From mboxrd@z Thu Jan 1 00:00:00 1970 From: Chen-Yu Tsai Subject: Re: Re: [PATCH 3/5] net: stmmac: dwmac-sun8i: Allow getting syscon regmap from device Date: Thu, 12 Apr 2018 23:23:30 +0800 Message-ID: References: <20180411141641.14675-1-icenowy@aosc.io> <20180411141641.14675-4-icenowy@aosc.io> <20180412145628.iaaeue2imiijwx5d@flea> Reply-To: wens-jdAy2FN1RRM@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org In-Reply-To: List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Icenowy Zheng Cc: Maxime Ripard , Rob Herring , Giuseppe Cavallaro , Corentin Labbe , netdev , devicetree , linux-arm-kernel , linux-kernel , linux-sunxi List-Id: devicetree@vger.kernel.org On Thu, Apr 12, 2018 at 11:11 PM, Icenowy Zheng wrote: > > > =E4=BA=8E 2018=E5=B9=B44=E6=9C=8812=E6=97=A5 GMT+08:00 =E4=B8=8B=E5=8D=88= 10:56:28, Maxime Ripard =E5=86=99=E5=88=B0: >>On Wed, Apr 11, 2018 at 10:16:39PM +0800, Icenowy Zheng wrote: >>> From: Chen-Yu Tsai >>> >>> On the Allwinner R40 SoC, the "GMAC clock" register is in the CCU >>> address space; on the A64 SoC this register is in the SRAM controller >>> address space, and with a different offset. >>> >>> To access the register from another device and hide the internal >>> difference between the device, let it register a regmap named >>> "emac-clock". We can then get the device from the phandle, and >>> retrieve the regmap with dev_get_regmap(); in this situation the >>> regmap_field will be set up to access the only register in the >>regmap. >>> >>> Signed-off-by: Chen-Yu Tsai >>> [Icenowy: change to use regmaps with single register, change commit >>> message] >>> Signed-off-by: Icenowy Zheng >>> --- >>> drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c | 48 >>++++++++++++++++++++++- >>> 1 file changed, 46 insertions(+), 2 deletions(-) >>> >>> diff --git a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c >>b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c >>> index 1037f6c78bca..b61210c0d415 100644 >>> --- a/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c >>> +++ b/drivers/net/ethernet/stmicro/stmmac/dwmac-sun8i.c >>> @@ -85,6 +85,13 @@ const struct reg_field old_syscon_reg_field =3D { >>> .msb =3D 31, >>> }; >>> >>> +/* Specially exported regmap which contains only EMAC register */ >>> +const struct reg_field single_reg_field =3D { >>> + .reg =3D 0, >>> + .lsb =3D 0, >>> + .msb =3D 31, >>> +}; >>> + >> >>I'm not sure this would be wise. If we ever need some other register >>exported through the regmap, will have to change all the calling sites >>everywhere in the kernel, which will be a pain and will break >>bisectability. > > In this situation the register can be exported as another > regmap. Currently the code will access a regmap with name > "emac-clock" for this register. > >> >>Chen-Yu's (or was it yours?) initial solution with a custom writeable >>hook only allowing a single register seemed like a better one. > > But I remember you mentioned that you want it to hide the > difference inside the device. Hi, The idea is that a device can export multiple regmaps. This one, the one named "gmac" (in my soon to come v2) or "emac-clock" here, is but one of many possible regmaps, and it only exports the register needed by the GMAC/EMAC. IMHO it is highly unlikely the same piece of hardware would need a second register from the same device. A more likely situation would be it needs another register from a different device, like on the H6 where the "internal PHY" is not so internal from a system bus point of view. ChenYu --=20 You received this message because you are subscribed to the Google Groups "= linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to linux-sunxi+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit https://groups.google.com/d/optout.