Commit 26aec6e1 authored by Jonathan Cameron's avatar Jonathan Cameron
Browse files

iio:gyro:mpu3050 Treat otp value as a __le64 and use FIELD_GET() to break up 



Inspired by Andy Shevchenko's proposal to use get_unaligned_leXX().

The whole one time programable memory is treated as a single 64bit
little endian value.  Thus we can avoid a lot of messy handling
of fields overlapping byte boundaries by just loading and manipulating
it as an __le64 converted to a u64.  That lets us just use FIELD_GET()
and GENMASK() to extract the values desired.

Note only build tested. We need to use GENMASK_ULL and %llX formatters
to account for the larger types used in computing the various fields.

Signed-off-by: default avatarJonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Reviewed-by: default avatarAndy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Cc: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20201128185156.428327-1-jic23@kernel.org
Link: https://lore.kernel.org/r/20201129184459.647538-1-jic23@kernel.org
parent 1e405bc2

drivers/iio/gyro/mpu3050-core.c

+16 −12
Original line number Diff line number Diff line
@@ -13,6 +13,7 @@ 
 * TODO: add support for setting up the low pass 3dB frequency.

 */



#include <linux/bitfield.h>

#include <linux/bitops.h>

#include <linux/delay.h>

#include <linux/err.h>
@@ -784,7 +785,8 @@ static int mpu3050_read_mem(struct mpu3050 *mpu3050, 
static int mpu3050_hw_init(struct mpu3050 *mpu3050)

{

	int ret;

	u8 otp[8];

	__le64 otp_le;

	u64 otp;



	/* Reset */

	ret = regmap_update_bits(mpu3050->map,
@@ -815,29 +817,31 @@ static int mpu3050_hw_init(struct mpu3050 *mpu3050) 
				MPU3050_MEM_USER_BANK |

				MPU3050_MEM_OTP_BANK_0),

			       0,

			       sizeof(otp),

			       otp);

			       sizeof(otp_le),

			       (u8 *)&otp_le);

	if (ret)

		return ret;



	/* This is device-unique data so it goes into the entropy pool */

	add_device_randomness(otp, sizeof(otp));

	add_device_randomness(&otp_le, sizeof(otp_le));



	otp = le64_to_cpu(otp_le);



	dev_info(mpu3050->dev,

		 "die ID: %04X, wafer ID: %02X, A lot ID: %04X, "

		 "W lot ID: %03X, WP ID: %01X, rev ID: %02X\n",

		 "die ID: %04llX, wafer ID: %02llX, A lot ID: %04llX, "

		 "W lot ID: %03llX, WP ID: %01llX, rev ID: %02llX\n",

		 /* Die ID, bits 0-12 */

		 (otp[1] << 8 | otp[0]) & 0x1fff,

		 FIELD_GET(GENMASK_ULL(12, 0), otp),

		 /* Wafer ID, bits 13-17 */

		 ((otp[2] << 8 | otp[1]) & 0x03e0) >> 5,

		 FIELD_GET(GENMASK_ULL(17, 13), otp),

		 /* A lot ID, bits 18-33 */

		 ((otp[4] << 16 | otp[3] << 8 | otp[2]) & 0x3fffc) >> 2,

		 FIELD_GET(GENMASK_ULL(33, 18), otp),

		 /* W lot ID, bits 34-45 */

		 ((otp[5] << 8 | otp[4]) & 0x3ffc) >> 2,

		 FIELD_GET(GENMASK_ULL(45, 34), otp),

		 /* WP ID, bits 47-49 */

		 ((otp[6] << 8 | otp[5]) & 0x0380) >> 7,

		 FIELD_GET(GENMASK_ULL(49, 47), otp),

		 /* rev ID, bits 50-55 */

		 otp[6] >> 2);

		 FIELD_GET(GENMASK_ULL(55, 50), otp));



	return 0;

}