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From: Stafford Horne <shorne@gmail.com>
To: Mateusz Holenko <mholenko@antmicro.com>
Cc: Rob Herring <robh+dt@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	Jiri Slaby <jslaby@suse.com>,
	devicetree@vger.kernel.org, linux-serial@vger.kernel.org,
	Karol Gugala <kgugala@antmicro.com>,
	Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
	"David S. Miller" <davem@davemloft.net>,
	"Paul E. McKenney" <paulmck@linux.ibm.com>,
	Filip Kokosinski <fkokosinski@antmicro.com>,
	Pawel Czarnecki <pczarnecki@internships.antmicro.com>,
	Joel Stanley <joel@jms.id.au>,
	Jonathan Cameron <Jonathan.Cameron@huawei.com>,
	Maxime Ripard <mripard@kernel.org>,
	Shawn Guo <shawnguo@kernel.org>, Heiko Stuebner <heiko@sntech.de>,
	Sam Ravnborg <sam@ravnborg.org>, Icenowy Zheng <icenowy@aosc.io>,
	Laurent Pinchart <laurent.pinchart@ideasonboard.com>,
	linux-kernel@vger.kernel.org,
	"Gabriel L. Somlo" <gsomlo@gmail.com>
Subject: Re: [PATCH v10 3/5] drivers/soc/litex: add LiteX SoC Controller driver
Date: Fri, 11 Sep 2020 09:57:40 +0900
Message-ID: <20200911005740.GN3562056@lianli.shorne-pla.net> (raw)
In-Reply-To: <20200812143324.2394375-3-mholenko@antmicro.com>

On Wed, Aug 12, 2020 at 02:34:34PM +0200, Mateusz Holenko wrote:
> From: Pawel Czarnecki <pczarnecki@internships.antmicro.com>
> 
> This commit adds driver for the FPGA-based LiteX SoC
> Controller from LiteX SoC builder.
> 
> Co-developed-by: Mateusz Holenko <mholenko@antmicro.com>
> Signed-off-by: Mateusz Holenko <mholenko@antmicro.com>
> Signed-off-by: Pawel Czarnecki <pczarnecki@internships.antmicro.com>
> ---
...
> +static int litex_check_csr_access(void __iomem *reg_addr)
> +{
> +	unsigned long reg;
> +
> +	reg = litex_get_reg(reg_addr + SCRATCH_REG_OFF, SCRATCH_REG_SIZE);
> +
> +	if (reg != SCRATCH_REG_VALUE) {
> +		panic("Scratch register read error! Expected: 0x%x but got: 0x%lx",
> +			SCRATCH_REG_VALUE, reg);
> +		return -EINVAL;
> +	}
> +
> +	litex_set_reg(reg_addr + SCRATCH_REG_OFF,
> +		SCRATCH_REG_SIZE, SCRATCH_TEST_VALUE);
> +	reg = litex_get_reg(reg_addr + SCRATCH_REG_OFF, SCRATCH_REG_SIZE);
> +
> +	if (reg != SCRATCH_TEST_VALUE) {
> +		panic("Scratch register write error! Expected: 0x%x but got: 0x%lx",
> +			SCRATCH_TEST_VALUE, reg);
> +		return -EINVAL;
> +	}
> +
> +	/* restore original value of the SCRATCH register */
> +	litex_set_reg(reg_addr + SCRATCH_REG_OFF,
> +		SCRATCH_REG_SIZE, SCRATCH_REG_VALUE);
> +
> +	/* Set flag for other drivers */
What does this comment mean?

> +	pr_info("LiteX SoC Controller driver initialized");
> +
> +	return 0;
> +}
> +
> +struct litex_soc_ctrl_device {
> +	void __iomem *base;
> +};
> +
> +static const struct of_device_id litex_soc_ctrl_of_match[] = {
> +	{.compatible = "litex,soc-controller"},
> +	{},
> +};
> +
> +MODULE_DEVICE_TABLE(of, litex_soc_ctrl_of_match);
> +
> +static int litex_soc_ctrl_probe(struct platform_device *pdev)
> +{
> +	int result;
> +	struct device *dev;
> +	struct device_node *node;
> +	struct litex_soc_ctrl_device *soc_ctrl_dev;
> +
> +	dev = &pdev->dev;
> +	node = dev->of_node;
> +	if (!node)
> +		return -ENODEV;
> +
> +	soc_ctrl_dev = devm_kzalloc(dev, sizeof(*soc_ctrl_dev), GFP_KERNEL);
> +	if (!soc_ctrl_dev)
> +		return -ENOMEM;
> +
> +	soc_ctrl_dev->base = devm_platform_ioremap_resource(pdev, 0);
> +	if (IS_ERR(soc_ctrl_dev->base))
> +		return PTR_ERR(soc_ctrl_dev->base);
> +
> +	result = litex_check_csr_access(soc_ctrl_dev->base);
> +	if (result) {
> +		// LiteX CSRs access is broken which means that
> +		// none of LiteX drivers will most probably
> +		// operate correctly
The comment format here with // is not usually used in the kernel, but its not
forbidded.  Could you use the /* */ multiline style?

> +		BUG();
Instead of stopping the system with BUG, could we just do:

	return litex_check_csr_access(soc_ctrl_dev->base);

We already have failure for NODEV/NOMEM so might as well not call BUG() here
too.

> +	}
> +
> +	return 0;
> +}
> +

Other than that it looks ok to me.

-Stafford

  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-12 12:33 [PATCH v10 0/5] LiteX SoC controller and LiteUART serial driver Mateusz Holenko
2020-08-12 12:34 ` [PATCH v10 1/5] dt-bindings: vendor: add vendor prefix for LiteX Mateusz Holenko
2020-08-12 12:34 ` [PATCH v10 2/5] dt-bindings: soc: document LiteX SoC Controller bindings Mateusz Holenko
2020-08-12 12:34 ` [PATCH v10 3/5] drivers/soc/litex: add LiteX SoC Controller driver Mateusz Holenko
2020-09-11  0:57   ` Stafford Horne [this message]
2020-09-14 10:33     ` Mateusz Holenko
2020-09-14 13:24       ` Stafford Horne
2020-09-15 12:58         ` Mateusz Holenko
2020-08-12 12:34 ` [PATCH v10 4/5] dt-bindings: serial: document LiteUART bindings Mateusz Holenko
2020-08-12 12:35 ` [PATCH v10 5/5] drivers/tty/serial: add LiteUART driver Mateusz Holenko
2020-08-28  8:18   ` Greg Kroah-Hartman
2020-09-11  1:00 ` [PATCH v10 0/5] LiteX SoC controller and LiteUART serial driver Stafford Horne

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