From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rich Felker Date: Fri, 20 May 2016 22:50:13 +0000 Subject: Re: [PATCH v2 10/12] spi: add driver for J-Core SPI controller Message-Id: <20160520225013.GX21636@brightrain.aerifal.cx> List-Id: References: <2e287ca758002621ef8eed3db9df37678e26af5e.1463708766.git.dalias@libc.org> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Geert Uytterhoeven Cc: "linux-kernel@vger.kernel.org" , Linux-sh list , linux-spi , Mark Brown On Fri, May 20, 2016 at 10:15:08AM +0200, Geert Uytterhoeven wrote: > On Fri, May 20, 2016 at 4:53 AM, Rich Felker wrote: > > --- /dev/null > > +++ b/drivers/spi/spi-jcore.c > > > +static int jcore_spi_txrx(struct spi_master *master, struct spi_device *spi, struct spi_transfer *t) > > +{ > > + struct jcore_spi *hw = spi_master_get_devdata(master); > > + > > + void *ctrl_reg = hw->base + CTRL_REG; > > + void *data_reg = hw->base + DATA_REG; > > + int timeout; > > unsigned int All of these have value ranges where the type is irrelevant, but I'm happy to change it to whatever types you prefer. > > + jcore_spi_baudrate(hw, t->speed_hz); > > + > > + xmit = hw->csReg | hw->speedReg | JCORE_SPI_CTRL_XMIT; > > + tx = t->tx_buf; > > + rx = t->rx_buf; > > + len = t->len; > > + > > + for (count = 0; count < len; count++) { > > + timeout = JCORE_SPI_WAIT_RDY_MAX_LOOP; > > + do status = readl(ctrl_reg); > > + while ((status & JCORE_SPI_STAT_BUSY) && --timeout); > > do { > ... > } while (...) > > > + if (!timeout) break; > > if (...) > ... OK. (for this and other instances) > > + > > + writel(tx ? *tx++ : 0, data_reg); > > You can remove the check for tx if you set the SPI_MASTER_MUST_TX > flag in spi_master.flags. I don't want to do that, because the new version of the hardware that's going to support DMA can only do unidirectional DMA, and thus we need to be able to see if either tx or rx is null. Rich From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751327AbcETWuS (ORCPT ); Fri, 20 May 2016 18:50:18 -0400 Received: from 216-12-86-13.cv.mvl.ntelos.net ([216.12.86.13]:58229 "EHLO brightrain.aerifal.cx" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750836AbcETWuQ (ORCPT ); Fri, 20 May 2016 18:50:16 -0400 Date: Fri, 20 May 2016 18:50:13 -0400 From: Rich Felker To: Geert Uytterhoeven Cc: "linux-kernel@vger.kernel.org" , Linux-sh list , linux-spi , Mark Brown Subject: Re: [PATCH v2 10/12] spi: add driver for J-Core SPI controller Message-ID: <20160520225013.GX21636@brightrain.aerifal.cx> References: <2e287ca758002621ef8eed3db9df37678e26af5e.1463708766.git.dalias@libc.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 20, 2016 at 10:15:08AM +0200, Geert Uytterhoeven wrote: > On Fri, May 20, 2016 at 4:53 AM, Rich Felker wrote: > > --- /dev/null > > +++ b/drivers/spi/spi-jcore.c > > > +static int jcore_spi_txrx(struct spi_master *master, struct spi_device *spi, struct spi_transfer *t) > > +{ > > + struct jcore_spi *hw = spi_master_get_devdata(master); > > + > > + void *ctrl_reg = hw->base + CTRL_REG; > > + void *data_reg = hw->base + DATA_REG; > > + int timeout; > > unsigned int All of these have value ranges where the type is irrelevant, but I'm happy to change it to whatever types you prefer. > > + jcore_spi_baudrate(hw, t->speed_hz); > > + > > + xmit = hw->csReg | hw->speedReg | JCORE_SPI_CTRL_XMIT; > > + tx = t->tx_buf; > > + rx = t->rx_buf; > > + len = t->len; > > + > > + for (count = 0; count < len; count++) { > > + timeout = JCORE_SPI_WAIT_RDY_MAX_LOOP; > > + do status = readl(ctrl_reg); > > + while ((status & JCORE_SPI_STAT_BUSY) && --timeout); > > do { > ... > } while (...) > > > + if (!timeout) break; > > if (...) > ... OK. (for this and other instances) > > + > > + writel(tx ? *tx++ : 0, data_reg); > > You can remove the check for tx if you set the SPI_MASTER_MUST_TX > flag in spi_master.flags. I don't want to do that, because the new version of the hardware that's going to support DMA can only do unidirectional DMA, and thus we need to be able to see if either tx or rx is null. Rich