linux-kernel - Re: [PATCH v3 3/5] net: ti: icss-iep: Add IEP driver

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Message-ID: <b43ee5ca-2aab-445a-e24b-cbc95f9186ea@ti.com>
Date:   Wed, 9 Aug 2023 10:00:11 -0500
From:   Andrew Davis <afd@...com>
To:     MD Danish Anwar <danishanwar@...com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Roger Quadros <rogerq@...nel.org>,
        Simon Horman <simon.horman@...igine.com>,
        Vignesh Raghavendra <vigneshr@...com>,
        Andrew Lunn <andrew@...n.ch>,
        Richard Cochran <richardcochran@...il.com>,
        Conor Dooley <conor+dt@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        "David S. Miller" <davem@...emloft.net>
CC:     <nm@...com>, <srk@...com>, <linux-kernel@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <netdev@...r.kernel.org>,
        <linux-omap@...r.kernel.org>,
        <linux-arm-kernel@...ts.infradead.org>
Subject: Re: [PATCH v3 3/5] net: ti: icss-iep: Add IEP driver

On 8/9/23 6:49 AM, MD Danish Anwar wrote:
> From: Roger Quadros <rogerq@...com>
> 
> Add a driver for Industrial Ethernet Peripheral (IEP) block of PRUSS to
> support timestamping of ethernet packets and thus support PTP and PPS
> for PRU ethernet ports.
> 
> Signed-off-by: Roger Quadros <rogerq@...com>
> Signed-off-by: Lokesh Vutla <lokeshvutla@...com>
> Signed-off-by: Murali Karicheri <m-karicheri2@...com>
> Signed-off-by: Vignesh Raghavendra <vigneshr@...com>
> Signed-off-by: MD Danish Anwar <danishanwar@...com>
> ---
>   drivers/net/ethernet/ti/Kconfig          |  12 +
>   drivers/net/ethernet/ti/Makefile         |   1 +
>   drivers/net/ethernet/ti/icssg/icss_iep.c | 935 +++++++++++++++++++++++
>   drivers/net/ethernet/ti/icssg/icss_iep.h |  38 +
>   4 files changed, 986 insertions(+)
>   create mode 100644 drivers/net/ethernet/ti/icssg/icss_iep.c
>   create mode 100644 drivers/net/ethernet/ti/icssg/icss_iep.h
> 
> diff --git a/drivers/net/ethernet/ti/Kconfig b/drivers/net/ethernet/ti/Kconfig
> index 63e510b6860f..88b5b1b47779 100644
> --- a/drivers/net/ethernet/ti/Kconfig
> +++ b/drivers/net/ethernet/ti/Kconfig
> @@ -186,6 +186,7 @@ config CPMAC
>   config TI_ICSSG_PRUETH
>   	tristate "TI Gigabit PRU Ethernet driver"
>   	select PHYLIB
> +	select TI_ICSS_IEP

Why not save selecting this until you add its use in the ICSSG_PRUETH driver in the next patch.

[...]

> +
> +static u32 icss_iep_readl(struct icss_iep *iep, int reg)
> +{
> +	return readl(iep->base + iep->plat_data->reg_offs[reg]);
> +}

Do these one line functions really add anything? Actually why
not use the regmap you have here.

[...]

> +static void icss_iep_enable(struct icss_iep *iep)
> +{
> +	regmap_update_bits(iep->map, ICSS_IEP_GLOBAL_CFG_REG,
> +			   IEP_GLOBAL_CFG_CNT_ENABLE,
> +			   IEP_GLOBAL_CFG_CNT_ENABLE);

Have you looked into regmap_fields?

[...]

> +
> +	if (!!(iep->latch_enable & BIT(index)) == !!on)
> +		goto exit;
> +

There has to be a better way to write this logic..

[...]

> +
> +static const struct of_device_id icss_iep_of_match[];
> +

Why the forward declaration?

> +static int icss_iep_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct icss_iep *iep;
> +	struct clk *iep_clk;
> +
> +	iep = devm_kzalloc(dev, sizeof(*iep), GFP_KERNEL);
> +	if (!iep)
> +		return -ENOMEM;
> +
> +	iep->dev = dev;
> +	iep->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(iep->base))
> +		return -ENODEV;
> +
> +	iep_clk = devm_clk_get(dev, NULL);
> +	if (IS_ERR(iep_clk))
> +		return PTR_ERR(iep_clk);
> +
> +	iep->refclk_freq = clk_get_rate(iep_clk);
> +
> +	iep->def_inc = NSEC_PER_SEC / iep->refclk_freq;	/* ns per clock tick */
> +	if (iep->def_inc > IEP_MAX_DEF_INC) {
> +		dev_err(dev, "Failed to set def_inc %d.  IEP_clock is too slow to be supported\n",
> +			iep->def_inc);
> +		return -EINVAL;
> +	}
> +
> +	iep->plat_data = of_device_get_match_data(dev);

Directly using of_*() functions is often wrong, try just device_get_match_data().

[...]

> +static struct platform_driver icss_iep_driver = {
> +	.driver = {
> +		.name = "icss-iep",
> +		.of_match_table = of_match_ptr(icss_iep_of_match),

This driver cannot work without OF, using of_match_ptr() is not needed.

Andrew