xref: /linux/drivers/clk/clk-scmi.c (revision 52338415)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * System Control and Power Interface (SCMI) Protocol based clock driver
4  *
5  * Copyright (C) 2018 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 struct scmi_clk {
17 	u32 id;
18 	struct clk_hw hw;
19 	const struct scmi_clock_info *info;
20 	const struct scmi_handle *handle;
21 };
22 
23 #define to_scmi_clk(clk) container_of(clk, struct scmi_clk, hw)
24 
25 static unsigned long scmi_clk_recalc_rate(struct clk_hw *hw,
26 					  unsigned long parent_rate)
27 {
28 	int ret;
29 	u64 rate;
30 	struct scmi_clk *clk = to_scmi_clk(hw);
31 
32 	ret = clk->handle->clk_ops->rate_get(clk->handle, clk->id, &rate);
33 	if (ret)
34 		return 0;
35 	return rate;
36 }
37 
38 static long scmi_clk_round_rate(struct clk_hw *hw, unsigned long rate,
39 				unsigned long *parent_rate)
40 {
41 	u64 fmin, fmax, ftmp;
42 	struct scmi_clk *clk = to_scmi_clk(hw);
43 
44 	/*
45 	 * We can't figure out what rate it will be, so just return the
46 	 * rate back to the caller. scmi_clk_recalc_rate() will be called
47 	 * after the rate is set and we'll know what rate the clock is
48 	 * running at then.
49 	 */
50 	if (clk->info->rate_discrete)
51 		return rate;
52 
53 	fmin = clk->info->range.min_rate;
54 	fmax = clk->info->range.max_rate;
55 	if (rate <= fmin)
56 		return fmin;
57 	else if (rate >= fmax)
58 		return fmax;
59 
60 	ftmp = rate - fmin;
61 	ftmp += clk->info->range.step_size - 1; /* to round up */
62 	do_div(ftmp, clk->info->range.step_size);
63 
64 	return ftmp * clk->info->range.step_size + fmin;
65 }
66 
67 static int scmi_clk_set_rate(struct clk_hw *hw, unsigned long rate,
68 			     unsigned long parent_rate)
69 {
70 	struct scmi_clk *clk = to_scmi_clk(hw);
71 
72 	return clk->handle->clk_ops->rate_set(clk->handle, clk->id, rate);
73 }
74 
75 static int scmi_clk_enable(struct clk_hw *hw)
76 {
77 	struct scmi_clk *clk = to_scmi_clk(hw);
78 
79 	return clk->handle->clk_ops->enable(clk->handle, clk->id);
80 }
81 
82 static void scmi_clk_disable(struct clk_hw *hw)
83 {
84 	struct scmi_clk *clk = to_scmi_clk(hw);
85 
86 	clk->handle->clk_ops->disable(clk->handle, clk->id);
87 }
88 
89 static const struct clk_ops scmi_clk_ops = {
90 	.recalc_rate = scmi_clk_recalc_rate,
91 	.round_rate = scmi_clk_round_rate,
92 	.set_rate = scmi_clk_set_rate,
93 	/*
94 	 * We can't provide enable/disable callback as we can't perform the same
95 	 * in atomic context. Since the clock framework provides standard API
96 	 * clk_prepare_enable that helps cases using clk_enable in non-atomic
97 	 * context, it should be fine providing prepare/unprepare.
98 	 */
99 	.prepare = scmi_clk_enable,
100 	.unprepare = scmi_clk_disable,
101 };
102 
103 static int scmi_clk_ops_init(struct device *dev, struct scmi_clk *sclk)
104 {
105 	int ret;
106 	struct clk_init_data init = {
107 		.flags = CLK_GET_RATE_NOCACHE,
108 		.num_parents = 0,
109 		.ops = &scmi_clk_ops,
110 		.name = sclk->info->name,
111 	};
112 
113 	sclk->hw.init = &init;
114 	ret = devm_clk_hw_register(dev, &sclk->hw);
115 	if (!ret)
116 		clk_hw_set_rate_range(&sclk->hw, sclk->info->range.min_rate,
117 				      sclk->info->range.max_rate);
118 	return ret;
119 }
120 
121 static int scmi_clocks_probe(struct scmi_device *sdev)
122 {
123 	int idx, count, err;
124 	struct clk_hw **hws;
125 	struct clk_hw_onecell_data *clk_data;
126 	struct device *dev = &sdev->dev;
127 	struct device_node *np = dev->of_node;
128 	const struct scmi_handle *handle = sdev->handle;
129 
130 	if (!handle || !handle->clk_ops)
131 		return -ENODEV;
132 
133 	count = handle->clk_ops->count_get(handle);
134 	if (count < 0) {
135 		dev_err(dev, "%pOFn: invalid clock output count\n", np);
136 		return -EINVAL;
137 	}
138 
139 	clk_data = devm_kzalloc(dev, struct_size(clk_data, hws, count),
140 				GFP_KERNEL);
141 	if (!clk_data)
142 		return -ENOMEM;
143 
144 	clk_data->num = count;
145 	hws = clk_data->hws;
146 
147 	for (idx = 0; idx < count; idx++) {
148 		struct scmi_clk *sclk;
149 
150 		sclk = devm_kzalloc(dev, sizeof(*sclk), GFP_KERNEL);
151 		if (!sclk)
152 			return -ENOMEM;
153 
154 		sclk->info = handle->clk_ops->info_get(handle, idx);
155 		if (!sclk->info) {
156 			dev_dbg(dev, "invalid clock info for idx %d\n", idx);
157 			continue;
158 		}
159 
160 		sclk->id = idx;
161 		sclk->handle = handle;
162 
163 		err = scmi_clk_ops_init(dev, sclk);
164 		if (err) {
165 			dev_err(dev, "failed to register clock %d\n", idx);
166 			devm_kfree(dev, sclk);
167 			hws[idx] = NULL;
168 		} else {
169 			dev_dbg(dev, "Registered clock:%s\n", sclk->info->name);
170 			hws[idx] = &sclk->hw;
171 		}
172 	}
173 
174 	return devm_of_clk_add_hw_provider(dev, of_clk_hw_onecell_get,
175 					   clk_data);
176 }
177 
178 static const struct scmi_device_id scmi_id_table[] = {
179 	{ SCMI_PROTOCOL_CLOCK },
180 	{ },
181 };
182 MODULE_DEVICE_TABLE(scmi, scmi_id_table);
183 
184 static struct scmi_driver scmi_clocks_driver = {
185 	.name = "scmi-clocks",
186 	.probe = scmi_clocks_probe,
187 	.id_table = scmi_id_table,
188 };
189 module_scmi_driver(scmi_clocks_driver);
190 
191 MODULE_AUTHOR("Sudeep Holla <sudeep.holla@arm.com>");
192 MODULE_DESCRIPTION("ARM SCMI clock driver");
193 MODULE_LICENSE("GPL v2");
194