linux-kernel - Re: [PATCH 20/21] PCI: designware: Make use of GENMASK/FIELD

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Date:   Wed, 26 Dec 2018 15:07:18 +0000
From:   Gustavo Pimentel <gustavo.pimentel@...opsys.com>
To:     Andrey Smirnov <andrew.smirnov@...il.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>
CC:     Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Fabio Estevam <fabio.estevam@....com>,
        Chris Healy <cphealy@...il.com>,
        Lucas Stach <l.stach@...gutronix.de>,
        Leonard Crestez <leonard.crestez@....com>,
        "A.s. Dong" <aisheng.dong@....com>,
        Richard Zhu <hongxing.zhu@....com>,
        "linux-imx@....com" <linux-imx@....com>,
        "linux-arm-kernel@...ts.infradead.org" 
        <linux-arm-kernel@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 20/21] PCI: designware: Make use of GENMASK/FIELD_PREP

Hi,

On 21/12/2018 07:27, Andrey Smirnov wrote:
> Convert various mult-bit fields to be defined using
> GENMASK/FIELD_PREP. This way bit field boundaries are defined in a
> single place only as well as defined in a way that makes it easier to
> verify them against reference manual. No functional change intended.
> 
> Cc: Lorenzo Pieralisi <lorenzo.pieralisi@....com>
> Cc: Bjorn Helgaas <bhelgaas@...gle.com>
> Cc: Fabio Estevam <fabio.estevam@....com>
> Cc: Chris Healy <cphealy@...il.com>
> Cc: Lucas Stach <l.stach@...gutronix.de>
> Cc: Leonard Crestez <leonard.crestez@....com>
> Cc: "A.s. Dong" <aisheng.dong@....com>
> Cc: Richard Zhu <hongxing.zhu@....com>
> Cc: linux-imx@....com
> Cc: linux-arm-kernel@...ts.infradead.org
> Cc: linux-kernel@...r.kernel.org
> Cc: linux-pci@...r.kernel.org
> Signed-off-by: Andrey Smirnov <andrew.smirnov@...il.com>
> ---
>  drivers/pci/controller/dwc/pcie-designware.h | 29 +++++++++++---------
>  1 file changed, 16 insertions(+), 13 deletions(-)
> 
> diff --git a/drivers/pci/controller/dwc/pcie-designware.h b/drivers/pci/controller/dwc/pcie-designware.h
> index 348e91b6daa2..0de653284fca 100644
> --- a/drivers/pci/controller/dwc/pcie-designware.h
> +++ b/drivers/pci/controller/dwc/pcie-designware.h
> @@ -11,6 +11,7 @@
>  #ifndef _PCIE_DESIGNWARE_H
>  #define _PCIE_DESIGNWARE_H
>  
> +#include <linux/bitfield.h>
>  #include <linux/dma-mapping.h>
>  #include <linux/irq.h>
>  #include <linux/msi.h>
> @@ -30,11 +31,12 @@
>  
>  /* Synopsys-specific PCIe configuration registers */
>  #define PCIE_PORT_LINK_CONTROL		0x710
> -#define PORT_LINK_MODE_MASK		(0x3f << 16)
> -#define PORT_LINK_MODE_1_LANES		(0x1 << 16)
> -#define PORT_LINK_MODE_2_LANES		(0x3 << 16)
> -#define PORT_LINK_MODE_4_LANES		(0x7 << 16)
> -#define PORT_LINK_MODE_8_LANES		(0xf << 16)
> +#define PORT_LINK_MODE_MASK		GENMASK(21, 16)
> +#define PORT_LINK_MODE(n)		FIELD_PREP(PORT_LINK_MODE_MASK, n)
> +#define PORT_LINK_MODE_1_LANES		PORT_LINK_MODE(0x1)
> +#define PORT_LINK_MODE_2_LANES		PORT_LINK_MODE(0x3)
> +#define PORT_LINK_MODE_4_LANES		PORT_LINK_MODE(0x7)
> +#define PORT_LINK_MODE_8_LANES		PORT_LINK_MODE(0xf)
>  
>  #define PCIE_PORT_DEBUG0		0x728
>  #define PORT_LOGIC_LTSSM_STATE_MASK	0x1f
> @@ -45,11 +47,12 @@
>  
>  #define PCIE_LINK_WIDTH_SPEED_CONTROL	0x80C
>  #define PORT_LOGIC_SPEED_CHANGE		BIT(17)
> -#define PORT_LOGIC_LINK_WIDTH_MASK	(0x1f << 8)
> -#define PORT_LOGIC_LINK_WIDTH_1_LANES	(0x1 << 8)
> -#define PORT_LOGIC_LINK_WIDTH_2_LANES	(0x2 << 8)
> -#define PORT_LOGIC_LINK_WIDTH_4_LANES	(0x4 << 8)
> -#define PORT_LOGIC_LINK_WIDTH_8_LANES	(0x8 << 8)
> +#define PORT_LOGIC_LINK_WIDTH_MASK	GENMASK(12, 8)
> +#define PORT_LOGIC_LINK_WIDTH(n)	FIELD_PREP(PORT_LOGIC_LINK_WIDTH_MASK, n)
> +#define PORT_LOGIC_LINK_WIDTH_1_LANES	PORT_LOGIC_LINK_WIDTH(0x1)
> +#define PORT_LOGIC_LINK_WIDTH_2_LANES	PORT_LOGIC_LINK_WIDTH(0x2)
> +#define PORT_LOGIC_LINK_WIDTH_4_LANES	PORT_LOGIC_LINK_WIDTH(0x4)
> +#define PORT_LOGIC_LINK_WIDTH_8_LANES	PORT_LOGIC_LINK_WIDTH(0x8)
>  
>  #define PCIE_MSI_ADDR_LO		0x820
>  #define PCIE_MSI_ADDR_HI		0x824
> @@ -75,9 +78,9 @@
>  #define PCIE_ATU_UPPER_BASE		0x910
>  #define PCIE_ATU_LIMIT			0x914
>  #define PCIE_ATU_LOWER_TARGET		0x918
> -#define PCIE_ATU_BUS(x)			(((x) & 0xff) << 24)
> -#define PCIE_ATU_DEV(x)			(((x) & 0x1f) << 19)
> -#define PCIE_ATU_FUNC(x)		(((x) & 0x7) << 16)
> +#define PCIE_ATU_BUS(x)			FIELD_PREP(GENMASK(31, 24), x)
> +#define PCIE_ATU_DEV(x)			FIELD_PREP(GENMASK(23, 19), x)
> +#define PCIE_ATU_FUNC(x)		FIELD_PREP(GENMASK(18, 16), x)
>  #define PCIE_ATU_UPPER_TARGET		0x91C
>  
>  #define PCIE_MISC_CONTROL_1_OFF		0x8BC
> 

I wasn't aware of the existence of FIELD_PREP(), seems to be quite handy :)

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

Thanks.