Subject: [PATCH v3 2/7] mfd: omap: control: core system control driver

From: [email-masked] (Konstantin Baydarov)
Date: Thu, 28 Jun 2012 14:12:45 +0400

Hello.

On 06/28/2012 01:49 PM, Valentin, Eduardo wrote:
> Hello,
>
> On Thu, Jun 28, 2012 at 12:37 PM, Konstantin Baydarov
> <[email-masked]> wrote:
>>  Hi.
>>
>> On 06/28/2012 08:50 AM, Eduardo Valentin wrote:
>>> Hello,
>>>
>>> On Wed, Jun 27, 2012 at 10:04:54PM +0400, Konstantin Baydarov 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.
>>>>
>>>> Changes since previous version:
>>>> - omap-control-core: resources aren't hardcoded, they are specified in dts file.
>>>> - omap-control-core: Control module is a built-in driver - added control module select to ARCH_HAS_CONTROL_MODULE and ARCH_OMAP4.
>>>> Probably, no configuration option is required!
>>>> - omap-control-core: Added early init call that ioremaps control module IOMEM window, this allows access of SCM registers very early, for example from omap_type()
>>>> - omap-control-core: Removed device pointer from omap-control-core API arguments, becuase there can be only one instance control
>>>> module device.
>>>> - omap-control-core: removed omap_control_get, omap_control_readl, omap_control_writel
>>>> - omap-control-core: added omap_control_status_read that is used early in omap_type
>>>>
>>>> Signed-off-by: Konstantin Baydarov <[email-masked]>
>>>> Signed-off-by: J Keerthy <[email-masked]>
>>>> Signed-off-by: Kishon Vijay Abraham I <[email-masked]>
>>>> Signed-off-by: Eduardo Valentin <[email-masked]>
>>>> ---
>>>>  .../devicetree/bindings/mfd/omap_control.txt       |   44 +++++++
>>>>  arch/arm/mach-omap2/Kconfig                        |    1 +
>>>>  arch/arm/plat-omap/Kconfig                         |    4 +
>>>>  drivers/mfd/Kconfig                                |    9 ++
>>>>  drivers/mfd/Makefile                               |    1 +
>>>>  drivers/mfd/omap-control-core.c                    |  131 ++++++++++++++++++++
>>>>  include/linux/mfd/omap_control.h                   |   52 ++++++++
>>>>  7 files changed, 242 insertions(+), 0 deletions(-)
>>>>  create mode 100644 Documentation/devicetree/bindings/mfd/omap_control.txt
>>>>  create mode 100644 drivers/mfd/omap-control-core.c
>>>>  create mode 100644 include/linux/mfd/omap_control.h
>>>>
>>>> diff --git a/Documentation/devicetree/bindings/mfd/omap_control.txt b/Documentation/devicetree/bindings/mfd/omap_control.txt
>>>> new file mode 100644
>>>> index 0000000..46d5e7e
>>>> --- /dev/null
>>>> +++ b/Documentation/devicetree/bindings/mfd/omap_control.txt
>>>> @@ -0,0 +1,44 @@
>>>> +* Texas Instrument OMAP System Control Module (SCM) bindings
>>>> +
>>>> +The control module allows software control of various static modes supported by
>>>> +the device. The control module controls the settings of various device  modules
>>>> +through register configuration and internal signals. It also controls  the  pad
>>>> +configuration, pin functional multiplexing, and the routing of internal signals
>>>> +(such as PRCM  signals or DMA requests)  to output pins configured for hardware
>>>> +observability.
>>>> +
>>>> +Required properties:
>>>> +- compatible : Should be:
>>>> +  - "ti,omap3-control" for OMAP3 support
>>>> +  - "ti,omap4-control" for OMAP4 support
>>>> +  - "ti,omap5-control" for OMAP5 support
>>>> +
>>>> +OMAP specific properties:
>>>> +- ti,hwmods: Name of the hwmod associated to the control module:
>>>> +  Should be "ctrl_module_core";
>>>> +
>>>> +Sub-nodes:
>>>> +- bandgap : contains the bandgap node
>>>> +
>>>> +  The bindings details of individual bandgap device can be found in:
>>>> +  Documentation/devicetree/bindings/thermal/omap_bandgap.txt
>>>> +
>>>> +- usb : contains the usb phy pin control node
>>>> +
>>>> +  The only required property for this child is:
>>>> +    - compatible = "ti,omap4-control-usb";
>>>> +
>>>> +Examples:
>>>> +
>>>> +ctrl_module_core: ctrl_module_core at 4a002000 {
>>>> +    compatible = "ti,omap4-control";
>>>> +    ti,hwmods = "ctrl_module_core";
>>>> +    bandgap {
>>>> +            compatible = "ti,omap4460-bandgap";
>>> You need to update the documentation if change the DT structure.
>> Ok.
>>>> +            interrupts = <0 126 4>; /* talert */
>>>> +            ti,tshut-gpio = <86>; /* tshut */
>>>> +    };
>>>> +    usb {
>>>> +            compatible = "ti,omap4-usb-phy";
>>>> +    };
>>>> +};
>>>> diff --git a/arch/arm/mach-omap2/Kconfig b/arch/arm/mach-omap2/Kconfig
>>>> index 4cf5142..c2ef07c 100644
>>>> --- a/arch/arm/mach-omap2/Kconfig
>>>> +++ b/arch/arm/mach-omap2/Kconfig
>>>> @@ -52,6 +52,7 @@ config ARCH_OMAP4
>>>>      select PL310_ERRATA_727915
>>>>      select ARM_ERRATA_720789
>>>>      select ARCH_HAS_OPP
>>>> +    select ARCH_HAS_CONTROL_MODULE
>>>>      select PM_OPP if PM
>>>>      select USB_ARCH_HAS_EHCI if USB_SUPPORT
>>>>      select ARM_CPU_SUSPEND if PM
>>>> diff --git a/arch/arm/plat-omap/Kconfig b/arch/arm/plat-omap/Kconfig
>>>> index ad95c7a..0f9b575 100644
>>>> --- a/arch/arm/plat-omap/Kconfig
>>>> +++ b/arch/arm/plat-omap/Kconfig
>>>> @@ -5,6 +5,10 @@ menu "TI OMAP Common Features"
>>>>  config ARCH_OMAP_OTG
>>>>      bool
>>>>
>>>> +config ARCH_HAS_CONTROL_MODULE
>>>> +    bool
>>>> +    select MFD_OMAP_CONTROL
>>>> +
>>> OK now I got what you meant in patch 0. Fine for me.
>>>
>>>>  choice
>>>>      prompt "OMAP System Type"
>>>>      default ARCH_OMAP2PLUS
>>>> diff --git a/drivers/mfd/Kconfig b/drivers/mfd/Kconfig
>>>> index e129c82..d0c5456 100644
>>>> --- a/drivers/mfd/Kconfig
>>>> +++ b/drivers/mfd/Kconfig
>>>> @@ -822,6 +822,15 @@ 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 75f6ed6..b037443 100644
>>>> --- a/drivers/mfd/Makefile
>>>> +++ b/drivers/mfd/Makefile
>>>> @@ -107,6 +107,7 @@ 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..724c51b
>>>> --- /dev/null
>>>> +++ b/drivers/mfd/omap-control-core.c
>>>> @@ -0,0 +1,131 @@
>>>> +/*
>>>> + * 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 <[email-masked]>
>>>> + *    Moiz Sonasath <[email-masked]>
>>>> + * MFD clean up and re-factoring:
>>>> + *    Eduardo Valentin <[email-masked]>
>>>> + *
>>>> + * 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>
>>>> +
>>>> +#include <linux/of.h>
>>>> +#include <linux/of_address.h>
>>>> +
>>>> +void __iomem *omap_control_base;
>>>> +
>>>> +u32 omap_control_status_read(u16 offset)
>>>> +{
>>>> +    return __raw_readl(omap_control_base + (offset));
>>>> +}
>>>> +
>>>> +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 device *dev = &pdev->dev;
>>>> +    struct device_node *np = dev->of_node;
>>>> +
>>>> +    /*
>>>> +     *  Build child defvices of ctrl_module_core
>>>> +     */
>>>> +    return of_platform_populate(np, of_omap_control_match, NULL, dev);
>>>> +}
>>>> +
>>>> +
>>>> +static struct platform_driver omap_control_driver = {
>>>> +    .probe                  = omap_control_probe,
>>>> +    .driver = {
>>>> +            .name           = "omap-control-core",
>>>> +            .owner          = THIS_MODULE,
>>>> +            .of_match_table = of_omap_control_match,
>>>> +    },
>>>> +};
>>>> +
>>>> +int __init omap_control_of_init(struct device_node *node,
>>>> +                         struct device_node *parent)
>>>> +{
>>>> +    struct resource res;
>>>> +
>>>> +    if (WARN_ON(!node))
>>>> +            return -ENODEV;
>>>> +
>>>> +    if (of_address_to_resource(node, 0, &res)) {
>>>> +            WARN(1, "unable to get intc registers\n");
>>>> +            return -EINVAL;
>>>> +    }
>>>> +
>>>> +    return 0;
>>>> +}
>>> The above function is used nowhere.
>> Agree.
>>>> +
>>>> +void __init of_omap_control_init(const struct of_device_id *matches)
>>>> +{
>>>> +    struct device_node *np;
>>>> +    struct property *pp = 0;
>>>> +    unsigned long phys_base = 0;
>>>> +    size_t mapsize = 0;
>>>> +
>>>> +    for_each_matching_node(np, matches) {
>>>> +
>>>> +            pp = of_find_property(np, "reg", NULL);
>>>> +            if(pp) {
>>>> +                    phys_base = (unsigned long)be32_to_cpup(pp->value);
>>>> +                    mapsize = (size_t)be32_to_cpup( (void*)((char*)pp->value + 4) );
>>>> +                    omap_control_base = ioremap(phys_base, mapsize);
>>> How the reservation is going to work?
>> This can be done following way:
>> - omap-control-core.c ioremaps and reserves SCM IOMEM window
>> - omap-control-core.c exports omap_control_get_base(virtual base address is returned) to use in bandgap and usb_phy driver.
>> IIUC, this way was suggested by Tony.
> how better is this way compared to having the access functions in the
> core? This way we just replicate the access functions in every
> children.
>
> I believe the suggestion was to have the ioremap and request done in
> chunks. So that children dont step into each other ioarea. But then
> again that can be a bit painful as the children registers are not
> contiguous.
The interface(design) of omap-control-core.c has already been discussed many times :(
Eduardo, in his patch set, suggested following design:
- omap-control-core.c ioremaps SCM window and provide functions to read/write SCP register for bandgap and usb.

IIRC, this approach didn't satisfy and it was suggested to have private read/write in bandgap and usb.

So, my patch set introduces following design:
- omap-control-core.c don't provide read/write functions for bandgap and usb.
- bandgap and usb use their own private read/write functions
- Each omap-control-core.c, bandgap and usb drivers remap SCM window. It's OK because SCM window is statically mapped to the same virtual address. But the problem is that SMP memory window isn't protected. I'm not sure whether it's possible to protect SCM window using this approach.

Another possible design is:
- omap-control-core.c ioremaps and reserves SCM IOMEM window
- omap-control-core.c exports omap_control_get_base(virtual base address is returned) to use in bandgap and usb_phy driver.
- Bandgap and usb phy uses their own private read/write function.
IIUC, this way was suggested by Tony.

I guess It's better to settle the design(interface) of omap-control-core.c, bandgap and usb phy and then submit the next version of patch set.

>
>>>> +            }
>>>> +    }
>>>> +}
>>>> +
>>>> +static int __init
>>>> +omap_control_early_initcall(void)
>>>> +{
>>>> +    of_omap_control_init(of_omap_control_match);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +early_initcall(omap_control_early_initcall);
>>>> +
>>>> +static int __init omap_control_init(void)
>>>> +{
>>>> +    return platform_driver_register(&omap_control_driver);
>>>> +}
>>>> +postcore_initcall_sync(omap_control_init);
>>>> +
>>>> +static void __exit omap_control_exit(void)
>>>> +{
>>>> +    platform_driver_unregister(&omap_control_driver);
>>>> +}
>>>> +module_exit(omap_control_exit);
>>>> +early_platform_init("early_omap_control", &omap_control_driver);
>>> early_platform_init is not needed as you are implementing the early reads in a different way.
>> Right.
>>>> +
>>>> +MODULE_DESCRIPTION("OMAP system control module driver");
>>>> +MODULE_LICENSE("GPL v2");
>>>> +MODULE_ALIAS("platform:omap-control-core");
>>>> +MODULE_AUTHOR("Texas Instruments Inc.");
>>>> diff --git a/include/linux/mfd/omap_control.h b/include/linux/mfd/omap_control.h
>>>> new file mode 100644
>>>> index 0000000..1795403
>>>> --- /dev/null
>>>> +++ b/include/linux/mfd/omap_control.h
>>>> @@ -0,0 +1,52 @@
>>>> +/*
>>>> + * OMAP system control module header file
>>>> + *
>>>> + * Copyright (C) 2011-2012 Texas Instruments Incorporated - http://www.ti.com/
>>>> + * Contact:
>>>> + *   J Keerthy <[email-masked]>
>>>> + *   Moiz Sonasath <[email-masked]>
>>>> + *   Abraham, Kishon Vijay <[email-masked]>
>>>> + *   Eduardo Valentin <[email-masked]>
>>>> + *
>>>> + * 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.
>>>> + *
>>>> + */
>>>> +
>>>> +#ifndef __DRIVERS_OMAP_CONTROL_H
>>>> +#define __DRIVERS_OMAP_CONTROL_H
>>>> +
>>>> +#include <linux/err.h>
>>>> +
>>>> +/**
>>>> + * struct system control module - scm device structure
>>>> + * @dev: device pointer
>>>> + * @base: Base of the temp I/O
>>>> + * @reg_lock: protect omap_control structure
>>>> + * @use_count: track API users
>>>> + */
>>>> +struct omap_control {
>>>> +    struct device           *dev;
>>>> +    void __iomem            *base;
>>>> +    /* protect this data structure and register access */
>>>> +    spinlock_t              reg_lock;
>>>> +    int                     use_count;
>>> I suppose the reg_lock and the use_count are not needed in this design?
>> Right.
>>>> +};
>>>> +
>>>> +/* TODO: Add helpers for 16bit and byte access */
>>>> +#ifdef CONFIG_MFD_OMAP_CONTROL
>>>> +u32 omap_control_status_read(u16 offset);
>>>> +#else
>>>> +static inline u32 omap_control_status_read(u16 offset)
>>>> +{
>>>> +    return 0;
>>>> +}
>>>> +#endif
>>>> +
>>>> +#endif /* __DRIVERS_OMAP_CONTROL_H */
>>>> --
>>>> 1.7.7.6
>>>>
>>>>
>>> --
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>
>