From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.windriver.com (mail.windriver.com [147.11.1.11]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client CN "mail.windriver.com", Issuer "Intel External Basic Issuing CA 3A" (not verified)) by ozlabs.org (Postfix) with ESMTPS id 44216B6EED for ; Wed, 13 Oct 2010 18:47:37 +1100 (EST) Message-ID: <4CB56496.7040809@windriver.com> Date: Wed, 13 Oct 2010 15:49:42 +0800 From: "tiejun.chen" MIME-Version: 1.0 To: WANG YiFei Subject: Re: ppc405 + MCP23S17 References: <4CB522D1.5090802@windriver.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Cc: linuxppc-dev@ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , WANG YiFei wrote: > Hi TieJun, > > Thanks a lot for your reply. > So far, I can get ppc405 spi to initialize, however > failed at MCP23S17's probe() routine, I checked the > code, it's due to un-initialized platform data. Here > is my part of dts: > > spi@ef600600 { > device_type = "spi"; > compatible = "ibm,ppc4xx-spi", "ibm,spi"; > reg = <0xef600600 0x7>; > interrupt-parent = <0x2>; > interrupts = <0x8 0x4>; > #address-cells = <0x1>; > #size-cells = <0x0>; > gpios = <0>; /* cs */ > > spi_gpio@0 { > compatible = "mcp,mcp23s08"; > spi-max-frequency = <1000000>; > reg = <0>; > }; > }; > > I don't know how to provide platform data from dts although > I understand the concept from code. Do I only need to modify > dts OR I need to write some code to supply platform data? Do > you have any URL or sample code to show passing of platform > data? Often you SPI bus driver should call spi_register_master() to register your SPI master controller. Then please go to the following path: ====== spi_register_master() | + scan_boardinfo() | + spi_new_device() ^ Here refer to the function, ------ struct spi_device *spi_new_device(struct spi_master *master, struct spi_board_info *chip) { struct spi_device *proxy; ...... proxy->dev.platform_data = (void *) chip->platform_data; ...... status = spi_add_device(proxy); ...... And as I previously comment 'spi->dev.platform_data' would be passed to your platform_data resided in your probe hook within your spi device driver. So firstly you should register call spi_register_board_info() to register one given spi_board_info by parsing your device nodes from your dts. I think you can refer to the file, arch/powerpc/platforms/83xx/mpc832x_rdb.c. > > Anyway, thanks a lot for guiding me. You're welcome :) Tiejun > YiFei > > -----Original Message----- > From: tiejun.chen [mailto:tiejun.chen@windriver.com] > Sent: Wednesday, October 13, 2010 11:09 AM > To: WANG YiFei > Cc: linuxppc-dev@ozlabs.org > Subject: Re: ppc405 + MCP23S17 > > WANG YiFei wrote: >> Hi, >> >> >> >> I'm a newbie for linux device driver development. >> >> We have a custom ppc405 board which has MCP23S17 >> >> (16-Bit I/O Expander with SPI Interface) on it. >> >> I noticed that current kernel has MCP23S08 driver >> >> support, I'd like to know: >> >> 1. if passing platform data to MCP23S08 driver, can it make >> >> MCP23S17 work? >> > > These chips should be same vendor product so I think 16-bit mcp23s17 may be > compatible to 8-bit modes. But you have to check the data sheet to confirm this > and track how to configure that as 8-bit mode. After that it's possible to run > mcp23s17 with mcp23s08.c. > >> 2. Generally, I'd like to know how to pass platform data to >> >> a particular device driver. In my mind, platform data should >> >> not be in driver code, right? However, I don't know where is > > Firstly you should define this on your dts. Then parse that to register > corresponding of_platform_device or platform_device when you setup your target > on .c. > > When spi_register_driver prober successfully, you can get the platform_data from > associated spi device. > >> the suitable place to pass platform data to driver. >> >> 3. How to describe this in dts file? >> > > You can get more from the file, Documentation/powerpc/dts-bindings/spi-bus.txt. > Or refer to those existed spi nodes on other platform dts. > > Tiejun > >> >> >> Thanks in advance, >> >> YiFei >> >> >> >>