| Message ID | 1411132009-11173-1-git-send-email-pankaj.dubey@samsung.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hello Pankaj, On Fri, Sep 19, 2014 at 3:06 PM, Pankaj Dubey <pankaj.dubey@samsung.com> 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 completly 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> > Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com> > --- > 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/2014/9/2/299 > drivers/mfd/syscon.c | 102 ++++++++++++++++++++++++++++++++++++++------------ > 1 file changed, 79 insertions(+), 23 deletions(-) > I tested this patch on an Exynos5420 Peach Pit Chromebook and I see that of_syscon_register() is called for the PMU system controller with compatible string "samsung,exynos5420-pmu", "syscon" which does not have a dedicated platform driver, so: Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk> Best regards, Javier
Hi Pankaj, Please see my comments inline. On 19.09.2014 15:06, 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. [snip] > -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 platform_device *pdev = NULL; > + struct syscon *syscon; > + struct regmap *regmap; > + void __iomem *base; > + > + nit: Stray blank line. > + if (!of_device_is_compatible(np, "syscon")) > + return ERR_PTR(-EINVAL); I don't think this check is needed at all. I'd say that drivers should be free to register a syscon provider for any node. > + > + syscon = kzalloc(sizeof(*syscon), GFP_KERNEL); > + if (!syscon) > + return ERR_PTR(-ENOMEM); > + > + base = of_iomap(np, 0); > + if (!base) > + return ERR_PTR(-ENOMEM); > + > + if (!of_device_is_available(np) || Wouldn't it be enough to simply call of_find_device_by_node(np) and if it fails then instead create a dummy device? > + of_node_test_and_set_flag(np, OF_POPULATED)) { > + /* if device is already populated and avaiable then use it */ > + pdev = of_find_device_by_node(np); > + if (!(&pdev->dev)) This is just plain wrong, because this condition will always evaluate to true (see the definition of struct platform_device). Shouldn't you rather just check the pdev pointer? > + return ERR_PTR(-ENODEV); > + > + } else { > + /* for early users create dummy syscon device and use it */ > + pdev = kzalloc(sizeof(*pdev), GFP_KERNEL); > + if (!pdev) > + return ERR_PTR(-ENOMEM); Any clean-up on error path? > + > + pdev->name = "dummy-syscon"; > + pdev->id = -1; Wouldn't you get an ID collision if more than one syscon is registered early? Maybe the naming scheme from of_device_alloc() could be adopted partially? > + device_initialize(&pdev->dev); I wonder if you couldn't simply reuse platform_device_alloc() for all of this, except the line below, which would still have to be handled separately. > + pdev->dev.of_node = np; > + } > + > + regmap = regmap_init_mmio(&pdev->dev, base, &syscon_regmap_config); > + if (IS_ERR(regmap)) { > + pr_err("regmap init failed\n"); If you have a dev here then you should be able to use dev_err() already. > + return ERR_CAST(regmap); > + } > + > + syscon->regmap = regmap; > + syscon->np = np; > > - return (dev->of_node == dn) ? 1 : 0; > + spin_lock(&syscon_list_slock); > + list_add_tail(&syscon->list, &syscon_list); > + spin_unlock(&syscon_list_slock); > + > + return syscon; > } > > 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; > + } > > - return syscon->regmap; > + spin_unlock(&syscon_list_slock); > + > + if (!syscon) > + syscon = of_syscon_register(np); > + > + if (!IS_ERR(syscon)) > + return syscon->regmap; > + > + return ERR_CAST(syscon); nit: Usually error checking is done the opposite way, i.e. if (IS_ERR(syscon)) return ERR_CAST(syscon); return syscon->regmap; Best regards, Tomasz
On 19.09.2014 17:11, Tomasz Figa wrote: >> + >> + if (!of_device_is_available(np) || > > Wouldn't it be enough to simply call of_find_device_by_node(np) and if > it fails then instead create a dummy device? > >> + of_node_test_and_set_flag(np, OF_POPULATED)) { One more thing I forgot to mention, the call to of_node_test_and_set_flag() is also wrong, because it sets the flag, marking the device as already populated, while it isn't. Best regards, Tomasz
Hi Tomasz, On Friday, September 19, 2014 Tomasz Figa wrote, > Hi Pankaj, > > Please see my comments inline. > > On 19.09.2014 15:06, 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. > > [snip] > > > -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 platform_device *pdev = NULL; > > + struct syscon *syscon; > > + struct regmap *regmap; > > + void __iomem *base; > > + > > + > > nit: Stray blank line. > OK. Will remove this. > > + if (!of_device_is_compatible(np, "syscon")) > > + return ERR_PTR(-EINVAL); > > I don't think this check is needed at all. I'd say that drivers should be free to register a > syscon provider for any node. I think this check is correct, as only nodes having "syscon" as secondary compatibility should be used to create a syscon provider. And that's why we have "syscon" as secondary compatibility in device nodes which can be a syscon provider. > > > + > > + syscon = kzalloc(sizeof(*syscon), GFP_KERNEL); > > + if (!syscon) > > + return ERR_PTR(-ENOMEM); > > + > > + base = of_iomap(np, 0); > > + if (!base) > > + return ERR_PTR(-ENOMEM); > > + > > + if (!of_device_is_available(np) || > > Wouldn't it be enough to simply call of_find_device_by_node(np) and if it fails then > instead create a dummy device? > OK, this could be also one of approach, I will change accordingly. > > + of_node_test_and_set_flag(np, OF_POPULATED)) { > > + /* if device is already populated and avaiable then use it */ > > + pdev = of_find_device_by_node(np); > > + if (!(&pdev->dev)) > > This is just plain wrong, because this condition will always evaluate to true (see the > definition of struct platform_device). Shouldn't you rather just check the pdev > pointer? OK, will update this. > > > + return ERR_PTR(-ENODEV); > > + > > + } else { > > + /* for early users create dummy syscon device and use it */ > > + pdev = kzalloc(sizeof(*pdev), GFP_KERNEL); > > + if (!pdev) > > + return ERR_PTR(-ENOMEM); > > Any clean-up on error path? OK, will add error path. Also will use platform_device_alloc as suggested. > > > + > > + pdev->name = "dummy-syscon"; > > + pdev->id = -1; > > Wouldn't you get an ID collision if more than one syscon is registered early? Maybe > the naming scheme from of_device_alloc() could be adopted partially? I think this should not be an issue, passing id as -1 should take care of this. As you know Exynos has two syscon providers "pmu" and "sysreg" I have written a test code to check this scenario and tested it during early stage and I am successfully able to get PMU and SYSREG handle. > > > + device_initialize(&pdev->dev); > > I wonder if you couldn't simply reuse platform_device_alloc() for all of this, except > the line below, which would still have to be handled separately. > > > + pdev->dev.of_node = np; > > + } > > + > > + regmap = regmap_init_mmio(&pdev->dev, base, &syscon_regmap_config); > > + if (IS_ERR(regmap)) { > > + pr_err("regmap init failed\n"); > > If you have a dev here then you should be able to use dev_err() already. OK. > > > + return ERR_CAST(regmap); > > + } [snip] > > + > > + if (!syscon) > > + syscon = of_syscon_register(np); > > + > > + if (!IS_ERR(syscon)) > > + return syscon->regmap; > > + > > + return ERR_CAST(syscon); > > nit: Usually error checking is done the opposite way, i.e. OK, will change accordingly. Thanks, Pankaj Dubey > > if (IS_ERR(syscon)) > return ERR_CAST(syscon); > > return syscon->regmap; > > Best regards, > Tomasz
diff --git a/drivers/mfd/syscon.c b/drivers/mfd/syscon.c index ca15878..630de0a 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> @@ -22,33 +23,100 @@ #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 platform_device *pdev = NULL; + struct syscon *syscon; + struct regmap *regmap; + void __iomem *base; + + + 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) + return ERR_PTR(-ENOMEM); + + if (!of_device_is_available(np) || + of_node_test_and_set_flag(np, OF_POPULATED)) { + /* if device is already populated and avaiable then use it */ + pdev = of_find_device_by_node(np); + if (!(&pdev->dev)) + return ERR_PTR(-ENODEV); + + } else { + /* for early users create dummy syscon device and use it */ + pdev = kzalloc(sizeof(*pdev), GFP_KERNEL); + if (!pdev) + return ERR_PTR(-ENOMEM); + + pdev->name = "dummy-syscon"; + pdev->id = -1; + device_initialize(&pdev->dev); + pdev->dev.of_node = np; + } + + regmap = regmap_init_mmio(&pdev->dev, base, &syscon_regmap_config); + if (IS_ERR(regmap)) { + pr_err("regmap init failed\n"); + return ERR_CAST(regmap); + } + + syscon->regmap = regmap; + syscon->np = np; - return (dev->of_node == dn) ? 1 : 0; + spin_lock(&syscon_list_slock); + list_add_tail(&syscon->list, &syscon_list); + spin_unlock(&syscon_list_slock); + + return syscon; } 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; + } - return syscon->regmap; + spin_unlock(&syscon_list_slock); + + if (!syscon) + syscon = of_syscon_register(np); + + if (!IS_ERR(syscon)) + return syscon->regmap; + + return ERR_CAST(syscon); } EXPORT_SYMBOL_GPL(syscon_node_to_regmap); @@ -110,17 +178,6 @@ 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 +224,6 @@ 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,