On Tue, 30 Sep 2014, Pankaj Dubey wrote: > Currently a syscon entity can be only registered directly through a > platform device that binds to a dedicated syscon driver. However in > certain use cases it is desirable to make a device used with another > driver a syscon interface provider. > > For example, certain SoCs (e.g. Exynos) contain system controller > blocks which perform various functions such as power domain control, > CPU power management, low power mode control, but in addition contain > certain IP integration glue, such as various signal masks, > coprocessor power control, etc. In such case, there is a need to have > a dedicated driver for such system controller but also share registers > with other drivers. The latter is where the syscon interface is helpful. > > In case of DT based platforms, this patch decouples syscon object from > syscon platform driver, and allows to create syscon objects first time > when it is required by calling of syscon_regmap_lookup_by APIs and keep > a list of such syscon objects along with syscon provider device_nodes > and regmap handles. > > For non-DT based platforms, this patch keeps syscon platform driver > structure so that syscon can be probed and such non-DT based drivers > can use syscon_regmap_lookup_by_pdev API and access regmap handles. > Once all users of "syscon_regmap_lookup_by_pdev" migrated to DT based, > we can completely remove platform driver of syscon, and keep only helper > functions to get regmap handles. > > Suggested-by: Arnd Bergmann <a...@arndb.de> > Suggested-by: Tomasz Figa <tomasz.f...@gmail.com> > Tested-by: Vivek Gautam <gautam.vi...@samsung.com> > Tested-by: Javier Martinez Canillas <javier.marti...@collabora.co.uk> > Signed-off-by: Pankaj Dubey <pankaj.du...@samsung.com> > Reviewed-by: Arnd Bergmann <a...@arndb.de> > Tested-by: Heiko Stuebner <he...@sntech.de> > Reviewed-by: Heiko Stuebner <he...@sntech.de>
Applied for v3.19. > --- > Patch v6 and related discussions can be found here [1]. > > Change since v5: > - Addressed review comments from "Heiko Stuebner". > - Updated commit description. > - Including Arnd's and Heiko's Reviewed-by. > > Change since v5: > - Dropping creation of dummy platform device in of_syscon_register. > - As we are changing syscon to decouple from platform_device, creation of > dummy platform_device does not look good option, and as suggested by Arnd, > I made another attempt so that regmap_mmio_init API should work with NULL > dev pointer itself. Since regmap needs to know about Syscon device node > properties so let's parse device node of syscon in syscon itself for any > such properties and using regmap_config parameter pass all such information > to regmap. Other concern of crashes due to NULL dev pointer in regmap > already > addressed in separate patches of regmap. Please see [2] and [3]. > > Changes since v4: > - Addressed Tomasz Figa's comments for v4. > - Added error handing in of_syscon_register function. > - Using devm_regmap_init_mmio instead of regmap_init_mmio. > > Changes since v3: > - Addressed Arnd's comment for v2. > - Updated of_syscon_register for adding dev pointer in regmap_init_mmio. > - For early users created dummy platform device. > > Changes since v2: > - Added back platform device support from syscon, with one change that > syscon will not be probed for DT based platform. > - Added back syscon_regmap_lookup_by_pdevname API so that non-DT base > users of syscon will not be broken. > - Removed unwanted change in syscon.h. > - Modified Signed-off-by list, added Suggested-by of Tomasz Figa and > Arnd Bergmann. > - Added Tested-by of Vivek Gautam for testing on Exynos platform. > > Changes since v1: > - Removed of_syscon_unregister function. > - Modified of_syscon_register function and it will be used by syscon.c > to create syscon objects whenever required. > - Removed platform device support from syscon. > - Removed syscon_regmap_lookup_by_pdevname API support. > - As there are significant changes w.r.t patchset v1, I am taking over > author for this patchset from Tomasz Figa. > > [1]: https://lkml.org/lkml/2014/9/29/99 > [2]: https://lkml.org/lkml/2014/9/18/130 > [3]: https://lkml.org/lkml/2014/9/27/2 > drivers/mfd/syscon.c | 96 > ++++++++++++++++++++++++++++++++++++++------------ > 1 file changed, 74 insertions(+), 22 deletions(-) > > diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c > index ca15878..72373b1 100644 > --- a/drivers/mfd/syscon.c > +++ b/drivers/mfd/syscon.c > @@ -15,6 +15,7 @@ > #include <linux/err.h> > #include <linux/io.h> > #include <linux/module.h> > +#include <linux/list.h> > #include <linux/of.h> > #include <linux/of_address.h> > #include <linux/of_platform.h> > @@ -22,31 +23,94 @@ > #include <linux/platform_device.h> > #include <linux/regmap.h> > #include <linux/mfd/syscon.h> > +#include <linux/slab.h> > > static struct platform_driver syscon_driver; > > +static DEFINE_SPINLOCK(syscon_list_slock); > +static LIST_HEAD(syscon_list); > + > struct syscon { > + struct device_node *np; > struct regmap *regmap; > + struct list_head list; > +}; > + > +static struct regmap_config syscon_regmap_config = { > + .reg_bits = 32, > + .val_bits = 32, > + .reg_stride = 4, > }; > > -static int syscon_match_node(struct device *dev, void *data) > +static struct syscon *of_syscon_register(struct device_node *np) > { > - struct device_node *dn = data; > + struct syscon *syscon; > + struct regmap *regmap; > + void __iomem *base; > + int ret; > + struct regmap_config syscon_config = syscon_regmap_config; > + > + if (!of_device_is_compatible(np, "syscon")) > + return ERR_PTR(-EINVAL); > + > + syscon = kzalloc(sizeof(*syscon), GFP_KERNEL); > + if (!syscon) > + return ERR_PTR(-ENOMEM); > + > + base = of_iomap(np, 0); > + if (!base) { > + ret = -ENOMEM; > + goto err_map; > + } > + > + /* Parse the device's DT node for an endianness specification */ > + if (of_property_read_bool(np, "big-endian")) > + syscon_config.val_format_endian = REGMAP_ENDIAN_BIG; > + else if (of_property_read_bool(np, "little-endian")) > + syscon_config.val_format_endian = REGMAP_ENDIAN_LITTLE; > + > + regmap = regmap_init_mmio(NULL, base, &syscon_config); > + if (IS_ERR(regmap)) { > + pr_err("regmap init failed\n"); > + ret = PTR_ERR(regmap); > + goto err_regmap; > + } > + > + syscon->regmap = regmap; > + syscon->np = np; > + > + spin_lock(&syscon_list_slock); > + list_add_tail(&syscon->list, &syscon_list); > + spin_unlock(&syscon_list_slock); > > - return (dev->of_node == dn) ? 1 : 0; > + return syscon; > + > +err_regmap: > + iounmap(base); > +err_map: > + kfree(syscon); > + return ERR_PTR(ret); > } > > struct regmap *syscon_node_to_regmap(struct device_node *np) > { > - struct syscon *syscon; > - struct device *dev; > + struct syscon *entry, *syscon = NULL; > > - dev = driver_find_device(&syscon_driver.driver, NULL, np, > - syscon_match_node); > - if (!dev) > - return ERR_PTR(-EPROBE_DEFER); > + spin_lock(&syscon_list_slock); > > - syscon = dev_get_drvdata(dev); > + list_for_each_entry(entry, &syscon_list, list) > + if (entry->np == np) { > + syscon = entry; > + break; > + } > + > + spin_unlock(&syscon_list_slock); > + > + if (!syscon) > + syscon = of_syscon_register(np); > + > + if (IS_ERR(syscon)) > + return ERR_CAST(syscon); > > return syscon->regmap; > } > @@ -110,17 +174,6 @@ struct regmap *syscon_regmap_lookup_by_phandle(struct > device_node *np, > } > EXPORT_SYMBOL_GPL(syscon_regmap_lookup_by_phandle); > > -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 syscon_probe(struct platform_device *pdev) > { > struct device *dev = &pdev->dev; > @@ -167,7 +220,6 @@ static struct platform_driver syscon_driver = { > .driver = { > .name = "syscon", > .owner = THIS_MODULE, > - .of_match_table = of_syscon_match, > }, > .probe = syscon_probe, > .id_table = syscon_ids, -- Lee Jones Linaro STMicroelectronics Landing Team Lead Linaro.org │ Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
