
188
189 count = scmi_proto_clk_ops->count_get(ph);
190 if (count < 0) {
191 dev_err(dev, "%pOFn: invalid clock output count\n", np);
192 return -EINVAL;
193 }
194
195 clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, count),
196 GFP_KERNEL);
197 if (!clk_data)
198 return -ENOMEM;
199
200 clk_data->num = count;
201 hws = clk_data->hws;
202
203 is_atomic = handle->is_transport_atomic(handle, &atomic_threshold);
204
205 for (idx = 0; idx < count; idx++) {
206 struct scmi_clk *sclk;
207 const struct clk_ops *scmi_ops;
208
209 sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
210 if (!sclk)
211 return -ENOMEM;
212
213 sclk->info = scmi_proto_clk_ops->info_get(ph, idx);
214 if (!sclk->info) {
215 dev_dbg(dev, "invalid clock info for idx %d\n", idx);
216 devm_kfree(dev, sclk);
217 continue;
218 }
219
220 sclk->id = idx;
221 sclk->ph = ph;
222
223 /*
224 * Note that when transport is atomic but SCMI protocol did not
225 * specify (or support) an enable_latency associated with a
226 * clock, we default to use atomic operations mode.
227 */
228 if (is_atomic &&
229 sclk->info->enable_latency <= atomic_threshold)
230 scmi_ops = &scmi_atomic_clk_ops;
231 else
232 scmi_ops = &scmi_clk_ops;
233
234 err = scmi_clk_ops_init(dev, sclk, scmi_ops);
235 if (err) {
236 dev_err(dev, "failed to register clock %d\n", idx);
237 devm_kfree(dev, sclk);
238 hws[idx] = NULL;
239 } else {
240 dev_dbg(dev, "Registered clock:%s%s\n",
241 sclk->info->name,
242 scmi_ops == &scmi_atomic_clk_ops ?
243 " (atomic ops)" : "");
244 hws[idx] = &sclk->hw;
245 }
246 }
247
248 return devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
249 clk_data);
250 }
251
252 static const struct scmi_device_id scmi_id_table[] = {
253 { SCMI_PROTOCOL_CLOCK, "clocks" },
254 { },
255 };
256 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
257
258 static struct scmi_driver scmi_clocks_driver = {
259 .name = "scmi-clocks",
260 .probe = scmi_clocks_probe,
261 .id_table = scmi_id_table,
262 };
263 module_scmi_driver(scmi_clocks_driver);
264
265 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
266 MODULE_DESCRIPTION("ARM SCMI clock driver");
267 MODULE_LICENSE("GPL v2");
268