[RFC PATCH 05/11] mfd: omap: control: core system control driver

[Shilimkar, Santosh]

On Fri, May 25, 2012 at 1:55 PM, Eduardo Valentin
<eduardo.valentin at ti.com> wrote:
> This patch introduces a MFD core device driver for
> OMAP system control module.
>
> The control module allows software control of
> various static modes supported by the device. It is
> composed of two control submodules: general control
> module and device (padconfiguration) control
> module.
>
> In this patch, the children defined are for:
> . USB-phy pin control
> . Bangap temperature sensor
>
> Device driver is probed with postcore_initcall.
> However, as some of the APIs exposed by this driver
> may be needed in very early init phase, an early init
> class is also available: "early_omap_control".
>
> Signed-off-by: J Keerthy <j-keerthy at ti.com>
> Signed-off-by: Kishon Vijay Abraham I <kishon at ti.com>
> Signed-off-by: Eduardo Valentin <eduardo.valentin at ti.com>
> ---

[..]
> diff --git a/arch/arm/plat-omap/Kconfig b/arch/arm/plat-omap/Kconfig
> index ad95c7a..222dbad 100644
> --- a/arch/arm/plat-omap/Kconfig
> +++ b/arch/arm/plat-omap/Kconfig
> @@ -5,6 +5,9 @@ menu "TI OMAP Common Features"
>  config ARCH_OMAP_OTG
>        bool
>
> +config ARCH_HAS_CONTROL_MODULE
> +       bool
> +
Thanks for getting rid of OMAP CONFIG here.

>  choice
>        prompt "OMAP System Type"
>        default ARCH_OMAP2PLUS
> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
> index 11e4438..25a66d8 100644
> --- a/drivers/mfd/Kconfig
> +++ b/drivers/mfd/Kconfig
> @@ -795,6 +795,15 @@ config MFD_WL1273_CORE
>          driver connects the radio-wl1273 V4L2 module and the wl1273
>          audio codec.
>
> +config MFD_OMAP_CONTROL
> +       bool "Texas Instruments OMAP System control module"
> +       depends on ARCH_HAS_CONTROL_MODULE
> +       help
> +         This is the core driver for system control module. This driver
> +         is responsible for creating the control module mfd child,
> +         like USB-pin control, pin muxing, MMC-pbias and DDR IO dynamic
> +         change for off mode.
> +
>  config MFD_OMAP_USB_HOST
>        bool "Support OMAP USBHS core driver"
>        depends on USB_EHCI_HCD_OMAP || USB_OHCI_HCD_OMAP3
> diff --git a/drivers/mfd/Makefile b/drivers/mfd/Makefile
> index 05fa538..00f99d6 100644
> --- a/drivers/mfd/Makefile
> +++ b/drivers/mfd/Makefile
> @@ -106,6 +106,7 @@ obj-$(CONFIG_MFD_TPS6586X)  += tps6586x.o
>  obj-$(CONFIG_MFD_VX855)                += vx855.o
>  obj-$(CONFIG_MFD_WL1273_CORE)  += wl1273-core.o
>  obj-$(CONFIG_MFD_CS5535)       += cs5535-mfd.o
> +obj-$(CONFIG_MFD_OMAP_CONTROL) += omap-control-core.o
>  obj-$(CONFIG_MFD_OMAP_USB_HOST)        += omap-usb-host.o
>  obj-$(CONFIG_MFD_PM8921_CORE)  += pm8921-core.o
>  obj-$(CONFIG_MFD_PM8XXX_IRQ)   += pm8xxx-irq.o
> diff --git a/drivers/mfd/omap-control-core.c b/drivers/mfd/omap-control-core.c
> new file mode 100644
> index 0000000..7d8d408
> --- /dev/null
> +++ b/drivers/mfd/omap-control-core.c
> @@ -0,0 +1,211 @@
> +/*
> + * OMAP system control module driver file
> + *
> + * Copyright (C) 2011-2012 Texas Instruments Incorporated - http://www.ti.com/
> + * Contacts:
> + * Based on original code written by:
> + *    J Keerthy <j-keerthy at ti.com>
> + *    Moiz Sonasath <m-sonasath at ti.com>
> + * MFD clean up and re-factoring:
> + *    Eduardo Valentin <eduardo.valentin at ti.com>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * 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/module.h>
> +#include <linux/export.h>
> +#include <linux/platform_device.h>
> +#include <linux/slab.h>
> +#include <linux/io.h>
> +#include <linux/err.h>
> +#include <linux/of_platform.h>
> +#include <linux/of_address.h>
> +#include <linux/mfd/core.h>
> +#include <linux/mfd/omap_control.h>
> +
> +static struct omap_control *omap_control_module;
> +
> +/**
> + * omap_control_readl: Read a single omap control module register.
> + *
> + * @dev: device to read from.
> + * @reg: register to read.
> + * @val: output with register value.
> + *
> + * returns 0 on success or -EINVAL in case struct device is invalid.
> + */
> +int omap_control_readl(struct device *dev, u32 reg, u32 *val)
> +{
> +       struct omap_control *omap_control = dev_get_drvdata(dev);
> +
> +       if (!omap_control)
> +               return -EINVAL;
> +
> +       *val = readl(omap_control->base + reg);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(omap_control_readl);
> +
I might have missed in the last scan, but can you let
function return the register value.

I am guessing, you did this for error case handling. You might
want to stick to read API semantic and just have WARN_ON()
to take care of error case.

> +/**
> + * omap_control_writel: Write a single omap control module register.
> + *
> + * @dev: device to read from.
> + * @val: value to write.
> + * @reg: register to write to.
> + *
> + * returns 0 on success or -EINVAL in case struct device is invalid.
> + */
> +int omap_control_writel(struct device *dev, u32 val, u32 reg)
> +{
> +       struct omap_control *omap_control = dev_get_drvdata(dev);
> +       unsigned long flags;
> +
> +       if (!omap_control)
> +               return -EINVAL;
> +
> +       spin_lock_irqsave(&omap_control->reg_lock, flags);
> +       writel(val, omap_control->base + reg);
> +       spin_unlock_irqrestore(&omap_control->reg_lock, flags);
> +
> +       return 0;
> +}
> +EXPORT_SYMBOL_GPL(omap_control_writel);
> +
> +/**
> + * omap_control_get: returns the control module device pinter
> + *
> + * The modules which has to use control module API's to read or write should
> + * call this API to get the control module device pointer.
> + */
> +struct device *omap_control_get(void)
> +{
> +       unsigned long flags;
> +
> +       if (!omap_control_module)
> +               return ERR_PTR(-ENODEV);
> +
> +       spin_lock_irqsave(&omap_control_module->reg_lock, flags);
> +       omap_control_module->use_count++;
> +       spin_unlock_irqrestore(&omap_control_module->reg_lock, flags);
> +
> +       return omap_control_module->dev;
> +}
> +EXPORT_SYMBOL_GPL(omap_control_get);
> +
> +/**
> + * omap_control_put: returns the control module device pinter
> + *
> + * The modules which has to use control module API's to read or write should
> + * call this API to get the control module device pointer.
> + */
> +void omap_control_put(struct device *dev)
> +{
> +       struct omap_control *omap_control = dev_get_drvdata(dev);
> +       unsigned long flags;
> +
> +       if (!omap_control)
> +               return;
> +
> +       spin_lock_irqsave(&omap_control->reg_lock, flags);
> +       omap_control->use_count--;
> +       spin_unlock_irqrestore(&omap_control_module->reg_lock, flags);
> +}
> +EXPORT_SYMBOL_GPL(omap_control_put);
> +
> +static const struct of_device_id of_omap_control_match[] = {
> +       { .compatible = "ti,omap3-control", },
> +       { .compatible = "ti,omap4-control", },
> +       { .compatible = "ti,omap5-control", },
> +       { },
> +};
> +
> +static int __devinit omap_control_probe(struct platform_device *pdev)
> +{
> +       struct resource *res;
> +       void __iomem *base;
> +       struct device *dev = &pdev->dev;
> +       struct device_node *np = dev->of_node;
> +       struct omap_control *omap_control;
> +
> +       omap_control = devm_kzalloc(dev, sizeof(*omap_control), GFP_KERNEL);
> +       if (!omap_control) {
> +               dev_err(dev, "not enough memory for omap_control\n");
> +               return -ENOMEM;
> +       }
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       if (!res) {
> +               dev_err(dev, "missing memory base resource\n");
> +               return -EINVAL;
> +       }
> +
> +       base = devm_request_and_ioremap(dev, res);
> +       if (!base) {
> +               dev_err(dev, "ioremap failed\n");
> +               return -EADDRNOTAVAIL;
> +       }
> +
> +       omap_control->base = base;
> +       omap_control->dev = dev;
> +       spin_lock_init(&omap_control->reg_lock);
> +
> +       platform_set_drvdata(pdev, omap_control);
> +       omap_control_module = omap_control;
> +
> +       return of_platform_populate(np, of_omap_control_match, NULL, dev);
> +}
> +

Will the probe get called on multiple devices and race ?

> +static int __devexit omap_control_remove(struct platform_device *pdev)
> +{
> +       struct omap_control *omap_control = platform_get_drvdata(pdev);
> +
> +       spin_lock(&omap_control->reg_lock);
> +       if (omap_control->use_count > 0) {
> +               spin_unlock(&omap_control->reg_lock);
> +               dev_err(&pdev->dev, "device removed while still being used\n");
> +               return -EBUSY;
> +       }
> +       spin_unlock(&omap_control->reg_lock);
> +
Do you really need above lock where you are just doing the
register read. smp_rmb(), should be enough, I guess.

Regards
Santosh