Alternative library and kernel for add-in development on fx-9860G and fx-CG50 under Linux.
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gint/include/gint/drivers.h

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4.6 KiB

//---
// gint:drivers - General tools for drivers
//---
#ifndef GINT_DRIVERS
#define GINT_DRIVERS
#include <gint/defs/attributes.h>
#include <gint/defs/types.h>
//---
// Driver procedure flow
//
// Drivers are initialized in priority order, and in linking order within
// the same priority level (pretty much undefined). Make sure every
// driver's priority level is higher than those of its dependencies.
//
// At initialization, the following functions are called:
// 1. driver_sh3() [if not NULL, SH3 fx9860g only]
// 2. ctx_save(sys_ctx) [if not NULL]
// 3. init() [if not NULL]
//
// Then, if the on-screen boot log is enabled, the status() function is
// called and the returned string is displayed (21 characters max).
// 4. status() [if not NULL, if GINT_BOOT_LOG is defined]
//
// If the gint_switch() function is called to temporarily give back
// control to the operating system, the state of each driver is saved to
// the stack, then restored from there.
// 5. ctx_save(stack) [if not NULL]
// 6. ctx_restore(stack) [if not NULL]
//
// When finally the driver is unloaded, the system context is restored.
// 7. ctx_restore(sys_ctx) [if not NULL]
//---
/* gint_driver_t - driver meta-information used by gint */
typedef struct
{
/* Driver name */
const char *name;
/* driver_sh3() - rectify driver initialization on SH3 platforms
This function is called during driver initialization on SH3. It may
be NULL. */
void (*driver_sh3)(void);
/* init() - initialize the driver
This function is called after ctx_save() and needs not save the
system setting. It is typically used to initialize registers to
suitable values on startup. If there is no init function, this field
may be set to NULL */
void (*init)(void);
/* unload() - deinitialize the driver
This function is called before ctx_restore() when gint is unloaded.
If there is no unload function, the field may be set to NULL */
void (*unload)(void);
/* Size of a context object for the driver */
uint ctx_size;
/* System context. The driver has to allocate a buffer of size at least
ctx_size, where gint stores the system's configuration. It is
advised to place this buffer in the .gint_bss section using the GBSS
macro of <defs/attributes.h> if it doesn't need to be initialized */
void *sys_ctx;
/* ctx_save() - save the driver's hardware support
This function is provided by the driver to save the state of its
hardware support (memory-mapped MPU registers, port state, etc).
@ctx A buffer of size ctx_size */
void (*ctx_save)(void *ctx);
/* ctx_restore() - restore a saved context
This function is provided by the driver to restore the state saved
by ctx_save(). It can alter the contents of the buffer freely.
@ctx A context buffer filled by ctx_save() */
void (*ctx_restore)(void *ctx);
/* status() - status string generation
When the boot log is defined, this function is called to print
information returned by the driver, for debugging purposes. This is
expected to be a short (max 21 bytes) string because only a few
lines are available for all drivers.
Returns a pointer to a string; a static buffer is suitable. */
const char * (*status)(void);
} GPACKED(4) gint_driver_t;
/* GINT_DECLARE_DRIVER() - make a driver visible to gint
Use this macro to expose a driver by passing it the name of a gint_driver_t
structure. This macro moves the structure to the .gint.drivers.* sections,
which are automatically traversed at startup.
The @level argument represents the priority level: lower numbers mean that
drivers will be loaded sooner. This numbering allows a primitive form of
dependency for drivers. You need to specify a level which is strictly
higher than the level of all the drivers you depend on. */
#define GINT_DECLARE_DRIVER(level, name) \
GSECTION(".gint.drivers." #level) extern gint_driver_t name;
/* GINT_DRIVER_SH3() - declare a function for SH3-rectification
This macro makes its argument NULL on fxcg50, this way the named function
can be defined under #ifdef FX9860G while keeping the structure clean. */
#ifdef FXCG50
#define GINT_DRIVER_SH3(name) NULL
#else
#define GINT_DRIVER_SH3(name) name
#endif
/* GINT_DRIVER_STATUS() - declare a function for status string generation
This macro makes its argument NULL when GINT_BOOT_LOG is defuned, this way
the named function can be defined under #ifdef GINT_BOOT_LOG while keeping
the structure clean. */
#ifdef GINT_BOOT_LOG
#define GINT_DRIVER_STATUS(name) name
#else
#define GINT_DRIVER_STATUS(name) NULL
#endif
#endif /* GINT_DRIVERS */