1 // SPDX-License-Identifier: GPL-2.0+
15  * Please see doc/driver-model/i2c-howto.txt for instructions.
96 /*-----------------------------------------------------------------------
101 #define I2C_ACK		0		/* PD_SDA level to ack a byte */
113 /*-----------------------------------------------------------------------
126 /*-----------------------------------------------------------------------
129  * <stop> at the end of the sequence for belts & suspenders.
155 /*-----------------------------------------------------------------------
156  * START: High -> Low on SDA while SCL is High
172 /*-----------------------------------------------------------------------
173  * STOP: Low -> High on SDA while SCL is High
191 /*-----------------------------------------------------------------------
192  * ack should be I2C_ACK or I2C_NOACK
194 static void send_ack(int ack)  in send_ack()  argument
201 	I2C_SDA(ack);  in send_ack()
210 /*-----------------------------------------------------------------------
233 	 * Look for an <ACK>(negative logic) and return it.  in write_byte()
248 	return(nack);	/* not a nack is an ack */  in write_byte()
251 /*-----------------------------------------------------------------------
252  * if ack == I2C_ACK, ACK the byte so can continue reading, else
255 static uchar read_byte(int ack)  in read_byte()  argument
276 	send_ack(ack);  in read_byte()
281 /*-----------------------------------------------------------------------
302 /*-----------------------------------------------------------------------
322 /*-----------------------------------------------------------------------
363 		shift = (alen-1) * 8;  in soft_i2c_read()
364 		while(alen-- > 0) {  in soft_i2c_read()
366 				PRINTD("i2c_read, address not <ACK>ed\n");  in soft_i2c_read()
369 			shift -= 8;  in soft_i2c_read()
372 		/* Some I2C chips need a stop/start sequence here,  in soft_i2c_read()
373 		 * other chips don't work with a full stop and need  in soft_i2c_read()
375 		 * stop/start sequence.  in soft_i2c_read()
387 	 * of an ACK(len == 0) to terminate the read.  in soft_i2c_read()
390 	while(len-- > 0) {  in soft_i2c_read()
397 /*-----------------------------------------------------------------------
414 	shift = (alen-1) * 8;  in soft_i2c_write()
415 	while(alen-- > 0) {  in soft_i2c_write()
417 			PRINTD("i2c_write, address not <ACK>ed\n");  in soft_i2c_write()
420 		shift -= 8;  in soft_i2c_write()
423 	while(len-- > 0) {  in soft_i2c_write()