1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (C) 2019 NVIDIA CORPORATION.  All rights reserved.
4  */
5 
6 #include <linux/clk.h>
7 #include <linux/debugfs.h>
8 #include <linux/module.h>
9 #include <linux/mod_devicetable.h>
10 #include <linux/platform_device.h>
11 
12 #include <soc/tegra/bpmp.h>
13 
14 struct tegra186_emc_dvfs {
15 	unsigned long latency;
16 	unsigned long rate;
17 };
18 
19 struct tegra186_emc {
20 	struct tegra_bpmp *bpmp;
21 	struct device *dev;
22 	struct clk *clk;
23 
24 	struct tegra186_emc_dvfs *dvfs;
25 	unsigned int num_dvfs;
26 
27 	struct {
28 		struct dentry *root;
29 		unsigned long min_rate;
30 		unsigned long max_rate;
31 	} debugfs;
32 };
33 
34 /*
35  * debugfs interface
36  *
37  * The memory controller driver exposes some files in debugfs that can be used
38  * to control the EMC frequency. The top-level directory can be found here:
39  *
40  *   /sys/kernel/debug/emc
41  *
42  * It contains the following files:
43  *
44  *   - available_rates: This file contains a list of valid, space-separated
45  *     EMC frequencies.
46  *
47  *   - min_rate: Writing a value to this file sets the given frequency as the
48  *       floor of the permitted range. If this is higher than the currently
49  *       configured EMC frequency, this will cause the frequency to be
50  *       increased so that it stays within the valid range.
51  *
52  *   - max_rate: Similarily to the min_rate file, writing a value to this file
53  *       sets the given frequency as the ceiling of the permitted range. If
54  *       the value is lower than the currently configured EMC frequency, this
55  *       will cause the frequency to be decreased so that it stays within the
56  *       valid range.
57  */
58 
59 static bool tegra186_emc_validate_rate(struct tegra186_emc *emc,
60 				       unsigned long rate)
61 {
62 	unsigned int i;
63 
64 	for (i = 0; i < emc->num_dvfs; i++)
65 		if (rate == emc->dvfs[i].rate)
66 			return true;
67 
68 	return false;
69 }
70 
71 static int tegra186_emc_debug_available_rates_show(struct seq_file *s,
72 						   void *data)
73 {
74 	struct tegra186_emc *emc = s->private;
75 	const char *prefix = "";
76 	unsigned int i;
77 
78 	for (i = 0; i < emc->num_dvfs; i++) {
79 		seq_printf(s, "%s%lu", prefix, emc->dvfs[i].rate);
80 		prefix = " ";
81 	}
82 
83 	seq_puts(s, "\n");
84 
85 	return 0;
86 }
87 
88 static int tegra186_emc_debug_available_rates_open(struct inode *inode,
89 						   struct file *file)
90 {
91 	return single_open(file, tegra186_emc_debug_available_rates_show,
92 			   inode->i_private);
93 }
94 
95 static const struct file_operations tegra186_emc_debug_available_rates_fops = {
96 	.open = tegra186_emc_debug_available_rates_open,
97 	.read = seq_read,
98 	.llseek = seq_lseek,
99 	.release = single_release,
100 };
101 
102 static int tegra186_emc_debug_min_rate_get(void *data, u64 *rate)
103 {
104 	struct tegra186_emc *emc = data;
105 
106 	*rate = emc->debugfs.min_rate;
107 
108 	return 0;
109 }
110 
111 static int tegra186_emc_debug_min_rate_set(void *data, u64 rate)
112 {
113 	struct tegra186_emc *emc = data;
114 	int err;
115 
116 	if (!tegra186_emc_validate_rate(emc, rate))
117 		return -EINVAL;
118 
119 	err = clk_set_min_rate(emc->clk, rate);
120 	if (err < 0)
121 		return err;
122 
123 	emc->debugfs.min_rate = rate;
124 
125 	return 0;
126 }
127 
128 DEFINE_SIMPLE_ATTRIBUTE(tegra186_emc_debug_min_rate_fops,
129 			tegra186_emc_debug_min_rate_get,
130 			tegra186_emc_debug_min_rate_set, "%llu\n");
131 
132 static int tegra186_emc_debug_max_rate_get(void *data, u64 *rate)
133 {
134 	struct tegra186_emc *emc = data;
135 
136 	*rate = emc->debugfs.max_rate;
137 
138 	return 0;
139 }
140 
141 static int tegra186_emc_debug_max_rate_set(void *data, u64 rate)
142 {
143 	struct tegra186_emc *emc = data;
144 	int err;
145 
146 	if (!tegra186_emc_validate_rate(emc, rate))
147 		return -EINVAL;
148 
149 	err = clk_set_max_rate(emc->clk, rate);
150 	if (err < 0)
151 		return err;
152 
153 	emc->debugfs.max_rate = rate;
154 
155 	return 0;
156 }
157 
158 DEFINE_SIMPLE_ATTRIBUTE(tegra186_emc_debug_max_rate_fops,
159 			tegra186_emc_debug_max_rate_get,
160 			tegra186_emc_debug_max_rate_set, "%llu\n");
161 
162 static int tegra186_emc_probe(struct platform_device *pdev)
163 {
164 	struct mrq_emc_dvfs_latency_response response;
165 	struct tegra_bpmp_message msg;
166 	struct tegra186_emc *emc;
167 	unsigned int i;
168 	int err;
169 
170 	emc = devm_kzalloc(&pdev->dev, sizeof(*emc), GFP_KERNEL);
171 	if (!emc)
172 		return -ENOMEM;
173 
174 	emc->bpmp = tegra_bpmp_get(&pdev->dev);
175 	if (IS_ERR(emc->bpmp))
176 		return dev_err_probe(&pdev->dev, PTR_ERR(emc->bpmp), "failed to get BPMP\n");
177 
178 	emc->clk = devm_clk_get(&pdev->dev, "emc");
179 	if (IS_ERR(emc->clk)) {
180 		err = PTR_ERR(emc->clk);
181 		dev_err(&pdev->dev, "failed to get EMC clock: %d\n", err);
182 		goto put_bpmp;
183 	}
184 
185 	platform_set_drvdata(pdev, emc);
186 	emc->dev = &pdev->dev;
187 
188 	memset(&msg, 0, sizeof(msg));
189 	msg.mrq = MRQ_EMC_DVFS_LATENCY;
190 	msg.tx.data = NULL;
191 	msg.tx.size = 0;
192 	msg.rx.data = &response;
193 	msg.rx.size = sizeof(response);
194 
195 	err = tegra_bpmp_transfer(emc->bpmp, &msg);
196 	if (err < 0) {
197 		dev_err(&pdev->dev, "failed to EMC DVFS pairs: %d\n", err);
198 		goto put_bpmp;
199 	}
200 
201 	emc->debugfs.min_rate = ULONG_MAX;
202 	emc->debugfs.max_rate = 0;
203 
204 	emc->num_dvfs = response.num_pairs;
205 
206 	emc->dvfs = devm_kmalloc_array(&pdev->dev, emc->num_dvfs,
207 				       sizeof(*emc->dvfs), GFP_KERNEL);
208 	if (!emc->dvfs) {
209 		err = -ENOMEM;
210 		goto put_bpmp;
211 	}
212 
213 	dev_dbg(&pdev->dev, "%u DVFS pairs:\n", emc->num_dvfs);
214 
215 	for (i = 0; i < emc->num_dvfs; i++) {
216 		emc->dvfs[i].rate = response.pairs[i].freq * 1000;
217 		emc->dvfs[i].latency = response.pairs[i].latency;
218 
219 		if (emc->dvfs[i].rate < emc->debugfs.min_rate)
220 			emc->debugfs.min_rate = emc->dvfs[i].rate;
221 
222 		if (emc->dvfs[i].rate > emc->debugfs.max_rate)
223 			emc->debugfs.max_rate = emc->dvfs[i].rate;
224 
225 		dev_dbg(&pdev->dev, "  %2u: %lu Hz -> %lu us\n", i,
226 			emc->dvfs[i].rate, emc->dvfs[i].latency);
227 	}
228 
229 	err = clk_set_rate_range(emc->clk, emc->debugfs.min_rate,
230 				 emc->debugfs.max_rate);
231 	if (err < 0) {
232 		dev_err(&pdev->dev,
233 			"failed to set rate range [%lu-%lu] for %pC\n",
234 			emc->debugfs.min_rate, emc->debugfs.max_rate,
235 			emc->clk);
236 		goto put_bpmp;
237 	}
238 
239 	emc->debugfs.root = debugfs_create_dir("emc", NULL);
240 	debugfs_create_file("available_rates", S_IRUGO, emc->debugfs.root,
241 			    emc, &tegra186_emc_debug_available_rates_fops);
242 	debugfs_create_file("min_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
243 			    emc, &tegra186_emc_debug_min_rate_fops);
244 	debugfs_create_file("max_rate", S_IRUGO | S_IWUSR, emc->debugfs.root,
245 			    emc, &tegra186_emc_debug_max_rate_fops);
246 
247 	return 0;
248 
249 put_bpmp:
250 	tegra_bpmp_put(emc->bpmp);
251 	return err;
252 }
253 
254 static int tegra186_emc_remove(struct platform_device *pdev)
255 {
256 	struct tegra186_emc *emc = platform_get_drvdata(pdev);
257 
258 	debugfs_remove_recursive(emc->debugfs.root);
259 	tegra_bpmp_put(emc->bpmp);
260 
261 	return 0;
262 }
263 
264 static const struct of_device_id tegra186_emc_of_match[] = {
265 #if defined(CONFIG_ARCH_TEGRA_186_SOC)
266 	{ .compatible = "nvidia,tegra186-emc" },
267 #endif
268 #if defined(CONFIG_ARCH_TEGRA_194_SOC)
269 	{ .compatible = "nvidia,tegra194-emc" },
270 #endif
271 	{ /* sentinel */ }
272 };
273 MODULE_DEVICE_TABLE(of, tegra186_emc_of_match);
274 
275 static struct platform_driver tegra186_emc_driver = {
276 	.driver = {
277 		.name = "tegra186-emc",
278 		.of_match_table = tegra186_emc_of_match,
279 		.suppress_bind_attrs = true,
280 	},
281 	.probe = tegra186_emc_probe,
282 	.remove = tegra186_emc_remove,
283 };
284 module_platform_driver(tegra186_emc_driver);
285 
286 MODULE_AUTHOR("Thierry Reding <treding@nvidia.com>");
287 MODULE_DESCRIPTION("NVIDIA Tegra186 External Memory Controller driver");
288 MODULE_LICENSE("GPL v2");
289