disable FB

hc

2024-01-04 1543e317f1da31b75942316931e8f491a8920811

 kernel/drivers/w1/slaves/w1_ds2408.c
..
..
@@ -1,10 +1,8 @@
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+// SPDX-License-Identifier: GPL-2.0-only
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 /*
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  *	w1_ds2408.c - w1 family 29 (DS2408) driver
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  *
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  * Copyright (c) 2010 Jean-Francois Dagenais <dagenaisj@sonatest.com>
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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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  */
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7
 
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 #include <linux/kernel.h>
..
..
@@ -138,14 +136,37 @@
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 		W1_F29_REG_CONTROL_AND_STATUS, buf);
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 }
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138
 
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+#ifdef CONFIG_W1_SLAVE_DS2408_READBACK
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+static bool optional_read_back_valid(struct w1_slave *sl, u8 expected)
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+{
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+	u8 w1_buf[3];
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+
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+	if (w1_reset_resume_command(sl->master))
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+		return false;
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+
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+	w1_buf[0] = W1_F29_FUNC_READ_PIO_REGS;
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+	w1_buf[1] = W1_F29_REG_OUTPUT_LATCH_STATE;
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+	w1_buf[2] = 0;
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+
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+	w1_write_block(sl->master, w1_buf, 3);
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+
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+	return (w1_read_8(sl->master) == expected);
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+}
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+#else
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+static bool optional_read_back_valid(struct w1_slave *sl, u8 expected)
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+{
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+	return true;
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+}
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+#endif
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+
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 static ssize_t output_write(struct file *filp, struct kobject *kobj,
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 			    struct bin_attribute *bin_attr, char *buf,
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 			    loff_t off, size_t count)
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 {
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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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-	u8 readBack;
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 	unsigned int retries = W1_F29_RETRIES;
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+	ssize_t bytes_written = -EIO;
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170
 
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 	if (count != 1 || off != 0)
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 		return -EFAULT;
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@@ -155,54 +176,33 @@
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 	dev_dbg(&sl->dev, "mutex locked");
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177
 
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 	if (w1_reset_select_slave(sl))
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-		goto error;
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+		goto out;
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180
 
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-	while (retries--) {
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+	do {
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 		w1_buf[0] = W1_F29_FUNC_CHANN_ACCESS_WRITE;
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 		w1_buf[1] = *buf;
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 		w1_buf[2] = ~(*buf);
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+
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 		w1_write_block(sl->master, w1_buf, 3);
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187
 
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-		readBack = w1_read_8(sl->master);
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-
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-		if (readBack != W1_F29_SUCCESS_CONFIRM_BYTE) {
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-			if (w1_reset_resume_command(sl->master))
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-				goto error;
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-			/* try again, the slave is ready for a command */
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-			continue;
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+		if (w1_read_8(sl->master) == W1_F29_SUCCESS_CONFIRM_BYTE &&
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+		    optional_read_back_valid(sl, *buf)) {
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+			bytes_written = 1;
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+			goto out;
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192
 		}
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193
 
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-#ifdef CONFIG_W1_SLAVE_DS2408_READBACK
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-		/* here the master could read another byte which
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-		   would be the PIO reg (the actual pin logic state)
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-		   since in this driver we don't know which pins are
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-		   in and outs, there's no value to read the state and
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-		   compare. with (*buf) so end this command abruptly: */
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 		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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+		/* try again, the slave is ready for a command */
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+	} while (--retries);
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198
 
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-		/* go read back the output latches */
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-		/* (the direct effect of the write above) */
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-		w1_buf[0] = W1_F29_FUNC_READ_PIO_REGS;
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-		w1_buf[1] = W1_F29_REG_OUTPUT_LATCH_STATE;
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-		w1_buf[2] = 0;
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-		w1_write_block(sl->master, w1_buf, 3);
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-		/* read the result of the READ_PIO_REGS command */
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-		if (w1_read_8(sl->master) == *buf)
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-#endif
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-		{
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-			/* success! */
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-			mutex_unlock(&sl->master->bus_mutex);
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-			dev_dbg(&sl->dev,
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-				"mutex unlocked, retries:%d", retries);
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-			return 1;
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-		}
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-	}
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-error:
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+out:
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 	mutex_unlock(&sl->master->bus_mutex);
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-	dev_dbg(&sl->dev, "mutex unlocked in error, retries:%d", retries);
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201
 
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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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+
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+	return bytes_written;
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 }
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207
 
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..
..
@@ -336,7 +336,7 @@
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 	NULL,
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 };
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338
 
339
-static struct w1_family_ops w1_f29_fops = {
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+static const struct w1_family_ops w1_f29_fops = {
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 	.add_slave      = w1_f29_disable_test_mode,
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 	.groups		= w1_f29_groups,
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 };