[PATCH 3/3] [RFC] mtd: m25p80: Make fast read configurable via DT

Marek Vasut
2012-07-06T06:11:43Z

Add DT property "m25p,fast-read" that signalises the particular
chip supports "fast read" opcode.

Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Cc: David Woodhouse <david.woodhouse@intel.com>
---
drivers/mtd/devices/m25p80.c | 32 +++++++++++++++++++-------------
1 file changed, 19 insertions(+), 13 deletions(-)

NOTE: I'm not sure where to document this property, as m25p80 is
a simple DT device. Any hints please?

diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 28e841d..08019b8 100644
--- a/drivers/mtd/devices/m25p80.c
+++ b/drivers/mtd/devices/m25p80.c
@@ -73,14 +73,6 @@
#define MAX_READY_WAIT_JIFFIES (40 * HZ) /* M25P16 specs 40s max chip erase */
#define MAX_CMD_SIZE 5

-#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
-
#define JEDEC_MFR(_jedec_id) ((_jedec_id) >> 16)

/****************************************************************************/
@@ -93,6 +85,7 @@ struct m25p {
u16 addr_width;
u8 erase_opcode;
u8 *command;
+ bool fast_read;
};

static inline struct m25p *mtd_to_m25p(struct mtd_info *mtd)
@@ -342,6 +335,7 @@ static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len,
struct m25p *flash = mtd_to_m25p(mtd);
struct spi_transfer t[2];
struct spi_message m;
+ uint8_t opcode;

pr_debug("%s: %s from 0x%08x, len %zd\n", dev_name(&flash->spi->dev),
__func__, (u32)from, len);
@@ -354,7 +348,7 @@ static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len,
* Should add 1 byte DUMMY_BYTE.
*/
t[0].tx_buf = flash->command;
- t[0].len = m25p_cmdsz(flash) + FAST_READ_DUMMY_BYTE;
+ t[0].len = m25p_cmdsz(flash) + (flash->fast_read ? 1 : 0);
spi_message_add_tail(&t[0], &m);

t[1].rx_buf = buf;
@@ -376,12 +370,14 @@ static int m25p80_read(struct mtd_info *mtd, loff_t from, size_t len,
*/

/* Set up the write data buffer. */
- flash->command[0] = OPCODE_READ;
+ opcode = flash->fast_read ? OPCODE_FAST_READ : OPCODE_NORM_READ;
+ flash->command[0] = opcode;
m25p_addr2cmd(flash, from, flash->command);

spi_sync(flash->spi, &m);

- *retlen = m.actual_length - m25p_cmdsz(flash) - FAST_READ_DUMMY_BYTE;
+ *retlen = m.actual_length - m25p_cmdsz(flash) -
+ (flash->fast_read ? 1 : 0);

mutex_unlock(&flash->lock);

@@ -803,9 +799,10 @@ static int __devinit m25p_probe(struct spi_device *spi)
struct flash_info *info;
unsigned i;
struct mtd_part_parser_data ppdata;
+ struct device_node *np = spi->dev.of_node;

#ifdef CONFIG_MTD_OF_PARTS
- if (!of_device_is_available(spi->dev.of_node))
+ if (!of_device_is_available(np))
return -ENODEV;
#endif

@@ -857,7 +854,8 @@ static int __devinit m25p_probe(struct spi_device *spi)
flash = kzalloc(sizeof *flash, GFP_KERNEL);
if (!flash)
return -ENOMEM;
- flash->command = kmalloc(MAX_CMD_SIZE + FAST_READ_DUMMY_BYTE, GFP_KERNEL);
+ flash->command = kmalloc(MAX_CMD_SIZE + (flash->fast_read ? 1 : 0),
+ GFP_KERNEL);
if (!flash->command) {
kfree(flash);
return -ENOMEM;
@@ -914,6 +912,14 @@ static int __devinit m25p_probe(struct spi_device *spi)
flash->page_size = info->page_size;
flash->mtd.writebufsize = flash->page_size;

+ flash->fast_read = false;
+ if (np && of_find_property(np, "m25p,fast-read", NULL))
+ flash->fast_read = true;
+
+#ifdef CONFIG_M25PXX_USE_FAST_READ
+ flash->fast_read = true;
+#endif
+
if (info->addr_width)
flash->addr_width = info->addr_width;
else {
--
1.7.10