mtd: spi-nor: fix page program issue when using spi-mem driver

Some SPI controllers can't write nor->page_size bytes in a single step
because their TX FIFO is too small, but when that happens we should
make sure a WRITE_EN command before each write access and READ_SR command
after each write access is issued.

We should allow nor->write() to return a size that is smaller than the
requested write size to gracefully handle this case.

Also, the spi_nor_write_data() should return the actual number of bytes
that were written during the spi_mem_exec_op() operation.

This patch is a combination of two commits backported from kernel:

  commit 630d6bd8a3b4 ("mtd: spi-nor: Support controllers with limit ...")
  commit 3baa8ec88c2f ("mtd: devices: m25p80: Make sure WRITE_EN is ...")

Cc: Vignesh R <vigneshr@ti.com>
Signed-off-by: Weijie Gao <weijie.gao@mediatek.com>
Acked-by: Vignesh R <vigneshr@ti.com>
Tested-by: Shyam Saini <shyam.saini@amarulasolutions.com> # microzed
Acked-by: Jagan Teki <jagan@amarulasolutions.com>

diff --git a/drivers/mtd/spi/spi-nor-core.c b/drivers/mtd/spi/spi-nor-core.c
index c4e2f6a08fa8372cde2e9e5981784e08ec0dac4d..1acff745d1a225e124ee6ec79bffeb3a86a21d16 100644 (file)
--- a/drivers/mtd/spi/spi-nor-core.c
+++ b/drivers/mtd/spi/spi-nor-core.c
@@ -116,7 +116,6 @@ static ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
                                   SPI_MEM_OP_ADDR(nor->addr_width, to, 1),
                                   SPI_MEM_OP_NO_DUMMY,
                                   SPI_MEM_OP_DATA_OUT(len, buf, 1));
-       size_t remaining = len;
        int ret;
 
        /* get transfer protocols. */
@@ -127,22 +126,16 @@ static ssize_t spi_nor_write_data(struct spi_nor *nor, loff_t to, size_t len,
        if (nor->program_opcode == SPINOR_OP_AAI_WP && nor->sst_write_second)
                op.addr.nbytes = 0;
 
-       while (remaining) {
-               op.data.nbytes = remaining < UINT_MAX ? remaining : UINT_MAX;
-               ret = spi_mem_adjust_op_size(nor->spi, &op);
-               if (ret)
-                       return ret;
-
-               ret = spi_mem_exec_op(nor->spi, &op);
-               if (ret)
-                       return ret;
+       ret = spi_mem_adjust_op_size(nor->spi, &op);
+       if (ret)
+               return ret;
+       op.data.nbytes = len < op.data.nbytes ? len : op.data.nbytes;
 
-               op.addr.val += op.data.nbytes;
-               remaining -= op.data.nbytes;
-               op.data.buf.out += op.data.nbytes;
-       }
+       ret = spi_mem_exec_op(nor->spi, &op);
+       if (ret)
+               return ret;
 
-       return len;
+       return op.data.nbytes;
 }
 
 /*
@@ -1101,10 +1094,6 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t to, size_t len,
                        goto write_err;
                *retlen += written;
                i += written;
-               if (written != page_remain) {
-                       ret = -EIO;
-                       goto write_err;
-               }
        }
 
 write_err: