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    SubjectRe: [PATCH v3] mfd: syscon: Add non-DT support
    Date
    On Monday 18 February 2013, Alexander Shiyan wrote:
    > diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c
    > index 4a7ed5a..3c0abcb 100644
    > --- a/drivers/mfd/syscon.c
    > +++ b/drivers/mfd/syscon.c

    Hi Alexander,

    > struct regmap *syscon_regmap_lookup_by_compatible(const char *s)
    > {
    > struct device_node *syscon_np;
    > struct regmap *regmap;
    > + struct syscon *syscon;
    > + struct device *dev;
    >
    > syscon_np = of_find_compatible_node(NULL, NULL, s);
    > - if (!syscon_np)
    > + if (syscon_np) {
    > + regmap = syscon_node_to_regmap(syscon_np);
    > + of_node_put(syscon_np);
    > +
    > + return regmap;
    > + }
    > +
    > + /* Fallback to search by id_entry.name string */
    > + dev = driver_find_device(&syscon_driver.driver, NULL, (void *)s,
    > + syscon_match_id);
    > + if (!dev)
    > return ERR_PTR(-ENODEV);
    >
    > - regmap = syscon_node_to_regmap(syscon_np);
    > - of_node_put(syscon_np);
    > + syscon = dev_get_drvdata(dev);
    >
    > - return regmap;
    > + return syscon->regmap;
    > }
    > EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_compatible);

    Since you are not actually comparing the "compatible" property here,
    I would suggest adding another function here, something like
    syscon_regmap_lookup_by_pdevname() that you can use in device
    drivers that are not DT-enabled. I would also recommend enclosing
    that function in #ifdef CONFIG_ATAGS.

    Which code do you have in mind that would call this anyway?
    The changeset description does not really explain what ATAG
    boot support in syscon is good for.

    > + if (IS_ENABLED(CONFIG_OF) && np) {
    > + syscon->base = of_iomap(np, 0);
    > + if (!syscon->base)
    > + return -EADDRNOTAVAIL;
    > +
    > + res = &res_of;
    > + ret = of_address_to_resource(np, 0, res);
    > + if (ret) {
    > + iounmap(syscon->base);
    > + return ret;
    > + }
    > + } else {
    > + res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
    > + if (!res)
    > + return -ENOENT;
    > +
    > + if (!devm_request_mem_region(dev, res->start,
    > + resource_size(res),
    > + dev_name(&pdev->dev)))
    > + return -EBUSY;
    > +
    > + syscon->base = ioremap(res->start, resource_size(res));
    > + if (!syscon->base)
    > + return -EADDRNOTAVAIL;
    > + }

    These two code paths look equivalent. Why not always use the second
    one? Also, you might want to convert this to devm_ioremap_resource()
    to simplify the code in the process.

    Arnd


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