Xilinx Spartan-3AN contain an embedded spi device where they keep their
configuration data and optionally some user data.

The protocol of this flash follows most of the spi-nor standard. With
the following differences:

- Page size might not be a power of two.
- The address calculation.
- The spi nor commands used.

Signed-off-by: Ricardo Ribalda Delgado <ricardo.riba...@gmail.com>
---

I did send this patch 3 months ago with no feedback.
I have rebased the code to the latest version of mtd/master


 drivers/mtd/devices/m25p80.c  |  3 ++
 drivers/mtd/spi-nor/spi-nor.c | 96 +++++++++++++++++++++++++++++++++++++++++--
 include/linux/mtd/spi-nor.h   | 13 ++++++
 3 files changed, 109 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index c9c3b7fa3051..869576735978 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -49,6 +49,9 @@ static int m25p80_read_reg(struct spi_nor *nor, u8 code, u8 
*val, int len)
 
 static void m25p_addr2cmd(struct spi_nor *nor, unsigned int addr, u8 *cmd)
 {
+       if (nor->addr_convert)
+               addr = nor->addr_convert(nor, addr);
+
        /* opcode is in cmd[0] */
        cmd[1] = addr >> (nor->addr_width * 8 -  8);
        cmd[2] = addr >> (nor->addr_width * 8 - 16);
diff --git a/drivers/mtd/spi-nor/spi-nor.c b/drivers/mtd/spi-nor/spi-nor.c
index 157841dc3e99..d07d763fcfc4 100644
--- a/drivers/mtd/spi-nor/spi-nor.c
+++ b/drivers/mtd/spi-nor/spi-nor.c
@@ -75,6 +75,7 @@ struct flash_info {
                                         * bit. Must be used with
                                         * SPI_NOR_HAS_LOCK.
                                         */
+#define        SPI_S3AN                BIT(10) /* Xililnx S3AN Embedded SPI 
nor*/
 };
 
 #define JEDEC_MFR(info)        ((info)->id[0])
@@ -217,6 +218,21 @@ static inline int set_4byte(struct spi_nor *nor, const 
struct flash_info *info,
                return nor->write_reg(nor, SPINOR_OP_BRWR, nor->cmd_buf, 1);
        }
 }
+
+static inline int s3an_sr_ready(struct spi_nor *nor)
+{
+       int ret;
+       u8 val;
+
+       ret = nor->read_reg(nor, SPINOR_OP_XRDSR, &val, 1);
+       if (ret < 0) {
+               pr_err("error %d reading SR\n", (int) ret);
+               return ret;
+       }
+
+       return !!(val & XSR_RDY);
+}
+
 static inline int spi_nor_sr_ready(struct spi_nor *nor)
 {
        int sr = read_sr(nor);
@@ -238,7 +254,7 @@ static inline int spi_nor_fsr_ready(struct spi_nor *nor)
 static int spi_nor_ready(struct spi_nor *nor)
 {
        int sr, fsr;
-       sr = spi_nor_sr_ready(nor);
+       sr = nor->sr_ready(nor);
        if (sr < 0)
                return sr;
        fsr = nor->flags & SNOR_F_USE_FSR ? spi_nor_fsr_ready(nor) : 1;
@@ -334,6 +350,9 @@ static int spi_nor_erase_sector(struct spi_nor *nor, u32 
addr)
         * Default implementation, if driver doesn't have a specialized HW
         * control
         */
+       if (nor->addr_convert)
+               addr = nor->addr_convert(nor, addr);
+
        for (i = nor->addr_width - 1; i >= 0; i--) {
                buf[i] = addr & 0xff;
                addr >>= 8;
@@ -368,7 +387,7 @@ static int spi_nor_erase(struct mtd_info *mtd, struct 
erase_info *instr)
                return ret;
 
        /* whole-chip erase? */
-       if (len == mtd->size) {
+       if (len == mtd->size && !(nor->flags & SNOR_F_NO_OP_CHIP_ERASE)) {
                unsigned long timeout;
 
                write_enable(nor);
@@ -782,6 +801,19 @@ static int spi_nor_is_locked(struct mtd_info *mtd, loff_t 
ofs, uint64_t len)
                .addr_width = (_addr_width),                            \
                .flags = (_flags),
 
+#define S3AN_INFO(_jedec_id, _n_sectors, _page_size)                   \
+               .id = {                                                 \
+                       ((_jedec_id) >> 16) & 0xff,                     \
+                       ((_jedec_id) >> 8) & 0xff,                      \
+                       (_jedec_id) & 0xff                              \
+                       },                                              \
+               .id_len = 3,                                            \
+               .sector_size = (8*_page_size),                          \
+               .n_sectors = (_n_sectors),                              \
+               .page_size = _page_size,                                \
+               .addr_width = 3,                                        \
+               .flags = SPI_NOR_NO_FR | SPI_S3AN,
+
 /* NOTE: double check command sets and memory organization when you add
  * more nor chips.  This current list focusses on newer chips, which
  * have been converging on command sets which including JEDEC ID.
@@ -991,6 +1023,13 @@ static const struct flash_info spi_nor_ids[] = {
        { "cat25c09", CAT25_INFO( 128, 8, 32, 2, SPI_NOR_NO_ERASE | 
SPI_NOR_NO_FR) },
        { "cat25c17", CAT25_INFO( 256, 8, 32, 2, SPI_NOR_NO_ERASE | 
SPI_NOR_NO_FR) },
        { "cat25128", CAT25_INFO(2048, 8, 64, 2, SPI_NOR_NO_ERASE | 
SPI_NOR_NO_FR) },
+
+       /* Xilinx S3AN Internal Flash */
+       { "3S50AN", S3AN_INFO(0x1f2200, 64, 264) },
+       { "3S200AN", S3AN_INFO(0x1f2400, 256, 264) },
+       { "3S400AN", S3AN_INFO(0x1f2400, 256, 264) },
+       { "3S700AN", S3AN_INFO(0x1f2500, 512, 264) },
+       { "3S1400AN", S3AN_INFO(0x1f2600, 512, 528) },
        { },
 };
 
@@ -1122,7 +1161,13 @@ static int spi_nor_write(struct mtd_info *mtd, loff_t 
to, size_t len,
 
        write_enable(nor);
 
-       page_offset = to & (nor->page_size - 1);
+       if (hweight32(nor->page_size) == 1)
+               page_offset = to & (nor->page_size - 1);
+       else {
+               uint64_t aux = to;
+
+               page_offset = do_div(aux, nor->page_size);
+       }
 
        /* do all the bytes fit onto one page? */
        if (page_offset + len <= nor->page_size) {
@@ -1250,6 +1295,43 @@ static int spi_nor_check(struct spi_nor *nor)
        return 0;
 }
 
+static unsigned int s3an_addr_convert(struct spi_nor *nor, unsigned int addr)
+{
+       if (nor->page_size == 264)
+               return (addr / 264) * 512 + (addr % 264);
+
+       return (addr / 528) * 1024 + (addr % 528);
+}
+
+static int s3an_nor_scan(const struct flash_info *info, struct spi_nor *nor)
+{
+       int ret;
+       u8 val;
+
+       ret = nor->read_reg(nor, SPINOR_OP_XRDSR, &val, 1);
+       if (ret < 0) {
+               pr_err("error %d reading SR\n", (int) ret);
+               return ret;
+       }
+
+       nor->erase_opcode = SPINOR_OP_XSE;
+       nor->program_opcode = SPINOR_OP_XPP;
+       nor->read_opcode = SPINOR_OP_READ;
+       nor->sr_ready = s3an_sr_ready;
+       nor->flags |= SNOR_F_NO_OP_CHIP_ERASE;
+
+       /*Flash in Power of 2 mode*/
+       if (val & XSR_PAGESIZE) {
+               nor->page_size = (nor->page_size == 264) ? 256 : 512;
+               nor->mtd.writebufsize = nor->page_size;
+               nor->mtd.size = 8 * nor->page_size * info->n_sectors;
+               nor->mtd.erasesize = 8 * nor->page_size;
+       } else
+               nor->addr_convert = s3an_addr_convert;
+
+       return 0;
+}
+
 int spi_nor_scan(struct spi_nor *nor, const char *name, enum read_mode mode)
 {
        const struct flash_info *info = NULL;
@@ -1415,6 +1497,7 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, 
enum read_mode mode)
        }
 
        nor->program_opcode = SPINOR_OP_PP;
+       nor->sr_ready = spi_nor_sr_ready;
 
        if (info->addr_width)
                nor->addr_width = info->addr_width;
@@ -1455,6 +1538,13 @@ int spi_nor_scan(struct spi_nor *nor, const char *name, 
enum read_mode mode)
 
        nor->read_dummy = spi_nor_read_dummy_cycles(nor);
 
+       if (info->flags & SPI_S3AN) {
+               ret = s3an_nor_scan(info, nor);
+
+               if (ret)
+                       return ret;
+       }
+
        dev_info(dev, "%s (%lld Kbytes)\n", info->name,
                        (long long)mtd->size >> 10);
 
diff --git a/include/linux/mtd/spi-nor.h b/include/linux/mtd/spi-nor.h
index 3c36113a88e1..0d4b57a0ccd6 100644
--- a/include/linux/mtd/spi-nor.h
+++ b/include/linux/mtd/spi-nor.h
@@ -67,6 +67,15 @@
 #define SPINOR_OP_WRDI         0x04    /* Write disable */
 #define SPINOR_OP_AAI_WP       0xad    /* Auto address increment word program 
*/
 
+/* Used for S3AN flashes only */
+#define SPINOR_OP_XSE          0x50    /* Sector erase */
+#define SPINOR_OP_XPP          0x82    /* Page program */
+#define SPINOR_OP_XRDSR                0xd7    /* Read status register */
+
+#define XSR_PAGESIZE           BIT(0)  /* Page size in Po2 or Linear */
+#define XSR_RDY                        BIT(7)  /* Ready */
+
+
 /* Used for Macronix and Winbond flashes. */
 #define SPINOR_OP_EN4B         0xb7    /* Enter 4-byte mode */
 #define SPINOR_OP_EX4B         0xe9    /* Exit 4-byte mode */
@@ -118,6 +127,7 @@ enum spi_nor_ops {
 enum spi_nor_option_flags {
        SNOR_F_USE_FSR          = BIT(0),
        SNOR_F_HAS_SR_TB        = BIT(1),
+       SNOR_F_NO_OP_CHIP_ERASE = BIT(2),
 };
 
 /**
@@ -172,6 +182,9 @@ struct spi_nor {
        int (*read_reg)(struct spi_nor *nor, u8 opcode, u8 *buf, int len);
        int (*write_reg)(struct spi_nor *nor, u8 opcode, u8 *buf, int len);
 
+       int (*sr_ready)(struct spi_nor *nor);
+       unsigned int (*addr_convert)(struct spi_nor *nor, unsigned int addr);
+
        int (*read)(struct spi_nor *nor, loff_t from,
                        size_t len, size_t *retlen, u_char *read_buf);
        void (*write)(struct spi_nor *nor, loff_t to,
-- 
2.8.0.rc3

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