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

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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: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Tested-by: Linus Walleij <linus.walleij@linaro.org>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Linus 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
This commit is contained in:
Jonathan Cameron 2020-11-29 18:44:59 +00:00
parent 1e405bc251
commit 26aec6e1b7
1 changed files with 16 additions and 12 deletions
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28
drivers/iio/gyro/mpu3050-core.c
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@ -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;
}