1 // SPDX-License-Identifier: GPL-2.0+
2 /* Realtek Simple Management Interface (SMI) driver
3 * It can be discussed how "simple" this interface is.
4 *
5 * The SMI protocol piggy-backs the MDIO MDC and MDIO signals levels
6 * but the protocol is not MDIO at all. Instead it is a Realtek
7 * pecularity that need to bit-bang the lines in a special way to
8 * communicate with the switch.
9 *
10 * ASICs we intend to support with this driver:
11 *
12 * RTL8366 - The original version, apparently
13 * RTL8369 - Similar enough to have the same datsheet as RTL8366
14 * RTL8366RB - Probably reads out "RTL8366 revision B", has a quite
15 * different register layout from the other two
16 * RTL8366S - Is this "RTL8366 super"?
17 * RTL8367 - Has an OpenWRT driver as well
18 * RTL8368S - Seems to be an alternative name for RTL8366RB
19 * RTL8370 - Also uses SMI
20 *
21 * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
22 * Copyright (C) 2010 Antti Seppälä <a.seppala@gmail.com>
23 * Copyright (C) 2010 Roman Yeryomin <roman@advem.lv>
24 * Copyright (C) 2011 Colin Leitner <colin.leitner@googlemail.com>
25 * Copyright (C) 2009-2010 Gabor Juhos <juhosg@openwrt.org>
26 */
27
28 #include <linux/kernel.h>
29 #include <linux/module.h>
30 #include <linux/device.h>
31 #include <linux/spinlock.h>
32 #include <linux/skbuff.h>
33 #include <linux/of.h>
34 #include <linux/delay.h>
35 #include <linux/gpio/consumer.h>
36 #include <linux/platform_device.h>
37 #include <linux/regmap.h>
38 #include <linux/bitops.h>
39 #include <linux/if_bridge.h>
40
41 #include "realtek.h"
42 #include "realtek-smi.h"
43 #include "rtl83xx.h"
44
45 #define REALTEK_SMI_ACK_RETRY_COUNT 5
46
realtek_smi_clk_delay(struct realtek_priv * priv)47 static inline void realtek_smi_clk_delay(struct realtek_priv *priv)
48 {
49 ndelay(priv->variant->clk_delay);
50 }
51
realtek_smi_start(struct realtek_priv * priv)52 static void realtek_smi_start(struct realtek_priv *priv)
53 {
54 /* Set GPIO pins to output mode, with initial state:
55 * SCK = 0, SDA = 1
56 */
57 gpiod_direction_output(priv->mdc, 0);
58 gpiod_direction_output(priv->mdio, 1);
59 realtek_smi_clk_delay(priv);
60
61 /* CLK 1: 0 -> 1, 1 -> 0 */
62 gpiod_set_value(priv->mdc, 1);
63 realtek_smi_clk_delay(priv);
64 gpiod_set_value(priv->mdc, 0);
65 realtek_smi_clk_delay(priv);
66
67 /* CLK 2: */
68 gpiod_set_value(priv->mdc, 1);
69 realtek_smi_clk_delay(priv);
70 gpiod_set_value(priv->mdio, 0);
71 realtek_smi_clk_delay(priv);
72 gpiod_set_value(priv->mdc, 0);
73 realtek_smi_clk_delay(priv);
74 gpiod_set_value(priv->mdio, 1);
75 }
76
realtek_smi_stop(struct realtek_priv * priv)77 static void realtek_smi_stop(struct realtek_priv *priv)
78 {
79 realtek_smi_clk_delay(priv);
80 gpiod_set_value(priv->mdio, 0);
81 gpiod_set_value(priv->mdc, 1);
82 realtek_smi_clk_delay(priv);
83 gpiod_set_value(priv->mdio, 1);
84 realtek_smi_clk_delay(priv);
85 gpiod_set_value(priv->mdc, 1);
86 realtek_smi_clk_delay(priv);
87 gpiod_set_value(priv->mdc, 0);
88 realtek_smi_clk_delay(priv);
89 gpiod_set_value(priv->mdc, 1);
90
91 /* Add a click */
92 realtek_smi_clk_delay(priv);
93 gpiod_set_value(priv->mdc, 0);
94 realtek_smi_clk_delay(priv);
95 gpiod_set_value(priv->mdc, 1);
96
97 /* Set GPIO pins to input mode */
98 gpiod_direction_input(priv->mdio);
99 gpiod_direction_input(priv->mdc);
100 }
101
realtek_smi_write_bits(struct realtek_priv * priv,u32 data,u32 len)102 static void realtek_smi_write_bits(struct realtek_priv *priv, u32 data, u32 len)
103 {
104 for (; len > 0; len--) {
105 realtek_smi_clk_delay(priv);
106
107 /* Prepare data */
108 gpiod_set_value(priv->mdio, !!(data & (1 << (len - 1))));
109 realtek_smi_clk_delay(priv);
110
111 /* Clocking */
112 gpiod_set_value(priv->mdc, 1);
113 realtek_smi_clk_delay(priv);
114 gpiod_set_value(priv->mdc, 0);
115 }
116 }
117
realtek_smi_read_bits(struct realtek_priv * priv,u32 len,u32 * data)118 static void realtek_smi_read_bits(struct realtek_priv *priv, u32 len, u32 *data)
119 {
120 gpiod_direction_input(priv->mdio);
121
122 for (*data = 0; len > 0; len--) {
123 u32 u;
124
125 realtek_smi_clk_delay(priv);
126
127 /* Clocking */
128 gpiod_set_value(priv->mdc, 1);
129 realtek_smi_clk_delay(priv);
130 u = !!gpiod_get_value(priv->mdio);
131 gpiod_set_value(priv->mdc, 0);
132
133 *data |= (u << (len - 1));
134 }
135
136 gpiod_direction_output(priv->mdio, 0);
137 }
138
realtek_smi_wait_for_ack(struct realtek_priv * priv)139 static int realtek_smi_wait_for_ack(struct realtek_priv *priv)
140 {
141 int retry_cnt;
142
143 retry_cnt = 0;
144 do {
145 u32 ack;
146
147 realtek_smi_read_bits(priv, 1, &ack);
148 if (ack == 0)
149 break;
150
151 if (++retry_cnt > REALTEK_SMI_ACK_RETRY_COUNT) {
152 dev_err(priv->dev, "ACK timeout\n");
153 return -ETIMEDOUT;
154 }
155 } while (1);
156
157 return 0;
158 }
159
realtek_smi_write_byte(struct realtek_priv * priv,u8 data)160 static int realtek_smi_write_byte(struct realtek_priv *priv, u8 data)
161 {
162 realtek_smi_write_bits(priv, data, 8);
163 return realtek_smi_wait_for_ack(priv);
164 }
165
realtek_smi_write_byte_noack(struct realtek_priv * priv,u8 data)166 static int realtek_smi_write_byte_noack(struct realtek_priv *priv, u8 data)
167 {
168 realtek_smi_write_bits(priv, data, 8);
169 return 0;
170 }
171
realtek_smi_read_byte0(struct realtek_priv * priv,u8 * data)172 static int realtek_smi_read_byte0(struct realtek_priv *priv, u8 *data)
173 {
174 u32 t;
175
176 /* Read data */
177 realtek_smi_read_bits(priv, 8, &t);
178 *data = (t & 0xff);
179
180 /* Send an ACK */
181 realtek_smi_write_bits(priv, 0x00, 1);
182
183 return 0;
184 }
185
realtek_smi_read_byte1(struct realtek_priv * priv,u8 * data)186 static int realtek_smi_read_byte1(struct realtek_priv *priv, u8 *data)
187 {
188 u32 t;
189
190 /* Read data */
191 realtek_smi_read_bits(priv, 8, &t);
192 *data = (t & 0xff);
193
194 /* Send an ACK */
195 realtek_smi_write_bits(priv, 0x01, 1);
196
197 return 0;
198 }
199
realtek_smi_read_reg(struct realtek_priv * priv,u32 addr,u32 * data)200 static int realtek_smi_read_reg(struct realtek_priv *priv, u32 addr, u32 *data)
201 {
202 unsigned long flags;
203 u8 lo = 0;
204 u8 hi = 0;
205 int ret;
206
207 spin_lock_irqsave(&priv->lock, flags);
208
209 realtek_smi_start(priv);
210
211 /* Send READ command */
212 ret = realtek_smi_write_byte(priv, priv->variant->cmd_read);
213 if (ret)
214 goto out;
215
216 /* Set ADDR[7:0] */
217 ret = realtek_smi_write_byte(priv, addr & 0xff);
218 if (ret)
219 goto out;
220
221 /* Set ADDR[15:8] */
222 ret = realtek_smi_write_byte(priv, addr >> 8);
223 if (ret)
224 goto out;
225
226 /* Read DATA[7:0] */
227 realtek_smi_read_byte0(priv, &lo);
228 /* Read DATA[15:8] */
229 realtek_smi_read_byte1(priv, &hi);
230
231 *data = ((u32)lo) | (((u32)hi) << 8);
232
233 ret = 0;
234
235 out:
236 realtek_smi_stop(priv);
237 spin_unlock_irqrestore(&priv->lock, flags);
238
239 return ret;
240 }
241
realtek_smi_write_reg(struct realtek_priv * priv,u32 addr,u32 data,bool ack)242 static int realtek_smi_write_reg(struct realtek_priv *priv,
243 u32 addr, u32 data, bool ack)
244 {
245 unsigned long flags;
246 int ret;
247
248 spin_lock_irqsave(&priv->lock, flags);
249
250 realtek_smi_start(priv);
251
252 /* Send WRITE command */
253 ret = realtek_smi_write_byte(priv, priv->variant->cmd_write);
254 if (ret)
255 goto out;
256
257 /* Set ADDR[7:0] */
258 ret = realtek_smi_write_byte(priv, addr & 0xff);
259 if (ret)
260 goto out;
261
262 /* Set ADDR[15:8] */
263 ret = realtek_smi_write_byte(priv, addr >> 8);
264 if (ret)
265 goto out;
266
267 /* Write DATA[7:0] */
268 ret = realtek_smi_write_byte(priv, data & 0xff);
269 if (ret)
270 goto out;
271
272 /* Write DATA[15:8] */
273 if (ack)
274 ret = realtek_smi_write_byte(priv, data >> 8);
275 else
276 ret = realtek_smi_write_byte_noack(priv, data >> 8);
277 if (ret)
278 goto out;
279
280 ret = 0;
281
282 out:
283 realtek_smi_stop(priv);
284 spin_unlock_irqrestore(&priv->lock, flags);
285
286 return ret;
287 }
288
289 /* There is one single case when we need to use this accessor and that
290 * is when issueing soft reset. Since the device reset as soon as we write
291 * that bit, no ACK will come back for natural reasons.
292 */
realtek_smi_write_reg_noack(void * ctx,u32 reg,u32 val)293 static int realtek_smi_write_reg_noack(void *ctx, u32 reg, u32 val)
294 {
295 return realtek_smi_write_reg(ctx, reg, val, false);
296 }
297
298 /* Regmap accessors */
299
realtek_smi_write(void * ctx,u32 reg,u32 val)300 static int realtek_smi_write(void *ctx, u32 reg, u32 val)
301 {
302 struct realtek_priv *priv = ctx;
303
304 return realtek_smi_write_reg(priv, reg, val, true);
305 }
306
realtek_smi_read(void * ctx,u32 reg,u32 * val)307 static int realtek_smi_read(void *ctx, u32 reg, u32 *val)
308 {
309 struct realtek_priv *priv = ctx;
310
311 return realtek_smi_read_reg(priv, reg, val);
312 }
313
314 static const struct realtek_interface_info realtek_smi_info = {
315 .reg_read = realtek_smi_read,
316 .reg_write = realtek_smi_write,
317 };
318
319 /**
320 * realtek_smi_probe() - Probe a platform device for an SMI-connected switch
321 * @pdev: platform_device to probe on.
322 *
323 * This function should be used as the .probe in a platform_driver. After
324 * calling the common probe function for both interfaces, it initializes the
325 * values specific for SMI-connected devices. Finally, it calls a common
326 * function to register the DSA switch.
327 *
328 * Context: Can sleep. Takes and releases priv->map_lock.
329 * Return: Returns 0 on success, a negative error on failure.
330 */
realtek_smi_probe(struct platform_device * pdev)331 int realtek_smi_probe(struct platform_device *pdev)
332 {
333 struct device *dev = &pdev->dev;
334 struct realtek_priv *priv;
335 int ret;
336
337 priv = rtl83xx_probe(dev, &realtek_smi_info);
338 if (IS_ERR(priv))
339 return PTR_ERR(priv);
340
341 /* Fetch MDIO pins */
342 priv->mdc = devm_gpiod_get_optional(dev, "mdc", GPIOD_OUT_LOW);
343 if (IS_ERR(priv->mdc)) {
344 rtl83xx_remove(priv);
345 return PTR_ERR(priv->mdc);
346 }
347
348 priv->mdio = devm_gpiod_get_optional(dev, "mdio", GPIOD_OUT_LOW);
349 if (IS_ERR(priv->mdio)) {
350 rtl83xx_remove(priv);
351 return PTR_ERR(priv->mdio);
352 }
353
354 priv->write_reg_noack = realtek_smi_write_reg_noack;
355
356 ret = rtl83xx_register_switch(priv);
357 if (ret) {
358 rtl83xx_remove(priv);
359 return ret;
360 }
361
362 return 0;
363 }
364 EXPORT_SYMBOL_NS_GPL(realtek_smi_probe, REALTEK_DSA);
365
366 /**
367 * realtek_smi_remove() - Remove the driver of a SMI-connected switch
368 * @pdev: platform_device to be removed.
369 *
370 * This function should be used as the .remove_new in a platform_driver. First
371 * it unregisters the DSA switch and then it calls the common remove function.
372 *
373 * Context: Can sleep.
374 * Return: Nothing.
375 */
realtek_smi_remove(struct platform_device * pdev)376 void realtek_smi_remove(struct platform_device *pdev)
377 {
378 struct realtek_priv *priv = platform_get_drvdata(pdev);
379
380 if (!priv)
381 return;
382
383 rtl83xx_unregister_switch(priv);
384
385 rtl83xx_remove(priv);
386 }
387 EXPORT_SYMBOL_NS_GPL(realtek_smi_remove, REALTEK_DSA);
388
389 /**
390 * realtek_smi_shutdown() - Shutdown the driver of a SMI-connected switch
391 * @pdev: platform_device shutting down.
392 *
393 * This function should be used as the .shutdown in a platform_driver. It calls
394 * the common shutdown function.
395 *
396 * Context: Can sleep.
397 * Return: Nothing.
398 */
realtek_smi_shutdown(struct platform_device * pdev)399 void realtek_smi_shutdown(struct platform_device *pdev)
400 {
401 struct realtek_priv *priv = platform_get_drvdata(pdev);
402
403 if (!priv)
404 return;
405
406 rtl83xx_shutdown(priv);
407 }
408 EXPORT_SYMBOL_NS_GPL(realtek_smi_shutdown, REALTEK_DSA);
409