Messages in this thread | | | From | Bhupesh SHARMA <> | Date | Tue, 5 Jun 2012 21:04:21 +0800 | Subject | RE: [PATCH RFC] c_can_pci: generic module for c_can on PCI |
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> -----Original Message----- > From: Federico Vaga [mailto:federico.vaga@gmail.com] > Sent: Tuesday, June 05, 2012 4:49 PM > To: Bhupesh SHARMA > Cc: Alan Cox; Wolfgang Grandegger; Marc Kleine-Budde; Giancarlo > ASNAGHI; Alan Cox; Alessandro Rubini; linux-can@vger.kernel.org; > netdev@vger.kernel.org; linux-kernel@vger.kernel.org > Subject: Re: [PATCH RFC] c_can_pci: generic module for c_can on PCI > > > In some of these SoC's the C_CAN registers which are essentially > > 16-bit or 32-bit registers are aligned always to a 32-bit boundary > > (i.e. even a 16-bit register is aligned to 32-bit boundary). > > > > So, I had to implement two variants of the read/write reg routines. I > > am not sure your SoC implementation needs them. If it does, I will > > categorize it as flaky as well :) > > My implementation is align to 32, but I'm trying to make a generic PCI > wrapper (some other could be aligned to 16)
So it means your implementation is also flaky and you are probably wasting HW memory space while integrating the Bosch C_CAN module in your SoC :)
> > See above. There was a reason for keeping these routines in > > c_can_platform.c Simply put, every platform having a Bosch C_CAN > > module can have it's own implementation of the bus (for example you > > use PCI) and register bank layout (16-bit or 32-bit aligned). > > I don't understand the reason to keep these functions in > c_can_platform.c . Two generic read/write functions could be written > into c_can.c by using a shift value (0 if aligned to 16, 1 if aligned > to > 32) as I showed in the previous mail: > > > > static u16 c_can_read_reg(struct c_can_priv *priv, enum reg index) > > > { > > > > > > return readw(priv->base + (priv->regs[index] << priv->offset)); > > > > > > } > > > static void c_can_write_reg(struct c_can_priv *priv, enum reg > index, > > > > > > u16 val) > > > > > > { > > > > > > writew(val, priv->base + (priv->regs[index] << priv->offset)); > > > > > > } > > Every platform having a Bosch C_CAN/D_CAN can specify its shift value > (0 > or 1) and it's done. >
I am not a big fan of adding platform specific flakes in any core file, that why we keep the platform file separate from the core ones. But I will left Marc and Wolfgang to further comment on the same.
Regards, Bhupesh
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