Message-id: <5357784B.5000501@samsung.com>
Date: Wed, 23 Apr 2014 17:22:35 +0900
From: Pankaj Dubey <pankaj.dubey@samsung.com>
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To: monstr@monstr.eu
Cc: Lee Jones <lee.jones@linaro.org>, Michal Simek <michal.simek@xilinx.com>,
        linux-kernel@vger.kernel.org, Samuel Ortiz <sameo@linux.intel.com>,
        Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH v3] mfd: syscon: Support early initialization
References: <3eb785d83c406f4a57508dc03610b05492e12bfd.1396969250.git.michal.simek@xilinx.com>
 <53463824.3040606@samsung.com> <5346377C.1030606@monstr.eu>
 <53576B68.70602@monstr.eu>
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On 04/23/2014 04:27 PM, Michal Simek wrote:
> On 04/10/2014 08:17 AM, Michal Simek wrote:
>> On 04/10/2014 08:20 AM, Pankaj Dubey wrote:
>>> Hi Michal,
>>>
>>> On 04/09/2014 12:00 AM, Michal Simek wrote:
>>>> Some platforms need to get system controller
>>>> ready as soon as possible.
>>>> The patch provides early_syscon_initialization
>>>> which create early mapping for all syscon compatible
>>>> devices in early_syscon_probe.
>>>> Regmap is get via syscon_early_regmap_lookup_by_phandle()
>>>>
>>>> Regular device probes attach device to regmap
>>>> via regmap_attach_dev().
>>>>
>>>> For early syscon initialization is necessary to extend
>>>> struct syscon and provide remove function
>>>> which unmap all early init structures.
>>>>
>>>> Signed-off-by: Michal Simek <michal.simek@xilinx.com>
>>>> ---
>>>>
>>>> Changes in v3:
>>>> - Keep backward compatibility for platform drivers and test it
>>>> - Use only one probe method which is early_syscon_probe
>>>>     suggested by Lee Jones. Do not force anybody to call early_syscon_init
>>>> - Add kernel-doc description
>>>>
>>>> Changes in v2:
>>>> - Fix bad logic in early_syscon_probe
>>>> - Fix compilation failure for x86_64 reported by zero day testing system
>>>> - Regmap change available here
>>>>     git://git.kernel.org/pub/scm/linux/kernel/git/broonie/regmap.git tags/nodev
>>>>
>>>>    drivers/mfd/syscon.c       | 159 ++++++++++++++++++++++++++++++++++++++++-----
>>>>    include/linux/mfd/syscon.h |  11 ++++
>>>>    2 files changed, 153 insertions(+), 17 deletions(-)
>>>>
>>>> diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
>>>> index 71841f9..8e2ff88 100644
>>>> --- a/drivers/mfd/syscon.c
>>>> +++ b/drivers/mfd/syscon.c
>>>> @@ -20,12 +20,15 @@
>>>>    #include <linux/of_platform.h>
>>>>    #include <linux/platform_device.h>
>>>>    #include <linux/regmap.h>
>>>> +#include <linux/slab.h>
>>>>    #include <linux/mfd/syscon.h>
>>>>
>>>>    static struct platform_driver syscon_driver;
>>>>
>>>>    struct syscon {
>>>> +    void __iomem *base;
>>>>        struct regmap *regmap;
>>>> +    struct resource res;
>>>>    };
>>>>
>>>>    static int syscon_match_node(struct device *dev, void *data)
>>>> @@ -95,6 +98,30 @@ struct regmap *syscon_regmap_lookup_by_pdevname(const char *s)
>>>>    }
>>>>    EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_pdevname);
>>>>
>>>> +/**
>>>> + * syscon_early_regmap_lookup_by_phandle - Early phandle lookup function
>>>> + * @np:        device_node pointer
>>>> + * @property:    property name which handle system controller phandle
>>>> + * Return:    regmap pointer, an error pointer otherwise
>>>> + */
>>>> +struct regmap *syscon_early_regmap_lookup_by_phandle(struct device_node *np,
>>>> +                             const char *property)
>>>> +{
>>>> +    struct device_node *syscon_np;
>>>> +    struct syscon *syscon;
>>>> +
>>>> +    syscon_np = of_parse_phandle(np, property, 0);
>>>> +    if (!syscon_np)
>>>> +        return ERR_PTR(-ENODEV);
>>>> +
>>>> +    syscon = syscon_np->data;
>>>> +
>>>> +    of_node_put(syscon_np);
>>>> +
>>>> +    return syscon->regmap;
>>>> +}
>>>> +EXPORT_SYMBOL_GPL(syscon_early_regmap_lookup_by_phandle);
>>>> +
>>>>    struct regmap *syscon_regmap_lookup_by_phandle(struct device_node *np,
>>>>                        const char *property)
>>>>    {
>>>> @@ -123,36 +150,118 @@ static struct regmap_config syscon_regmap_config = {
>>>>        .reg_stride = 4,
>>>>    };
>>>>
>>>> -static int syscon_probe(struct platform_device *pdev)
>>>> +/**
>>>> + * early_syscon_probe - Early system controller probe method
>>>> + * @np:        device_node pointer
>>>> + * @syscon_p:    syscon pointer
>>>> + * @res:    device IO resource
>>>> + * Return:    0 if successful, a negative error code otherwise
>>>> + */
>>>> +static int early_syscon_probe(struct device_node *np, struct syscon **syscon_p,
>>>> +                  struct resource *res)
>>>>    {
>>>> -    struct device *dev = &pdev->dev;
>>>>        struct syscon *syscon;
>>>> -    struct resource *res;
>>>> -    void __iomem *base;
>>>> +    int ret;
>>>> +
>>>> +    if (np && np->data) {
>>>> +        pr_debug("Early syscon was called\n");
>>>> +        *syscon_p = (struct syscon *)&np->data;
>>>> +        return 0;
>>>> +    }
>>>>
>>>> -    syscon = devm_kzalloc(dev, sizeof(*syscon), GFP_KERNEL);
>>>> +    syscon = kzalloc(sizeof(*syscon), GFP_KERNEL);
>>>>        if (!syscon)
>>>>            return -ENOMEM;
>>>>
>>>> -    res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>> -    if (!res)
>>>> -        return -ENOENT;
>>>> +    *syscon_p = (struct syscon *)&syscon;
>>>>
>>>> -    base = devm_ioremap(dev, res->start, resource_size(res));
>>>> -    if (!base)
>>>> -        return -ENOMEM;
>>>> +    if (!res && np) {
>>>> +        if (of_address_to_resource(np, 0, &syscon->res)) {
>>>> +            ret = -EINVAL;
>>>> +            goto alloc;
>>>> +        }
>>>> +
>>>> +        np->data = syscon;
>>>> +        of_node_put(np);
>>>> +    } else {
>>>> +        syscon->res = *res;
>>>> +    }
>>>>
>>>> -    syscon_regmap_config.max_register = res->end - res->start - 3;
>>>> -    syscon->regmap = devm_regmap_init_mmio(dev, base,
>>>> -                    &syscon_regmap_config);
>>>> +    syscon->base = ioremap(syscon->res.start, resource_size(&syscon->res));
>>>> +    if (!syscon->base) {
>>>> +        pr_err("%s: Unable to map I/O memory\n", __func__);
>>>> +        ret = PTR_ERR(syscon->base);
>>>> +        goto alloc;
>>>> +    }
>>>> +
>>>> +    syscon_regmap_config.max_register = syscon->res.end -
>>>> +                        syscon->res.start - 3;
>>>> +    syscon->regmap = regmap_init_mmio(NULL, syscon->base,
>>>> +                      &syscon_regmap_config);
>>>>        if (IS_ERR(syscon->regmap)) {
>>>> -        dev_err(dev, "regmap init failed\n");
>>>> -        return PTR_ERR(syscon->regmap);
>>>> +        pr_err("regmap init failed\n");
>>>> +        ret = PTR_ERR(syscon->regmap);
>>>> +        goto iomap;
>>>>        }
>>>> +    if (np)
>>>> +        pr_info("syscon: %s regmap %pR registered\n", np->name,
>>>> +            &syscon->res);
>>>> +
>>>> +    return 0;
>>>> +
>>>> +iomap:
>>>> +    iounmap(syscon->base);
>>>> +alloc:
>>>> +    kfree(syscon);
>>>> +
>>>> +    return ret;
>>>> +}
>>>> +
>>>> +/**
>>>> + * early_syscon_init - Early system controller initialization
>>>> + */
>>>> +void __init early_syscon_init(void)
>>>> +{
>>>> +    struct device_node *np;
>>>> +    struct syscon *syscon = NULL;
>>>> +
>>>> +    for_each_matching_node_and_match(np, of_syscon_match, NULL) {
>>>> +        if (early_syscon_probe(np, &syscon, NULL))
>>>> +            BUG();
>>>> +    }
>>>> +}
>>>> +
>>>> +/**
>>>> + * syscon_probe - System controller probe method
>>>> + * @pdev:    Platform device
>>>> + * Return:    0 if successful, a negative error code otherwise
>>>> + */
>>>> +static int syscon_probe(struct platform_device *pdev)
>>>> +{
>>>> +    struct syscon *syscon, *syscon_p;
>>>> +    struct resource *res = NULL;
>>>> +    struct device *dev = &pdev->dev;
>>>> +    struct device_node *np = pdev->dev.of_node;
>>>> +    int ret;
>>>> +
>>>> +    if (!np) {
>>>> +        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>>>> +        if (!res)
>>>> +            return -ENOENT;
>>>> +    }
>>>> +    ret = early_syscon_probe(np, &syscon_p, res);
>>>> +    if (ret) {
>>>> +        dev_err(dev, "Syscon probe failed\n");
>>>> +        return ret;
>>>> +    }
>>>> +
>>>> +    syscon = *(struct syscon **)syscon_p;
>>>> +
>>>> +    regmap_attach_dev(dev, syscon->regmap, &syscon_regmap_config);
>>>>
>>>>        platform_set_drvdata(pdev, syscon);
>>>>
>>>> -    dev_info(dev, "regmap %pR registered\n", res);
>>>> +    dev_info(dev, "regmap attach device to %pR\n", &syscon->res);
>>>>
>>>>        return 0;
>>>>    }
>>>> @@ -162,6 +271,21 @@ static const struct platform_device_id syscon_ids[] = {
>>>>        { }
>>>>    };
>>>>
>>>> +/**
>>>> + * syscon_remove - System controller cleanup function
>>>> + * @pdev:    Platform device
>>>> + * Return:    0 always
>>>> + */
>>>> +static int syscon_remove(struct platform_device *pdev)
>>>> +{
>>>> +    struct syscon *syscon = platform_get_drvdata(pdev);
>>>> +
>>>> +    iounmap(syscon->base);
>>>> +    kfree(syscon);
>>>> +
>>>> +    return 0;
>>>> +}
>>>> +
>>>>    static struct platform_driver syscon_driver = {
>>>>        .driver = {
>>>>            .name = "syscon",
>>>> @@ -169,6 +293,7 @@ static struct platform_driver syscon_driver = {
>>>>            .of_match_table = of_syscon_match,
>>>>        },
>>>>        .probe        = syscon_probe,
>>>> +    .remove        = syscon_remove,
>>>>        .id_table    = syscon_ids,
>>>>    };
>>>>
>>>> diff --git a/include/linux/mfd/syscon.h b/include/linux/mfd/syscon.h
>>>> index 8789fa3..465c092 100644
>>>> --- a/include/linux/mfd/syscon.h
>>>> +++ b/include/linux/mfd/syscon.h
>>>> @@ -24,6 +24,10 @@ extern struct regmap *syscon_regmap_lookup_by_pdevname(const char *s);
>>>>    extern struct regmap *syscon_regmap_lookup_by_phandle(
>>>>                        struct device_node *np,
>>>>                        const char *property);
>>>> +extern struct regmap *syscon_early_regmap_lookup_by_phandle(
>>>> +                    struct device_node *np,
>>>> +                    const char *property);
>>>> +extern void early_syscon_init(void);
>>>>    #else
>>>>    static inline struct regmap *syscon_node_to_regmap(struct device_node *np)
>>>>    {
>>>> @@ -46,6 +50,13 @@ static inline struct regmap *syscon_regmap_lookup_by_phandle(
>>>>    {
>>>>        return ERR_PTR(-ENOSYS);
>>>>    }
>>>> +
>>>> +static struct regmap *syscon_early_regmap_lookup_by_phandle(
>>>> +                    struct device_node *np,
>>>> +                    const char *property)
>>>> +{
>>>> +    return ERR_PTR(-ENOSYS);
>>>> +}
>>>>    #endif
>>>>
>>>>    #endif /* __LINUX_MFD_SYSCON_H__ */
>>>> -- 
>>>> 1.8.2.3
>>>>
>>> Thanks for CC'ing me.
>> no problem.
>>
>>> I have tested this patch along with Exynos PMU related changes posted here
>>> https://lkml.org/lkml/2014/4/2/53 and modified it for using Syscon, and it's working for me.
>> great.
>>
>>
>>> I have observed one issue during this testing:
>>>
>>> Even though we are saying early initialization I could not use "early_syscon_init" from machine's
>>> "map_io" or "init_early". I observed that "early_syscon_init" failed to called "early_syscon_probe",
>>> because it can not get any matching node, when I debug further I found that as "early_syscon_init"
>>> is calling "for_each_matching_node_and_match" and it can't work before unflatten'ing device tree,
>>> which happens in "setup_arch" a bit late, after "map_io" and "init_early" calls of machine.
>>>
>>> So if I have to use "early_syscon_init" I MUST call it after device tree is unflattened. It worked for me
>>> when I called it from "init_machine" (from exynos_dt_machine_init), But if someone needs it at very
>>> early stage then it might not work. So how about using "of_scan_flat_dt" in "early_syscon_init"?, so that
>>> we can use this functionality at very early stage if required.
>> Yes you are right. I have discussed this with Arnd and for Zynq there is no need to call it so early
>> that's why using this function is fine. Arnd wasn't sure if there is any need to call it before unflattening
>> that's why I didn't try to solve this case.
>>
>> Can you send me that patch? I will test it on Zynq and if it is working, let's include it to v4.
> Pankaj: Any update on this? I think that your patch can be applied on the top of this one.

Hi Michal,
Sorry for late reply, I was a bit busy with some official assignments.
Usage of "of_scan_flat_dt" in "early_syscon_init" was just a suggestion from my 
side, and I have
not worked on it till now. As I mentioned your patches worked for me if I call 
them a bit late in "init_machine".
I do not see as such any issues, until some one needs it before DT gets unflattened.


>
> Lee: Can you please look at these changes?  It is around for a while and I would like to close it.
>
> Thanks,
> Michal
>
>
>


-- 
Best Regards,
Pankaj Dubey

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