Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754987AbbLAEqH (ORCPT ); Mon, 30 Nov 2015 23:46:07 -0500 Received: from devils.ext.ti.com ([198.47.26.153]:45100 "EHLO devils.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752150AbbLAEqF (ORCPT ); Mon, 30 Nov 2015 23:46:05 -0500 Subject: Re: [PATCH v4 4/5] ARM: dts: DRA7: add entry for qspi mmap region To: Tony Lindgren References: <1448860515-28336-1-git-send-email-vigneshr@ti.com> <1448860515-28336-5-git-send-email-vigneshr@ti.com> <20151130223408.GJ23396@atomide.com> CC: Brian Norris , Mark Brown , Rob Herring , Russell King , , , , , , , From: Vignesh R Message-ID: <565D25E6.4070206@ti.com> Date: Tue, 1 Dec 2015 10:15:26 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151130223408.GJ23396@atomide.com> Content-Type: text/plain; charset="windows-1252" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3133 Lines: 82 On 12/01/2015 04:04 AM, Tony Lindgren wrote: > * Vignesh R [151129 21:16]: >> Add qspi memory mapped region entries for DRA7xx based SoCs. Also, >> update the binding documents for the controller to document this change. >> >> Acked-by: Rob Herring >> Signed-off-by: Vignesh R > ... >> --- a/Documentation/devicetree/bindings/spi/ti_qspi.txt >> +++ b/Documentation/devicetree/bindings/spi/ti_qspi.txt >> @@ -26,3 +26,17 @@ qspi: qspi@4b300000 { >> spi-max-frequency = <25000000>; >> ti,hwmods = "qspi"; >> }; >> + >> +For dra7xx: >> +qspi: qspi@4b300000 { >> + compatible = "ti,dra7xxx-qspi"; >> + reg = <0x4b300000 0x100>, >> + <0x5c000000 0x4000000>, >> + <0x4a002558 0x4>; >> + reg-names = "qspi_base", "qspi_mmap", >> + "qspi_ctrlmod"; >> + #address-cells = <1>; >> + #size-cells = <0>; >> + spi-max-frequency = <48000000>; >> + ti,hwmods = "qspi"; >> +}; > > 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). 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. 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. 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. > 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. > 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? -- Regards Vignesh -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/