disable FB

hc

2024-01-04 1543e317f1da31b75942316931e8f491a8920811

 kernel/drivers/w1/slaves/w1_ds2413.c
..
..
@@ -1,11 +1,9 @@
1
+// SPDX-License-Identifier: GPL-2.0-only
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2
 /*
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  * w1_ds2413.c - w1 family 3a (DS2413) driver
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  * based on w1_ds2408.c by Jean-Francois Dagenais <dagenaisj@sonatest.com>
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  *
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  * Copyright (c) 2013 Mariusz Bialonczyk <manio@skyboo.net>
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- *
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- * This source code is licensed under the GNU General Public License,
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- * Version 2. See the file COPYING for more details.
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7
  */
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8
 
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9
 #include <linux/kernel.h>
..
..
@@ -24,12 +22,17 @@
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 #define W1_F3A_FUNC_PIO_ACCESS_READ        0xF5
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23
 #define W1_F3A_FUNC_PIO_ACCESS_WRITE       0x5A
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24
 #define W1_F3A_SUCCESS_CONFIRM_BYTE        0xAA
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+#define W1_F3A_INVALID_PIO_STATE           0xFF
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26
 
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 static ssize_t state_read(struct file *filp, struct kobject *kobj,
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 			  struct bin_attribute *bin_attr, char *buf, loff_t off,
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 			  size_t count)
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 {
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 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
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+	unsigned int retries = W1_F3A_RETRIES;
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+	ssize_t bytes_read = -EIO;
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+	u8 state;
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+
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 	dev_dbg(&sl->dev,
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 		"Reading %s kobj: %p, off: %0#10x, count: %zu, buff addr: %p",
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 		bin_attr->attr.name, kobj, (unsigned int)off, count, buf);
..
..
@@ -42,22 +45,37 @@
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 	mutex_lock(&sl->master->bus_mutex);
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 	dev_dbg(&sl->dev, "mutex locked");
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47
 
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-	if (w1_reset_select_slave(sl)) {
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-		mutex_unlock(&sl->master->bus_mutex);
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-		return -EIO;
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+next:
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+	if (w1_reset_select_slave(sl))
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+		goto out;
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+
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+	while (retries--) {
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+		w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
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+
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+		state = w1_read_8(sl->master);
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+		if ((state & 0x0F) == ((~state >> 4) & 0x0F)) {
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+			/* complement is correct */
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+			*buf = state;
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+			bytes_read = 1;
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+			goto out;
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+		} else if (state == W1_F3A_INVALID_PIO_STATE) {
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+			/* slave didn't respond, try to select it again */
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+			dev_warn(&sl->dev, "slave device did not respond to PIO_ACCESS_READ, " \
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+					    "reselecting, retries left: %d\n", retries);
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+			goto next;
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+		}
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+
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+		if (w1_reset_resume_command(sl->master))
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+			goto out; /* unrecoverable error */
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+
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+		dev_warn(&sl->dev, "PIO_ACCESS_READ error, retries left: %d\n", retries);
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72
 	}
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73
 
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-	w1_write_8(sl->master, W1_F3A_FUNC_PIO_ACCESS_READ);
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-	*buf = w1_read_8(sl->master);
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-
74
+out:
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 	mutex_unlock(&sl->master->bus_mutex);
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-	dev_dbg(&sl->dev, "mutex unlocked");
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-
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-	/* check for correct complement */
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-	if ((*buf & 0x0F) != ((~*buf >> 4) & 0x0F))
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-		return -EIO;
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-	else
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-		return 1;
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+	dev_dbg(&sl->dev, "%s, mutex unlocked, retries: %d\n",
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+		(bytes_read > 0) ? "succeeded" : "error", retries);
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+	return bytes_read;
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79
 }
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80
 
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81
 static BIN_ATTR_RO(state, 1);
..
..
@@ -69,6 +87,7 @@
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 	struct w1_slave *sl = kobj_to_w1_slave(kobj);
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 	u8 w1_buf[3];
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89
 	unsigned int retries = W1_F3A_RETRIES;
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+	ssize_t bytes_written = -EIO;
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91
 
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 	if (count != 1 || off != 0)
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93
 		return -EFAULT;
..
..
@@ -78,7 +97,7 @@
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 	dev_dbg(&sl->dev, "mutex locked");
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98
 
80
99
 	if (w1_reset_select_slave(sl))
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-		goto error;
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+		goto out;
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101
 
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 	/* according to the DS2413 datasheet the most significant 6 bits
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103
 	   should be set to "1"s, so do it now */
..
..
@@ -91,18 +110,20 @@
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 		w1_write_block(sl->master, w1_buf, 3);
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111
 
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 		if (w1_read_8(sl->master) == W1_F3A_SUCCESS_CONFIRM_BYTE) {
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-			mutex_unlock(&sl->master->bus_mutex);
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-			dev_dbg(&sl->dev, "mutex unlocked, retries:%d", retries);
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-			return 1;
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+			bytes_written = 1;
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+			goto out;
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115
 		}
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116
 		if (w1_reset_resume_command(sl->master))
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-			goto error;
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+			goto out; /* unrecoverable error */
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+
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+		dev_warn(&sl->dev, "PIO_ACCESS_WRITE error, retries left: %d\n", retries);
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120
 	}
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121
 
102
-error:
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+out:
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123
 	mutex_unlock(&sl->master->bus_mutex);
104
-	dev_dbg(&sl->dev, "mutex unlocked in error, retries:%d", retries);
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-	return -EIO;
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+	dev_dbg(&sl->dev, "%s, mutex unlocked, retries: %d\n",
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+		(bytes_written > 0) ? "succeeded" : "error", retries);
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+	return bytes_written;
106
127
 }
107
128
 
108
129
 static BIN_ATTR(output, S_IRUGO | S_IWUSR | S_IWGRP, NULL, output_write, 1);
..
..
@@ -122,7 +143,7 @@
122
143
 	NULL,
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144
 };
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145
 
125
-static struct w1_family_ops w1_f3a_fops = {
146
+static const struct w1_family_ops w1_f3a_fops = {
126
147
 	.groups		= w1_f3a_groups,
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148
 };
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149