1 // SPDX-License-Identifier: GPL-2.0-or-later
3  * Linux I2C core SMBus and SMBus emulation code
5  * This file contains the SMBus functions which are always included in the I2C
6  * core because they can be emulated via I2C. SMBus specific extensions
7  * (e.g. smbalert) are handled in a separate i2c-smbus module.
9  * All SMBus-related things are written by Frodo Looijaard <frodol@dds.nl>
15 #include <linux/i2c.h>
16 #include <linux/i2c-smbus.h>
21 #include "i2c-core.h"
43  * i2c_smbus_pec - Incremental CRC8 over the given input data array
60 /* Assume a 7-bit address, which is reasonable for SMBus */
68 	return i2c_smbus_pec(pec, msg->buf, msg->len);  in i2c_smbus_msg_pec()
74 	msg->buf[msg->len] = i2c_smbus_msg_pec(0, msg);  in i2c_smbus_add_pec()
75 	msg->len++;  in i2c_smbus_add_pec()
85 	u8 rpec = msg->buf[--msg->len];  in i2c_smbus_check_pec()
91 		return -EBADMSG;  in i2c_smbus_check_pec()
97  * i2c_smbus_read_byte - SMBus "receive byte" protocol
100  * This executes the SMBus "receive byte" protocol, returning negative errno
108 	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,  in i2c_smbus_read_byte()
116  * i2c_smbus_write_byte - SMBus "send byte" protocol
120  * This executes the SMBus "send byte" protocol, returning negative errno
125 	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,  in i2c_smbus_write_byte()
131  * i2c_smbus_read_byte_data - SMBus "read byte" protocol
135  * This executes the SMBus "read byte" protocol, returning negative errno
143 	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,  in i2c_smbus_read_byte_data()
151  * i2c_smbus_write_byte_data - SMBus "write byte" protocol
156  * This executes the SMBus "write byte" protocol, returning negative errno
164 	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,  in i2c_smbus_write_byte_data()
171  * i2c_smbus_read_word_data - SMBus "read word" protocol
175  * This executes the SMBus "read word" protocol, returning negative errno
176  * else a 16-bit unsigned "word" received from the device.
183 	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,  in i2c_smbus_read_word_data()
191  * i2c_smbus_write_word_data - SMBus "write word" protocol
194  * @value: 16-bit "word" being written
196  * This executes the SMBus "write word" protocol, returning negative errno
204 	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,  in i2c_smbus_write_word_data()
211  * i2c_smbus_read_block_data - SMBus "block read" protocol
217  * This executes the SMBus "block read" protocol, returning negative errno
222  * support this; its emulation through I2C messaging relies on a specific
231 	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,  in i2c_smbus_read_block_data()
243  * i2c_smbus_write_block_data - SMBus "block write" protocol
249  * This executes the SMBus "block write" protocol, returning negative errno
261 	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,  in i2c_smbus_write_block_data()
277 	status = i2c_smbus_xfer(client->adapter, client->addr, client->flags,  in i2c_smbus_read_i2c_block_data()
297 	return i2c_smbus_xfer(client->adapter, client->addr, client->flags,  in i2c_smbus_write_i2c_block_data()
305 	bool is_read = msg->flags & I2C_M_RD;  in i2c_smbus_try_get_dmabuf()
312 	msg->buf = dma_buf;  in i2c_smbus_try_get_dmabuf()
313 	msg->flags |= I2C_M_DMA_SAFE;  in i2c_smbus_try_get_dmabuf()
316 		msg->buf[0] = init_val;  in i2c_smbus_try_get_dmabuf()
320  * Simulate a SMBus command using the I2C protocol.
376 			msgbuf0[1] = data->byte;  in i2c_smbus_xfer_emulated()
384 			msgbuf0[1] = data->word & 0xff;  in i2c_smbus_xfer_emulated()
385 			msgbuf0[2] = data->word >> 8;  in i2c_smbus_xfer_emulated()
393 		msgbuf0[1] = data->word & 0xff;  in i2c_smbus_xfer_emulated()
394 		msgbuf0[2] = data->word >> 8;  in i2c_smbus_xfer_emulated()
403 			msg[0].len = data->block[0] + 2;  in i2c_smbus_xfer_emulated()
405 				dev_err(&adapter->dev,  in i2c_smbus_xfer_emulated()
407 					data->block[0]);  in i2c_smbus_xfer_emulated()
408 				return -EINVAL;  in i2c_smbus_xfer_emulated()
412 			memcpy(msg[0].buf + 1, data->block, msg[0].len - 1);  in i2c_smbus_xfer_emulated()
418 		if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {  in i2c_smbus_xfer_emulated()
419 			dev_err(&adapter->dev,  in i2c_smbus_xfer_emulated()
421 				data->block[0]);  in i2c_smbus_xfer_emulated()
422 			return -EINVAL;  in i2c_smbus_xfer_emulated()
425 		msg[0].len = data->block[0] + 2;  in i2c_smbus_xfer_emulated()
427 		memcpy(msg[0].buf + 1, data->block, msg[0].len - 1);  in i2c_smbus_xfer_emulated()
435 		if (data->block[0] > I2C_SMBUS_BLOCK_MAX) {  in i2c_smbus_xfer_emulated()
436 			dev_err(&adapter->dev, "Invalid block %s size %d\n",  in i2c_smbus_xfer_emulated()
438 				data->block[0]);  in i2c_smbus_xfer_emulated()
439 			return -EINVAL;  in i2c_smbus_xfer_emulated()
443 			msg[1].len = data->block[0];  in i2c_smbus_xfer_emulated()
446 			msg[0].len = data->block[0] + 1;  in i2c_smbus_xfer_emulated()
449 			memcpy(msg[0].buf + 1, data->block + 1, data->block[0]);  in i2c_smbus_xfer_emulated()
453 		dev_err(&adapter->dev, "Unsupported transaction %d\n", size);  in i2c_smbus_xfer_emulated()
454 		return -EOPNOTSUPP;  in i2c_smbus_xfer_emulated()
466 		if (msg[nmsgs - 1].flags & I2C_M_RD)  in i2c_smbus_xfer_emulated()
467 			msg[nmsgs - 1].len++;  in i2c_smbus_xfer_emulated()
474 		status = -EIO;  in i2c_smbus_xfer_emulated()
480 	if (wants_pec && (msg[nmsgs - 1].flags & I2C_M_RD)) {  in i2c_smbus_xfer_emulated()
481 		status = i2c_smbus_check_pec(partial_pec, &msg[nmsgs - 1]);  in i2c_smbus_xfer_emulated()
489 			data->byte = msgbuf0[0];  in i2c_smbus_xfer_emulated()
492 			data->byte = msgbuf1[0];  in i2c_smbus_xfer_emulated()
496 			data->word = msgbuf1[0] | (msgbuf1[1] << 8);  in i2c_smbus_xfer_emulated()
499 			memcpy(data->block + 1, msg[1].buf, data->block[0]);  in i2c_smbus_xfer_emulated()
504 				dev_err(&adapter->dev,  in i2c_smbus_xfer_emulated()
507 				status = -EPROTO;  in i2c_smbus_xfer_emulated()
510 			memcpy(data->block, msg[1].buf, msg[1].buf[0] + 1);  in i2c_smbus_xfer_emulated()
524  * i2c_smbus_xfer - execute SMBus protocol operations
525  * @adapter: Handle to I2C bus
530  * @protocol: SMBus protocol operation to execute, such as I2C_SMBUS_PROC_CALL
533  * This executes an SMBus protocol operation, and returns a negative
538 		   u8 command, int protocol, union i2c_smbus_data *data)  in i2c_smbus_xfer()  argument
547 			       command, protocol, data);  in i2c_smbus_xfer()
556 		     u8 command, int protocol, union i2c_smbus_data *data)  in __i2c_smbus_xfer()  argument
570 	 * read_write and protocol.  in __i2c_smbus_xfer()
573 			  command, protocol, data);  in __i2c_smbus_xfer()
575 			 command, protocol);  in __i2c_smbus_xfer()
579 	xfer_func = adapter->algo->smbus_xfer;  in __i2c_smbus_xfer()
581 		if (adapter->algo->smbus_xfer_atomic)  in __i2c_smbus_xfer()
582 			xfer_func = adapter->algo->smbus_xfer_atomic;  in __i2c_smbus_xfer()
583 		else if (adapter->algo->master_xfer_atomic)  in __i2c_smbus_xfer()
584 			xfer_func = NULL; /* fallback to I2C emulation */  in __i2c_smbus_xfer()
590 		for (res = 0, try = 0; try <= adapter->retries; try++) {  in __i2c_smbus_xfer()
592 					command, protocol, data);  in __i2c_smbus_xfer()
593 			if (res != -EAGAIN)  in __i2c_smbus_xfer()
596 				       orig_jiffies + adapter->timeout))  in __i2c_smbus_xfer()
600 		if (res != -EOPNOTSUPP || !adapter->algo->master_xfer)  in __i2c_smbus_xfer()
609 				      command, protocol, data);  in __i2c_smbus_xfer()
614 			  command, protocol, data, res);  in __i2c_smbus_xfer()
616 			   command, protocol, res);  in __i2c_smbus_xfer()
623  * i2c_smbus_read_i2c_block_data_or_emulated - read block or emulate
631  * This executes the SMBus "block read" protocol if supported by the adapter.
635  * The addresses of the I2C slave device that are accessed with this function
637  * effect as a byte read. Before using this function you must double-check
638  * if the I2C slave does support exchanging a block transfer with a byte
650 	if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_I2C_BLOCK))  in i2c_smbus_read_i2c_block_data_or_emulated()
653 	if (!i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_BYTE_DATA))  in i2c_smbus_read_i2c_block_data_or_emulated()
654 		return -EOPNOTSUPP;  in i2c_smbus_read_i2c_block_data_or_emulated()
656 	if (i2c_check_functionality(client->adapter, I2C_FUNC_SMBUS_READ_WORD_DATA)) {  in i2c_smbus_read_i2c_block_data_or_emulated()
680  * i2c_new_smbus_alert_device - get ara client for SMBus alert support
685  * Setup handling of the SMBus alert protocol on a given I2C bus segment.
709 	struct device *parent = adapter->dev.parent;  in i2c_setup_smbus_alert()
717 	irq = device_property_match_string(parent, "interrupt-names", "smbus_alert");  in i2c_setup_smbus_alert()
718 	if (irq < 0 && irq != -EINVAL && irq != -ENODATA)  in i2c_setup_smbus_alert()
722 	if (irq < 0 && !device_property_present(parent, "smbalert-gpios"))  in i2c_setup_smbus_alert()