On 12/01/2015 10:09 PM, Tony Lindgren wrote: > * Vignesh R <vigneshr@xxxxxx> [151130 20:46]: >> On 12/01/2015 04:04 AM, Tony Lindgren wrote: >>> >>> Actually none of the IO areas above are within the same interconnect target: >>> >>> 0x4b300000 QSPI0 address space in L3 main interconnect >>> 0x5c000000 QSPI1 address space in L3 main interconnect >> >> >> First address range (configuration port: 0x4b300000) corresponds to QSPI >> registers space. These registers alone are sufficient for generic SPI >> communication (serial flash as well as non-flash SPI devices). > > OK > >> In order to speed up SPI flash reads SFI_MM_IF(SPI memory mapped >> interface) is provided by QSPI IP. This _cannot_ be used with non-flash >> devices. > > OK > >> The second address range (0x5c000000) corresponds to memory-mapped >> region of SFI_MM_IF, through which SPI flash memories can be read as if >> though they were RAM addresses (i.e using readl/memcpy). The SFI_MM_IF >> block that takes care of communicating over SPI bus and getting the data >> from flash device. > > OK > >> But SFI_MM_IF block needs to know some flash specific information(such >> as read opcode, address bytes, dummy bytes, mode). This information must >> first be populated in QSPI_SPI_SETUP*_REG(0x4B300054-60) before >> accessing SFI_MM_IF address range via readl. >> Both addresses space belong to same instance of the driver, one >> corresponds to register space and other is memory-mapped region. >> Therefore both regions are claimed by the same driver. > > OK > >>> 0x4a002558 CTRL_CORE_CONTROL_IO_2 in System Control Module (SCM) in L4_CFG >>> >>> The first two address spaces should be two separate instances of this driver. >> >> Not actually two instances. > > OK. They are both on L3 main so that won't cause any issues for separate > interconnect driver instances. As they are still separate targets flushing > a posted write to one area will not flush anything to the other. > I didn't quite understand what you meant by interconnect driver instance. qspi_base and qspi_mmap region are tightly bound to each other and both needs to be accessed by ti-qspi driver (though different targets). Besides qspi_mmap region is only used to read data, there will not be any write accesses to this target. Are you saying this binding is not viable? >>> The CTRL_CORE_CONTROL_IO_2 needs seems like a shared clock register that >>> needs to be accessed using the clock framework most likely. >>> >> >> Not shared clock. >> The CTRL_CORE_CONTROL_IO_2[10:8] QSPI_MEMMAPPED_CS bit fields provides a >> functionality for remapping the previously described address space which >> starts at 0x5C000000 L3_MAIN address to one of the four supported chip >> selects. >> How about using syscon to access CTRL_CORE_CONTROL_IO_2? > > A separate driver implementing some Linux generic framework would be idael :) > > But if that does not fit, yeah then syscon makes sense as that IO range > will be on separate interconnect driver (and clock and possibly power domain) > instances eventually. > I will go ahead with syscon for accessing CTRL_CORE_CONTROL_IO_2 register. -- Regards Vignesh -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
