1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Hi6220 stub clock driver
4  *
5  * Copyright (c) 2015 Hisilicon Limited.
6  * Copyright (c) 2015 Linaro Limited.
7  *
8  * Author: Leo Yan <leo.yan@linaro.org>
9  */
10 
11 #include <linux/clk-provider.h>
12 #include <linux/err.h>
13 #include <linux/kernel.h>
14 #include <linux/mfd/syscon.h>
15 #include <linux/mailbox_client.h>
16 #include <linux/of.h>
17 #include <linux/platform_device.h>
18 #include <linux/regmap.h>
19 
20 /* Stub clocks id */
21 #define HI6220_STUB_ACPU0		0
22 #define HI6220_STUB_ACPU1		1
23 #define HI6220_STUB_GPU			2
24 #define HI6220_STUB_DDR			5
25 
26 /* Mailbox message */
27 #define HI6220_MBOX_MSG_LEN		8
28 
29 #define HI6220_MBOX_FREQ		0xA
30 #define HI6220_MBOX_CMD_SET		0x3
31 #define HI6220_MBOX_OBJ_AP		0x0
32 
33 /* CPU dynamic frequency scaling */
34 #define ACPU_DFS_FREQ_MAX		0x1724
35 #define ACPU_DFS_CUR_FREQ		0x17CC
36 #define ACPU_DFS_FLAG			0x1B30
37 #define ACPU_DFS_FREQ_REQ		0x1B34
38 #define ACPU_DFS_FREQ_LMT		0x1B38
39 #define ACPU_DFS_LOCK_FLAG		0xAEAEAEAE
40 
41 #define to_stub_clk(hw) container_of(hw, struct hi6220_stub_clk, hw)
42 
43 struct hi6220_stub_clk {
44 	u32 id;
45 
46 	struct device *dev;
47 	struct clk_hw hw;
48 
49 	struct regmap *dfs_map;
50 	struct mbox_client cl;
51 	struct mbox_chan *mbox;
52 };
53 
54 struct hi6220_mbox_msg {
55 	unsigned char type;
56 	unsigned char cmd;
57 	unsigned char obj;
58 	unsigned char src;
59 	unsigned char para[4];
60 };
61 
62 union hi6220_mbox_data {
63 	unsigned int data[HI6220_MBOX_MSG_LEN];
64 	struct hi6220_mbox_msg msg;
65 };
66 
67 static unsigned int hi6220_acpu_get_freq(struct hi6220_stub_clk *stub_clk)
68 {
69 	unsigned int freq;
70 
71 	regmap_read(stub_clk->dfs_map, ACPU_DFS_CUR_FREQ, &freq);
72 	return freq;
73 }
74 
75 static int hi6220_acpu_set_freq(struct hi6220_stub_clk *stub_clk,
76 				unsigned int freq)
77 {
78 	union hi6220_mbox_data data;
79 
80 	/* set the frequency in sram */
81 	regmap_write(stub_clk->dfs_map, ACPU_DFS_FREQ_REQ, freq);
82 
83 	/* compound mailbox message */
84 	data.msg.type = HI6220_MBOX_FREQ;
85 	data.msg.cmd  = HI6220_MBOX_CMD_SET;
86 	data.msg.obj  = HI6220_MBOX_OBJ_AP;
87 	data.msg.src  = HI6220_MBOX_OBJ_AP;
88 
89 	mbox_send_message(stub_clk->mbox, &data);
90 	return 0;
91 }
92 
93 static int hi6220_acpu_round_freq(struct hi6220_stub_clk *stub_clk,
94 				  unsigned int freq)
95 {
96 	unsigned int limit_flag, limit_freq = UINT_MAX;
97 	unsigned int max_freq;
98 
99 	/* check the constrained frequency */
100 	regmap_read(stub_clk->dfs_map, ACPU_DFS_FLAG, &limit_flag);
101 	if (limit_flag == ACPU_DFS_LOCK_FLAG)
102 		regmap_read(stub_clk->dfs_map, ACPU_DFS_FREQ_LMT, &limit_freq);
103 
104 	/* check the supported maximum frequency */
105 	regmap_read(stub_clk->dfs_map, ACPU_DFS_FREQ_MAX, &max_freq);
106 
107 	/* calculate the real maximum frequency */
108 	max_freq = min(max_freq, limit_freq);
109 
110 	if (WARN_ON(freq > max_freq))
111 		freq = max_freq;
112 
113 	return freq;
114 }
115 
116 static unsigned long hi6220_stub_clk_recalc_rate(struct clk_hw *hw,
117 		unsigned long parent_rate)
118 {
119 	u32 rate = 0;
120 	struct hi6220_stub_clk *stub_clk = to_stub_clk(hw);
121 
122 	switch (stub_clk->id) {
123 	case HI6220_STUB_ACPU0:
124 		rate = hi6220_acpu_get_freq(stub_clk);
125 
126 		/* convert from kHz to Hz */
127 		rate *= 1000;
128 		break;
129 
130 	default:
131 		dev_err(stub_clk->dev, "%s: un-supported clock id %d\n",
132 			__func__, stub_clk->id);
133 		break;
134 	}
135 
136 	return rate;
137 }
138 
139 static int hi6220_stub_clk_set_rate(struct clk_hw *hw, unsigned long rate,
140 		unsigned long parent_rate)
141 {
142 	struct hi6220_stub_clk *stub_clk = to_stub_clk(hw);
143 	unsigned long new_rate = rate / 1000;  /* kHz */
144 	int ret = 0;
145 
146 	switch (stub_clk->id) {
147 	case HI6220_STUB_ACPU0:
148 		ret = hi6220_acpu_set_freq(stub_clk, new_rate);
149 		if (ret < 0)
150 			return ret;
151 
152 		break;
153 
154 	default:
155 		dev_err(stub_clk->dev, "%s: un-supported clock id %d\n",
156 			__func__, stub_clk->id);
157 		break;
158 	}
159 
160 	pr_debug("%s: set rate=%ldkHz\n", __func__, new_rate);
161 	return ret;
162 }
163 
164 static long hi6220_stub_clk_round_rate(struct clk_hw *hw, unsigned long rate,
165 		unsigned long *parent_rate)
166 {
167 	struct hi6220_stub_clk *stub_clk = to_stub_clk(hw);
168 	unsigned long new_rate = rate / 1000;  /* kHz */
169 
170 	switch (stub_clk->id) {
171 	case HI6220_STUB_ACPU0:
172 		new_rate = hi6220_acpu_round_freq(stub_clk, new_rate);
173 
174 		/* convert from kHz to Hz */
175 		new_rate *= 1000;
176 		break;
177 
178 	default:
179 		dev_err(stub_clk->dev, "%s: un-supported clock id %d\n",
180 			__func__, stub_clk->id);
181 		break;
182 	}
183 
184 	return new_rate;
185 }
186 
187 static const struct clk_ops hi6220_stub_clk_ops = {
188 	.recalc_rate	= hi6220_stub_clk_recalc_rate,
189 	.round_rate	= hi6220_stub_clk_round_rate,
190 	.set_rate	= hi6220_stub_clk_set_rate,
191 };
192 
193 static int hi6220_stub_clk_probe(struct platform_device *pdev)
194 {
195 	struct device *dev = &pdev->dev;
196 	struct clk_init_data init;
197 	struct hi6220_stub_clk *stub_clk;
198 	struct clk *clk;
199 	struct device_node *np = pdev->dev.of_node;
200 	int ret;
201 
202 	stub_clk = devm_kzalloc(dev, sizeof(*stub_clk), GFP_KERNEL);
203 	if (!stub_clk)
204 		return -ENOMEM;
205 
206 	stub_clk->dfs_map = syscon_regmap_lookup_by_phandle(np,
207 				"hisilicon,hi6220-clk-sram");
208 	if (IS_ERR(stub_clk->dfs_map)) {
209 		dev_err(dev, "failed to get sram regmap\n");
210 		return PTR_ERR(stub_clk->dfs_map);
211 	}
212 
213 	stub_clk->hw.init = &init;
214 	stub_clk->dev = dev;
215 	stub_clk->id = HI6220_STUB_ACPU0;
216 
217 	/* Use mailbox client with blocking mode */
218 	stub_clk->cl.dev = dev;
219 	stub_clk->cl.tx_done = NULL;
220 	stub_clk->cl.tx_block = true;
221 	stub_clk->cl.tx_tout = 500;
222 	stub_clk->cl.knows_txdone = false;
223 
224 	/* Allocate mailbox channel */
225 	stub_clk->mbox = mbox_request_channel(&stub_clk->cl, 0);
226 	if (IS_ERR(stub_clk->mbox)) {
227 		dev_err(dev, "failed get mailbox channel\n");
228 		return PTR_ERR(stub_clk->mbox);
229 	}
230 
231 	init.name = "acpu0";
232 	init.ops = &hi6220_stub_clk_ops;
233 	init.num_parents = 0;
234 	init.flags = 0;
235 
236 	clk = devm_clk_register(dev, &stub_clk->hw);
237 	if (IS_ERR(clk))
238 		return PTR_ERR(clk);
239 
240 	ret = of_clk_add_provider(np, of_clk_src_simple_get, clk);
241 	if (ret) {
242 		dev_err(dev, "failed to register OF clock provider\n");
243 		return ret;
244 	}
245 
246 	/* initialize buffer to zero */
247 	regmap_write(stub_clk->dfs_map, ACPU_DFS_FLAG, 0x0);
248 	regmap_write(stub_clk->dfs_map, ACPU_DFS_FREQ_REQ, 0x0);
249 	regmap_write(stub_clk->dfs_map, ACPU_DFS_FREQ_LMT, 0x0);
250 
251 	dev_dbg(dev, "Registered clock '%s'\n", init.name);
252 	return 0;
253 }
254 
255 static const struct of_device_id hi6220_stub_clk_of_match[] = {
256 	{ .compatible = "hisilicon,hi6220-stub-clk", },
257 	{}
258 };
259 
260 static struct platform_driver hi6220_stub_clk_driver = {
261 	.driver	= {
262 		.name = "hi6220-stub-clk",
263 		.of_match_table = hi6220_stub_clk_of_match,
264 	},
265 	.probe = hi6220_stub_clk_probe,
266 };
267 
268 static int __init hi6220_stub_clk_init(void)
269 {
270 	return platform_driver_register(&hi6220_stub_clk_driver);
271 }
272 subsys_initcall(hi6220_stub_clk_init);
273