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RADIO(9) FreeBSD Kernel Developer's Manual RADIO(9) NAME radio - interface between low- and high-level FM radio drivers SYNOPSIS #include <dev/radio_if.h> device_t radio_attach_mi(const struct radio_hw_if *rhwp, void *hdlp, device_t dev); DESCRIPTION The radio layer provides support for digitally programmable FM radio tuners. It is divided into a machine independent, high-level part responsible for managing device files, and low-level hardware drivers. The high-level radio driver attaches to the low-level driver when the latter calls radio_attach_mi(). The radio_hw_if struct contains pointers to functions provided by the low-level driver. The hdlp argument is a handle to a low-level driver's softc structure. It is sent as the first argument to all the functions in radio_hw_if when the high-level driver calls them. dev is the device struct for the hardware device. The fields of radio_hw_if are described in some more detail below. struct radio_hw_if { int (*open)(void *, int, int, struct lwp *); int (*close)(void *, int, int, struct lwp *); int (*get_info)(void *, struct radio_info *); int (*set_info)(void *, struct radio_info *); int (*search)(void *, int); }; (*open)(sc, flags, fmt, lwp) Called when the radio device is opened. Optionally, if there is no need to call a driver's function when the device file is opened, NULL should be passed in this field. Returns 0 on success, otherwise an error code. (*close)(sc, flags, fmt, lwp) Called when the radio device is closed. Optionally, if there is no need to call a driver's function when the device file is closed, NULL should be passed in thie field. Returns 0 on success, otherwise an error code. (*get_info)(sc, ri) Fills the radio_info struct. This function is used to obtain the current state of a hardware device. It is executed as a result of calling RIOCGINFO on a device file managed by the high-level driver. Returns 0 on success, otherwise an error code. (*set_info)(sc, ri) Set values from the radio_info struct. This function is used to modify the current state of a hardware device (enable/disable various modes and parameters). It is executed as a result of calling RIOCSINFO on a device file managed by the high-level driver. Returns 0 on success, otherwise an error code. (*search)(sc, ri) Initiates automatic search for the radio station. It is executed as a result of calling RIOCSSRCH on a device file managed by the high-level driver. Returns 0 on success, otherwise an error code. SEE ALSO radio(4) AUTHORS The radio API was written by Vladimir Popov and Maxim Tsyplakov for OpenBSD and ported to NetBSD by Lennart Augustsson. FreeBSD 14.1-RELEASE-p8 July 9, 2018 FreeBSD 14.1-RELEASE-p8