Hello! On 06/25/2019 10:57 AM, Vignesh Raghavendra wrote: > 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 with respect to bits per clock > cycle. But HyperBus operates at >166MHz frequencies. > HyperRAM provides direct random read/write access to flash memory > array. > > But, HyperBus memory controllers seem to abstract implementation details > and expose a simple MMIO interface to access connected flash. > > Add support for registering HyperFlash devices with MTD framework. MTD > maps framework along with CFI chip support framework are used to support > communicating with flash. > > Framework is modelled along the lines of spi-nor framework. HyperBus > memory controller (HBMC) drivers calls hyperbus_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. > > Some HBMC masters need calibration/training sequence[3] to be carried > out, in order for DLL inside the controller to lock, by reading a known > string/pattern. This is done by repeatedly reading CFI Query > Identification String. Calibration needs to be done before trying to detect > flash as part of CFI flash probe. > > HyperRAM is not supported at the moment. > > HyperBus specification can be found at[1] > HyperFlash datasheet can be found at[2] > > [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 > > Signed-off-by: Vignesh Raghavendra <vigneshr@xxxxxx> [...] > diff --git a/drivers/mtd/Makefile b/drivers/mtd/Makefile > index 806287e80e84..62d649a959e2 100644 > --- a/drivers/mtd/Makefile > +++ b/drivers/mtd/Makefile > @@ -34,3 +34,4 @@ obj-y += chips/ lpddr/ maps/ devices/ nand/ tests/ > > obj-$(CONFIG_MTD_SPI_NOR) += spi-nor/ > obj-$(CONFIG_MTD_UBI) += ubi/ > +obj-$(CONFIG_MTD_HYPERBUS) += hyperbus/ > diff --git a/drivers/mtd/hyperbus/Kconfig b/drivers/mtd/hyperbus/Kconfig > new file mode 100644 > index 000000000000..98147e28caa0 > --- /dev/null > +++ b/drivers/mtd/hyperbus/Kconfig > @@ -0,0 +1,11 @@ > +menuconfig MTD_HYPERBUS > + tristate "HyperBus support" > + select MTD_CFI > + select MTD_MAP_BANK_WIDTH_2 > + select MTD_CFI_AMDSTD > + select MTD_COMPLEX_MAPPINGS > + help > + This is the framework for the HyperBus which can be used by > + the HyperBus Controller driver to communicate with > + HyperFlash. See Cypress HyperBus specification for more > + details > diff --git a/drivers/mtd/hyperbus/Makefile b/drivers/mtd/hyperbus/Makefile > new file mode 100644 > index 000000000000..ca61dedd730d > --- /dev/null > +++ b/drivers/mtd/hyperbus/Makefile > @@ -0,0 +1,3 @@ > +# SPDX-License-Identifier: GPL-2.0 > + > +obj-$(CONFIG_MTD_HYPERBUS) += hyperbus-core.o > diff --git a/drivers/mtd/hyperbus/hyperbus-core.c b/drivers/mtd/hyperbus/hyperbus-core.c > new file mode 100644 > index 000000000000..63a9e64895bc > --- /dev/null > +++ b/drivers/mtd/hyperbus/hyperbus-core.c > @@ -0,0 +1,154 @@ [...] > +int hyperbus_register_device(struct hyperbus_device *hbdev) > +{ [...] > + hbdev->mtd = do_map_probe("cfi_probe", map); > + if (!hbdev->mtd) { > + dev_err(dev, "probing of hyperbus device failed\n"); > + return -ENODEV; > + } > + > + hbdev->mtd->dev.parent = dev; > + mtd_set_of_node(hbdev->mtd, np); > + > + ret = mtd_device_register(hbdev->mtd, NULL, 0); > + if (ret) { > + dev_err(dev, "failed to register mtd device\n"); > + map_destroy(hbdev->mtd); > + return ret; > + } > + hbdev->registered = true; I doubt that you actually need this flag... > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(hyperbus_register_device); > + > +int hyperbus_unregister_device(struct hyperbus_device *hbdev) > +{ > + int ret = 0; > + > + if (hbdev && hbdev->mtd && hbdev->registered) { ... as you missed clearing that 'registered' flag. > + ret = mtd_device_unregister(hbdev->mtd); > + map_destroy(hbdev->mtd); > + } > + > + return ret; > +} > +EXPORT_SYMBOL_GPL(hyperbus_unregister_device); [...] MBR, Sergei
