[PATCH v4 06/11] mtd: intel-dg: align 64bit read and write

[Alexander Usyskin]

GSC NVM controller HW errors on quad access overlapping 1K border.
Align 64bit read and write to avoid readq/writeq over 1K border.

Acked-by: Miquel Raynal <miquel.ray...@bootlin.com>
Signed-off-by: Alexander Usyskin <alexander.usys...@intel.com>
---
 drivers/mtd/devices/mtd-intel-dg.c | 35 ++++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/mtd/devices/mtd-intel-dg.c 
b/drivers/mtd/devices/mtd-intel-dg.c
index 76ef7198fff8..230bf444b7fe 100644
--- a/drivers/mtd/devices/mtd-intel-dg.c
+++ b/drivers/mtd/devices/mtd-intel-dg.c
@@ -238,6 +238,24 @@ static ssize_t idg_write(struct intel_dg_nvm *nvm, u8 
region,
                len_s -= to_shift;
        }
 
+       if (!IS_ALIGNED(to, sizeof(u64)) &&
+           ((to ^ (to + len_s)) & GENMASK(31, 10))) {
+               /*
+                * Workaround reads/writes across 1k-aligned addresses
+                * (start u32 before 1k, end u32 after)
+                * as this fails on hardware.
+                */
+               u32 data;
+
+               memcpy(&data, &buf[0], sizeof(u32));
+               idg_nvm_write32(nvm, to, data);
+               if (idg_nvm_error(nvm))
+                       return -EIO;
+               buf += sizeof(u32);
+               to += sizeof(u32);
+               len_s -= sizeof(u32);
+       }
+
        len8 = ALIGN_DOWN(len_s, sizeof(u64));
        for (i = 0; i < len8; i += sizeof(u64)) {
                u64 data;
@@ -295,6 +313,23 @@ static ssize_t idg_read(struct intel_dg_nvm *nvm, u8 
region,
                from += from_shift;
        }
 
+       if (!IS_ALIGNED(from, sizeof(u64)) &&
+           ((from ^ (from + len_s)) & GENMASK(31, 10))) {
+               /*
+                * Workaround reads/writes across 1k-aligned addresses
+                * (start u32 before 1k, end u32 after)
+                * as this fails on hardware.
+                */
+               u32 data = idg_nvm_read32(nvm, from);
+
+               if (idg_nvm_error(nvm))
+                       return -EIO;
+               memcpy(&buf[0], &data, sizeof(data));
+               len_s -= sizeof(u32);
+               buf += sizeof(u32);
+               from += sizeof(u32);
+       }
+
        len8 = ALIGN_DOWN(len_s, sizeof(u64));
        for (i = 0; i < len8; i += sizeof(u64)) {
                u64 data = idg_nvm_read64(nvm, from + i);
-- 
2.43.0