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  *   http://www.maxim-ic.com/quick_view2.cfm/qv_pk/4382
25  * The APU bit controls whether an active pullup (controlled slew-rate
26  * transistor) or a passive pullup (Rwpu resistor) will be used to drive
27  * a 1-Wire line from low to high. When APU = 0, active pullup is disabled
29  * only a single slave on the 1-Wire line.
34 				"0-disable, 1-enable (default)");
36 /* extra configurations - e.g. 1WS */
42  * The DS2482 registers - there are 3 registers that are addressed by a read
49 #define DS2482_CMD_CHANNEL_SELECT	0xC3	/* Param: Channel byte - DS2482-800 only */
61 #define DS2482_PTR_CODE_CHANNEL		0xD2	/* DS2482-800 only */
69 #define DS2482_REG_CFG_1WS		0x08	/* 1-wire speed */
70 #define DS2482_REG_CFG_SPU		0x04	/* strong pull-up */
72 #define DS2482_REG_CFG_APU		0x01	/* active pull-up */
76  * Write and verify codes for the CHANNEL_SELECT command (DS2482-800 only).
112 	/* 1-wire interface(s) */
113 	int			w1_count;	/* 1 or 8 */
116 	/* per-device values */
124  * ds2482_calculate_config - Helper to calculate values for configuration register
140  * ds2482_select_register - Sets the read pointer.
143  * Return: -1 on failure, 0 on success
147 	if (pdev->read_prt != read_ptr) {  in ds2482_select_register()
148 		if (i2c_smbus_write_byte_data(pdev->client,  in ds2482_select_register()
151 			return -1;  in ds2482_select_register()
153 		pdev->read_prt = read_ptr;  in ds2482_select_register()
159  * ds2482_send_cmd - Sends a command without a parameter
164  * Return: -1 on failure, 0 on success
168 	if (i2c_smbus_write_byte(pdev->client, cmd) < 0)  in ds2482_send_cmd()
169 		return -1;  in ds2482_send_cmd()
171 	pdev->read_prt = DS2482_PTR_CODE_STATUS;  in ds2482_send_cmd()
176  * ds2482_send_cmd_data - Sends a command with a parameter
183  * Return: -1 on failure, 0 on success
188 	if (i2c_smbus_write_byte_data(pdev->client, cmd, byte) < 0)  in ds2482_send_cmd_data()
189 		return -1;  in ds2482_send_cmd_data()
192 	pdev->read_prt = (cmd != DS2482_CMD_WRITE_CONFIG) ?  in ds2482_send_cmd_data()
199  * 1-Wire interface code
205  * ds2482_wait_1wire_idle - Waits until the 1-wire interface is idle (not busy)
208  * Return: the last value read from status or -1 (failure)
212 	int temp = -1;  in ds2482_wait_1wire_idle()
217 			temp = i2c_smbus_read_byte(pdev->client);  in ds2482_wait_1wire_idle()
224 		       __func__, pdev->channel);  in ds2482_wait_1wire_idle()
230  * ds2482_set_channel - Selects a w1 channel.
231  * The 1-wire interface must be idle before calling this function.
234  * @channel:		0-7
235  * Return:		-1 (failure) or 0 (success)
239 	if (i2c_smbus_write_byte_data(pdev->client, DS2482_CMD_CHANNEL_SELECT,  in ds2482_set_channel()
241 		return -1;  in ds2482_set_channel()
243 	pdev->read_prt = DS2482_PTR_CODE_CHANNEL;  in ds2482_set_channel()
244 	pdev->channel = -1;  in ds2482_set_channel()
245 	if (i2c_smbus_read_byte(pdev->client) == ds2482_chan_rd[channel]) {  in ds2482_set_channel()
246 		pdev->channel = channel;  in ds2482_set_channel()
249 	return -1;  in ds2482_set_channel()
254  * ds2482_w1_touch_bit - Performs the touch-bit function, which writes a 0 or 1 and reads the level.
257  * @bit:	The level to write: 0 or non-zero
258  * Return:	The level read: 0 or 1
263 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_touch_bit()
264 	int status = -1;  in ds2482_w1_touch_bit()
266 	mutex_lock(&pdev->access_lock);  in ds2482_w1_touch_bit()
270 	if (pdev->w1_count > 1)  in ds2482_w1_touch_bit()
271 		ds2482_set_channel(pdev, pchan->channel);  in ds2482_w1_touch_bit()
278 	mutex_unlock(&pdev->access_lock);  in ds2482_w1_touch_bit()
284  * ds2482_w1_triplet - Performs the triplet function, which reads two bits and writes a bit.
295 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_triplet()
298 	mutex_lock(&pdev->access_lock);  in ds2482_w1_triplet()
302 	if (pdev->w1_count > 1)  in ds2482_w1_triplet()
303 		ds2482_set_channel(pdev, pchan->channel);  in ds2482_w1_triplet()
310 	mutex_unlock(&pdev->access_lock);  in ds2482_w1_triplet()
317  * ds2482_w1_write_byte - Performs the write byte function.
325 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_write_byte()
327 	mutex_lock(&pdev->access_lock);  in ds2482_w1_write_byte()
331 	if (pdev->w1_count > 1)  in ds2482_w1_write_byte()
332 		ds2482_set_channel(pdev, pchan->channel);  in ds2482_w1_write_byte()
337 	mutex_unlock(&pdev->access_lock);  in ds2482_w1_write_byte()
341  * ds2482_w1_read_byte - Performs the read byte function.
349 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_read_byte()
352 	mutex_lock(&pdev->access_lock);  in ds2482_w1_read_byte()
356 	if (pdev->w1_count > 1)  in ds2482_w1_read_byte()
357 		ds2482_set_channel(pdev, pchan->channel);  in ds2482_w1_read_byte()
369 	result = i2c_smbus_read_byte(pdev->client);  in ds2482_w1_read_byte()
371 	mutex_unlock(&pdev->access_lock);  in ds2482_w1_read_byte()
378  * ds2482_w1_reset_bus - Sends a reset on the 1-wire interface
381  * Return:	0=Device present, 1=No device present or error
386 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_reset_bus()
390 	mutex_lock(&pdev->access_lock);  in ds2482_w1_reset_bus()
394 	if (pdev->w1_count > 1)  in ds2482_w1_reset_bus()
395 		ds2482_set_channel(pdev, pchan->channel);  in ds2482_w1_reset_bus()
404 		/* If the chip did reset since detect, re-config it */  in ds2482_w1_reset_bus()
410 	mutex_unlock(&pdev->access_lock);  in ds2482_w1_reset_bus()
418 	struct ds2482_data    *pdev = pchan->pdev;  in ds2482_w1_set_pullup()
421 	/* if delay is non-zero activate the pullup,  in ds2482_w1_set_pullup()
445 	int err = -ENODEV;  in ds2482_probe()
449 	if (!i2c_check_functionality(client->adapter,  in ds2482_probe()
452 		return -ENODEV;  in ds2482_probe()
456 		err = -ENOMEM;  in ds2482_probe()
460 	data->client = client;  in ds2482_probe()
465 		dev_warn(&client->dev, "DS2482 reset failed.\n");  in ds2482_probe()
472 	/* Read the status byte - only reset bit and line should be set */  in ds2482_probe()
475 		dev_warn(&client->dev, "DS2482 reset status "  in ds2482_probe()
476 			 "0x%02X - not a DS2482\n", temp1);  in ds2482_probe()
480 	/* Detect the 8-port version */  in ds2482_probe()
481 	data->w1_count = 1;  in ds2482_probe()
483 		data->w1_count = 8;  in ds2482_probe()
489 	mutex_init(&data->access_lock);  in ds2482_probe()
491 	/* Register 1-wire interface(s) */  in ds2482_probe()
492 	for (idx = 0; idx < data->w1_count; idx++) {  in ds2482_probe()
493 		data->w1_ch[idx].pdev = data;  in ds2482_probe()
494 		data->w1_ch[idx].channel = idx;  in ds2482_probe()
497 		data->w1_ch[idx].w1_bm.data       = &data->w1_ch[idx];  in ds2482_probe()
498 		data->w1_ch[idx].w1_bm.read_byte  = ds2482_w1_read_byte;  in ds2482_probe()
499 		data->w1_ch[idx].w1_bm.write_byte = ds2482_w1_write_byte;  in ds2482_probe()
500 		data->w1_ch[idx].w1_bm.touch_bit  = ds2482_w1_touch_bit;  in ds2482_probe()
501 		data->w1_ch[idx].w1_bm.triplet    = ds2482_w1_triplet;  in ds2482_probe()
502 		data->w1_ch[idx].w1_bm.reset_bus  = ds2482_w1_reset_bus;  in ds2482_probe()
503 		data->w1_ch[idx].w1_bm.set_pullup = ds2482_w1_set_pullup;  in ds2482_probe()
505 		err = w1_add_master_device(&data->w1_ch[idx].w1_bm);  in ds2482_probe()
507 			data->w1_ch[idx].pdev = NULL;  in ds2482_probe()
515 	for (idx = 0; idx < data->w1_count; idx++) {  in ds2482_probe()
516 		if (data->w1_ch[idx].pdev != NULL)  in ds2482_probe()
517 			w1_remove_master_device(&data->w1_ch[idx].w1_bm);  in ds2482_probe()
530 	/* Unregister the 1-wire bridge(s) */  in ds2482_remove()
531 	for (idx = 0; idx < data->w1_count; idx++) {  in ds2482_remove()
532 		if (data->w1_ch[idx].pdev != NULL)  in ds2482_remove()
533 			w1_remove_master_device(&data->w1_ch[idx].w1_bm);  in ds2482_remove()