iio: __iio_format_value(): Convert to sysfs_emit_at()

sysfs_emit() is preferred over raw s*printf() for sysfs attributes since it
knows about the sysfs buffer specifics and has some built-in sanity checks.

Convert __iio_format_value() and related functions to use this new
interface.

This conversion involves changing the signature of __iio_format_value() so
that it similar to sysfs_emit_at() and takes the buffers start address and
an offset where to write within the buffer.

Signed-off-by: Lars-Peter Clausen <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Jonathan Cameron <[email protected]>

Author: larsclausen

drivers/iio/industrialio-core.c

@@ -623,7 +623,7 @@ int iio_read_mount_matrix(struct device *dev, const char *propname,
 }
 EXPORT_SYMBOL(iio_read_mount_matrix);
 
-static ssize_t __iio_format_value(char *buf, size_t len, unsigned int type,
+static ssize_t __iio_format_value(char *buf, size_t offset, unsigned int type,
 				  int size, const int *vals)
 {
 	int tmp0, tmp1;
@@ -632,52 +632,53 @@ static ssize_t __iio_format_value(char *buf, size_t len, unsigned int type,
 
 	switch (type) {
 	case IIO_VAL_INT:
-		return scnprintf(buf, len, "%d", vals[0]);
+		return sysfs_emit_at(buf, offset, "%d", vals[0]);
 	case IIO_VAL_INT_PLUS_MICRO_DB:
 		scale_db = true;
 		fallthrough;
 	case IIO_VAL_INT_PLUS_MICRO:
 		if (vals[1] < 0)
-			return scnprintf(buf, len, "-%d.%06u%s", abs(vals[0]),
-					-vals[1], scale_db ? " dB" : "");
+			return sysfs_emit_at(buf, offset, "-%d.%06u%s",
+					     abs(vals[0]), -vals[1],
+					     scale_db ? " dB" : "");
 		else
-			return scnprintf(buf, len, "%d.%06u%s", vals[0], vals[1],
-					scale_db ? " dB" : "");
+			return sysfs_emit_at(buf, offset, "%d.%06u%s", vals[0],
+					     vals[1], scale_db ? " dB" : "");
 	case IIO_VAL_INT_PLUS_NANO:
 		if (vals[1] < 0)
-			return scnprintf(buf, len, "-%d.%09u", abs(vals[0]),
-					-vals[1]);
+			return sysfs_emit_at(buf, offset, "-%d.%09u",
+					     abs(vals[0]), -vals[1]);
 		else
-			return scnprintf(buf, len, "%d.%09u", vals[0], vals[1]);
+			return sysfs_emit_at(buf, offset, "%d.%09u", vals[0],
+					     vals[1]);
 	case IIO_VAL_FRACTIONAL:
 		tmp2 = div_s64((s64)vals[0] * 1000000000LL, vals[1]);
 		tmp1 = vals[1];
 		tmp0 = (int)div_s64_rem(tmp2, 1000000000, &tmp1);
 		if ((tmp2 < 0) && (tmp0 == 0))
-			return snprintf(buf, len, "-0.%09u", abs(tmp1));
+			return sysfs_emit_at(buf, offset, "-0.%09u", abs(tmp1));
 		else
-			return snprintf(buf, len, "%d.%09u", tmp0, abs(tmp1));
+			return sysfs_emit_at(buf, offset, "%d.%09u", tmp0,
+					     abs(tmp1));
 	case IIO_VAL_FRACTIONAL_LOG2:
 		tmp2 = shift_right((s64)vals[0] * 1000000000LL, vals[1]);
 		tmp0 = (int)div_s64_rem(tmp2, 1000000000LL, &tmp1);
 		if (tmp0 == 0 && tmp2 < 0)
-			return snprintf(buf, len, "-0.%09u", abs(tmp1));
+			return sysfs_emit_at(buf, offset, "-0.%09u", abs(tmp1));
 		else
-			return scnprintf(buf, len, "%d.%09u", tmp0, abs(tmp1));
+			return sysfs_emit_at(buf, offset, "%d.%09u", tmp0,
+					     abs(tmp1));
 	case IIO_VAL_INT_MULTIPLE:
 	{
 		int i;
 		int l = 0;
 
-		for (i = 0; i < size; ++i) {
-			l += scnprintf(&buf[l], len - l, "%d ", vals[i]);
-			if (l >= len)
-				break;
-		}
+		for (i = 0; i < size; ++i)
+			l += sysfs_emit_at(buf, offset + l, "%d ", vals[i]);
 		return l;
 	}
 	case IIO_VAL_CHAR:
-		return scnprintf(buf, len, "%c", (char)vals[0]);
+		return sysfs_emit_at(buf, offset, "%c", (char)vals[0]);
 	default:
 		return 0;
 	}
@@ -701,11 +702,11 @@ ssize_t iio_format_value(char *buf, unsigned int type, int size, int *vals)
 {
 	ssize_t len;
 
-	len = __iio_format_value(buf, PAGE_SIZE, type, size, vals);
+	len = __iio_format_value(buf, 0, type, size, vals);
 	if (len >= PAGE_SIZE - 1)
 		return -EFBIG;
 
-	return len + sprintf(buf + len, "\n");
+	return len + sysfs_emit_at(buf, len, "\n");
 }
 EXPORT_SYMBOL_GPL(iio_format_value);
 
@@ -763,22 +764,21 @@ static ssize_t iio_format_list(char *buf, const int *vals, int type, int length,
 		break;
 	}
 
-	len = scnprintf(buf, PAGE_SIZE, prefix);
+	len = sysfs_emit(buf, prefix);
 
 	for (i = 0; i <= length - stride; i += stride) {
 		if (i != 0) {
-			len += scnprintf(buf + len, PAGE_SIZE - len, " ");
+			len += sysfs_emit_at(buf, len, " ");
 			if (len >= PAGE_SIZE)
 				return -EFBIG;
 		}
 
-		len += __iio_format_value(buf + len, PAGE_SIZE - len, type,
-					  stride, &vals[i]);
+		len += __iio_format_value(buf, len, type, stride, &vals[i]);
 		if (len >= PAGE_SIZE)
 			return -EFBIG;
 	}
 
-	len += scnprintf(buf + len, PAGE_SIZE - len, "%s\n", suffix);
+	len += sysfs_emit_at(buf, len, "%s\n", suffix);
 
 	return len;
 }