From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Jayachandran C." Subject: Re: [PATCH v3 4/4] i2c: i2c-ocores: support for 16bit and 32bit IO Date: Fri, 13 Jul 2012 19:28:48 +0530 Message-ID: <20120713135848.GC18519@jayachandranc.netlogicmicro.com> References: <1342187065-1651-1-git-send-email-jayachandranc@netlogicmicro.com> <1342187065-1651-5-git-send-email-jayachandranc@netlogicmicro.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline Sender: linux-i2c-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Shubhrajyoti Datta Cc: linux-i2c-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, w.sang-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org, jacmet-OfajU3CKLf1/SzgSGea1oA@public.gmane.org, richard.rojfors-gfIc91nka+FZroRs9YW3xA@public.gmane.org, devicetree-discuss-mnsaURCQ41sdnm+yROfE0A@public.gmane.org, Ganesan Ramalingam List-Id: devicetree@vger.kernel.org On Fri, Jul 13, 2012 at 07:18:35PM +0530, Shubhrajyoti Datta wrote: > Hello, > > On Fri, Jul 13, 2012 at 7:14 PM, Jayachandran C > wrote: > > From: Ganesan Ramalingam > > > > Some architectures supports only 16-bit or 32-bit read/write access to > > their IO space. Add a 'reg-io-width' platform and OF parameter which > > specifies the IO width to support these platforms. > > > > reg-io-width can be specified as 1, 2 or 4, and has a default value > > of 1 if it is unspecified. > > > > Signed-off-by: Ganesan Ramalingam > > Signed-off-by: Jayachandran C > > --- > > .../devicetree/bindings/i2c/i2c-ocores.txt | 2 ++ > > drivers/i2c/busses/i2c-ocores.c | 21 ++++++++++++++++++-- > > include/linux/i2c-ocores.h | 1 + > > 3 files changed, 22 insertions(+), 2 deletions(-) > > > > diff --git a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt > > index 1c9334b..c15781f 100644 > > --- a/Documentation/devicetree/bindings/i2c/i2c-ocores.txt > > +++ b/Documentation/devicetree/bindings/i2c/i2c-ocores.txt > > @@ -10,6 +10,7 @@ Required properties: > > > > Optional properties: > > - reg-shift : device register offsets are shifted by this value > > +- reg-io-width : io register width in bytes (1, 2 or 4) > > - regstep : deprecated, use reg-shift above > > > > Example: > > @@ -23,6 +24,7 @@ Example: > > clock-frequency = <20000000>; > > > > reg-shift = <0>; /* 8 bit registers */ > > + reg-io-width = <1>; /* 8 bit read/write */ > > > > dummy@60 { > > compatible = "dummy"; > > diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c > > index 721ead9..de3b119 100644 > > --- a/drivers/i2c/busses/i2c-ocores.c > > +++ b/drivers/i2c/busses/i2c-ocores.c > > @@ -30,6 +30,7 @@ > > struct ocores_i2c { > > void __iomem *base; > > u32 reg_shift; > > + u32 reg_io_width; > > wait_queue_head_t wait; > > struct i2c_adapter adap; > > struct i2c_msg *msg; > > @@ -72,12 +73,22 @@ struct ocores_i2c { > > > > static inline void oc_setreg(struct ocores_i2c *i2c, int reg, u8 value) > > { > > - iowrite8(value, i2c->base + (reg << i2c->reg_shift)); > > + if (i2c->reg_io_width == 4) > > + iowrite32(value, i2c->base + (reg << i2c->reg_shift)); > > + else if (i2c->reg_io_width == 2) > > + iowrite16(value, i2c->base + (reg << i2c->reg_shift)); > > + else > > + iowrite8(value, i2c->base + (reg << i2c->reg_shift)); > > } > > > > static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg) > > Should the return type be changed. > Now that it is returning more that than 8 bits. > > Did I miss something? Only 8 bits of the register is significant, so even if we read 16 or 32 bits only the lowest 8 bits are returned. JC.