From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx> 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@xxxxxxxxxx> Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> Cc: Linus Walleij <linus.walleij@xxxxxxxxxx> Link: https://lore.kernel.org/r/20201128185156.428327-1-jic23@xxxxxxxxxx --- Changes since v1: * Fix 32 bit builds by using GENMASK_ULL (thanks to Linus + Andy) drivers/iio/gyro/mpu3050-core.c | 28 ++++++++++++++++------------ 1 file changed, 16 insertions(+), 12 deletions(-) diff --git a/drivers/iio/gyro/mpu3050-core.c b/drivers/iio/gyro/mpu3050-core.c index 00e58060968c..dfa31a23500f 100644 --- a/drivers/iio/gyro/mpu3050-core.c +++ b/drivers/iio/gyro/mpu3050-core.c @@ -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; } -- 2.29.2
