1 // SPDX-License-Identifier: GPL-2.0-only
3  * ds2482.c - provides i2c to w1-master bridge(s)
7  * It is a I2C to 1-wire bridge.
8  * There are two variations: -100 and -800, which have 1 or 8 1-wire ports.
10  *   https://www.analog.com/en/products/ds2482-100.html
26  * The APU bit controls whether an active pullup (controlled slew-rate
28  * a 1-Wire line from low to high. When APU = 0, active pullup is disabled
30  * only a single slave on the 1-Wire line.
35 				"0-disable, 1-enable (default)");
37 /* extra configurations - e.g. 1WS */
43  * The DS2482 registers - there are 3 registers that are addressed by a read
50 #define DS2482_CMD_CHANNEL_SELECT	0xC3	/* Param: Channel byte - DS2482-800 only */
62 #define DS2482_PTR_CODE_CHANNEL		0xD2	/* DS2482-800 only */
70 #define DS2482_REG_CFG_1WS		0x08	/* 1-wire speed */
71 #define DS2482_REG_CFG_SPU		0x04	/* strong pull-up */
73 #define DS2482_REG_CFG_APU		0x01	/* active pull-up */
77  * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).
113 	/* 1-wire interface(s) */
117 	/* per-device values */
125  * ds2482_calculate_config - Helper to calculate values for configuration register
141  * ds2482_select_register - Sets the read pointer.
144  * Return: -1 on failure, 0 on success
148 	if (pdev->read_prt != read_ptr) {  in ds2482_select_register()
149 		if (i2c_smbus_write_byte_data(pdev->client,  in ds2482_select_register()
152 			return -1;  in ds2482_select_register()
154 		pdev->read_prt = read_ptr;  in ds2482_select_register()
160  * ds2482_send_cmd - Sends a command without a parameter
165  * Return: -1 on failure, 0 on success
169 	if (i2c_smbus_write_byte(pdev->client, cmd) < 0)  in ds2482_send_cmd()
170 		return -1;  in ds2482_send_cmd()
172 	pdev->read_prt = DS2482_PTR_CODE_STATUS;  in ds2482_send_cmd()
177  * ds2482_send_cmd_data - Sends a command with a parameter
184  * Return: -1 on failure, 0 on success
189 	if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)  in ds2482_send_cmd_data()
190 		return -1;  in ds2482_send_cmd_data()
193 	pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?  in ds2482_send_cmd_data()
200  * 1-Wire interface code
206  * ds2482_wait_1wire_idle - Waits until the 1-wire interface is idle (not busy)
209  * Return: the last value read from status or -1 (failure)
213 	int temp = -1;  in ds2482_wait_1wire_idle()
218 			temp = i2c_smbus_read_byte(pdev->client);  in ds2482_wait_1wire_idle()
225 		       __func__, pdev->channel);  in ds2482_wait_1wire_idle()
231  * ds2482_set_channel - Selects a w1 channel.
232  * The 1-wire interface must be idle before calling this function.
235  * @channel:		0-7
236  * Return:		-1 (failure) or 0 (success)
240 	if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,  in ds2482_set_channel()
242 		return -1;  in ds2482_set_channel()
244 	pdev->read_prt = DS2482_PTR_CODE_CHANNEL;  in ds2482_set_channel()
245 	pdev->channel = -1;  in ds2482_set_channel()
246 	if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {  in ds2482_set_channel()
247 		pdev->channel = channel;  in ds2482_set_channel()
250 	return -1;  in ds2482_set_channel()
255  * ds2482_w1_touch_bit - Performs the touch-bit function, which writes a 0 or 1 and reads the level.
258  * @bit:	The level to write: 0 or non-zero
264 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_touch_bit()
265 	int status = -1;  in ds2482_w1_touch_bit()
267 	mutex_lock(&pdev->access_lock);  in ds2482_w1_touch_bit()
271 	if (pdev->w1_count > 1)  in ds2482_w1_touch_bit()
272 		ds2482_set_channel(pdev, pchan->channel);  in ds2482_w1_touch_bit()
279 	mutex_unlock(&pdev->access_lock);  in ds2482_w1_touch_bit()
285  * ds2482_w1_triplet - Performs the triplet function, which reads two bits and writes a bit.
286  * The bit written is determined by the two reads:
296 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_triplet()
299 	mutex_lock(&pdev->access_lock);  in ds2482_w1_triplet()
303 	if (pdev->w1_count > 1)  in ds2482_w1_triplet()
304 		ds2482_set_channel(pdev, pchan->channel);  in ds2482_w1_triplet()
311 	mutex_unlock(&pdev->access_lock);  in ds2482_w1_triplet()
318  * ds2482_w1_write_byte - Performs the write byte function.
326 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_write_byte()
328 	mutex_lock(&pdev->access_lock);  in ds2482_w1_write_byte()
332 	if (pdev->w1_count > 1)  in ds2482_w1_write_byte()
333 		ds2482_set_channel(pdev, pchan->channel);  in ds2482_w1_write_byte()
338 	mutex_unlock(&pdev->access_lock);  in ds2482_w1_write_byte()
342  * ds2482_w1_read_byte - Performs the read byte function.
350 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_read_byte()
353 	mutex_lock(&pdev->access_lock);  in ds2482_w1_read_byte()
357 	if (pdev->w1_count > 1)  in ds2482_w1_read_byte()
358 		ds2482_set_channel(pdev, pchan->channel);  in ds2482_w1_read_byte()
370 	result = i2c_smbus_read_byte(pdev->client);  in ds2482_w1_read_byte()
372 	mutex_unlock(&pdev->access_lock);  in ds2482_w1_read_byte()
379  * ds2482_w1_reset_bus - Sends a reset on the 1-wire interface
387 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_reset_bus()
391 	mutex_lock(&pdev->access_lock);  in ds2482_w1_reset_bus()
395 	if (pdev->w1_count > 1)  in ds2482_w1_reset_bus()
396 		ds2482_set_channel(pdev, pchan->channel);  in ds2482_w1_reset_bus()
405 		/* If the chip did reset since detect, re-config it */  in ds2482_w1_reset_bus()
411 	mutex_unlock(&pdev->access_lock);  in ds2482_w1_reset_bus()
419 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_set_pullup()
422 	/* if delay is non-zero activate the pullup,  in ds2482_w1_set_pullup()
446 	int err = -ENODEV;  in ds2482_probe()
451 	if (!i2c_check_functionality(client->adapter,  in ds2482_probe()
454 		return -ENODEV;  in ds2482_probe()
456 	data = devm_kzalloc(&client->dev, sizeof(struct ds2482_data), GFP_KERNEL);  in ds2482_probe()
458 		return -ENOMEM;  in ds2482_probe()
460 	ret = devm_regulator_get_enable(&client->dev, "vcc");  in ds2482_probe()
462 		return dev_err_probe(&client->dev, ret, "Failed to enable regulator\n");  in ds2482_probe()
464 	data->client = client;  in ds2482_probe()
469 		dev_warn(&client->dev, "DS2482 reset failed.\n");  in ds2482_probe()
476 	/* Read the status byte - only reset bit and line should be set */  in ds2482_probe()
479 		dev_warn(&client->dev, "DS2482 reset status "  in ds2482_probe()
480 			 "0x%02X - not a DS2482\n", temp1);  in ds2482_probe()
484 	/* Detect the 8-port version */  in ds2482_probe()
485 	data->w1_count = 1;  in ds2482_probe()
487 		data->w1_count = 8;  in ds2482_probe()
493 	mutex_init(&data->access_lock);  in ds2482_probe()
495 	/* Register 1-wire interface(s) */  in ds2482_probe()
496 	for (idx = 0; idx < data->w1_count; idx++) {  in ds2482_probe()
497 		data->w1_ch[idx].pdev = data;  in ds2482_probe()
498 		data->w1_ch[idx].channel = idx;  in ds2482_probe()
501 		data->w1_ch[idx].w1_bm.data       = &data->w1_ch[idx];  in ds2482_probe()
502 		data->w1_ch[idx].w1_bm.read_byte  = ds2482_w1_read_byte;  in ds2482_probe()
503 		data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;  in ds2482_probe()
504 		data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;  in ds2482_probe()
505 		data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;  in ds2482_probe()
506 		data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;  in ds2482_probe()
507 		data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup;  in ds2482_probe()
509 		err = w1_add_master_device(&data->w1_ch[idx].w1_bm);  in ds2482_probe()
511 			data->w1_ch[idx].pdev = NULL;  in ds2482_probe()
519 	for (idx = 0; idx < data->w1_count; idx++) {  in ds2482_probe()
520 		if (data->w1_ch[idx].pdev != NULL)  in ds2482_probe()
521 			w1_remove_master_device(&data->w1_ch[idx].w1_bm);  in ds2482_probe()
531 	/* Unregister the 1-wire bridge(s) */  in ds2482_remove()
532 	for (idx = 0; idx < data->w1_count; idx++) {  in ds2482_remove()
533 		if (data->w1_ch[idx].pdev != NULL)  in ds2482_remove()
534 			w1_remove_master_device(&data->w1_ch[idx].w1_bm);  in ds2482_remove()