On 02/07/19 11:23 PM, Sergei Shtylyov wrote: > 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> > [...] > > I have at least created my HyperBus driver and unfortunately I'm having serious > issues with the design of the support core (see below)... > > [...] >> 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) >> +{ >> + const struct hyperbus_ops *ops; >> + struct hyperbus_ctlr *ctlr; >> + struct device_node *np; >> + struct map_info *map; >> + struct resource res; >> + struct device *dev; >> + int ret; >> + >> + if (!hbdev || !hbdev->np || !hbdev->ctlr || !hbdev->ctlr->dev) { >> + pr_err("hyperbus: please fill all the necessary fields!\n"); >> + return -EINVAL; >> + } >> + >> + np = hbdev->np; >> + ctlr = hbdev->ctlr; >> + if (!of_device_is_compatible(np, "cypress,hyperflash")) >> + return -ENODEV; >> + >> + hbdev->memtype = HYPERFLASH; >> + >> + ret = of_address_to_resource(np, 0, &res); > > Hm, I doubt that the HB devices are wholly mapped into memory space, that seems > like a property of the HB controller. In my case, the flash device in the DT has > only single-cell "reg" prop (equal to the chip select #). Then this function returns > -EINVAL and the registration fails. Also, in my case such mapping is R/O, not R/W. > You could declare R/O MMIO region in controla and set up a translation using ranges from slave's reg CS based reg mapping like: + hbmc: hyperbus@47034000 { + compatible = "ti,am654-hbmc"; + reg = <0x0 0x47034000 0x0 0x100>, + <0x5 0x00000000 0x1 0x0000000>; + #address-cells = <2>; + #size-cells = <1>; + ranges = <0x0 0x0 0x5 0x00000000 0x4000000>, /* CS0 - 64MB */ + <0x1 0x0 0x5 0x04000000 0x4000000>; /* CS1 - 64MB */ + + /* Slave flash node */ + flash@0,0 { + compatible = "cypress,hyperflash", "cfi-flash"; + reg = <0x0 0x0 0x4000000>; + }; + }; If you use just CS# how would you handle CS to MMIO region mapping? Does both CS use the same MMIO base for reads? >> + if (ret) >> + return ret; >> + >> + dev = ctlr->dev; >> + map = &hbdev->map; >> + map->size = resource_size(&res); >> + map->virt = devm_ioremap_resource(dev, &res); >> + if (IS_ERR(map->virt)) >> + return PTR_ERR(map->virt); > > Again, I doubt that this should be done here, and not in the HB controller driver... If multiple CS use same MMIO base, then I can make this part of code non fatal when reg entry is a single cell and introduce notion of CS like SPI > > [...] > > MBR, Sergei > -- Regards Vignesh
