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    Subject[RFC PATCH 0/5] MTD: Add Initial Hyperbus support
    Date
    Cypress HyperBus is Low Signal Count, High Performance Double Data Rate Bus
    interface between a host system master and one or more slave interfaces.
    HyperBus is used to connect microprocessor, microcontroller, or ASIC
    devices with random access NOR flash memory(called HyperFlash) or
    self refresh DRAM(called HyperRAM).

    Its a 8-bit data bus (DQ[7:0]) with Read-Write Data Strobe (RWDS)
    signal and either Single-ended clock(3.0V parts) or Differential clock
    (1.8V parts). It uses ChipSelect lines to select b/w multiple slaves.
    At bus level, it follows a separate protocol described in HyperBus
    specification[1].

    HyperFlash follows CFI AMD/Fujitsu Extended Command Set (0x0002) similar
    to that of existing parallel NORs. Since Hyperbus is x8 DDR bus,
    its equivalent to x16 parallel NOR flash wrt bits per clk. But Hyperbus
    operates at >166MHz frequencies.
    HyperRAM provides direct random read/write access to flash memory
    array.
    Framework is modelled along the lines of spi-nor framework. HyperBus
    memory controller(HBMC) drivers call hb_register_device() to register a
    single HyperFlash device. HyperFlash core parses MMIO access
    information from DT, sets up the map_info struct, probes CFI flash and
    registers it with MTD framework.

    This is an early RFC, to know if its okay to use maps framework and existing
    CFI compliant flash support code to support Hyperflash
    Also would like input on different types of HBMC master IPs out there
    and their programming sequences.
    Would appreciate any testing/review.

    Tested on modified TI AM654 EVM with Cypress Hyperflash S26KS512 by
    creating a UBIFS partition and writing and reading files to it.
    Stress tested by writing/reading 16MB flash repeatedly at different
    offsets using dd commmand.

    HyperBus specification can be found at[1]
    HyperFlash datasheet can be found at[2]
    TI's HBMC controller details at[3]

    [1] https://www.cypress.com/file/213356/download
    [2] https://www.cypress.com/file/213346/download
    [3] http://www.ti.com/lit/ug/spruid7b/spruid7b.pdf
    Table 12-5741. HyperFlash Access Sequence

    Vignesh R (5):
    mtd: cfi_cmdset_0002: Add support for polling status register
    dt-bindings: mtd: Add binding documentation for Hyperbus memory
    devices
    mtd: Add support for Hyperbus memory devices
    dt-bindings: mtd: Add bindings for TI's AM654 Hyperbus memory
    controller
    mtd: hyperbus: Add driver for TI's Hyperbus memory controller

    .../bindings/mtd/cypress,hyperbus.txt | 6 +
    .../devicetree/bindings/mtd/ti,am654-hbmc.txt | 27 +++
    MAINTAINERS | 8 +
    drivers/mtd/Kconfig | 2 +
    drivers/mtd/Makefile | 1 +
    drivers/mtd/chips/cfi_cmdset_0002.c | 50 ++++++
    drivers/mtd/hyperbus/Kconfig | 23 +++
    drivers/mtd/hyperbus/Makefile | 4 +
    drivers/mtd/hyperbus/core.c | 167 ++++++++++++++++++
    drivers/mtd/hyperbus/hbmc_am654.c | 105 +++++++++++
    include/linux/mtd/cfi.h | 5 +
    include/linux/mtd/hyperbus.h | 73 ++++++++
    12 files changed, 471 insertions(+)
    create mode 100644 Documentation/devicetree/bindings/mtd/cypress,hyperbus.txt
    create mode 100644 Documentation/devicetree/bindings/mtd/ti,am654-hbmc.txt
    create mode 100644 drivers/mtd/hyperbus/Kconfig
    create mode 100644 drivers/mtd/hyperbus/Makefile
    create mode 100644 drivers/mtd/hyperbus/core.c
    create mode 100644 drivers/mtd/hyperbus/hbmc_am654.c
    create mode 100644 include/linux/mtd/hyperbus.h

    --
    2.20.1

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