From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jonathan Richardson Subject: Re: [PATCH 1/4] ARM: dts: Add binding for Broadcom MSPI driver. Date: Mon, 6 Apr 2015 11:45:06 -0700 Message-ID: <5522D432.10604@broadcom.com> References: <1428002603-21892-1-git-send-email-jonathar@broadcom.com> <1428002603-21892-2-git-send-email-jonathar@broadcom.com> <552038E5.6050609@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: Mark Brown , Dmitry Torokhov , Anatol Pomazau , Scott Branden , Rob Herring , Pawel Moll , "Mark Rutland" , Ian Campbell , Kumar Gala , , , bcm-kernel-feedback-list , , Rafal Milecki , Brian Norris , Kevin Cernekee To: Florian Fainelli Return-path: In-Reply-To: <552038E5.6050609@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-spi.vger.kernel.org On 15-04-04 12:17 PM, Florian Fainelli wrote: > Le 02/04/2015 12:23, Jonathan Richardson a =C3=A9crit : >> >> Signed-off-by: Jonathan Richardson >> --- >> .../devicetree/bindings/spi/brcm,mspi-spi.txt | 38 +++++++++= +++++++++++ >> 1 file changed, 38 insertions(+) >> create mode 100644 Documentation/devicetree/bindings/spi/brcm,mspi-= spi.txt >> >> diff --git a/Documentation/devicetree/bindings/spi/brcm,mspi-spi.txt= b/Documentation/devicetree/bindings/spi/brcm,mspi-spi.txt >> new file mode 100644 >> index 0000000..16164e3 >> --- /dev/null >> +++ b/Documentation/devicetree/bindings/spi/brcm,mspi-spi.txt >> @@ -0,0 +1,38 @@ >> +Broadcom MSPI controller >> + >> +Required properties: >> +- compatible: Must be either "brcm,mspi" or "brcm,bcma-mspi". Use >> + "brcm,bcma-mspi" for controllers on a bcma bus and "brcm,mspi" ot= herwise. >=20 > We need a more specific compatible property here since there are at > least 3 known SoCs families within Broadcom (Cygnus, BCM53xx, BCM7xxx= ) > that use this controller, also older versions of the core did not hav= e a > revision register, yet they had an internal version numbering that we > might want to reflect here. This does not need to be fixed immediatel= y > though, we can add compatible strings as we start adding support for > older cores. >=20 >> + >> +- reg: Physical base address and length of the controller's regist= ers. >> + >> +- interrupts: The interrupt id for the controller. >=20 > I think this should be two cells, on BCM7xxx chips there is a MSPI_DO= NE > and a MSPI_ERROR interrupt bit, we typically only use the first one, = but > since we are describing the hardware here, we need to be exhaustive. My mistake. Interrupts are not supported by this driver yet. I intend o= n adding this later. I will remove this from the docs. >=20 >> + >> +- #address-cells: should be 1. >> + >> +- #size-cells: should be 0. >> + >> +Optional properties: >> +- clocks: The MSPI reference clock. If not provided then it is assu= med a clock >> + is enabled by default and no control of clock-frequency (see belo= w) is >> + possible. >> + >> +- clock-names: The name of the reference clock. >> + >> +- clock-frequency: Desired frequency of the clock. This will set th= e serial >> + clock baud rate (SPBR) based on the reference clock frequency. Th= e frequency >> + of the SPBR is mspi_clk / (2 * SPBR) where SPBR is a value betwee= n 1-255 >> + determined by the desired 'clock-frequency'. If not provided then= the default >> + baud rate of the controller is used. >=20 > See my reply to the patch 4, that does not seem to match the > "clock-frequency" vs. clock phandles practices in DT. I could use a different property for it. I agree it's a bit weird since we're not changing the frequency of the reference clock but the clock derived from it for the baud rate of the controller. Does this warrant adding a different property though? >=20 >> + >> +Example: >> + >> +mspi@18047000 { >> + #address-cells =3D <1>; >> + #size-cells =3D <0>; >> + compatible =3D "brcm,mspi"; >> + reg =3D <0x18047000 0x1000>; >> + clocks =3D <&axi41_clk>; >> + clock-names =3D "mspi_clk"; >> + clock-frequency =3D <12500000>; >=20 > Since "interrupts" is a mandatory property you might want the example= to > show it for consistency. > -- > Florian >=20