mtd: m25p80: Add dual read support

Add support for Dual SPI read transfers, which is supported by some
Spansion SPI FLASHes.

Signed-off-by: Geert Uytterhoeven <geert+renesas@linux-m68k.org>
Acked-by: Marek Vasut <marex@denx.de>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index ad19139097025b97839fb7cbe123a1261e6cf876..73bf661100f7deaa6efcdd57d806c3c5872037b6 100644 (file)
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -41,7 +41,8 @@
 #define        OPCODE_WRSR             0x01    /* Write status register 1 byte */
 #define        OPCODE_NORM_READ        0x03    /* Read data bytes (low frequency) */
 #define        OPCODE_FAST_READ        0x0b    /* Read data bytes (high frequency) */
-#define        OPCODE_QUAD_READ        0x6b    /* Read data bytes */
+#define        OPCODE_DUAL_READ        0x3b    /* Read data bytes (Dual SPI) */
+#define        OPCODE_QUAD_READ        0x6b    /* Read data bytes (Quad SPI) */
 #define        OPCODE_PP               0x02    /* Page program (up to 256 bytes) */
 #define        OPCODE_BE_4K            0x20    /* Erase 4KiB block */
 #define        OPCODE_BE_4K_PMC        0xd7    /* Erase 4KiB block on PMC chips */
@@ -54,7 +55,8 @@
 /* 4-byte address opcodes - used on Spansion and some Macronix flashes. */
 #define        OPCODE_NORM_READ_4B     0x13    /* Read data bytes (low frequency) */
 #define        OPCODE_FAST_READ_4B     0x0c    /* Read data bytes (high frequency) */
-#define        OPCODE_QUAD_READ_4B     0x6c    /* Read data bytes */
+#define        OPCODE_DUAL_READ_4B     0x3c    /* Read data bytes (Dual SPI) */
+#define        OPCODE_QUAD_READ_4B     0x6c    /* Read data bytes (Quad SPI) */
 #define        OPCODE_PP_4B            0x12    /* Page program (up to 256 bytes) */
 #define        OPCODE_SE_4B            0xdc    /* Sector erase (usually 64KiB) */
 
@@ -95,6 +97,7 @@
 enum read_type {
        M25P80_NORMAL = 0,
        M25P80_FAST,
+       M25P80_DUAL,
        M25P80_QUAD,
 };
 
@@ -479,6 +482,7 @@ static inline int m25p80_dummy_cycles_read(struct m25p *flash)
 {
        switch (flash->flash_read) {
        case M25P80_FAST:
+       case M25P80_DUAL:
        case M25P80_QUAD:
                return 1;
        case M25P80_NORMAL:
@@ -492,6 +496,8 @@ static inline int m25p80_dummy_cycles_read(struct m25p *flash)
 static inline unsigned int m25p80_rx_nbits(const struct m25p *flash)
 {
        switch (flash->flash_read) {
+       case M25P80_DUAL:
+               return 2;
        case M25P80_QUAD:
                return 4;
        default:
@@ -855,7 +861,8 @@ struct flash_info {
 #define        SST_WRITE       0x04            /* use SST byte programming */
 #define        M25P_NO_FR      0x08            /* Can't do fastread */
 #define        SECT_4K_PMC     0x10            /* OPCODE_BE_4K_PMC works uniformly */
-#define        M25P80_QUAD_READ        0x20    /* Flash supports Quad Read */
+#define        M25P80_DUAL_READ        0x20    /* Flash supports Dual Read */
+#define        M25P80_QUAD_READ        0x40    /* Flash supports Quad Read */
 };
 
 #define INFO(_jedec_id, _ext_id, _sector_size, _n_sectors, _flags)     \
@@ -1226,7 +1233,7 @@ static int m25p_probe(struct spi_device *spi)
        if (info->flags & M25P_NO_FR)
                flash->flash_read = M25P80_NORMAL;
 
-       /* Quad-read mode takes precedence over fast/normal */
+       /* Quad/Dual-read mode takes precedence over fast/normal */
        if (spi->mode & SPI_RX_QUAD && info->flags & M25P80_QUAD_READ) {
                ret = set_quad_mode(flash, info->jedec_id);
                if (ret) {
@@ -1234,6 +1241,8 @@ static int m25p_probe(struct spi_device *spi)
                        return ret;
                }
                flash->flash_read = M25P80_QUAD;
+       } else if (spi->mode & SPI_RX_DUAL && info->flags & M25P80_DUAL_READ) {
+               flash->flash_read = M25P80_DUAL;
        }
 
        /* Default commands */
@@ -1241,6 +1250,9 @@ static int m25p_probe(struct spi_device *spi)
        case M25P80_QUAD:
                flash->read_opcode = OPCODE_QUAD_READ;
                break;
+       case M25P80_DUAL:
+               flash->read_opcode = OPCODE_DUAL_READ;
+               break;
        case M25P80_FAST:
                flash->read_opcode = OPCODE_FAST_READ;
                break;
@@ -1265,6 +1277,9 @@ static int m25p_probe(struct spi_device *spi)
                        case M25P80_QUAD:
                                flash->read_opcode = OPCODE_QUAD_READ_4B;
                                break;
+                       case M25P80_DUAL:
+                               flash->read_opcode = OPCODE_DUAL_READ_4B;
+                               break;
                        case M25P80_FAST:
                                flash->read_opcode = OPCODE_FAST_READ_4B;
                                break;