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2024-12-19 9370bb92b2d16684ee45cf24e879c93c509162da 
 kernel/drivers/spi/spi-bitbang.c
....@@ -1,15 +1,6 @@
1
+// SPDX-License-Identifier: GPL-2.0-or-later
12 /*
23  * polling/bitbanging SPI master controller driver utilities
3
- *
4
- * This program is free software; you can redistribute it and/or modify
5
- * it under the terms of the GNU General Public License as published by
6
- * the Free Software Foundation; either version 2 of the License, or
7
- * (at your option) any later version.
8
- *
9
- * This program is distributed in the hope that it will be useful,
10
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
11
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12
- * GNU General Public License for more details.
134  */
145 
156 #include <linux/spinlock.h>
....@@ -183,13 +174,15 @@
183174 }
184175 EXPORT_SYMBOL_GPL(spi_bitbang_setup_transfer);
185176 
186
-/**
177
+/*
187178  * spi_bitbang_setup - default setup for per-word I/O loops
188179  */
189180 int spi_bitbang_setup(struct spi_device *spi)
190181 {
191182 	struct spi_bitbang_cs	*cs = spi->controller_state;
192183 	struct spi_bitbang	*bitbang;
184
+	bool			initial_setup = false;
185
+	int			retval;
193186 
194187 	bitbang = spi_master_get_devdata(spi->master);
195188 
....@@ -198,39 +191,34 @@
198191 		if (!cs)
199192 			return -ENOMEM;
200193 		spi->controller_state = cs;
194
+		initial_setup = true;
201195 	}
202196 
203197 	/* per-word shift register access, in hardware or bitbanging */
204198 	cs->txrx_word = bitbang->txrx_word[spi->mode & (SPI_CPOL|SPI_CPHA)];
205
-	if (!cs->txrx_word)
206
-		return -EINVAL;
199
+	if (!cs->txrx_word) {
200
+		retval = -EINVAL;
201
+		goto err_free;
202
+	}
207203 
208204 	if (bitbang->setup_transfer) {
209
-		int retval = bitbang->setup_transfer(spi, NULL);
205
+		retval = bitbang->setup_transfer(spi, NULL);
210206 		if (retval < 0)
211
-			return retval;
207
+			goto err_free;
212208 	}
213209 
214210 	dev_dbg(&spi->dev, "%s, %u nsec/bit\n", __func__, 2 * cs->nsecs);
215211 
216
-	/* NOTE we _need_ to call chipselect() early, ideally with adapter
217
-	 * setup, unless the hardware defaults cooperate to avoid confusion
218
-	 * between normal (active low) and inverted chipselects.
219
-	 */
220
-
221
-	/* deselect chip (low or high) */
222
-	mutex_lock(&bitbang->lock);
223
-	if (!bitbang->busy) {
224
-		bitbang->chipselect(spi, BITBANG_CS_INACTIVE);
225
-		ndelay(cs->nsecs);
226
-	}
227
-	mutex_unlock(&bitbang->lock);
228
-
229212 	return 0;
213
+
214
+err_free:
215
+	if (initial_setup)
216
+		kfree(cs);
217
+	return retval;
230218 }
231219 EXPORT_SYMBOL_GPL(spi_bitbang_setup);
232220 
233
-/**
221
+/*
234222  * spi_bitbang_cleanup - default cleanup for per-word I/O loops
235223  */
236224 void spi_bitbang_cleanup(struct spi_device *spi)
....@@ -348,6 +336,59 @@
348336 
349337 /*----------------------------------------------------------------------*/
350338 
339
+int spi_bitbang_init(struct spi_bitbang *bitbang)
340
+{
341
+	struct spi_master *master = bitbang->master;
342
+	bool custom_cs;
343
+
344
+	if (!master)
345
+		return -EINVAL;
346
+	/*
347
+	 * We only need the chipselect callback if we are actually using it.
348
+	 * If we just use GPIO descriptors, it is surplus. If the
349
+	 * SPI_MASTER_GPIO_SS flag is set, we always need to call the
350
+	 * driver-specific chipselect routine.
351
+	 */
352
+	custom_cs = (!master->use_gpio_descriptors ||
353
+		     (master->flags & SPI_MASTER_GPIO_SS));
354
+
355
+	if (custom_cs && !bitbang->chipselect)
356
+		return -EINVAL;
357
+
358
+	mutex_init(&bitbang->lock);
359
+
360
+	if (!master->mode_bits)
361
+		master->mode_bits = SPI_CPOL | SPI_CPHA | bitbang->flags;
362
+
363
+	if (master->transfer || master->transfer_one_message)
364
+		return -EINVAL;
365
+
366
+	master->prepare_transfer_hardware = spi_bitbang_prepare_hardware;
367
+	master->unprepare_transfer_hardware = spi_bitbang_unprepare_hardware;
368
+	master->transfer_one = spi_bitbang_transfer_one;
369
+	/*
370
+	 * When using GPIO descriptors, the ->set_cs() callback doesn't even
371
+	 * get called unless SPI_MASTER_GPIO_SS is set.
372
+	 */
373
+	if (custom_cs)
374
+		master->set_cs = spi_bitbang_set_cs;
375
+
376
+	if (!bitbang->txrx_bufs) {
377
+		bitbang->use_dma = 0;
378
+		bitbang->txrx_bufs = spi_bitbang_bufs;
379
+		if (!master->setup) {
380
+			if (!bitbang->setup_transfer)
381
+				bitbang->setup_transfer =
382
+					 spi_bitbang_setup_transfer;
383
+			master->setup = spi_bitbang_setup;
384
+			master->cleanup = spi_bitbang_cleanup;
385
+		}
386
+	}
387
+
388
+	return 0;
389
+}
390
+EXPORT_SYMBOL_GPL(spi_bitbang_init);
391
+
351392 /**
352393  * spi_bitbang_start - start up a polled/bitbanging SPI master driver
353394  * @bitbang: driver handle
....@@ -381,33 +422,9 @@
381422 	struct spi_master *master = bitbang->master;
382423 	int ret;
383424 
384
-	if (!master || !bitbang->chipselect)
385
-		return -EINVAL;
386
-
387
-	mutex_init(&bitbang->lock);
388
-
389
-	if (!master->mode_bits)
390
-		master->mode_bits = SPI_CPOL | SPI_CPHA | bitbang->flags;
391
-
392
-	if (master->transfer || master->transfer_one_message)
393
-		return -EINVAL;
394
-
395
-	master->prepare_transfer_hardware = spi_bitbang_prepare_hardware;
396
-	master->unprepare_transfer_hardware = spi_bitbang_unprepare_hardware;
397
-	master->transfer_one = spi_bitbang_transfer_one;
398
-	master->set_cs = spi_bitbang_set_cs;
399
-
400
-	if (!bitbang->txrx_bufs) {
401
-		bitbang->use_dma = 0;
402
-		bitbang->txrx_bufs = spi_bitbang_bufs;
403
-		if (!master->setup) {
404
-			if (!bitbang->setup_transfer)
405
-				bitbang->setup_transfer =
406
-					 spi_bitbang_setup_transfer;
407
-			master->setup = spi_bitbang_setup;
408
-			master->cleanup = spi_bitbang_cleanup;
409
-		}
410
-	}
425
+	ret = spi_bitbang_init(bitbang);
426
+	if (ret)
427
+		return ret;
411428 
412429 	/* driver may get busy before register() returns, especially
413430 	 * if someone registered boardinfo for devices
....@@ -420,7 +437,7 @@
420437 }
421438 EXPORT_SYMBOL_GPL(spi_bitbang_start);
422439 
423
-/**
440
+/*
424441  * spi_bitbang_stop - stops the task providing spi communication
425442  */
426443 void spi_bitbang_stop(struct spi_bitbang *bitbang)