Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751994AbbLLJUU (ORCPT ); Sat, 12 Dec 2015 04:20:20 -0500 Received: from [188.166.43.21] ([188.166.43.21]:47492 "EHLO plaes.org" rhost-flags-FAIL-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1751227AbbLLJUP (ORCPT ); Sat, 12 Dec 2015 04:20:15 -0500 Message-ID: <1449911980.29015.7.camel@plaes.org> Subject: Re: [linux-sunxi] [PATCH v2] spi: dts: sun4i: Add support for inter-word wait cycles using the SPI Wait Clock Register From: Priit Laes To: mweseloh42@gmail.com, linux-sunxi@googlegroups.com Cc: Rob Herring , Pawel Moll , Mark Rutland , Ian Campbell , Kumar Gala , Maxime Ripard , Chen-Yu Tsai , Mark Brown , devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-spi@vger.kernel.org Date: Sat, 12 Dec 2015 11:19:40 +0200 In-Reply-To: <1449873940-10167-1-git-send-email-mweseloh42@gmail.com> References: <1449873940-10167-1-git-send-email-mweseloh42@gmail.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.19.2 Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2828 Lines: 95 On Fri, 2015-12-11 at 23:45 +0100, Marcus Weseloh wrote: [...] > > diff --git a/Documentation/devicetree/bindings/spi/spi-sun4i.txt b/Documentation/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: >    - "mod": the parent module clock >  - clock-names: Must contain the clock names described just above >   > +Optional properties for slave devices: > +- sun4i,spi-word-wait-ns: hardware based delay in nanoseconds between > +   transmission of words Should be 'allwinner,spi-word-wait-ns' Vendor prefix do come from: Documentation/devicetree/bindings/vendor-prefixes.txt > + >  Example: >   >  spi1: spi@01c06000 { > @@ -21,4 +25,11 @@ spi1: spi@01c06000 { >   status = "disabled"; >   #address-cells = <1>; >   #size-cells = <0>; > + > + spi1_0 { > + compatible = "example,dummy"; > + reg = <0>; > + spi-max-frequency = <1000000>; > + sun4i,spi-word-wait-ns = <12000>; > + }; >  }; > 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 @@ >  #include >  #include >  #include > +#include >   >  #include >   > @@ -173,6 +174,9 @@ static int sun4i_spi_transfer_one(struct spi_master *master, >   unsigned int tx_len = 0; >   int ret = 0; >   u32 reg; > + u32 wait_ns = 0; > + int wait_clk = 0; > + int clk_ns = 0; >   >   /* We don't support transfer larger than the FIFO */ >   if (tfr->len > SUN4I_FIFO_DEPTH) > @@ -261,6 +265,25 @@ static int sun4i_spi_transfer_one(struct spi_master *master, >   >   sun4i_spi_write(sspi, SUN4I_CLK_CTL_REG, reg); >   > + /* Setup wait time beteen words */ typo > + of_property_read_u32(spi->dev.of_node, "sun4i,spi-word-wait-ns", > +      &wait_ns); > + if (wait_ns) { > + /* The wait time is set in SPI_CLK cycles. The SPI hardware > +  * needs 3 additional cycles to setup the wait counter, so > +  * the minimum delay time is 4 cycles. > +  */ > + clk_ns = DIV_ROUND_UP(1000000000, tfr->speed_hz); > + wait_clk = DIV_ROUND_UP(wait_ns, clk_ns) - 3; > + if (wait_clk < 1) { > + wait_clk = 1; > + dev_info(&spi->dev, > +  "using minimum of 4 word wait cycles (%uns)", > +  4 * clk_ns); > + } > + } > + sun4i_spi_write(sspi, SUN4I_WAIT_REG, (u16)wait_clk); > + >   /* Setup the transfer now... */ >   if (sspi->tx_buf) >   tx_len = tfr->len; > --  > 1.9.1 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/