RADIO(9)

🌸 RADIO(9) 🌸

okay so this is the Kernel Developer's Manual page for radio and bestie, it's literally the glow-up guide for FM radio drivers 💅

---

✨ NAME ✨

radio — the 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 💖

so the radio layer is the whole support system for digitally programmable FM radio tuners ✨ like, it's giving backstage crew for your tuner's main character moment.

It's split into two parts, no cap:

• a machine independent, high-level part whose whole job is managing device files 👑
• the low-level hardware drivers 🧚

The high-level radio driver attaches to the low-level driver when the latter calls radio_attach_mi(). that's the meet-cute fr fr 🫶

The radio_hw_if struct holds pointers to functions that the low-level driver provides. The hdlp argument is a handle to a low-level driver's softc structure — it gets sent as the first argument to all the functions in radio_hw_if whenever the high-level driver calls them, every single time, no exceptions 💀 And dev is the device struct for the hardware device.

The fields of radio_hw_if get described in a lil more detail right 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);
};

🌈 the function pointers, one by one

• (*open)(sc, flags, fmt, lwp) — gets called when the radio device is opened 🚪 Optionally, if there's genuinely no need to call a driver's function when the device file is opened, pass NULL in this field. Returns 0 on success, otherwise an error code.
• (*close)(sc, flags, fmt, lwp) — gets called when the radio device is closed 🚪✨ Optionally, if there's no need to call a driver's function when the device file is closed, pass NULL in this field. Returns 0 on success, otherwise an error code.
• (*get_info)(sc, ri) — fills the radio_info struct 💖 This one is used to obtain the current state of a hardware device. It runs 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) — sets values from the radio_info struct 🔥 This one is used to modify the current state of a hardware device (enable/disable various modes and parameters). It runs 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) — kicks off the automatic search for the radio station 📻✨ It runs as a result of calling RIOCSSRCH on a device file managed by the high-level driver. Returns 0 on success, otherwise an error code.

friendly reminder bestie: every single one of these returns 0 on success, and an error code otherwise. that part is not optional, it's the vibe check 😌

---

👀 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. legends only 👑💅

---

okay that's the whole page, bestie — go forth and slay those tuners 📻✨

this lil treasure came from the Debian edition, dated July 9, 2018 — mwah, sign-off complete 🎀💖