linux-kernel - Re: [PATCH 01/10] PCI: Use FIELD

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Date:   Wed, 11 Oct 2023 14:24:02 +0300 (EEST)
From:   Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To:     Bjorn Helgaas <helgaas@...nel.org>
cc:     linux-pci@...r.kernel.org,
        Jonathan Cameron <Jonathan.Cameron@...wei.com>,
        Krzysztof Wilczyński <kw@...ux.com>,
        Lorenzo Pieralisi <lpieralisi@...nel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [PATCH 01/10] PCI: Use FIELD_GET()

On Tue, 10 Oct 2023, Bjorn Helgaas wrote:

> From: Bjorn Helgaas <bhelgaas@...gle.com>
> 
> Use FIELD_GET() to remove dependences on the field position, i.e., the
> shift value.  No functional change intended.

FIELD_PREP() is also used below.

> Signed-off-by: Bjorn Helgaas <bhelgaas@...gle.com>
> ---
>  drivers/pci/pci.c   | 45 ++++++++++++++++++++++-----------------------
>  drivers/pci/probe.c |  8 ++++----
>  2 files changed, 26 insertions(+), 27 deletions(-)
> 
> diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
> index a8adc34dc86f..848c9ee65d7f 100644
> --- a/drivers/pci/pci.c
> +++ b/drivers/pci/pci.c
> @@ -1776,8 +1776,7 @@ static void pci_restore_rebar_state(struct pci_dev *pdev)
>  		return;
>  
>  	pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
> -	nbars = (ctrl & PCI_REBAR_CTRL_NBAR_MASK) >>
> -		    PCI_REBAR_CTRL_NBAR_SHIFT;
> +	nbars = FIELD_GET(PCI_REBAR_CTRL_NBAR_MASK, ctrl);
>  
>  	for (i = 0; i < nbars; i++, pos += 8) {
>  		struct resource *res;
> @@ -1788,7 +1787,7 @@ static void pci_restore_rebar_state(struct pci_dev *pdev)
>  		res = pdev->resource + bar_idx;
>  		size = pci_rebar_bytes_to_size(resource_size(res));
>  		ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
> -		ctrl |= size << PCI_REBAR_CTRL_BAR_SHIFT;
> +		ctrl |= FIELD_PREP(PCI_REBAR_CTRL_BAR_SIZE, size);
>  		pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
>  	}
>  }
> @@ -3229,7 +3228,7 @@ void pci_pm_init(struct pci_dev *dev)
>  			 (pmc & PCI_PM_CAP_PME_D2) ? " D2" : "",
>  			 (pmc & PCI_PM_CAP_PME_D3hot) ? " D3hot" : "",
>  			 (pmc & PCI_PM_CAP_PME_D3cold) ? " D3cold" : "");
> -		dev->pme_support = pmc >> PCI_PM_CAP_PME_SHIFT;
> +		dev->pme_support = FIELD_GET(PCI_PM_CAP_PME_MASK, pmc);
>  		dev->pme_poll = true;
>  		/*
>  		 * Make device's PM flags reflect the wake-up capability, but
> @@ -3300,20 +3299,20 @@ static int pci_ea_read(struct pci_dev *dev, int offset)
>  	ent_offset += 4;
>  
>  	/* Entry size field indicates DWORDs after 1st */
> -	ent_size = ((dw0 & PCI_EA_ES) + 1) << 2;
> +	ent_size = (FIELD_GET(PCI_EA_ES, dw0) + 1) << 2;
>  
>  	if (!(dw0 & PCI_EA_ENABLE)) /* Entry not enabled */
>  		goto out;
>  
> -	bei = (dw0 & PCI_EA_BEI) >> 4;
> -	prop = (dw0 & PCI_EA_PP) >> 8;
> +	bei = FIELD_GET(PCI_EA_BEI, dw0);
> +	prop = FIELD_GET(PCI_EA_PP, dw0);
>  
>  	/*
>  	 * If the Property is in the reserved range, try the Secondary
>  	 * Property instead.
>  	 */
>  	if (prop > PCI_EA_P_BRIDGE_IO && prop < PCI_EA_P_MEM_RESERVED)
> -		prop = (dw0 & PCI_EA_SP) >> 16;
> +		prop = FIELD_GET(PCI_EA_SP, dw0);
>  	if (prop > PCI_EA_P_BRIDGE_IO)
>  		goto out;
>  
> @@ -3720,14 +3719,13 @@ static int pci_rebar_find_pos(struct pci_dev *pdev, int bar)
>  		return -ENOTSUPP;
>  
>  	pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
> -	nbars = (ctrl & PCI_REBAR_CTRL_NBAR_MASK) >>
> -		    PCI_REBAR_CTRL_NBAR_SHIFT;
> +	nbars = FIELD_GET(PCI_REBAR_CTRL_NBAR_MASK, ctrl);
>  
>  	for (i = 0; i < nbars; i++, pos += 8) {
>  		int bar_idx;
>  
>  		pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
> -		bar_idx = ctrl & PCI_REBAR_CTRL_BAR_IDX;
> +		bar_idx = FIELD_GET(PCI_REBAR_CTRL_BAR_IDX, ctrl);
>  		if (bar_idx == bar)
>  			return pos;
>  	}
> @@ -3782,7 +3780,7 @@ int pci_rebar_get_current_size(struct pci_dev *pdev, int bar)
>  		return pos;
>  
>  	pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
> -	return (ctrl & PCI_REBAR_CTRL_BAR_SIZE) >> PCI_REBAR_CTRL_BAR_SHIFT;
> +	return FIELD_GET(PCI_REBAR_CTRL_BAR_SIZE, ctrl);
>  }
>  
>  /**
> @@ -3805,7 +3803,7 @@ int pci_rebar_set_size(struct pci_dev *pdev, int bar, int size)
>  
>  	pci_read_config_dword(pdev, pos + PCI_REBAR_CTRL, &ctrl);
>  	ctrl &= ~PCI_REBAR_CTRL_BAR_SIZE;
> -	ctrl |= size << PCI_REBAR_CTRL_BAR_SHIFT;
> +	ctrl |= FIELD_PREP(PCI_REBAR_CTRL_BAR_SIZE, size);
>  	pci_write_config_dword(pdev, pos + PCI_REBAR_CTRL, ctrl);
>  	return 0;
>  }
> @@ -6043,7 +6041,7 @@ int pcix_get_max_mmrbc(struct pci_dev *dev)
>  	if (pci_read_config_dword(dev, cap + PCI_X_STATUS, &stat))
>  		return -EINVAL;
>  
> -	return 512 << ((stat & PCI_X_STATUS_MAX_READ) >> 21);
> +	return 512 << FIELD_GET(PCI_X_STATUS_MAX_READ, stat);
>  }
>  EXPORT_SYMBOL(pcix_get_max_mmrbc);
>  
> @@ -6066,7 +6064,7 @@ int pcix_get_mmrbc(struct pci_dev *dev)
>  	if (pci_read_config_word(dev, cap + PCI_X_CMD, &cmd))
>  		return -EINVAL;
>  
> -	return 512 << ((cmd & PCI_X_CMD_MAX_READ) >> 2);
> +	return 512 << FIELD_GET(PCI_X_CMD_MAX_READ, cmd);
>  }
>  EXPORT_SYMBOL(pcix_get_mmrbc);
>  
> @@ -6097,19 +6095,19 @@ int pcix_set_mmrbc(struct pci_dev *dev, int mmrbc)
>  	if (pci_read_config_dword(dev, cap + PCI_X_STATUS, &stat))
>  		return -EINVAL;
>  
> -	if (v > (stat & PCI_X_STATUS_MAX_READ) >> 21)
> +	if (v > FIELD_GET(PCI_X_STATUS_MAX_READ, stat))
>  		return -E2BIG;
>  
>  	if (pci_read_config_word(dev, cap + PCI_X_CMD, &cmd))
>  		return -EINVAL;
>  
> -	o = (cmd & PCI_X_CMD_MAX_READ) >> 2;
> +	o = FIELD_GET(PCI_X_CMD_MAX_READ, cmd);
>  	if (o != v) {
>  		if (v > o && (dev->bus->bus_flags & PCI_BUS_FLAGS_NO_MMRBC))
>  			return -EIO;
>  
>  		cmd &= ~PCI_X_CMD_MAX_READ;
> -		cmd |= v << 2;
> +		cmd |= FIELD_PREP(PCI_X_CMD_MAX_READ, v);
>  		if (pci_write_config_word(dev, cap + PCI_X_CMD, cmd))
>  			return -EIO;
>  	}
> @@ -6129,7 +6127,7 @@ int pcie_get_readrq(struct pci_dev *dev)
>  
>  	pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &ctl);
>  
> -	return 128 << ((ctl & PCI_EXP_DEVCTL_READRQ) >> 12);
> +	return 128 << FIELD_GET(PCI_EXP_DEVCTL_READRQ, ctl);
>  }
>  EXPORT_SYMBOL(pcie_get_readrq);
>  
> @@ -6162,7 +6160,7 @@ int pcie_set_readrq(struct pci_dev *dev, int rq)
>  			rq = mps;
>  	}
>  
> -	v = (ffs(rq) - 8) << 12;
> +	v = FIELD_PREP(PCI_EXP_DEVCTL_READRQ, ffs(rq) - 8);
>  
>  	if (bridge->no_inc_mrrs) {
>  		int max_mrrs = pcie_get_readrq(dev);
> @@ -6192,7 +6190,7 @@ int pcie_get_mps(struct pci_dev *dev)
>  
>  	pcie_capability_read_word(dev, PCI_EXP_DEVCTL, &ctl);
>  
> -	return 128 << ((ctl & PCI_EXP_DEVCTL_PAYLOAD) >> 5);
> +	return 128 << FIELD_GET(PCI_EXP_DEVCTL_PAYLOAD, ctl);
>  }
>  EXPORT_SYMBOL(pcie_get_mps);
>  
> @@ -6215,7 +6213,7 @@ int pcie_set_mps(struct pci_dev *dev, int mps)
>  	v = ffs(mps) - 8;
>  	if (v > dev->pcie_mpss)
>  		return -EINVAL;
> -	v <<= 5;
> +	v = FIELD_PREP(PCI_EXP_DEVCTL_PAYLOAD, v);


-- 
 i.