Re: [PATCH v2 1/7] mfd: add syscon driver based on regmap

From: Shawn Guo <shawn.guo@linaro.org>
To: Dong Aisheng <b29396@freescale.com>
Cc: linux-kernel@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	linus.walleij@stericsson.com, s.hauer@pengutronix.de,
	kernel@pengutronix.de, grant.likely@secretlab.ca,
	rob.herring@calxeda.com, sameo@linux.intel.com, lrg@ti.com,
	broonie@opensource.wolfsonmicro.com, richard.zhao@freescale.com,
	devicetree-discuss@lists.ozlabs.org, swarren@wwwdotorg.org
Subject: Re: [PATCH v2 1/7] mfd: add syscon driver based on regmap
Date: Tue, 28 Aug 2012 06:08:32 +0800	[thread overview]
Message-ID: <20120827220830.GB2281@r65073-Latitude-D630> (raw)
In-Reply-To: <1346052285-4344-2-git-send-email-b29396@freescale.com>

On Mon, Aug 27, 2012 at 03:24:39PM +0800, Dong Aisheng wrote:
> From: Dong Aisheng <dong.aisheng@linaro.org>
> 
> Add regmap based syscon driver.
> This is usually used for access misc bits in registers which does not belong
> to a specific module, for example, IMX IOMUXC GPR and ANATOP.
> With this driver, client can use generic regmap API to access registers
> which are registered into syscon.
> 
> Reviwed-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
> Signed-off-by: Dong Aisheng <dong.aisheng@linaro.org>
> ---
> ChangeLog:
> v1->v2:
>  * provide a way of retrieving the regmap, suggested by Mark Brown.
>  * delete imx-syscon io accessors and using generic regmap API for client drivers.
>  * change to a more generic name for other SoCs to use.
> ---
>  .../devicetree/bindings/mfd/imx-syscon.txt         |   11 ++

So, this file should be renamed as well.

>  drivers/mfd/Kconfig                                |    7 +
>  drivers/mfd/Makefile                               |    1 +
>  drivers/mfd/syscon.c                               |  169 ++++++++++++++++++++
>  include/linux/mfd/syscon.h                         |   22 +++
>  5 files changed, 210 insertions(+), 0 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/mfd/imx-syscon.txt b/Documentation/devicetree/bindings/mfd/imx-syscon.txt
> new file mode 100644
> index 0000000..c1a13b4
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/mfd/imx-syscon.txt
> @@ -0,0 +1,11 @@
> +* System Controller Registers R/W driver
> +
> +Required properties:
> +- compatible: Should contain "syscon".
> +- reg: the register range can be access from syscon
> +
> +Examples:
> +gpr: iomuxc-gpr@020e0000 {
> +	compatible = "fsl,imx6q-iomuxc", "syscon";
> +	reg = <0x020e0000 0x38>;
> +};
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index b1a1462..4a6c48e 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -993,6 +993,13 @@ config MFD_ANATOP
>  	  MFD controller. This controller embeds regulator and
>  	  thermal devices for Freescale i.MX platforms.
>  
> +config MFD_SYSCON
> +        bool "System Controller Register R/W Based on Regmap"
> +        select REGMAP_MMIO
> +        help
> +          Select this option to enable accessing system control registers
> +	  via regmap.
> +
>  config MFD_PALMAS
>  	bool "Support for the TI Palmas series chips"
>  	select MFD_CORE
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 79dd22d..8384bc9 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -131,4 +131,5 @@ obj-$(CONFIG_MFD_PALMAS)	+= palmas.o
>  obj-$(CONFIG_MFD_RC5T583)	+= rc5t583.o rc5t583-irq.o
>  obj-$(CONFIG_MFD_SEC_CORE)	+= sec-core.o sec-irq.o
>  obj-$(CONFIG_MFD_ANATOP)	+= anatop-mfd.o
> +obj-$(CONFIG_MFD_SYSCON)	+= syscon.o
>  obj-$(CONFIG_MFD_LM3533)	+= lm3533-core.o lm3533-ctrlbank.o
> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
> new file mode 100644
> index 0000000..da2464f
> --- /dev/null
> +++ b/drivers/mfd/syscon.c
> @@ -0,0 +1,169 @@
> +/*
> + * System Control Driver
> + *
> + * Copyright (C) 2012 Freescale Semiconductor, Inc.
> + * Copyright (C) 2012 Linaro Ltd.
> + *
> + * Author: Dong Aisheng <dong.aisheng@linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#include <linux/err.h>
> +#include <linux/io.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/of_address.h>
> +#include <linux/of_platform.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>
> +
> +static struct platform_driver syscon_driver;
> +
> +struct syscon {
> +	struct device *dev;
> +	void __iomem *base;
> +	struct regmap *regmap;
> +};
> +
> +static int syscon_match(struct device *dev, void *data)
> +{
> +	struct syscon *syscon = dev_get_drvdata(dev);
> +	struct device_node *dn = data;
> +
> +	return (syscon->dev->of_node == dn) ? 1 : 0;
> +}
> +
> +static struct regmap *syscon_node_to_regmap(struct device_node *np)
> +{
> +	struct syscon *syscon;
> +	struct device *dev;
> +
> +	dev = driver_find_device(&syscon_driver.driver, NULL, np,
> +				 syscon_match);
> +	of_node_put(np);
> +
> +	if (!dev)
> +		return ERR_PTR(-EPROBE_DEFER);
> +
> +	syscon = dev_get_drvdata(dev);
> +
> +	return syscon->regmap;
> +}
> +
> +struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
> +{
> +	struct device_node *syscon_np;
> +
> +	syscon_np = of_find_compatible_node(NULL, NULL, s);
> +	if (!syscon_np)
> +		return ERR_PTR(-ENODEV);
> +
> +	return syscon_node_to_regmap(syscon_np);
> +}
> +
> +struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
> +					const char *property)
> +{
> +	struct device_node *syscon_np;
> +
> +	syscon_np = of_parse_phandle(np, property, 0);
> +	if (!syscon_np)
> +		return ERR_PTR(-ENODEV);
> +
> +	return syscon_node_to_regmap(syscon_np);
> +}

The above two APIs are all about finding the device_node for syscon,
and can be done by clients in whatever way that is easy for them.
Then we can save these APIs and export syscon_node_to_regmap directly.

> +
> +static const struct of_device_id of_syscon_match[] = {
> +	{ .compatible = "syscon", },
> +	{ },
> +};
> +
> +static struct regmap_config syscon_regmap_config = {
> +	.reg_bits = 32,
> +	.val_bits = 32,
> +	.reg_stride = 4,
> +};
> +
> +static int __devinit syscon_probe(struct platform_device *pdev)
> +{
> +	struct device *dev = &pdev->dev;
> +	struct device_node *np = dev->of_node;
> +	struct syscon *syscon;
> +	struct resource res;
> +	int ret;
> +
> +	if (!np)
> +		return -ENOENT;
> +
> +	syscon = devm_kzalloc(&pdev->dev, sizeof(struct syscon),
> +			    GFP_KERNEL);
> +	if (!syscon)
> +		return -ENOMEM;
> +
> +	syscon->base = of_iomap(np, 0);
> +	if (!syscon->base)
> +		return -EADDRNOTAVAIL;
> +
> +	ret = of_address_to_resource(np, 0, &res);
> +	if (ret)
> +		return ret;
> +
> +	syscon_regmap_config.max_register = res.end - res.start - 3;
> +	syscon->regmap = devm_regmap_init_mmio(&pdev->dev, syscon->base,
> +					&syscon_regmap_config);
> +	if (IS_ERR(syscon->regmap)) {
> +		dev_err(&pdev->dev, "regmap init failed\n");
> +		return PTR_ERR(syscon->regmap);
> +	}
> +
> +	regcache_cache_only(syscon->regmap, false);
> +
> +	syscon->dev = &pdev->dev;
> +	platform_set_drvdata(pdev, syscon);
> +
> +	dev_info(dev, "syscon regmap start 0x%x end 0x%x registered\n",
> +		res.start, res.end);
> +
> +	return 0;
> +}
> +
> +static int __devexit syscon_remove(struct platform_device *pdev)
> +{
> +	struct syscon *syscon;
> +
> +	syscon = platform_get_drvdata(pdev);
> +	iounmap(syscon->base);
> +	platform_set_drvdata(pdev, NULL);
> +
> +	return 0;
> +}
> +
> +static struct platform_driver syscon_driver = {
> +	.driver = {
> +		.name = "syscon",
> +		.owner = THIS_MODULE,
> +		.of_match_table = of_syscon_match,
> +	},
> +	.probe		= syscon_probe,
> +	.remove		= syscon_remove,
> +};
> +
> +static int __init syscon_init(void)
> +{
> +	return platform_driver_register(&syscon_driver);
> +}
> +postcore_initcall(syscon_init);
> +
> +static void __exit anatop_exit(void)

s/anatop_exit/syscon_exit

> +{
> +	platform_driver_unregister(&syscon_driver);
> +}
> +module_exit(anatop_exit);

Ditto.

Regards,
Shawn

> +
> +MODULE_AUTHOR("Dong Aisheng <dong.aisheng@linaro.org>");
> +MODULE_DESCRIPTION("System Control driver");
> +MODULE_LICENSE("GPL v2");
> diff --git a/include/linux/mfd/syscon.h b/include/linux/mfd/syscon.h
> new file mode 100644
> index 0000000..990d7cf
> --- /dev/null
> +++ b/include/linux/mfd/syscon.h
> @@ -0,0 +1,22 @@
> +/*
> + * System Control Driver
> + *
> + * Copyright (C) 2012 Freescale Semiconductor, Inc.
> + * Copyright (C) 2012 Linaro Ltd.
> + *
> + * Author: Dong Aisheng <dong.aisheng@linaro.org>
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation; either version 2 of the License, or
> + * (at your option) any later version.
> + */
> +
> +#ifndef __LINUX_MFD_SYSCON_H__
> +#define __LINUX_MFD_SYSCON_H__
> +
> +extern struct regmap *syscon_regmap_lookup_by_compatible(const char *s);
> +extern struct regmap *syscon_regmap_lookup_by_phandle(
> +					struct device_node *np,
> +					const char *property);
> +#endif /* __LINUX_MFD_SYSCON_H__ */
> -- 
> 1.7.0.4
> 
> 