target/linux/generic/patches-4.4/045-mtd-devices-m25p80-add-support-for-mmap-read-request.patch

   1 From 08922f644878c9163ada8df3ef9def89be1d5e90 Mon Sep 17 00:00:00 2001
   2 From: Vignesh R <vigneshr@ti.com>
   3 Date: Tue, 29 Mar 2016 11:16:17 +0530
   4 Subject: [PATCH] mtd: devices: m25p80: add support for mmap read request
   5
   6 Certain SPI controllers may provide accelerated hardware interface to
   7 read from m25p80 type flash devices in order to provide better read
   8 performance. SPI core supports such devices with spi_flash_read() API.
   9 Call spi_flash_read(), if supported, to make use of such interface.
  10
  11 Signed-off-by: Vignesh R <vigneshr@ti.com>
  12 [Brian: add memset()]
  13 Signed-off-by: Brian Norris <computersforpeace@gmail.com>
  14 ---
  15
  16 --- a/drivers/mtd/devices/m25p80.c
  17 +++ b/drivers/mtd/devices/m25p80.c
  18 @@ -131,6 +131,28 @@ static int m25p80_read(struct spi_nor *nor, loff_t from, size_t len,
  19         /* convert the dummy cycles to the number of bytes */
  20         dummy /= 8;
  21
  22 +       if (spi_flash_read_supported(spi)) {
  23 +               struct spi_flash_read_message msg;
  24 +               int ret;
  25 +
  26 +               memset(&msg, 0, sizeof(msg));
  27 +
  28 +               msg.buf = buf;
  29 +               msg.from = from;
  30 +               msg.len = len;
  31 +               msg.read_opcode = nor->read_opcode;
  32 +               msg.addr_width = nor->addr_width;
  33 +               msg.dummy_bytes = dummy;
  34 +               /* TODO: Support other combinations */
  35 +               msg.opcode_nbits = SPI_NBITS_SINGLE;
  36 +               msg.addr_nbits = SPI_NBITS_SINGLE;
  37 +               msg.data_nbits = m25p80_rx_nbits(nor);
  38 +
  39 +               ret = spi_flash_read(spi, &msg);
  40 +               *retlen = msg.retlen;
  41 +               return ret;
  42 +       }
  43 +
  44         spi_message_init(&m);
  45         memset(t, 0, (sizeof t));
  46