| Message ID | 1411980458-32329-1-git-send-email-pankaj.dubey@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Monday 29 September 2014 14:17:38 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 where is can be probed and such non-DT based drivers can use > syscon_regmap_lookup_by_pdev API and get access to 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 <arnd@arndb.de> > Suggested-by: Tomasz Figa <tomasz.figa@gmail.com> > Tested-by: Vivek Gautam <gautam.vivek@samsung.com> > Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> > Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com> > --- > Patch v5 and related discussions can be found here [1]. > > 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]. > > > Reviewed-by: Arnd Bergmann <arnd@arndb.de> Looks good to me, thanks a lot! Arnd
Am Montag, 29. September 2014, 14:17:38 schrieb Pankaj Dubey: > 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 where is can be probed and such non-DT based drivers can use > syscon_regmap_lookup_by_pdev API and get access to 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 <arnd@arndb.de> > Suggested-by: Tomasz Figa <tomasz.figa@gmail.com> > Tested-by: Vivek Gautam <gautam.vivek@samsung.com> > Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> > Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com> > --- On Rockchip boards during core clock init (aka before timers) Tested-by: Heiko Stuebner <heiko@sntech.de> Except one issue described inline below Reviewed-by: Heiko Stuebner <heiko@sntech.de> And I'm really looking forward to having this in the kernel :-) Thanks for working on this Heiko > Patch v5 and related discussions can be found here [1]. > > 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/2014/9/22/12 > [2]: https://lkml.org/lkml/2014/9/18/130 > [3]: https://lkml.org/lkml/2014/9/27/2 > > drivers/mfd/syscon.c | 106 > +++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 84 > insertions(+), 22 deletions(-) > > diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c > index ca15878..00a8410 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 +23,104 @@ > #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; > + enum regmap_endian endian = REGMAP_ENDIAN_DEFAULT; > + > + 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")) > + endian = REGMAP_ENDIAN_BIG; > + else if (of_property_read_bool(np, "little-endian")) > + endian = REGMAP_ENDIAN_LITTLE; > + > + /* If the endianness was specified in DT, use that */ > + if (endian != REGMAP_ENDIAN_DEFAULT) > + syscon_regmap_config.val_format_endian = endian; > + > + regmap = regmap_init_mmio(NULL, base, &syscon_regmap_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; > + /* Change back endianness of syscon_regmap_config. > + * As this is static config in this file and in one system we may > + * have more than one syscon > + */ > + syscon_regmap_config.val_format_endian = REGMAP_ENDIAN_DEFAULT; This should also be done in the error case. Currently when you goto err_regmap the overridden value will be left in the struct. While on this, is there a concurrency issue here, aka of_syscon_register could be called in parallel and what happens with syscon_regmap_config.val_format_endian then? > + > + 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 +184,6 @@ 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 +230,6 @@ 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,
Hi, On Monday, September 29, 2014 9:38 PM, Heiko Stübner wrote, > Am Montag, 29. September 2014, 14:17:38 schrieb Pankaj Dubey: > > 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 where is can be probed and such non-DT based drivers can use > > syscon_regmap_lookup_by_pdev API and get access to 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 <arnd@arndb.de> > > Suggested-by: Tomasz Figa <tomasz.figa@gmail.com> > > Tested-by: Vivek Gautam <gautam.vivek@samsung.com> > > Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> > > Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com> > > --- > > On Rockchip boards during core clock init (aka before timers) > Tested-by: Heiko Stuebner <heiko@sntech.de> > Thanks for testing. > Except one issue described inline below > Reviewed-by: Heiko Stuebner <heiko@sntech.de> > > > And I'm really looking forward to having this in the kernel :-) > > Thanks for working on this > Heiko > > [snip] > > > > drivers/mfd/syscon.c | 106 > > +++++++++++++++++++++++++++++++++++++++----------- 1 file > changed, 84 > > insertions(+), 22 deletions(-) > > > > diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c index > > ca15878..00a8410 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 +23,104 @@ > > #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; > > + enum regmap_endian endian = REGMAP_ENDIAN_DEFAULT; > > + > > + 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")) > > + endian = REGMAP_ENDIAN_BIG; > > + else if (of_property_read_bool(np, "little-endian")) > > + endian = REGMAP_ENDIAN_LITTLE; > > + > > + /* If the endianness was specified in DT, use that */ > > + if (endian != REGMAP_ENDIAN_DEFAULT) > > + syscon_regmap_config.val_format_endian = endian; > > + > > + regmap = regmap_init_mmio(NULL, base, &syscon_regmap_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; > > + /* Change back endianness of syscon_regmap_config. > > + * As this is static config in this file and in one system we may > > + * have more than one syscon > > + */ > > + syscon_regmap_config.val_format_endian = > REGMAP_ENDIAN_DEFAULT; > > This should also be done in the error case. Currently when you goto err_regmap the > overridden value will be left in the struct. > Thanks, will handle this in error condition also. > While on this, is there a concurrency issue here, aka of_syscon_register could be > called in parallel and what happens with syscon_regmap_config.val_format_endian > then? I can think of two approaches to solve this. 1: Updating syscon_regmap_config, under spin_lock "syscon_list_slock". 2: Creation of local copy of syscon_regmap_config in "of_syscon_register" and using it. In this case changing back of endianness in syscon_regmap_config, will not be needed and code will be a bit cleaner. I would prefer second one, what is your opinion? Thanks, Pankaj Dubey > > > > + > > + 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 +184,6 @@ 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 +230,6 @@ 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,
Hi Pankaj, On Tue, 30 Sep 2014 09:33:38 +0530 Pankaj Dubey <pankaj.dubey@samsung.com> wrote: > Hi, > > On Monday, September 29, 2014 9:38 PM, Heiko Stübner wrote, > > Am Montag, 29. September 2014, 14:17:38 schrieb Pankaj Dubey: > > > 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 where is can be probed and such non-DT based drivers can use > > > syscon_regmap_lookup_by_pdev API and get access to 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 <arnd@arndb.de> > > > Suggested-by: Tomasz Figa <tomasz.figa@gmail.com> > > > Tested-by: Vivek Gautam <gautam.vivek@samsung.com> > > > Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> > > > Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com> > > > --- > > > > On Rockchip boards during core clock init (aka before timers) > > Tested-by: Heiko Stuebner <heiko@sntech.de> > > > > Thanks for testing. > > > Except one issue described inline below > > Reviewed-by: Heiko Stuebner <heiko@sntech.de> > > > > > > And I'm really looking forward to having this in the kernel :-) Me too :-). > > > > Thanks for working on this > > Heiko > > > > > > [snip] > > > > > > > drivers/mfd/syscon.c | 106 > > > +++++++++++++++++++++++++++++++++++++++----------- 1 file > > changed, 84 > > > insertions(+), 22 deletions(-) > > > > > > diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c index > > > ca15878..00a8410 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 +23,104 @@ > > > #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; > > > + enum regmap_endian endian = REGMAP_ENDIAN_DEFAULT; > > > + > > > + 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")) > > > + endian = REGMAP_ENDIAN_BIG; > > > + else if (of_property_read_bool(np, "little-endian")) > > > + endian = REGMAP_ENDIAN_LITTLE; > > > + > > > + /* If the endianness was specified in DT, use that */ > > > + if (endian != REGMAP_ENDIAN_DEFAULT) > > > + syscon_regmap_config.val_format_endian = endian; > > > + > > > + regmap = regmap_init_mmio(NULL, base, &syscon_regmap_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; > > > + /* Change back endianness of syscon_regmap_config. > > > + * As this is static config in this file and in one system we may > > > + * have more than one syscon > > > + */ > > > + syscon_regmap_config.val_format_endian = > > REGMAP_ENDIAN_DEFAULT; > > > > This should also be done in the error case. Currently when you goto > err_regmap the > > overridden value will be left in the struct. > > > > Thanks, will handle this in error condition also. > > > While on this, is there a concurrency issue here, aka of_syscon_register > could be > > called in parallel and what happens with > syscon_regmap_config.val_format_endian > > then? > > I can think of two approaches to solve this. > > 1: Updating syscon_regmap_config, under spin_lock "syscon_list_slock". > 2: Creation of local copy of syscon_regmap_config in "of_syscon_register" > and using > it. In this case changing back of endianness in syscon_regmap_config, will > not be needed > and code will be a bit cleaner. > > I would prefer second one, what is your opinion? I too prefer the second solution, but it's not my call :-). Best Regards, Boris
Hi Pankaj, Am Dienstag, 30. September 2014, 09:33:38 schrieb Pankaj Dubey: > Hi, > > On Monday, September 29, 2014 9:38 PM, Heiko Stübner wrote, > > > Am Montag, 29. September 2014, 14:17:38 schrieb Pankaj Dubey: > > > 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 where is can be probed and such non-DT based drivers can use > > > syscon_regmap_lookup_by_pdev API and get access to 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 <arnd@arndb.de> > > > Suggested-by: Tomasz Figa <tomasz.figa@gmail.com> > > > Tested-by: Vivek Gautam <gautam.vivek@samsung.com> > > > Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> > > > Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com> > > > --- > > > > On Rockchip boards during core clock init (aka before timers) > > Tested-by: Heiko Stuebner <heiko@sntech.de> > > Thanks for testing. > > > Except one issue described inline below > > Reviewed-by: Heiko Stuebner <heiko@sntech.de> > > > > > > And I'm really looking forward to having this in the kernel :-) > > > > Thanks for working on this > > Heiko > > [snip] > > > > drivers/mfd/syscon.c | 106 > > > > > > +++++++++++++++++++++++++++++++++++++++----------- 1 file > > > > changed, 84 > > > > > insertions(+), 22 deletions(-) > > > > > > diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c index > > > ca15878..00a8410 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 +23,104 @@ > > > > > > #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; > > > + enum regmap_endian endian = REGMAP_ENDIAN_DEFAULT; > > > + > > > + 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")) > > > + endian = REGMAP_ENDIAN_BIG; > > > + else if (of_property_read_bool(np, "little-endian")) > > > + endian = REGMAP_ENDIAN_LITTLE; > > > + > > > + /* If the endianness was specified in DT, use that */ > > > + if (endian != REGMAP_ENDIAN_DEFAULT) > > > + syscon_regmap_config.val_format_endian = endian; > > > + > > > + regmap = regmap_init_mmio(NULL, base, &syscon_regmap_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; > > > + /* Change back endianness of syscon_regmap_config. > > > + * As this is static config in this file and in one system we may > > > + * have more than one syscon > > > + */ > > > + syscon_regmap_config.val_format_endian = > > > > REGMAP_ENDIAN_DEFAULT; > > > > This should also be done in the error case. Currently when you goto > > err_regmap the > > > overridden value will be left in the struct. > > Thanks, will handle this in error condition also. > > > While on this, is there a concurrency issue here, aka of_syscon_register > > could be > > > called in parallel and what happens with > > syscon_regmap_config.val_format_endian > > > then? > > I can think of two approaches to solve this. > > 1: Updating syscon_regmap_config, under spin_lock "syscon_list_slock". > 2: Creation of local copy of syscon_regmap_config in "of_syscon_register" > and using > it. In this case changing back of endianness in syscon_regmap_config, will > not be needed > and code will be a bit cleaner. > > I would prefer second one, what is your opinion? I would also vote for the second option. Heiko
diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c index ca15878..00a8410 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 +23,104 @@ #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; + enum regmap_endian endian = REGMAP_ENDIAN_DEFAULT; + + 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")) + endian = REGMAP_ENDIAN_BIG; + else if (of_property_read_bool(np, "little-endian")) + endian = REGMAP_ENDIAN_LITTLE; + + /* If the endianness was specified in DT, use that */ + if (endian != REGMAP_ENDIAN_DEFAULT) + syscon_regmap_config.val_format_endian = endian; + + regmap = regmap_init_mmio(NULL, base, &syscon_regmap_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; + /* Change back endianness of syscon_regmap_config. + * As this is static config in this file and in one system we may + * have more than one syscon + */ + syscon_regmap_config.val_format_endian = REGMAP_ENDIAN_DEFAULT; + + 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 +184,6 @@ 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 +230,6 @@ 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,