From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CDF7FC433E1 for ; Fri, 5 Jun 2020 08:47:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A7BDC207D3 for ; Fri, 5 Jun 2020 08:47:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726192AbgFEIrF (ORCPT ); Fri, 5 Jun 2020 04:47:05 -0400 Received: from mx2.suse.de ([195.135.220.15]:42012 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726084AbgFEIrE (ORCPT ); Fri, 5 Jun 2020 04:47:04 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id 796BAACD0; Fri, 5 Jun 2020 08:47:05 +0000 (UTC) Message-ID: Subject: Re: [PATCH v2] spi: bcm2835: Enable shared interrupt support From: Nicolas Saenz Julienne To: Florian Fainelli , linux-kernel@vger.kernel.org Cc: "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , Scott Branden , lukas@wunner.de, Ray Jui , Rob Herring , "open list:SPI SUBSYSTEM" , Mark Brown , "maintainer:BROADCOM BCM281XX/BCM11XXX/BCM216XX ARM ARCHITE..." , "moderated list:BROADCOM BCM2711/BCM2835 ARM ARCHITECTURE" , Martin Sperl Date: Fri, 05 Jun 2020 10:46:57 +0200 In-Reply-To: <20200604212819.715-1-f.fainelli@gmail.com> References: <20200604212819.715-1-f.fainelli@gmail.com> Content-Type: multipart/signed; micalg="pgp-sha256"; protocol="application/pgp-signature"; boundary="=-mEv3c87MBb44GSiC5RXV" User-Agent: Evolution 3.36.2 MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-mEv3c87MBb44GSiC5RXV Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Hi Florian, Thanks for taking over this! On Thu, 2020-06-04 at 14:28 -0700, Florian Fainelli wrote: > The 4 SPI controller instances added in BCM2711 and BCM7211 SoCs (SPI3, > SPI4, SPI5 and SPI6) share the same interrupt line with SPI0. I think this isn't 100% correct. SPI0 has its own interrupt, but SPI[3-6] s= hare the same interrupt. > For the BCM2835 case which is deemed performance critical, we would like > to continue using an interrupt handler which does not have the extra > comparison on BCM2835_SPI_CS_INTR. >=20 > To support that requirement the common interrupt handling code between > the shared and non-shared interrupt paths is split into a > bcm2835_spi_interrupt_common() and both bcm2835_spi_interrupt() as well > as bcm2835_spi_shared_interrupt() make use of it. >=20 > During probe, we determine if there is at least another instance of this > SPI controller, and if there is, then we install a shared interrupt > handler. As there was pushback to use a different compatible string for an otherwise identical IP, I think it's a good compromise. >=20 > Signed-off-by: Florian Fainelli > --- > Changes in v2: >=20 > - identify other available SPI nodes to determine if we need to set-up > interrupt sharing. This needs to happen for the very first instance > since we cannot know for the first instance whether interrupt sharing > is needed or not. >=20 > drivers/spi/spi-bcm2835.c | 61 ++++++++++++++++++++++++++++++++------- > 1 file changed, 50 insertions(+), 11 deletions(-) >=20 > diff --git a/drivers/spi/spi-bcm2835.c b/drivers/spi/spi-bcm2835.c > index 237bd306c268..0288b5b3de1e 100644 > --- a/drivers/spi/spi-bcm2835.c > +++ b/drivers/spi/spi-bcm2835.c > @@ -361,11 +361,10 @@ static void bcm2835_spi_reset_hw(struct spi_control= ler > *ctlr) > bcm2835_wr(bs, BCM2835_SPI_DLEN, 0); > } > =20 > -static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id) > +static inline irqreturn_t bcm2835_spi_interrupt_common(struct spi_contro= ller > *ctlr, > + u32 cs) Keep in mind the new 100 character limit. > { > - struct spi_controller *ctlr =3D dev_id; > struct bcm2835_spi *bs =3D spi_controller_get_devdata(ctlr); > - u32 cs =3D bcm2835_rd(bs, BCM2835_SPI_CS); > =20 > /* > * An interrupt is signaled either if DONE is set (TX FIFO empty) > @@ -394,6 +393,27 @@ static irqreturn_t bcm2835_spi_interrupt(int irq, vo= id > *dev_id) > return IRQ_HANDLED; > } > =20 > +static irqreturn_t bcm2835_spi_interrupt(int irq, void *dev_id) > +{ > + struct spi_controller *ctlr =3D dev_id; > + struct bcm2835_spi *bs =3D spi_controller_get_devdata(ctlr); > + u32 cs =3D bcm2835_rd(bs, BCM2835_SPI_CS); > + > + return bcm2835_spi_interrupt_common(ctlr, cs); > +} > + > +static irqreturn_t bcm2835_spi_shared_interrupt(int irq, void *dev_id) > +{ > + struct spi_controller *ctlr =3D dev_id; > + struct bcm2835_spi *bs =3D spi_controller_get_devdata(ctlr); > + u32 cs =3D bcm2835_rd(bs, BCM2835_SPI_CS); > + > + if (!(cs & BCM2835_SPI_CS_INTR)) > + return IRQ_NONE; > + > + return bcm2835_spi_interrupt_common(ctlr, cs); > +} > + > static int bcm2835_spi_transfer_one_irq(struct spi_controller *ctlr, > struct spi_device *spi, > struct spi_transfer *tfr, > @@ -1287,12 +1307,37 @@ static int bcm2835_spi_setup(struct spi_device *s= pi) > return 0; > } > =20 > +static const struct of_device_id bcm2835_spi_match[] =3D { > + { .compatible =3D "brcm,bcm2835-spi", }, > + {} > +}; > +MODULE_DEVICE_TABLE(of, bcm2835_spi_match); > + > static int bcm2835_spi_probe(struct platform_device *pdev) > { > + irq_handler_t bcm2835_spi_isr_func =3D bcm2835_spi_interrupt; > struct spi_controller *ctlr; > + unsigned long flags =3D 0; > + struct device_node *dn; > struct bcm2835_spi *bs; > int err; > =20 > + /* On BCM2711 there can be multiple SPI controllers enabled sharing the > + * same interrupt line, but we also want to minimize the overhead if > + * there is no need to support interrupt sharing. If we find at least > + * another available instane (not counting the one we are probed from), "instance" > + * then we assume that interrupt sharing is necessary. > + */ > + for_each_compatible_node(dn, NULL, bcm2835_spi_match[0].compatible) { > + err =3D of_device_is_available(dn) && dn !=3D pdev->dev.of_node; nit: maybe err is not the ideal variable name here. > + of_node_put(dn); > + if (err) { > + flags =3D IRQF_SHARED; > + bcm2835_spi_isr_func =3D bcm2835_spi_shared_interrupt; > + break; > + } > + } > + > ctlr =3D spi_alloc_master(&pdev->dev, ALIGN(sizeof(*bs), > dma_get_cache_alignment())); > if (!ctlr) > @@ -1344,8 +1389,8 @@ static int bcm2835_spi_probe(struct platform_device > *pdev) > bcm2835_wr(bs, BCM2835_SPI_CS, > BCM2835_SPI_CS_CLEAR_RX | BCM2835_SPI_CS_CLEAR_TX); > =20 > - err =3D devm_request_irq(&pdev->dev, bs->irq, bcm2835_spi_interrupt, 0, > - dev_name(&pdev->dev), ctlr); > + err =3D devm_request_irq(&pdev->dev, bs->irq, bcm2835_spi_isr_func, > + flags, dev_name(&pdev->dev), ctlr); > if (err) { > dev_err(&pdev->dev, "could not request IRQ: %d\n", err); > goto out_dma_release; > @@ -1400,12 +1445,6 @@ static void bcm2835_spi_shutdown(struct platform_d= evice > *pdev) > dev_err(&pdev->dev, "failed to shutdown\n"); > } > =20 > -static const struct of_device_id bcm2835_spi_match[] =3D { > - { .compatible =3D "brcm,bcm2835-spi", }, > - {} > -}; > -MODULE_DEVICE_TABLE(of, bcm2835_spi_match); > - > static struct platform_driver bcm2835_spi_driver =3D { > .driver =3D { > .name =3D DRV_NAME, --=-mEv3c87MBb44GSiC5RXV Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- iQEzBAABCAAdFiEErOkkGDHCg2EbPcGjlfZmHno8x/4FAl7aBoIACgkQlfZmHno8 x/76iQf/YhcuGS7sdr9nlK7KZasWwzVQMm4sUpwC4aTP2ok0f8XY2omANTcOMXPi boV38p9L8EZnRCGxPJH5gcd+P+mzq7E36L0CmhXh0llna9Y0PCDNRiAun7xax26+ AdZ5CP5pxseRYL/hvDKGiErbDAaygtPFdxvo9u034SYQyQTnP5J8YxjTX0V0TTVz NWPslb+n33JCLVrkFhoIsxr2sgW/dFJTaZ3V1/Bzj5Lktz4dw16ro4tCX86I4ltO NlvwGVykL6qjn+j0dOvnx6JvHoI5ScPqzkCDXDwQJekTzitTIdiaD2e70AZZ1B+q S0WCbZgciVz5xKBJn1sx5kPtsVZwng== =mzr5 -----END PGP SIGNATURE----- --=-mEv3c87MBb44GSiC5RXV--