1 // SPDX-License-Identifier: GPL-2.0
2
3 /* Copyright (c) 2012-2018, The Linux Foundation. All rights reserved.
4 * Copyright (C) 2018-2020 Linaro Ltd.
5 */
6
7 #include <linux/refcount.h>
8 #include <linux/mutex.h>
9 #include <linux/clk.h>
10 #include <linux/device.h>
11 #include <linux/interconnect.h>
12
13 #include "ipa.h"
14 #include "ipa_clock.h"
15 #include "ipa_modem.h"
16
17 /**
18 * DOC: IPA Clocking
19 *
20 * The "IPA Clock" manages both the IPA core clock and the interconnects
21 * (buses) the IPA depends on as a single logical entity. A reference count
22 * is incremented by "get" operations and decremented by "put" operations.
23 * Transitions of that count from 0 to 1 result in the clock and interconnects
24 * being enabled, and transitions of the count from 1 to 0 cause them to be
25 * disabled. We currently operate the core clock at a fixed clock rate, and
26 * all buses at a fixed average and peak bandwidth. As more advanced IPA
27 * features are enabled, we can make better use of clock and bus scaling.
28 *
29 * An IPA clock reference must be held for any access to IPA hardware.
30 */
31
32 #define IPA_CORE_CLOCK_RATE (75UL * 1000 * 1000) /* Hz */
33
34 /* Interconnect path bandwidths (each times 1000 bytes per second) */
35 #define IPA_MEMORY_AVG (80 * 1000) /* 80 MBps */
36 #define IPA_MEMORY_PEAK (600 * 1000)
37
38 #define IPA_IMEM_AVG (80 * 1000)
39 #define IPA_IMEM_PEAK (350 * 1000)
40
41 #define IPA_CONFIG_AVG (40 * 1000)
42 #define IPA_CONFIG_PEAK (40 * 1000)
43
44 /**
45 * struct ipa_clock - IPA clocking information
46 * @count: Clocking reference count
47 * @mutex: Protects clock enable/disable
48 * @core: IPA core clock
49 * @memory_path: Memory interconnect
50 * @imem_path: Internal memory interconnect
51 * @config_path: Configuration space interconnect
52 */
53 struct ipa_clock {
54 refcount_t count;
55 struct mutex mutex; /* protects clock enable/disable */
56 struct clk *core;
57 struct icc_path *memory_path;
58 struct icc_path *imem_path;
59 struct icc_path *config_path;
60 };
61
62 static struct icc_path *
ipa_interconnect_init_one(struct device * dev,const char * name)63 ipa_interconnect_init_one(struct device *dev, const char *name)
64 {
65 struct icc_path *path;
66
67 path = of_icc_get(dev, name);
68 if (IS_ERR(path))
69 dev_err(dev, "error %ld getting %s interconnect\n",
70 PTR_ERR(path), name);
71
72 return path;
73 }
74
75 /* Initialize interconnects required for IPA operation */
ipa_interconnect_init(struct ipa_clock * clock,struct device * dev)76 static int ipa_interconnect_init(struct ipa_clock *clock, struct device *dev)
77 {
78 struct icc_path *path;
79
80 path = ipa_interconnect_init_one(dev, "memory");
81 if (IS_ERR(path))
82 goto err_return;
83 clock->memory_path = path;
84
85 path = ipa_interconnect_init_one(dev, "imem");
86 if (IS_ERR(path))
87 goto err_memory_path_put;
88 clock->imem_path = path;
89
90 path = ipa_interconnect_init_one(dev, "config");
91 if (IS_ERR(path))
92 goto err_imem_path_put;
93 clock->config_path = path;
94
95 return 0;
96
97 err_imem_path_put:
98 icc_put(clock->imem_path);
99 err_memory_path_put:
100 icc_put(clock->memory_path);
101 err_return:
102 return PTR_ERR(path);
103 }
104
105 /* Inverse of ipa_interconnect_init() */
ipa_interconnect_exit(struct ipa_clock * clock)106 static void ipa_interconnect_exit(struct ipa_clock *clock)
107 {
108 icc_put(clock->config_path);
109 icc_put(clock->imem_path);
110 icc_put(clock->memory_path);
111 }
112
113 /* Currently we only use one bandwidth level, so just "enable" interconnects */
ipa_interconnect_enable(struct ipa * ipa)114 static int ipa_interconnect_enable(struct ipa *ipa)
115 {
116 struct ipa_clock *clock = ipa->clock;
117 int ret;
118
119 ret = icc_set_bw(clock->memory_path, IPA_MEMORY_AVG, IPA_MEMORY_PEAK);
120 if (ret)
121 return ret;
122
123 ret = icc_set_bw(clock->imem_path, IPA_IMEM_AVG, IPA_IMEM_PEAK);
124 if (ret)
125 goto err_memory_path_disable;
126
127 ret = icc_set_bw(clock->config_path, IPA_CONFIG_AVG, IPA_CONFIG_PEAK);
128 if (ret)
129 goto err_imem_path_disable;
130
131 return 0;
132
133 err_imem_path_disable:
134 (void)icc_set_bw(clock->imem_path, 0, 0);
135 err_memory_path_disable:
136 (void)icc_set_bw(clock->memory_path, 0, 0);
137
138 return ret;
139 }
140
141 /* To disable an interconnect, we just its bandwidth to 0 */
ipa_interconnect_disable(struct ipa * ipa)142 static int ipa_interconnect_disable(struct ipa *ipa)
143 {
144 struct ipa_clock *clock = ipa->clock;
145 int ret;
146
147 ret = icc_set_bw(clock->memory_path, 0, 0);
148 if (ret)
149 return ret;
150
151 ret = icc_set_bw(clock->imem_path, 0, 0);
152 if (ret)
153 goto err_memory_path_reenable;
154
155 ret = icc_set_bw(clock->config_path, 0, 0);
156 if (ret)
157 goto err_imem_path_reenable;
158
159 return 0;
160
161 err_imem_path_reenable:
162 (void)icc_set_bw(clock->imem_path, IPA_IMEM_AVG, IPA_IMEM_PEAK);
163 err_memory_path_reenable:
164 (void)icc_set_bw(clock->memory_path, IPA_MEMORY_AVG, IPA_MEMORY_PEAK);
165
166 return ret;
167 }
168
169 /* Turn on IPA clocks, including interconnects */
ipa_clock_enable(struct ipa * ipa)170 static int ipa_clock_enable(struct ipa *ipa)
171 {
172 int ret;
173
174 ret = ipa_interconnect_enable(ipa);
175 if (ret)
176 return ret;
177
178 ret = clk_prepare_enable(ipa->clock->core);
179 if (ret)
180 ipa_interconnect_disable(ipa);
181
182 return ret;
183 }
184
185 /* Inverse of ipa_clock_enable() */
ipa_clock_disable(struct ipa * ipa)186 static void ipa_clock_disable(struct ipa *ipa)
187 {
188 clk_disable_unprepare(ipa->clock->core);
189 (void)ipa_interconnect_disable(ipa);
190 }
191
192 /* Get an IPA clock reference, but only if the reference count is
193 * already non-zero. Returns true if the additional reference was
194 * added successfully, or false otherwise.
195 */
ipa_clock_get_additional(struct ipa * ipa)196 bool ipa_clock_get_additional(struct ipa *ipa)
197 {
198 return refcount_inc_not_zero(&ipa->clock->count);
199 }
200
201 /* Get an IPA clock reference. If the reference count is non-zero, it is
202 * incremented and return is immediate. Otherwise it is checked again
203 * under protection of the mutex, and if appropriate the IPA clock
204 * is enabled.
205 *
206 * Incrementing the reference count is intentionally deferred until
207 * after the clock is running and endpoints are resumed.
208 */
ipa_clock_get(struct ipa * ipa)209 void ipa_clock_get(struct ipa *ipa)
210 {
211 struct ipa_clock *clock = ipa->clock;
212 int ret;
213
214 /* If the clock is running, just bump the reference count */
215 if (ipa_clock_get_additional(ipa))
216 return;
217
218 /* Otherwise get the mutex and check again */
219 mutex_lock(&clock->mutex);
220
221 /* A reference might have been added before we got the mutex. */
222 if (ipa_clock_get_additional(ipa))
223 goto out_mutex_unlock;
224
225 ret = ipa_clock_enable(ipa);
226 if (ret) {
227 dev_err(&ipa->pdev->dev, "error %d enabling IPA clock\n", ret);
228 goto out_mutex_unlock;
229 }
230
231 refcount_set(&clock->count, 1);
232
233 out_mutex_unlock:
234 mutex_unlock(&clock->mutex);
235 }
236
237 /* Attempt to remove an IPA clock reference. If this represents the
238 * last reference, disable the IPA clock under protection of the mutex.
239 */
ipa_clock_put(struct ipa * ipa)240 void ipa_clock_put(struct ipa *ipa)
241 {
242 struct ipa_clock *clock = ipa->clock;
243
244 /* If this is not the last reference there's nothing more to do */
245 if (!refcount_dec_and_mutex_lock(&clock->count, &clock->mutex))
246 return;
247
248 ipa_clock_disable(ipa);
249
250 mutex_unlock(&clock->mutex);
251 }
252
253 /* Return the current IPA core clock rate */
ipa_clock_rate(struct ipa * ipa)254 u32 ipa_clock_rate(struct ipa *ipa)
255 {
256 return ipa->clock ? (u32)clk_get_rate(ipa->clock->core) : 0;
257 }
258
259 /* Initialize IPA clocking */
ipa_clock_init(struct device * dev)260 struct ipa_clock *ipa_clock_init(struct device *dev)
261 {
262 struct ipa_clock *clock;
263 struct clk *clk;
264 int ret;
265
266 clk = clk_get(dev, "core");
267 if (IS_ERR(clk)) {
268 dev_err(dev, "error %ld getting core clock\n", PTR_ERR(clk));
269 return ERR_CAST(clk);
270 }
271
272 ret = clk_set_rate(clk, IPA_CORE_CLOCK_RATE);
273 if (ret) {
274 dev_err(dev, "error %d setting core clock rate to %lu\n",
275 ret, IPA_CORE_CLOCK_RATE);
276 goto err_clk_put;
277 }
278
279 clock = kzalloc(sizeof(*clock), GFP_KERNEL);
280 if (!clock) {
281 ret = -ENOMEM;
282 goto err_clk_put;
283 }
284 clock->core = clk;
285
286 ret = ipa_interconnect_init(clock, dev);
287 if (ret)
288 goto err_kfree;
289
290 mutex_init(&clock->mutex);
291 refcount_set(&clock->count, 0);
292
293 return clock;
294
295 err_kfree:
296 kfree(clock);
297 err_clk_put:
298 clk_put(clk);
299
300 return ERR_PTR(ret);
301 }
302
303 /* Inverse of ipa_clock_init() */
ipa_clock_exit(struct ipa_clock * clock)304 void ipa_clock_exit(struct ipa_clock *clock)
305 {
306 struct clk *clk = clock->core;
307
308 WARN_ON(refcount_read(&clock->count) != 0);
309 mutex_destroy(&clock->mutex);
310 ipa_interconnect_exit(clock);
311 kfree(clock);
312 clk_put(clk);
313 }
314