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authorLinus Torvalds <torvalds@linux-foundation.org>2014-06-11 08:35:34 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2014-06-11 08:35:34 -0700
commite413a19a8ef49ae3b76310bb569dabe66b22f5a3 (patch)
treef171d40fd0ec69296458173d7ec470339f93f53b /Documentation
parent8d0304e69dc960ae7683943ac5b9c4c685d409d7 (diff)
parentf1900c79633e9ed757319e63aefb8e29443ea35e (diff)
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Merge tag 'for-linus-20140610' of git://git.infradead.org/linux-mtd
Pull MTD updates from Brian Norris: - refactor m25p80.c driver for use as a general SPI NOR framework for other drivers which may speak to SPI NOR flash without providing full SPI support (i.e., not part of drivers/spi/) - new Freescale QuadSPI driver (utilizing new SPI NOR framework) - updates for the STMicro "FSM" SPI NOR driver - fix sync/flush behavior on mtd_blkdevs - fixup subpage write support on a few NAND drivers - correct the MTD OOB test for odd-sized OOB areas - add BCH-16 support for OMAP NAND - fix warnings and trivial refactoring - utilize new ECC DT bindings in pxa3xx NAND driver - new LPDDR NVM driver - address a few assorted bugs caught by Coverity - add new imx6sx support for GPMI NAND - use a bounce buffer for NAND when non-DMA-able buffers are used * tag 'for-linus-20140610' of git://git.infradead.org/linux-mtd: (77 commits) mtd: gpmi: add gpmi support for imx6sx mtd: maps: remove check for CONFIG_MTD_SUPERH_RESERVE mtd: bf5xx_nand: use the managed version of kzalloc mtd: pxa3xx_nand: make the driver work on big-endian systems mtd: nand: omap: fix omap_calculate_ecc_bch() for-loop error mtd: nand: r852: correct write_buf loop bounds mtd: nand_bbt: handle error case for nand_create_badblock_pattern() mtd: nand_bbt: remove unused variable mtd: maps: sc520cdp: fix warnings mtd: slram: fix unused variable warning mtd: pfow: remove unused variable mtd: lpddr: fix Kconfig dependency, for I/O accessors mtd: nand: pxa3xx: Add supported ECC strength and step size to the DT binding mtd: nand: pxa3xx: Use ECC strength and step size devicetree binding mtd: nand: pxa3xx: Clean pxa_ecc_init() error handling mtd: nand: Warn the user if the selected ECC strength is too weak mtd: nand: omap: Documentation: How to select correct ECC scheme for your device ? mtd: nand: omap: add support for BCH16_ECC - NAND driver updates mtd: nand: omap: add support for BCH16_ECC - ELM driver updates mtd: nand: omap: add support for BCH16_ECC - GPMC driver updates ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/devicetree/bindings/mtd/fsl-quadspi.txt35
-rw-r--r--Documentation/devicetree/bindings/mtd/gpmc-nand.txt45
-rw-r--r--Documentation/devicetree/bindings/mtd/m25p80.txt4
-rw-r--r--Documentation/devicetree/bindings/mtd/pxa3xx-nand.txt8
-rw-r--r--Documentation/mtd/spi-nor.txt62
5 files changed, 152 insertions, 2 deletions
diff --git a/Documentation/devicetree/bindings/mtd/fsl-quadspi.txt b/Documentation/devicetree/bindings/mtd/fsl-quadspi.txt
new file mode 100644
index 000000000000..823d13412195
--- /dev/null
+++ b/Documentation/devicetree/bindings/mtd/fsl-quadspi.txt
@@ -0,0 +1,35 @@
+* Freescale Quad Serial Peripheral Interface(QuadSPI)
+
+Required properties:
+ - compatible : Should be "fsl,vf610-qspi"
+ - reg : the first contains the register location and length,
+ the second contains the memory mapping address and length
+ - reg-names: Should contain the reg names "QuadSPI" and "QuadSPI-memory"
+ - interrupts : Should contain the interrupt for the device
+ - clocks : The clocks needed by the QuadSPI controller
+ - clock-names : the name of the clocks
+
+Optional properties:
+ - fsl,qspi-has-second-chip: The controller has two buses, bus A and bus B.
+ Each bus can be connected with two NOR flashes.
+ Most of the time, each bus only has one NOR flash
+ connected, this is the default case.
+ But if there are two NOR flashes connected to the
+ bus, you should enable this property.
+ (Please check the board's schematic.)
+
+Example:
+
+qspi0: quadspi@40044000 {
+ compatible = "fsl,vf610-qspi";
+ reg = <0x40044000 0x1000>, <0x20000000 0x10000000>;
+ reg-names = "QuadSPI", "QuadSPI-memory";
+ interrupts = <0 24 IRQ_TYPE_LEVEL_HIGH>;
+ clocks = <&clks VF610_CLK_QSPI0_EN>,
+ <&clks VF610_CLK_QSPI0>;
+ clock-names = "qspi_en", "qspi";
+
+ flash0: s25fl128s@0 {
+ ....
+ };
+};
diff --git a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
index eb05255b6788..65f4f7c43136 100644
--- a/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
+++ b/Documentation/devicetree/bindings/mtd/gpmc-nand.txt
@@ -28,6 +28,8 @@ Optional properties:
"ham1" 1-bit Hamming ecc code
"bch4" 4-bit BCH ecc code
"bch8" 8-bit BCH ecc code
+ "bch16" 16-bit BCH ECC code
+ Refer below "How to select correct ECC scheme for your device ?"
- ti,nand-xfer-type: A string setting the data transfer type. One of:
@@ -90,3 +92,46 @@ Example for an AM33xx board:
};
};
+How to select correct ECC scheme for your device ?
+--------------------------------------------------
+Higher ECC scheme usually means better protection against bit-flips and
+increased system lifetime. However, selection of ECC scheme is dependent
+on various other factors also like;
+
+(1) support of built in hardware engines.
+ Some legacy OMAP SoC do not have ELM harware engine, so those SoC cannot
+ support ecc-schemes with hardware error-correction (BCHx_HW). However
+ such SoC can use ecc-schemes with software library for error-correction
+ (BCHx_HW_DETECTION_SW). The error correction capability with software
+ library remains equivalent to their hardware counter-part, but there is
+ slight CPU penalty when too many bit-flips are detected during reads.
+
+(2) Device parameters like OOBSIZE.
+ Other factor which governs the selection of ecc-scheme is oob-size.
+ Higher ECC schemes require more OOB/Spare area to store ECC syndrome,
+ so the device should have enough free bytes available its OOB/Spare
+ area to accomodate ECC for entire page. In general following expression
+ helps in determining if given device can accomodate ECC syndrome:
+ "2 + (PAGESIZE / 512) * ECC_BYTES" >= OOBSIZE"
+ where
+ OOBSIZE number of bytes in OOB/spare area
+ PAGESIZE number of bytes in main-area of device page
+ ECC_BYTES number of ECC bytes generated to protect
+ 512 bytes of data, which is:
+ '3' for HAM1_xx ecc schemes
+ '7' for BCH4_xx ecc schemes
+ '14' for BCH8_xx ecc schemes
+ '26' for BCH16_xx ecc schemes
+
+ Example(a): For a device with PAGESIZE = 2048 and OOBSIZE = 64 and
+ trying to use BCH16 (ECC_BYTES=26) ecc-scheme.
+ Number of ECC bytes per page = (2 + (2048 / 512) * 26) = 106 B
+ which is greater than capacity of NAND device (OOBSIZE=64)
+ Hence, BCH16 cannot be supported on given device. But it can
+ probably use lower ecc-schemes like BCH8.
+
+ Example(b): For a device with PAGESIZE = 2048 and OOBSIZE = 128 and
+ trying to use BCH16 (ECC_BYTES=26) ecc-scheme.
+ Number of ECC bytes per page = (2 + (2048 / 512) * 26) = 106 B
+ which can be accomodate in the OOB/Spare area of this device
+ (OOBSIZE=128). So this device can use BCH16 ecc-scheme.
diff --git a/Documentation/devicetree/bindings/mtd/m25p80.txt b/Documentation/devicetree/bindings/mtd/m25p80.txt
index 6d3d57609470..4611aa83531b 100644
--- a/Documentation/devicetree/bindings/mtd/m25p80.txt
+++ b/Documentation/devicetree/bindings/mtd/m25p80.txt
@@ -5,8 +5,8 @@ Required properties:
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.
+ "spi_nor_ids" table in drivers/mtd/spi-nor/spi-nor.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
diff --git a/Documentation/devicetree/bindings/mtd/pxa3xx-nand.txt b/Documentation/devicetree/bindings/mtd/pxa3xx-nand.txt
index 86e0a5601ff5..de8b517a5521 100644
--- a/Documentation/devicetree/bindings/mtd/pxa3xx-nand.txt
+++ b/Documentation/devicetree/bindings/mtd/pxa3xx-nand.txt
@@ -17,6 +17,14 @@ Optional properties:
- num-cs: Number of chipselect lines to usw
- nand-on-flash-bbt: boolean to enable on flash bbt option if
not present false
+ - nand-ecc-strength: number of bits to correct per ECC step
+ - nand-ecc-step-size: number of data bytes covered by a single ECC step
+
+The following ECC strength and step size are currently supported:
+
+ - nand-ecc-strength = <1>, nand-ecc-step-size = <512>
+ - nand-ecc-strength = <4>, nand-ecc-step-size = <512>
+ - nand-ecc-strength = <8>, nand-ecc-step-size = <512>
Example:
diff --git a/Documentation/mtd/spi-nor.txt b/Documentation/mtd/spi-nor.txt
new file mode 100644
index 000000000000..548d6306ebca
--- /dev/null
+++ b/Documentation/mtd/spi-nor.txt
@@ -0,0 +1,62 @@
+ SPI NOR framework
+ ============================================
+
+Part I - Why do we need this framework?
+---------------------------------------
+
+SPI bus controllers (drivers/spi/) only deal with streams of bytes; the bus
+controller operates agnostic of the specific device attached. However, some
+controllers (such as Freescale's QuadSPI controller) cannot easily handle
+arbitrary streams of bytes, but rather are designed specifically for SPI NOR.
+
+In particular, Freescale's QuadSPI controller must know the NOR commands to
+find the right LUT sequence. Unfortunately, the SPI subsystem has no notion of
+opcodes, addresses, or data payloads; a SPI controller simply knows to send or
+receive bytes (Tx and Rx). Therefore, we must define a new layering scheme under
+which the controller driver is aware of the opcodes, addressing, and other
+details of the SPI NOR protocol.
+
+Part II - How does the framework work?
+--------------------------------------
+
+This framework just adds a new layer between the MTD and the SPI bus driver.
+With this new layer, the SPI NOR controller driver does not depend on the
+m25p80 code anymore.
+
+ Before this framework, the layer is like:
+
+ MTD
+ ------------------------
+ m25p80
+ ------------------------
+ SPI bus driver
+ ------------------------
+ SPI NOR chip
+
+ After this framework, the layer is like:
+ MTD
+ ------------------------
+ SPI NOR framework
+ ------------------------
+ m25p80
+ ------------------------
+ SPI bus driver
+ ------------------------
+ SPI NOR chip
+
+ With the SPI NOR controller driver (Freescale QuadSPI), it looks like:
+ MTD
+ ------------------------
+ SPI NOR framework
+ ------------------------
+ fsl-quadSPI
+ ------------------------
+ SPI NOR chip
+
+Part III - How can drivers use the framework?
+---------------------------------------------
+
+The main API is spi_nor_scan(). Before you call the hook, a driver should
+initialize the necessary fields for spi_nor{}. Please see
+drivers/mtd/spi-nor/spi-nor.c for detail. Please also refer to fsl-quadspi.c
+when you want to write a new driver for a SPI NOR controller.