WhyCan Forum(哇酷开发者社区)

/*
 * Enable/disable 4-byte addressing mode.
 */
static inline int set_4byte(struct m25p *flash, u32 jedec_id, int enable)
{
	printk("jedec_id=%x,JEDEC_MFR(jedec_id)=%x,CFI_MFR_MACRONIX=%x\n", jedec_id, JEDEC_MFR(jedec_id), CFI_MFR_MACRONIX);
	switch (JEDEC_MFR(jedec_id)) {
	case CFI_MFR_MACRONIX:
	case 0xEF /* winbond */:
		if(enable) {
			printk("mx enter 4bytes mode\n");
		} else {
			printk("mx exit 4bytes mode\n");
		}
		flash->command[0] = enable ? OPCODE_EN4B : OPCODE_EX4B;
		return spi_write(flash->spi, flash->command, 1);
	default:
		/* Spansion style */
		flash->command[0] = OPCODE_BRWR;
		flash->command[1] = enable << 7;
		return spi_write(flash->spi, flash->command, 2);
	}
}

static int m25p_probe(struct spi_device *spi)
{
....
	if (info->addr_width)
		flash->addr_width = info->addr_width;
	else {
		/* enable 4-byte addressing if the device exceeds 16MiB */
		if (flash->mtd.size > 0x1000000) {
			flash->addr_width = 4;
			set_4byte(flash, info->jedec_id, 1);
		} else
			flash->addr_width = 3;
	}
....
}

static void m25p_shutdown(struct spi_device *spi)
{
	struct m25p *flash = dev_get_drvdata(&spi->dev);
	pr_info("m25p: spinor shutdown\n");

	if (flash->addr_width == 4) {
		const struct spi_device_id  *id = spi_get_device_id(spi);
		struct flash_info *info = (void *)id->driver_data;

		if (info->jedec_id) {
			const struct spi_device_id *jid;

			jid = jedec_probe(spi);
			if (IS_ERR(jid)) {
				pr_debug("IS_ERR(jid)\n");
				return;
			} else if (jid != id) {
				id = jid;
				info = (void *)id->driver_data;
			}
		}
		set_4byte(flash, info->jedec_id, 0);
	}
}