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: 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

diff --git a/drivers/iio/gyro/mpu3050-core.c b/drivers/iio/gyro/mpu3050-core.c
index 00e58060968c9da81133711ac6aa7c2c5a157ca1..dfa31a23500f0d622f026a9991eec23e1054818a 100644 (file)
--- 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;
 }