From mboxrd@z Thu Jan 1 00:00:00 1970 From: Priit Laes Subject: Re: [PATCH v2] spi: dts: sun4i: Add support for inter-word wait cycles using the SPI Wait Clock Register Date: Sat, 12 Dec 2015 11:19:40 +0200 Message-ID: <1449911980.29015.7.camel@plaes.org> References: <1449873940-10167-1-git-send-email-mweseloh42@gmail.com> Reply-To: plaes-q/aMd4JkU83YtjvyW6yDsg@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable Return-path: In-Reply-To: <1449873940-10167-1-git-send-email-mweseloh42-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: mweseloh42-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Cc: Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Maxime Ripard , Chen-Yu Tsai , Mark Brown , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-spi-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: devicetree@vger.kernel.org On Fri, 2015-12-11 at 23:45 +0100, Marcus Weseloh wrote: [...] >=20 > diff --git a/Documentation/devicetree/bindings/spi/spi-sun4i.txt b/Docume= ntation/devicetree/bindings/spi/spi-sun4i.txt > index de827f5..d6c55fc 100644 > --- a/Documentation/devicetree/bindings/spi/spi-sun4i.txt > +++ b/Documentation/devicetree/bindings/spi/spi-sun4i.txt > @@ -10,6 +10,10 @@ Required properties: > =C2=A0=C2=A0=C2=A0- "mod": the parent module clock > =C2=A0- clock-names: Must contain the clock names described just above > =C2=A0 > +Optional properties for slave devices: > +- sun4i,spi-word-wait-ns: hardware based delay in nanoseconds between > + =C2=A0=C2=A0transmission of words Should be 'allwinner,spi-word-wait-ns' Vendor prefix do come from: Documentation/devicetree/bindings/vendor-prefixes.txt > + > =C2=A0Example: > =C2=A0 > =C2=A0spi1: spi@01c06000 { > @@ -21,4 +25,11 @@ spi1: spi@01c06000 { > =C2=A0 status =3D "disabled"; > =C2=A0 #address-cells =3D <1>; > =C2=A0 #size-cells =3D <0>; > + > + spi1_0 { > + compatible =3D "example,dummy"; > + reg =3D <0>; > + spi-max-frequency =3D <1000000>; > + sun4i,spi-word-wait-ns =3D <12000>; > + }; > =C2=A0}; > diff --git a/drivers/spi/spi-sun4i.c b/drivers/spi/spi-sun4i.c > index f60a6d6..8cfd96c 100644 > --- a/drivers/spi/spi-sun4i.c > +++ b/drivers/spi/spi-sun4i.c > @@ -19,6 +19,7 @@ > =C2=A0#include=20 > =C2=A0#include=20 > =C2=A0#include=20 > +#include=20 > =C2=A0 > =C2=A0#include=20 > =C2=A0 > @@ -173,6 +174,9 @@ static int sun4i_spi_transfer_one(struct spi_master *= master, > =C2=A0 unsigned int tx_len =3D 0; > =C2=A0 int ret =3D 0; > =C2=A0 u32 reg; > + u32 wait_ns =3D 0; > + int wait_clk =3D 0; > + int clk_ns =3D 0; > =C2=A0 > =C2=A0 /* We don't support transfer larger than the FIFO */ > =C2=A0 if (tfr->len > SUN4I_FIFO_DEPTH) > @@ -261,6 +265,25 @@ static int sun4i_spi_transfer_one(struct spi_master = *master, > =C2=A0 > =C2=A0 sun4i_spi_write(sspi, SUN4I_CLK_CTL_REG, reg); > =C2=A0 > + /* Setup wait time beteen words */ typo > + of_property_read_u32(spi->dev.of_node, "sun4i,spi-word-wait-ns", > + =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0&wait_ns); > + if (wait_ns) { > + /* The wait time is set in SPI_CLK cycles. The SPI hardware > + =C2=A0* needs 3 additional cycles to setup the wait counter, so > + =C2=A0* the minimum delay time is 4 cycles. > + =C2=A0*/ > + clk_ns =3D DIV_ROUND_UP(1000000000, tfr->speed_hz); > + wait_clk =3D DIV_ROUND_UP(wait_ns, clk_ns) - 3; > + if (wait_clk < 1) { > + wait_clk =3D 1; > + dev_info(&spi->dev, > + =C2=A0"using minimum of 4 word wait cycles (%uns)", > + =C2=A04 * clk_ns); > + } > + } > + sun4i_spi_write(sspi, SUN4I_WAIT_REG, (u16)wait_clk); > + > =C2=A0 /* Setup the transfer now... */ > =C2=A0 if (sspi->tx_buf) > =C2=A0 tx_len =3D tfr->len; > --=C2=A0 > 1.9.1 >=20 --=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.