drivers/staging/fbtft/fbtft-bus.c

Source file repositories/reference/linux-study-clean/drivers/staging/fbtft/fbtft-bus.c

File Facts

System
Linux kernel
Corpus path
drivers/staging/fbtft/fbtft-bus.c
Extension
.c
Size
7436 bytes
Lines
235
Domain
Driver Families
Bucket
drivers/staging
Inferred role
Driver Families: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

// SPDX-License-Identifier: GPL-2.0
#include <linux/export.h>
#include <linux/errno.h>
#include <linux/gpio/consumer.h>
#include <linux/spi/spi.h>
#include "fbtft.h"

/*****************************************************************************
 *
 *   void (*write_reg)(struct fbtft_par *par, int len, ...);
 *
 *****************************************************************************/

#define define_fbtft_write_reg(func, buffer_type, data_type, modifier)        \
void func(struct fbtft_par *par, int len, ...)                                \
{                                                                             \
	va_list args;                                                         \
	int i, ret;                                                           \
	int offset = 0;                                                       \
	buffer_type *buf = (buffer_type *)par->buf;                           \
									      \
	if (unlikely(par->debug & DEBUG_WRITE_REGISTER)) {                    \
		va_start(args, len);                                          \
		for (i = 0; i < len; i++) {                                   \
			buf[i] = modifier((data_type)va_arg(args,             \
							    unsigned int));   \
		}                                                             \
		va_end(args);                                                 \
		fbtft_par_dbg_hex(DEBUG_WRITE_REGISTER, par,                  \
				  par->info->device, buffer_type, buf, len,   \
				  "%s: ", __func__);                          \
	}                                                                     \
									      \
	va_start(args, len);                                                  \
									      \
	if (par->startbyte) {                                                 \
		*(u8 *)par->buf = par->startbyte;                             \
		buf = (buffer_type *)(par->buf + 1);                          \
		offset = 1;                                                   \
	}                                                                     \
									      \
	*buf = modifier((data_type)va_arg(args, unsigned int));               \
	ret = fbtft_write_buf_dc(par, par->buf, sizeof(data_type) + offset,   \
				 0);                                          \
	if (ret < 0)							      \
		goto out;						      \
	len--;                                                                \
									      \
	if (par->startbyte)                                                   \
		*(u8 *)par->buf = par->startbyte | 0x2;                       \
									      \
	if (len) {                                                            \
		i = len;                                                      \
		while (i--)						      \
			*buf++ = modifier((data_type)va_arg(args,             \
							    unsigned int));   \
		fbtft_write_buf_dc(par, par->buf,			      \
				   len * (sizeof(data_type) + offset), 1);    \
	}                                                                     \
out:									      \
	va_end(args);                                                         \
}                                                                             \
EXPORT_SYMBOL(func);

define_fbtft_write_reg(fbtft_write_reg8_bus8, u8, u8, )
define_fbtft_write_reg(fbtft_write_reg16_bus8, __be16, u16, cpu_to_be16)
define_fbtft_write_reg(fbtft_write_reg16_bus16, u16, u16, )

void fbtft_write_reg8_bus9(struct fbtft_par *par, int len, ...)
{
	va_list args;
	int i, ret;
	int pad = 0;
	u16 *buf = (u16 *)par->buf;

	if (unlikely(par->debug & DEBUG_WRITE_REGISTER)) {
		va_start(args, len);
		for (i = 0; i < len; i++)
			*(((u8 *)buf) + i) = (u8)va_arg(args, unsigned int);
		va_end(args);
		fbtft_par_dbg_hex(DEBUG_WRITE_REGISTER, par,
				  par->info->device, u8, buf, len, "%s: ",
				  __func__);
	}
	if (len <= 0)
		return;

	if (par->spi && (par->spi->bits_per_word == 8)) {
		/* we're emulating 9-bit, pad start of buffer with no-ops
		 * (assuming here that zero is a no-op)

Annotation

Implementation Notes