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charset="utf-8" Message-Id: <20261102-e-notation-v5-6-d399e544a982@analog.com> References: <20261102-e-notation-v5-0-d399e544a982@analog.com> In-Reply-To: <20261102-e-notation-v5-0-d399e544a982@analog.com> To: linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org Cc: Andrew Morton , Jonathan Cameron , David Lechner , Andy Shevchenko , Rodrigo Alencar X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=ed25519-sha256; t=1793616082; l=7784; i=rodrigo.alencar@analog.com; s=default; h=from:subject:message-id; bh=dUhNeZXo5vFzXntF/nMNYwVrkSGbdT2vPYrOiXpyQTQ=; b=Mq2OoyL0WKj+I52nUPvdIMaNYqQ8FtHcphsTDxYTZOWtDucvKpH1jXatvIQfqsUS3rUp8G7KA Cb/vfITm8vwDqVPlkmA51tD+z4eQa/s8dE/y8XphSgc2BYixsKAf0An X-Developer-Key: i=rodrigo.alencar@analog.com; a=ed25519; pk=ULeHbgU/OYh/PG/4anHDfLgldFItQHAhOktYRVLMFRo= X-Endpoint-Received: by B4 Relay for rodrigo.alencar@analog.com/default with auth_id=561 X-Original-From: Rodrigo Alencar Reply-To: rodrigo.alencar@analog.com Content-Transfer-Encoding: 7bit From: Rodrigo Alencar Replace the open-coded __iio_str_to_fixpoint() parser with kstrtodec64(), so sysfs writes of fixed-point values also accept E notation. The fractional part only keeps the sign when the integer part is zero, as before. The dB suffix for scale attributes is now handled by a separate iio_str_to_fixpoint_units() helper. It strips an optional trailing newline and the "dB" or " dB" suffix before parsing. When there is no fractional part (fract_mult == 0, or dec_scale == 0 for 64-bit values), try base-autodetecting kstrtoll() first so hexadecimal and octal input keeps its meaning ("010" is still 8). Fall back to kstrtodec64() on -EINVAL to accept E notation. As a side effect, inputs that used to be rejected for integer-only attributes are now accepted. An invalid octal number such as "08" is parsed as decimal 8, and a fractional value such as "1.5" is rounded to 2. Signed-off-by: Rodrigo Alencar --- drivers/iio/industrialio-core.c | 177 +++++++++++++++++++++++----------------- 1 file changed, 104 insertions(+), 73 deletions(-) diff --git a/drivers/iio/industrialio-core.c b/drivers/iio/industrialio-core.c index 825cf7f32059..71e9faad4049 100644 --- a/drivers/iio/industrialio-core.c +++ b/drivers/iio/industrialio-core.c @@ -995,76 +995,21 @@ static ssize_t iio_read_channel_info_avail(struct device *dev, } } -/** - * __iio_str_to_fixpoint() - Parse a fixed-point number from a string - * @str: The string to parse - * @fract_mult: Multiplier for the first decimal place, should be a power of 10 - * @integer: The integer part of the number - * @fract: The fractional part of the number - * @scale_db: True if this should parse as dB - * - * Returns: - * 0 on success, or a negative error code if the string could not be parsed. - */ -static int __iio_str_to_fixpoint(const char *str, int fract_mult, - int *integer, int *fract, bool scale_db) +static int iio_str_to_s64(const char *str, s64 *val) { - int i = 0, f = 0; - bool integer_part = true, negative = false; - - if (fract_mult == 0) { - *fract = 0; - - return kstrtoint(str, 0, integer); - } - - if (str[0] == '-') { - negative = true; - str++; - } else if (str[0] == '+') { - str++; - } - - while (*str) { - if ('0' <= *str && *str <= '9') { - if (integer_part) { - int digit = *str - '0'; - - /* Accumulate with the sign applied so INT_MIN fits */ - if (check_mul_overflow(i, 10, &i) || - check_add_overflow(i, negative ? -digit : digit, &i)) - return -ERANGE; - } else { - f += fract_mult * (*str - '0'); - fract_mult /= 10; - } - } else if (*str == '\n') { - if (*(str + 1) == '\0') - break; - return -EINVAL; - } else if (!strncmp(str, " dB", sizeof(" dB") - 1) && scale_db) { - /* Ignore the dB suffix */ - str += sizeof(" dB") - 1; - continue; - } else if (!strncmp(str, "dB", sizeof("dB") - 1) && scale_db) { - /* Ignore the dB suffix */ - str += sizeof("dB") - 1; - continue; - } else if (*str == '.' && integer_part) { - integer_part = false; - } else { - return -EINVAL; - } - str++; - } - - if (negative && !i) - f = -f; - - *integer = i; - *fract = f; - - return 0; + int ret; + + /* + * Keep hex/octal support for integers. E notation and decimal values + * result in -EINVAL from kstrtoll(), due to unexpected termination on + * '.' or 'e'. It falls back to kstrtodec64() for decimal fixed-point + * numbers with zero scale. + */ + ret = kstrtoll(str, 0, val); + if (ret == -EINVAL) + return kstrtodec64(str, 0, val); + + return ret; } /** @@ -1074,16 +1019,98 @@ static int __iio_str_to_fixpoint(const char *str, int fract_mult, * @integer: The integer part of the number * @fract: The fractional part of the number * + * Parses a decimal number with an optional sign and an optional E notation + * exponent. The string may end with a single newline. Digits beyond the + * precision set by @fract_mult are rounded to nearest, ties to even, so with + * @fract_mult = 100000 the input "0.0000025" results in 2 micro. The sign is + * carried by @integer, or by @fract when @integer is zero. + * + * When @fract_mult is 0, the number is an integer and @fract is set to 0. + * Hexadecimal ("0x10") and octal ("010") inputs are accepted with their usual + * meaning. Any other input is parsed as a decimal number and rounded to + * nearest. For example, "1e3" results in 1000 and "1.5" in 2. Leading zeros + * that do not form a valid octal number fall back to decimal, so "08" results + * in 8. + * * Returns: * 0 on success, or a negative error code if the string could not be parsed. */ int iio_str_to_fixpoint(const char *str, int fract_mult, int *integer, int *fract) { - return __iio_str_to_fixpoint(str, fract_mult, integer, fract, false); + s64 dec64; + int ret; + + if (fract_mult) { + /* scale = ffs(fract_mult) = ffs(10^n) = ffs(2^n * 5^n) = n + 1 */ + ret = kstrtodec64(str, ffs(fract_mult), &dec64); + if (ret) + return ret; + + dec64 = div_s64_rem(dec64, fract_mult * 10, fract); + /* only carry the sign in fract if the integer is zero */ + if (dec64) + *fract = abs(*fract); + } else { + ret = iio_str_to_s64(str, &dec64); + if (ret) + return ret; + + *fract = 0; + } + + if (dec64 > INT_MAX || dec64 < INT_MIN) + return -ERANGE; + + *integer = dec64; + + return 0; } EXPORT_SYMBOL_GPL(iio_str_to_fixpoint); +/** + * iio_str_to_fixpoint_units() - Parse a fixed-point number with units from a string + * @str: The string to parse + * @fract_mult: Multiplier for the first decimal place, should be a power of 10 + * @integer: The integer part of the number + * @fract: The fractional part of the number + * @units: The units to expect at the end of the string + * + * Parses a fixed-point/decimal number from a string, optionally with units at + * the end. The string should be in the format "[ ]". For example, + * the input "7.2 dB" would be parsed as integer = 7 and fract = 200000 with + * units = "dB" and fract_mult = 100000. + * + * Returns: + * 0 on success, or a negative error code if the string could not be parsed. + */ +static int iio_str_to_fixpoint_units(const char *str, int fract_mult, + int *integer, int *fract, + const char *units) +{ + size_t units_len = strlen(units); + size_t s_len = strlen(str); + const char *dec_str = str; + char buf[64]; + + if (s_len && str[s_len - 1] == '\n') + s_len--; + + if (s_len > units_len && + !strncmp(str + s_len - units_len, units, units_len)) { + s_len -= units_len; + if (str[s_len - 1] == ' ') + s_len--; + if (s_len >= sizeof(buf)) + return -EINVAL; + memcpy(buf, str, s_len); + buf[s_len] = '\0'; + dec_str = buf; + } + + return iio_str_to_fixpoint(dec_str, fract_mult, integer, fract); +} + static ssize_t iio_write_channel_info(struct device *dev, struct device_attribute *attr, const char *buf, @@ -1148,14 +1175,18 @@ static ssize_t iio_write_channel_info(struct device *dev, if (dec_scale) ret = kstrtodec64(buf, dec_scale, &integer64); else - ret = kstrtoll(buf, 0, &integer64); + ret = iio_str_to_s64(buf, &integer64); if (ret) return ret; iio_val_s64_decompose(integer64, &integer, &fract); } else { - ret = __iio_str_to_fixpoint(buf, fract_mult, &integer, &fract, - scale_db); + if (scale_db) + ret = iio_str_to_fixpoint_units(buf, fract_mult, + &integer, &fract, "dB"); + else + ret = iio_str_to_fixpoint(buf, fract_mult, &integer, + &fract); if (ret) return ret; } -- 2.43.0