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
47static inline void realtek_smi_clk_delay(struct realtek_priv *priv)
48{
49 ndelay(priv->variant->clk_delay);
50}
51
52static 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(desc: priv->mdc, value: 0);
58 gpiod_direction_output(desc: priv->mdio, value: 1);
59 realtek_smi_clk_delay(priv);
60
61 /* CLK 1: 0 -> 1, 1 -> 0 */
62 gpiod_set_value(desc: priv->mdc, value: 1);
63 realtek_smi_clk_delay(priv);
64 gpiod_set_value(desc: priv->mdc, value: 0);
65 realtek_smi_clk_delay(priv);
66
67 /* CLK 2: */
68 gpiod_set_value(desc: priv->mdc, value: 1);
69 realtek_smi_clk_delay(priv);
70 gpiod_set_value(desc: priv->mdio, value: 0);
71 realtek_smi_clk_delay(priv);
72 gpiod_set_value(desc: priv->mdc, value: 0);
73 realtek_smi_clk_delay(priv);
74 gpiod_set_value(desc: priv->mdio, value: 1);
75}
76
77static void realtek_smi_stop(struct realtek_priv *priv)
78{
79 realtek_smi_clk_delay(priv);
80 gpiod_set_value(desc: priv->mdio, value: 0);
81 gpiod_set_value(desc: priv->mdc, value: 1);
82 realtek_smi_clk_delay(priv);
83 gpiod_set_value(desc: priv->mdio, value: 1);
84 realtek_smi_clk_delay(priv);
85 gpiod_set_value(desc: priv->mdc, value: 1);
86 realtek_smi_clk_delay(priv);
87 gpiod_set_value(desc: priv->mdc, value: 0);
88 realtek_smi_clk_delay(priv);
89 gpiod_set_value(desc: priv->mdc, value: 1);
90
91 /* Add a click */
92 realtek_smi_clk_delay(priv);
93 gpiod_set_value(desc: priv->mdc, value: 0);
94 realtek_smi_clk_delay(priv);
95 gpiod_set_value(desc: priv->mdc, value: 1);
96
97 /* Set GPIO pins to input mode */
98 gpiod_direction_input(desc: priv->mdio);
99 gpiod_direction_input(desc: priv->mdc);
100}
101
102static 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(desc: priv->mdio, value: !!(data & (1 << (len - 1))));
109 realtek_smi_clk_delay(priv);
110
111 /* Clocking */
112 gpiod_set_value(desc: priv->mdc, value: 1);
113 realtek_smi_clk_delay(priv);
114 gpiod_set_value(desc: priv->mdc, value: 0);
115 }
116}
117
118static void realtek_smi_read_bits(struct realtek_priv *priv, u32 len, u32 *data)
119{
120 gpiod_direction_input(desc: 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(desc: priv->mdc, value: 1);
129 realtek_smi_clk_delay(priv);
130 u = !!gpiod_get_value(desc: priv->mdio);
131 gpiod_set_value(desc: priv->mdc, value: 0);
132
133 *data |= (u << (len - 1));
134 }
135
136 gpiod_direction_output(desc: priv->mdio, value: 0);
137}
138
139static 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, len: 1, data: &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
160static int realtek_smi_write_byte(struct realtek_priv *priv, u8 data)
161{
162 realtek_smi_write_bits(priv, data, len: 8);
163 return realtek_smi_wait_for_ack(priv);
164}
165
166static int realtek_smi_write_byte_noack(struct realtek_priv *priv, u8 data)
167{
168 realtek_smi_write_bits(priv, data, len: 8);
169 return 0;
170}
171
172static 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, len: 8, data: &t);
178 *data = (t & 0xff);
179
180 /* Send an ACK */
181 realtek_smi_write_bits(priv, data: 0x00, len: 1);
182
183 return 0;
184}
185
186static 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, len: 8, data: &t);
192 *data = (t & 0xff);
193
194 /* Send an ACK */
195 realtek_smi_write_bits(priv, data: 0x01, len: 1);
196
197 return 0;
198}
199
200static 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, data: priv->variant->cmd_read);
213 if (ret)
214 goto out;
215
216 /* Set ADDR[7:0] */
217 ret = realtek_smi_write_byte(priv, data: addr & 0xff);
218 if (ret)
219 goto out;
220
221 /* Set ADDR[15:8] */
222 ret = realtek_smi_write_byte(priv, data: addr >> 8);
223 if (ret)
224 goto out;
225
226 /* Read DATA[7:0] */
227 realtek_smi_read_byte0(priv, data: &lo);
228 /* Read DATA[15:8] */
229 realtek_smi_read_byte1(priv, data: &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(lock: &priv->lock, flags);
238
239 return ret;
240}
241
242static 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, data: priv->variant->cmd_write);
254 if (ret)
255 goto out;
256
257 /* Set ADDR[7:0] */
258 ret = realtek_smi_write_byte(priv, data: addr & 0xff);
259 if (ret)
260 goto out;
261
262 /* Set ADDR[15:8] */
263 ret = realtek_smi_write_byte(priv, data: addr >> 8);
264 if (ret)
265 goto out;
266
267 /* Write DATA[7:0] */
268 ret = realtek_smi_write_byte(priv, data: 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: data >> 8);
275 else
276 ret = realtek_smi_write_byte_noack(priv, data: data >> 8);
277 if (ret)
278 goto out;
279
280 ret = 0;
281
282 out:
283 realtek_smi_stop(priv);
284 spin_unlock_irqrestore(lock: &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 */
293static int realtek_smi_write_reg_noack(void *ctx, u32 reg, u32 val)
294{
295 return realtek_smi_write_reg(priv: ctx, addr: reg, data: val, ack: false);
296}
297
298/* Regmap accessors */
299
300static 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, addr: reg, data: val, ack: true);
305}
306
307static 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, addr: reg, data: val);
312}
313
314static 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 */
331int 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, interface_info: &realtek_smi_info);
338 if (IS_ERR(ptr: priv))
339 return PTR_ERR(ptr: priv);
340
341 /* Fetch MDIO pins */
342 priv->mdc = devm_gpiod_get_optional(dev, con_id: "mdc", flags: GPIOD_OUT_LOW);
343 if (IS_ERR(ptr: priv->mdc)) {
344 rtl83xx_remove(priv);
345 return PTR_ERR(ptr: priv->mdc);
346 }
347
348 priv->mdio = devm_gpiod_get_optional(dev, con_id: "mdio", flags: GPIOD_OUT_LOW);
349 if (IS_ERR(ptr: priv->mdio)) {
350 rtl83xx_remove(priv);
351 return PTR_ERR(ptr: 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}
364EXPORT_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 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 */
376void 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}
387EXPORT_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 */
399void 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}
408EXPORT_SYMBOL_NS_GPL(realtek_smi_shutdown, "REALTEK_DSA");
409

source code of linux/drivers/net/dsa/realtek/realtek-smi.c