[PATCH V6] mtd: m25p80: Make fast read configurable via DT
Marek Vasut
marex at denx.de
Sun Sep 23 21:39:39 EDT 2012
Add DT property "m25p,fast-read" that signalises the particular
chip supports "fast read" opcode.
Signed-off-by: Marek Vasut <marex at denx.de>
Cc: Artem Bityutskiy <artem.bityutskiy at linux.intel.com>
Cc: David Woodhouse <david.woodhouse at intel.com>
---
Documentation/devicetree/bindings/mtd/m25p80.txt | 29 ++++++++++++++++++
drivers/mtd/devices/m25p80.c | 34 +++++++++++++---------
2 files changed, 50 insertions(+), 13 deletions(-)
create mode 100644 Documentation/devicetree/bindings/mtd/m25p80.txt
V2: Add documentation for the DT property.
V3: Use of_property_get_bool() instead of of_find_property().
V4: Adjust the documentation's "compatible:" section, make it not
Linux-specific, but keep the reference to Linux's list of
supported devices. Also, use the default name, spansion,m25p80
in the example.
V5: Enclose of_property_read_bool() into CONFIG_OF for systems that do not
use OF / Device Tree .
V6: Supress the following warning by using __maybe_unused on np:
808:23: warning: unused variable ‘np’ [-Wunused-variable]
diff --git a/Documentation/devicetree/bindings/mtd/m25p80.txt b/Documentation/devicetree/bindings/mtd/m25p80.txt
new file mode 100644
index 0000000..6d3d576
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/m25p80.txt
@@ -0,0 +1,29 @@
+* MTD SPI driver for ST M25Pxx (and similar) serial flash chips
+
+Required properties:
+- #address-cells, #size-cells : Must be present if the device has sub-nodes
+ representing partitions.
+- compatible : Should be the manufacturer and the name of the chip. Bear in mind
+ the DT binding is not Linux-only, but in case of Linux, see the
+ "m25p_ids" table in drivers/mtd/devices/m25p80.c for the list of
+ supported chips.
+- reg : Chip-Select number
+- spi-max-frequency : Maximum frequency of the SPI bus the chip can operate at
+
+Optional properties:
+- m25p,fast-read : Use the "fast read" opcode to read data from the chip instead
+ of the usual "read" opcode. This opcode is not supported by
+ all chips and support for it can not be detected at runtime.
+ Refer to your chips' datasheet to check if this is supported
+ by your chip.
+
+Example:
+
+ flash: m25p80 at 0 {
+ #address-cells = <1>;
+ #size-cells = <1>;
+ compatible = "spansion,m25p80";
+ reg = <0>;
+ spi-max-frequency = <40000000>;
+ m25p,fast-read;
+ };
diff --git a/drivers/mtd/devices/m25p80.c b/drivers/mtd/devices/m25p80.c
index 33213c7..8741dbc 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);
@@ -809,9 +805,10 @@ static int __devinit m25p_probe(struct spi_device *spi)
struct flash_info *info;
unsigned i;
struct mtd_part_parser_data ppdata;
+ struct device_node __maybe_unused *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
@@ -863,7 +860,8 @@ 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;
@@ -920,6 +918,16 @@ 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;
+#ifdef CONFIG_OF
+ if (np && of_property_read_bool(np, "m25p,fast-read"))
+ flash->fast_read = true;
+#endif
+
+#ifdef CONFIG_M25PXX_USE_FAST_READ
+ flash->fast_read = true;
+#endif
+
if (info->addr_width)
flash->addr_width = info->addr_width;
else {
--
1.7.10.4
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