kernel driver code snippet to read unique ID of W25Q128

W25Q128-ID.c

#include <linux/random.h>

int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode) {
	// ...
	// after mutex_init(&nor->lock);
	if(memcmp(info->id, "\xef\x40\x18", 3) == 0) {
		int ret;
		u8 buf[4+8]; // 4 dummy + 64-bit ID
		dev_warn(dev, "reading unique ID\n");
		ret = nor->read_reg(nor, 0x4B, buf, sizeof(buf)); // Read Unique ID number
		if (ret < 0) {
			pr_err("error %d reading unique ID\n", (int) ret);
		} else {
			pr_info("Unique ID:");
			for ( ret = 0; ret < 8; ret++)
				pr_info(" %02x", buf[4+ret]);
			pr_info("\n");
			add_device_randomness(buf+4, 8);
			pr_info("random added\n");
		}
	}
	// ...
}