Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751311AbaKCFor (ORCPT ); Mon, 3 Nov 2014 00:44:47 -0500 Received: from mailgw01.mediatek.com ([218.249.47.110]:34931 "EHLO mailgw01.mediatek.com" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1750826AbaKCFon (ORCPT ); Mon, 3 Nov 2014 00:44:43 -0500 X-Listener-Flag: 11101 Message-ID: <1414993470.10276.19.camel@mhfsdcap03> Subject: Re: [PATCH 3/3] I2C: mediatek: Add driver for MediaTek I2C controller From: xudong chen To: Matthias Brugger CC: Yingjoe Chen , Mark Rutland , , Wolfram Sang , srv_heupstream , Sascha Hauer , Rob Herring , Pawel Moll , Ian Campbell , "Kumar Gala" , Russell King , "Grant Likely" , Jean Delvare , "Arnd Bergmann" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , , "Eddie Huang" , Nathan Chung , YH Chen Date: Mon, 3 Nov 2014 13:44:30 +0800 In-Reply-To: References: <1414561058-23803-1-git-send-email-xudong.chen@mediatek.com> <1414561058-23803-4-git-send-email-xudong.chen@mediatek.com> <1414737101.32208.18.camel@mhfsdcap03> <1414766288.5833.46.camel@mtksdaap41> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-MTK: N Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2014-10-31 at 17:10 +0100, Matthias Brugger wrote: > 2014-10-31 15:38 GMT+01:00 Yingjoe Chen : > > On Fri, 2014-10-31 at 11:48 +0100, Matthias Brugger wrote: > >> 2014-10-31 7:31 GMT+01:00 xudong chen : > >> > On Thu, 2014-10-30 at 14:16 +0100, Matthias Brugger wrote: > >> >> 2014-10-29 6:37 GMT+01:00 Xudong Chen : > >> >> > The mediatek SoCs have I2C controller that handle I2C transfer. > >> >> > This patch include common I2C bus driver. > >> >> > This driver is compatible with I2C controller on mt65xx/mt81xx. > >> >> > > >> >> > Signed-off-by: Xudong Chen > >> >> > Change-Id: Icc17e326b9df46a226d536956e103f17b0382b6e > >> >> > --- > >> >> > drivers/i2c/busses/Kconfig | 9 + > >> >> > drivers/i2c/busses/Makefile | 1 + > >> >> > drivers/i2c/busses/i2c-mt65xx.c | 728 ++++++++++++++++++++++++++++++++++++++++ > >> >> > 3 files changed, 738 insertions(+) > >> >> > create mode 100644 drivers/i2c/busses/i2c-mt65xx.c > >> >> > > >> >> > diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig > >> >> > index 917c358..0d7d0a4 100644 > >> >> > --- a/drivers/i2c/busses/Kconfig > >> >> > +++ b/drivers/i2c/busses/Kconfig > >> >> > @@ -564,6 +564,15 @@ config I2C_MPC > >> >> > This driver can also be built as a module. If so, the module > >> >> > will be called i2c-mpc. > >> >> > > >> >> > +config I2C_MT65XX > >> >> > + tristate "MediaTek I2C adapter" > >> >> > + depends on ARCH_MEDIATEK > >> >> > + help > >> >> > + This selects the MediaTek(R) Integrated Inter Circuit bus driver > >> >> > + for MT65xx and MT81xx. > >> >> > + If you want to use MediaTek(R) I2C interface, say Y or M here. > >> >> > + If unsure, say N. > >> >> > + > >> >> > config I2C_MV64XXX > >> >> > tristate "Marvell mv64xxx I2C Controller" > >> >> > depends on MV64X60 || PLAT_ORION || ARCH_SUNXI > >> >> > diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile > >> >> > index 78d56c5..7a9f0f3 100644 > >> >> > --- a/drivers/i2c/busses/Makefile > >> >> > +++ b/drivers/i2c/busses/Makefile > >> >> > @@ -54,6 +54,7 @@ obj-$(CONFIG_I2C_IMX) += i2c-imx.o > >> >> > obj-$(CONFIG_I2C_IOP3XX) += i2c-iop3xx.o > >> >> > obj-$(CONFIG_I2C_KEMPLD) += i2c-kempld.o > >> >> > obj-$(CONFIG_I2C_MPC) += i2c-mpc.o > >> >> > +obj-$(CONFIG_I2C_MT65XX) += i2c-mt65xx.o > >> >> > + > >> >> > +static int mt_i2c_do_transfer(struct mt_i2c *i2c) > >> >> > +{ > >> >> > + u16 addr_reg; > >> >> > + u16 control_reg; > >> >> > + int tmo = i2c->adap.timeout; > >> >> > + > >> >> > + i2c->trans_stop = false; > >> >> > + i2c->irq_stat = 0; > >> >> > + > >> >> > + /* If use i2c pin from PMIC mt6397 side, need set PATH_DIR first */ > >> >> > + if (i2c->have_pmic) > >> >> > + i2c_writew(I2C_CONTROL_WRAPPER, i2c, OFFSET_PATH_DIR); > >> >> > >> >> So this is some sort of multiplexer bit, right? > >> >> I think in this case we need to build a multi function device (mfd) > >> >> where the pmic driver will set this bit. > >> >> > >> > Hi, > >> > > >> > This feature means the chip can use I2C pins from PMIC(mt6397). > >> > In this case, > >> > 1. We actually control the register on mt8135 and the DMA/Control Logic > >> > is on mt8135, only use pins from mt6397. If set register OFFSET_PATH_DIR > >> > bit0 to 1, the I2C data will go/from PMIC pins. > >> > >> Sorry but I'm a bit puzzled. mt6397 is the PMIC, right? > >> So from the mt6589 datasheet it says: > >> "PATH_DIR Decides transmission direction > >> If set, the I2C data will go/from PMIC; otherwise, the I2C data will > >> go/from main die." > >> > >> From my understanding the I2C bus will be multiplexed depending on > >> this bit. The bit decides if it the data will be send to the PMIC or > >> to some other I2C peripheral. > >> > >> So we need a mfd and the PMIC device driver sets/unsets the PATH_DIR register. > > > > Yes, mt6397 is the PMIC work with mt8135 or mt8127. > > > > I think the datasheet is a little misleading here. AFAIK, on 8135 even > > if your clear the bit for I2C4, there are no corresponding pins for this > > i2c port on 8135. So it is not really multiplexed. Base on my > > understanding this is more like "Set this bit if this a PMIC I2C port". > > I had a look at mt6589. The SoC has seven i2c controller. Looking at > the source code all controller with an ID bigger then 3 can be set to > pmic wrapper state. I have checked the mt8135 and mt6589 GPIO datasheet, there are pins on mt8135 or mt6589 for i2c4~i2c6, we also can use i2c4~i2c6 modules on mt8135 or mt6589 after set pinmux. Sorry about the misunderstand before. I will add i2c4~i2c6 nodes to the mt8135.dtsi in next patch. > So I would say that the PATH_DIR bit is not always bound to i2c4. We > should implement a driver which will work on all possible > configurations. We don't know if apart from mt6589 and mt8135 some > other SoC in the future will use this i2c controller. > Because the mt6397 HW limitation, it's i2c module cannot be used when apart from mt6589 or mt8135. Take mt6589 for example: If we want to use mt6397 i2c pins, it must work together with mt6589, also we need to set the i2c control register on mt6589(DIR_PATH and the other registers) and then the HW will auto handle the communication between mt6397 and mt6589 internal(do not need any SW control), so data can go/from mt6397 pins. In this case the i2c pins on mt6397 will work just like the i2c pins is from mt6589. > Maybe you can check with the HW guys how this is implemented to shed > some light on the issue. > -- 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/