linux-kernel - Re: [PATCH v3 2/3] power: reset: imx-snvs-poweroff: add power off driver for i.mx6

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Message-ID: <20140917131005.7d8ab95c@ipc1.ka-ro>
Date:	Wed, 17 Sep 2014 13:10:05 +0200
From:	Lothar Waßmann <LW@...O-electronics.de>
To:	Robin Gong <b38343@...escale.com>
Cc:	<robh+dt@...nel.org>, <pawel.moll@....com>, <mark.rutland@....com>,
	<ijc+devicetree@...lion.org.uk>, <galak@...eaurora.org>,
	<shawn.guo@...escale.com>, <kernel@...gutronix.de>,
	<sre@...nel.org>, <dbaryshkov@...il.com>, <dwmw2@...radead.org>,
	<grant.likely@...aro.org>, <linux@....linux.org.uk>,
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-pm@...r.kernel.org
Subject: Re: [PATCH v3 2/3] power: reset: imx-snvs-poweroff: add power off
 driver for i.mx6

Hi,

Robin Gong wrote:
> This driver register pm_power_off with snvs power off function. If
> your boards NOT use PMIC_ON_REQ to turn on/off external pmic, or use
> other pin to do, please disable the driver in dts, otherwise, your
> pm_power_off maybe overwrote by this driver.
> 
> Signed-off-by: Robin Gong <b38343@...escale.com>
> ---
>  .../bindings/power_supply/imx-snvs-poweroff.txt    |   23 +++++++
>  drivers/power/reset/Kconfig                        |    9 +++
>  drivers/power/reset/Makefile                       |    1 +
>  drivers/power/reset/imx-snvs-poweroff.c            |   66 ++++++++++++++++++++
>  4 files changed, 99 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/power_supply/imx-snvs-poweroff.txt
>  create mode 100644 drivers/power/reset/imx-snvs-poweroff.c
> 
[...]
> diff --git a/drivers/power/reset/imx-snvs-poweroff.c b/drivers/power/reset/imx-snvs-poweroff.c
> new file mode 100644
> index 0000000..d726ac4
> --- /dev/null
> +++ b/drivers/power/reset/imx-snvs-poweroff.c
> @@ -0,0 +1,66 @@
> +/* Power off driver for i.mx6
> + * Copyright (c) 2014, FREESCALE CORPORATION.  All rights reserved.
> + *
> + * based on msm-poweroff.c
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 and
> + * only version 2 as published by the Free Software Foundation.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
> + * GNU General Public License for more details.
> + *
> + */
> +
> +#include <linux/err.h>
> +#include <linux/init.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/platform_device.h>
> +
> +static void __iomem *snvs_base;
> +
> +static void do_imx_poweroff(void)
> +{
> +	u32 value = readl(snvs_base);
> +
> +	/* set TOP and DP_EN bit */
> +	writel(value | 0x60, snvs_base);
> +}
> +
> +static int imx_poweroff_probe(struct platform_device *pdev)
> +{
> +	snvs_base = of_iomap(pdev->dev.of_node, 0);
> +	if (!snvs_base) {
> +		dev_err(&pdev->dev, "failed to get memory\n");
> +		return -EIO;
>
I don't think EIO is an appropriate return code here. There was no I/O
in progress that had an error. IMO ENODEV would be more appropriate
here.

> +static const struct of_device_id of_imx_poweroff_match[] = {
> +	{ .compatible = "fsl,sec-v4.0-poweroff", },
> +	{},
>
useless comma after terminating NULL element of array.
You never want any patch to add an entry after this one.
Without the comma doing so (e.g. because of a badly resolved merge
conflict) would lead to a compile error.


> +};
> +MODULE_DEVICE_TABLE(of, of_imx_poweroff_match);
> +
> +static struct platform_driver imx_poweroff_driver = {
> +	.probe = imx_poweroff_probe,
> +	.driver = {
> +		.name = "imx-snvs-poweroff",
> +		.of_match_table = of_match_ptr(of_imx_poweroff_match),
>
useless use of of_match_ptr()


Lothar Waßmann
-- 
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