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From:   Gustavo Pimentel <Gustavo.Pimentel@synopsys.com>
To:     Alan Mikhak <alan.mikhak@sifive.com>,
        "dmaengine@vger.kernel.org" <dmaengine@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        "linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
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        "vkoul@kernel.org" <vkoul@kernel.org>,
        "kishon@ti.com" <kishon@ti.com>,
        "paul.walmsley@sifive.com" <paul.walmsley@sifive.com>
Subject: RE: [PATCH v2] dmaengine: dw-edma: Decouple dw-edma-core.c from
 struct pci_dev
Thread-Topic: [PATCH v2] dmaengine: dw-edma: Decouple dw-edma-core.c from
 struct pci_dev
Thread-Index: AQHWE0sygCutMVZpvUOHmfmKj/MAvah6g1/Q
Date:   Wed, 15 Apr 2020 18:38:24 +0000
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On Wed, Apr 15, 2020 at 18:27:9, Alan Mikhak <alan.mikhak@sifive.com>=20
wrote:

> From: Alan Mikhak <alan.mikhak@sifive.com>
>=20
> Decouple dw-edma-core.c from struct pci_dev as a step toward integration
> of dw-edma with pci-epf-test so the latter can initiate dma operations
> locally from the endpoint side. A barrier to such integration is the
> dependency of dw_edma_probe() and other functions in dw-edma-core.c on
> struct pci_dev.
>=20
> The Synopsys DesignWare dw-edma driver was designed to run on host side
> of PCIe link to initiate DMA operations remotely using eDMA channels of
> PCIe controller on the endpoint side. This can be inferred from seeing
> that dw-edma uses struct pci_dev and accesses hardware registers of dma
> channels across the bus using BAR0 and BAR2.
>=20
> The ops field of struct dw_edma in dw-edma-core.h is currenty undefined:
>=20
> const struct dw_edma_core_ops   *ops;
>=20
> However, the kernel builds without failure even when dw-edma driver is
> enabled. Instead of removing the currently undefined and usued ops field,
> define struct dw_edma_core_ops and use the ops field to decouple
> dw-edma-core.c from struct pci_dev.
>=20
> Signed-off-by: Alan Mikhak <alan.mikhak@sifive.com>
> ---
>  drivers/dma/dw-edma/dw-edma-core.c | 29 ++++++++++++++++++++---------
>  drivers/dma/dw-edma/dw-edma-core.h |  4 ++++
>  drivers/dma/dw-edma/dw-edma-pcie.c | 10 ++++++++++
>  3 files changed, 34 insertions(+), 9 deletions(-)
>=20
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-=
edma-core.c
> index ff392c01bad1..db401eb11322 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -14,7 +14,7 @@
>  #include <linux/err.h>
>  #include <linux/interrupt.h>
>  #include <linux/dma/edma.h>
> -#include <linux/pci.h>
> +#include <linux/dma-mapping.h>
> =20
>  #include "dw-edma-core.h"
>  #include "dw-edma-v0-core.h"
> @@ -781,7 +781,7 @@ static int dw_edma_irq_request(struct dw_edma_chip *c=
hip,
> =20
>  	if (dw->nr_irqs =3D=3D 1) {
>  		/* Common IRQ shared among all channels */
> -		err =3D request_irq(pci_irq_vector(to_pci_dev(dev), 0),
> +		err =3D request_irq(dw->ops->irq_vector(dev, 0),
>  				  dw_edma_interrupt_common,
>  				  IRQF_SHARED, dw->name, &dw->irq[0]);
>  		if (err) {
> @@ -789,7 +789,7 @@ static int dw_edma_irq_request(struct dw_edma_chip *c=
hip,
>  			return err;
>  		}
> =20
> -		get_cached_msi_msg(pci_irq_vector(to_pci_dev(dev), 0),
> +		get_cached_msi_msg(dw->ops->irq_vector(dev, 0),
>  				   &dw->irq[0].msi);
>  	} else {
>  		/* Distribute IRQs equally among all channels */
> @@ -804,7 +804,7 @@ static int dw_edma_irq_request(struct dw_edma_chip *c=
hip,
>  		dw_edma_add_irq_mask(&rd_mask, *rd_alloc, dw->rd_ch_cnt);
> =20
>  		for (i =3D 0; i < (*wr_alloc + *rd_alloc); i++) {
> -			err =3D request_irq(pci_irq_vector(to_pci_dev(dev), i),
> +			err =3D request_irq(dw->ops->irq_vector(dev, i),
>  					  i < *wr_alloc ?
>  						dw_edma_interrupt_write :
>  						dw_edma_interrupt_read,
> @@ -815,7 +815,7 @@ static int dw_edma_irq_request(struct dw_edma_chip *c=
hip,
>  				return err;
>  			}
> =20
> -			get_cached_msi_msg(pci_irq_vector(to_pci_dev(dev), i),
> +			get_cached_msi_msg(dw->ops->irq_vector(dev, i),
>  					   &dw->irq[i].msi);
>  		}
> =20
> @@ -827,12 +827,23 @@ static int dw_edma_irq_request(struct dw_edma_chip =
*chip,
> =20
>  int dw_edma_probe(struct dw_edma_chip *chip)
>  {
> -	struct device *dev =3D chip->dev;
> -	struct dw_edma *dw =3D chip->dw;
> +	struct device *dev;
> +	struct dw_edma *dw;
>  	u32 wr_alloc =3D 0;
>  	u32 rd_alloc =3D 0;
>  	int i, err;
> =20
> +	if (!chip)
> +		return -EINVAL;
> +
> +	dev =3D chip->dev;
> +	if (!dev)
> +		return -EINVAL;
> +
> +	dw =3D chip->dw;
> +	if (!dw || !dw->irq || !dw->ops || !dw->ops->irq_vector)
> +		return -EINVAL;
> +
>  	raw_spin_lock_init(&dw->lock);
> =20
>  	/* Find out how many write channels are supported by hardware */
> @@ -884,7 +895,7 @@ int dw_edma_probe(struct dw_edma_chip *chip)
> =20
>  err_irq_free:
>  	for (i =3D (dw->nr_irqs - 1); i >=3D 0; i--)
> -		free_irq(pci_irq_vector(to_pci_dev(dev), i), &dw->irq[i]);
> +		free_irq(dw->ops->irq_vector(dev, i), &dw->irq[i]);
> =20
>  	dw->nr_irqs =3D 0;
> =20
> @@ -904,7 +915,7 @@ int dw_edma_remove(struct dw_edma_chip *chip)
> =20
>  	/* Free irqs */
>  	for (i =3D (dw->nr_irqs - 1); i >=3D 0; i--)
> -		free_irq(pci_irq_vector(to_pci_dev(dev), i), &dw->irq[i]);
> +		free_irq(dw->ops->irq_vector(dev, i), &dw->irq[i]);
> =20
>  	/* Power management */
>  	pm_runtime_disable(dev);
> diff --git a/drivers/dma/dw-edma/dw-edma-core.h b/drivers/dma/dw-edma/dw-=
edma-core.h
> index 4e5f9f6e901b..31fc50d31792 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.h
> +++ b/drivers/dma/dw-edma/dw-edma-core.h
> @@ -103,6 +103,10 @@ struct dw_edma_irq {
>  	struct dw_edma			*dw;
>  };
> =20
> +struct dw_edma_core_ops {
> +	int	(*irq_vector)(struct device *dev, unsigned int nr);
> +};
> +
>  struct dw_edma {
>  	char				name[20];
> =20
> diff --git a/drivers/dma/dw-edma/dw-edma-pcie.c b/drivers/dma/dw-edma/dw-=
edma-pcie.c
> index dc85f55e1bb8..1eafc602e17e 100644
> --- a/drivers/dma/dw-edma/dw-edma-pcie.c
> +++ b/drivers/dma/dw-edma/dw-edma-pcie.c
> @@ -54,6 +54,15 @@ static const struct dw_edma_pcie_data snps_edda_data =
=3D {
>  	.irqs				=3D 1,
>  };
> =20
> +static int dw_edma_pcie_irq_vector(struct device *dev, unsigned int nr)
> +{
> +	return pci_irq_vector(to_pci_dev(dev), nr);
> +}
> +
> +static const struct dw_edma_core_ops dw_edma_pcie_core_ops =3D {
> +	.irq_vector =3D dw_edma_pcie_irq_vector,
> +};
> +
>  static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  			      const struct pci_device_id *pid)
>  {
> @@ -151,6 +160,7 @@ static int dw_edma_pcie_probe(struct pci_dev *pdev,
>  	dw->version =3D pdata->version;
>  	dw->mode =3D pdata->mode;
>  	dw->nr_irqs =3D nr_irqs;
> +	dw->ops =3D &dw_edma_pcie_core_ops;
> =20
>  	/* Debug info */
>  	pci_dbg(pdev, "Version:\t%u\n", dw->version);
> --=20
> 2.7.4


Acked-by: Gustavo Pimentel <gustavo.pimentel@synopsys.com>