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Message-Id: <1209096453-21610-3-git-send-email-cooloney@kernel.org>
Date: Fri, 25 Apr 2008 12:07:32 +0800
From: Bryan Wu <cooloney@...nel.org>
To: linux-mtd@...ts.infradead.org, dwmw2@...radead.org,
linux-kernel@...r.kernel.org
Cc: Bryan Wu <cooloney@...nel.org>
Subject: [PATCH 2/3] [MTD] m25p80: add FAST_READ access support to M25Pxx
Signed-off-by: Bryan Wu <cooloney@...nel.org>
---
drivers/mtd/devices/Kconfig | 7 +++++++
drivers/mtd/devices/m25p80.c | 31 +++++++++++++++++++++----------
2 files changed, 28 insertions(+), 10 deletions(-)
diff --git a/drivers/mtd/devices/Kconfig b/drivers/mtd/devices/Kconfig
index 811d56f..35ed110 100644
--- a/drivers/mtd/devices/Kconfig
+++ b/drivers/mtd/devices/Kconfig
@@ -77,6 +77,13 @@ config MTD_M25P80
if you want to specify device partitioning or to use a device which
doesn't support the JEDEC ID instruction.
+config M25PXX_USE_FAST_READ
+ bool "Use FAST_READ OPCode allowing SPI CLK <= 50MHz"
+ depends on MTD_M25P80
+ default y
+ help
+ This option enables FAST_READ access supported by ST M25Pxx.
+
config MTD_SLRAM
tristate "Uncached system RAM"
help
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 98df5bc..14dd88d 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -33,7 +33,7 @@
/* Flash opcodes. */
#define OPCODE_WREN 0x06 /* Write enable */
#define OPCODE_RDSR 0x05 /* Read status register */
-#define OPCODE_READ 0x03 /* Read data bytes (low frequency) */
+#define OPCODE_NORM_READ 0x03 /* Read data bytes (low frequency) */
#define OPCODE_FAST_READ 0x0b /* Read data bytes (high frequency) */
#define OPCODE_PP 0x02 /* Page program (up to 256 bytes) */
#define OPCODE_BE_4K 0x20 /* Erase 4KiB block */
@@ -52,7 +52,15 @@
/* Define max times to check status register before we give up. */
#define MAX_READY_WAIT_COUNT 100000
+#define CMD_SIZE 4
+#ifdef CONFIG_M25PXX_USE_FAST_READ
+#define OPCODE_READ OPCODE_FAST_READ
+#define FAST_READ_DUMMY_BYTE 1
+#else
+#define OPCODE_READ OPCODE_NORM_READ
+#define FAST_READ_DUMMY_BYTE 0
+#endif
#ifdef CONFIG_MTD_PARTITIONS
#define mtd_has_partitions() (1)
@@ -68,7 +76,7 @@ struct m25p {
struct mtd_info mtd;
unsigned partitioned:1;
u8 erase_opcode;
- u8 command[4];
+ u8 command[CMD_SIZE + FAST_READ_DUMMY_BYTE];
};
static inline struct m25p *mtd_to_m25p(struct mtd_info *mtd)
@@ -167,7 +175,7 @@ static int erase_sector(struct m25p *flash, u32 offset)
flash->command[2] = offset >> 8;
flash->command[3] = offset;
- spi_write(flash->spi, flash->command, sizeof(flash->command));
+ spi_write(flash->spi, flash->command, CMD_SIZE);
return 0;
}
@@ -253,8 +261,12 @@ static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len,
spi_message_init(&m);
memset(t, 0, (sizeof t));
+ /* NOTE:
+ * OPCODE_FAST_READ (if available) is faster.
+ * Should add 1 byte DUMMY_BYTE.
+ */
t[0].tx_buf = flash->command;
- t[0].len = sizeof(flash->command);
+ t[0].len = CMD_SIZE + FAST_READ_DUMMY_BYTE;
spi_message_add_tail(&t[0], &m);
t[1].rx_buf = buf;
@@ -287,7 +299,7 @@ static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len,
spi_sync(flash->spi, &m);
- *retlen = m.actual_length - sizeof(flash->command);
+ *retlen = m.actual_length - CMD_SIZE - FAST_READ_DUMMY_BYTE;
mutex_unlock(&flash->lock);
@@ -325,7 +337,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
memset(t, 0, (sizeof t));
t[0].tx_buf = flash->command;
- t[0].len = sizeof(flash->command);
+ t[0].len = CMD_SIZE;
spi_message_add_tail(&t[0], &m);
t[1].tx_buf = buf;
@@ -354,7 +366,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
spi_sync(flash->spi, &m);
- *retlen = m.actual_length - sizeof(flash->command);
+ *retlen = m.actual_length - CMD_SIZE;
} else {
u32 i;
@@ -364,7 +376,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
t[1].len = page_size;
spi_sync(flash->spi, &m);
- *retlen = m.actual_length - sizeof(flash->command);
+ *retlen = m.actual_length - CMD_SIZE;
/* write everything in PAGESIZE chunks */
for (i = page_size; i < len; i += page_size) {
@@ -387,8 +399,7 @@ static int m25p80_write(struct mtd_info *mtd, loff_t to, size_t len,
spi_sync(flash->spi, &m);
if (retlen)
- *retlen += m.actual_length
- - sizeof(flash->command);
+ *retlen += m.actual_length - CMD_SIZE;
}
}
--
1.5.5
--
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