From 3cc50d07be10f67aff836f8247a240ec132c6a67 Mon Sep 17 00:00:00 2001 From: Lukas Wunner Date: Sat, 20 Apr 2024 22:00:01 +0200 Subject: driver core: Add device_show_string() helper for sysfs attributes For drivers wishing to expose an unsigned long, int or bool at a static memory location in sysfs, the driver core provides ready-made helpers such as device_show_ulong() to be used as ->show() callback. Some drivers need to expose a string and so far they all provide their own ->show() implementation. arch/powerpc/perf/hv-24x7.c went so far as to create a device_show_string() helper but kept it private. Make it public for reuse by other drivers. The pattern seems to be sufficiently frequent to merit a public helper. Add a DEVICE_STRING_ATTR_RO() macro in line with the existing DEVICE_ULONG_ATTR() and similar macros to ease declaration of string attributes. Signed-off-by: Lukas Wunner Acked-by: Michael Ellerman Link: https://lore.kernel.org/r/2e3eaaf2600bb55c0415c23ba301e809403a7aa2.1713608122.git.lukas@wunner.de Signed-off-by: Greg Kroah-Hartman --- include/linux/device.h | 15 +++++++++++++++ 1 file changed, 15 insertions(+) (limited to 'include/linux') diff --git a/include/linux/device.h b/include/linux/device.h index 07f4d2af1e3c..b6b6ff881a3f 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -132,6 +132,8 @@ ssize_t device_show_bool(struct device *dev, struct device_attribute *attr, char *buf); ssize_t device_store_bool(struct device *dev, struct device_attribute *attr, const char *buf, size_t count); +ssize_t device_show_string(struct device *dev, struct device_attribute *attr, + char *buf); /** * DEVICE_ATTR - Define a device attribute. @@ -251,6 +253,19 @@ ssize_t device_store_bool(struct device *dev, struct device_attribute *attr, struct dev_ext_attribute dev_attr_##_name = \ { __ATTR(_name, _mode, device_show_bool, device_store_bool), &(_var) } +/** + * DEVICE_STRING_ATTR_RO - Define a device attribute backed by a r/o string. + * @_name: Attribute name. + * @_mode: File mode. + * @_var: Identifier of string. + * + * Like DEVICE_ULONG_ATTR(), but @_var is a string. Because the length of the + * string allocation is unknown, the attribute must be read-only. + */ +#define DEVICE_STRING_ATTR_RO(_name, _mode, _var) \ + struct dev_ext_attribute dev_attr_##_name = \ + { __ATTR(_name, (_mode) & ~0222, device_show_string, NULL), (_var) } + #define DEVICE_ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) \ struct device_attribute dev_attr_##_name = \ __ATTR_IGNORE_LOCKDEP(_name, _mode, _show, _store) -- cgit v1.2.3