target/linux/generic/patches-4.4/042-0006-mtd-bcm47xxsflash-support-reading-flash-out-of-mappi.patch

   1 From ccc38234fdc70120be79e7fb2df5c27ca5cd4c8a Mon Sep 17 00:00:00 2001
   2 From: =?UTF-8?q?Rafa=C5=82=20Mi=C5=82ecki?= <rafal@milecki.pl>
   3 Date: Wed, 8 Feb 2017 23:53:44 +0100
   4 Subject: [PATCH] mtd: bcm47xxsflash: support reading flash out of mapping
   5  window
   6 MIME-Version: 1.0
   7 Content-Type: text/plain; charset=UTF-8
   8 Content-Transfer-Encoding: 8bit
   9
  10 For reading flash content we use MMIO but it's possible to read only
  11 first 16 MiB this way. It's simply an arch design/limitation.
  12 To support flash sizes bigger than 16 MiB implement indirect access
  13 using ChipCommon registers.
  14 This has been tested using MX25L25635F.
  15
  16 Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
  17 Acked-by: Marek Vasut <marek.vasut@gmail.com>
  18 Signed-off-by: Brian Norris <computersforpeace@gmail.com>
  19 ---
  20  drivers/mtd/devices/bcm47xxsflash.c | 24 +++++++++++++++++++++---
  21  drivers/mtd/devices/bcm47xxsflash.h |  3 +++
  22  2 files changed, 24 insertions(+), 3 deletions(-)
  23
  24 --- a/drivers/mtd/devices/bcm47xxsflash.c
  25 +++ b/drivers/mtd/devices/bcm47xxsflash.c
  26 @@ -105,15 +105,33 @@ static int bcm47xxsflash_read(struct mtd
  27                               size_t *retlen, u_char *buf)
  28  {
  29         struct bcm47xxsflash *b47s = mtd->priv;
  30 +       size_t orig_len = len;
  31
  32         /* Check address range */
  33         if ((from + len) > mtd->size)
  34                 return -EINVAL;
  35
  36 -       memcpy_fromio(buf, b47s->window + from, len);
  37 -       *retlen = len;
  38 +       /* Read as much as possible using fast MMIO window */
  39 +       if (from < BCM47XXSFLASH_WINDOW_SZ) {
  40 +               size_t memcpy_len;
  41
  42 -       return len;
  43 +               memcpy_len = min(len, (size_t)(BCM47XXSFLASH_WINDOW_SZ - from));
  44 +               memcpy_fromio(buf, b47s->window + from, memcpy_len);
  45 +               from += memcpy_len;
  46 +               len -= memcpy_len;
  47 +               buf += memcpy_len;
  48 +       }
  49 +
  50 +       /* Use indirect access for content out of the window */
  51 +       for (; len; len--) {
  52 +               b47s->cc_write(b47s, BCMA_CC_FLASHADDR, from++);
  53 +               bcm47xxsflash_cmd(b47s, OPCODE_ST_READ4B);
  54 +               *buf++ = b47s->cc_read(b47s, BCMA_CC_FLASHDATA);
  55 +       }
  56 +
  57 +       *retlen = orig_len;
  58 +
  59 +       return orig_len;
  60  }
  61
  62  static int bcm47xxsflash_write_st(struct mtd_info *mtd, u32 offset, size_t len,
  63 --- a/drivers/mtd/devices/bcm47xxsflash.h
  64 +++ b/drivers/mtd/devices/bcm47xxsflash.h
  65 @@ -3,6 +3,8 @@
  66
  67  #include <linux/mtd/mtd.h>
  68
  69 +#define BCM47XXSFLASH_WINDOW_SZ                        SZ_16M
  70 +
  71  /* Used for ST flashes only. */
  72  #define OPCODE_ST_WREN         0x0006          /* Write Enable */
  73  #define OPCODE_ST_WRDIS                0x0004          /* Write Disable */
  74 @@ -16,6 +18,7 @@
  75  #define OPCODE_ST_RES          0x03ab          /* Read Electronic Signature */
  76  #define OPCODE_ST_CSA          0x1000          /* Keep chip select asserted */
  77  #define OPCODE_ST_SSE          0x0220          /* Sub-sector Erase */
  78 +#define OPCODE_ST_READ4B       0x6313          /* Read Data Bytes in 4Byte addressing mode */
  79
  80  /* Used for Atmel flashes only. */
  81  #define OPCODE_AT_READ                         0x07e8