1 // SPDX-License-Identifier: GPL-2.0-or-later
8  * extensive empirical testing has revealed that auto-detection of
9  * limit-registers will fail in a random fashion unless the delay
10  * parameter is set to above about 80us. The default delay is set
11  * to 100us to include some safety margin.
21 #include <linux/delay.h>
35 	int delay;		/* Delay between chip accesses in us */  member
41 #define MAX15301_WAIT_TIME		100	/* us	*/
43 static ushort delay = MAX15301_WAIT_TIME;  variable
44 module_param(delay, ushort, 0644);
45 MODULE_PARM_DESC(delay, "Delay between chip accesses in us");
58 /* This chip needs a delay between accesses */
61 	if (data->delay) {  in max15301_wait()
62 		s64 delta = ktime_us_delta(ktime_get(), data->access);  in max15301_wait()
64 		if (delta < data->delay)  in max15301_wait()
65 			udelay(data->delay - delta);  in max15301_wait()
77 		return -ENXIO;  in max15301_read_word_data()
80 		return -ENXIO;  in max15301_read_word_data()
84 	data->access = ktime_get();  in max15301_read_word_data()
96 		return -ENXIO;  in max15301_read_byte_data()
100 	data->access = ktime_get();  in max15301_read_byte_data()
113 		return -ENXIO;  in max15301_write_word_data()
116 		return -ENXIO;  in max15301_write_word_data()
120 	data->access = ktime_get();  in max15301_write_word_data()
132 		return -ENXIO;  in max15301_write_byte()
136 	data->access = ktime_get();  in max15301_write_byte()
148 	if (!i2c_check_functionality(client->adapter,  in max15301_probe()
151 		return -ENODEV;  in max15301_probe()
155 		dev_err(&client->dev, "Failed to read Device Id\n");  in max15301_probe()
158 	for (mid = max15301_id; mid->name[0]; mid++) {  in max15301_probe()
159 		if (!strncasecmp(mid->name, device_id, strlen(mid->name)))  in max15301_probe()
162 	if (!mid->name[0]) {  in max15301_probe()
163 		dev_err(&client->dev, "Unsupported device\n");  in max15301_probe()
164 		return -ENODEV;  in max15301_probe()
167 	max15301_data.delay = delay;  in max15301_probe()
169 	info->read_byte_data = max15301_read_byte_data;  in max15301_probe()
170 	info->read_word_data = max15301_read_word_data;  in max15301_probe()
171 	info->write_byte = max15301_write_byte;  in max15301_probe()
172 	info->write_word_data = max15301_write_word_data;  in max15301_probe()