From 4731210c09f5977300f439b6c56ba220c65b2348 Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Fri, 22 Jan 2021 11:35:59 -0800 Subject: gpiolib: Bind gpio_device to a driver to enable fw_devlink=on by default There are multiple instances of GPIO device tree nodes of the form: foo { compatible = "acme,foo"; ... gpio0: gpio0@xxxxxxxx { compatible = "acme,bar"; ... gpio-controller; }; gpio1: gpio1@xxxxxxxx { compatible = "acme,bar"; ... gpio-controller; }; ... } bazz { my-gpios = <&gpio0 ...>; } Case 1: The driver for "foo" populates struct device for these gpio* nodes and then probes them using a driver that binds with "acme,bar". This driver for "acme,bar" then registers the gpio* nodes with gpiolib. This lines up with how DT nodes with the "compatible" property are typically converted to struct devices and then registered with driver core to probe them. This also allows the gpio* devices to hook into all the driver core capabilities like runtime PM, probe deferral, suspend/resume ordering, device links, etc. Case 2: The driver for "foo" doesn't populate struct devices for these gpio* nodes before registering them with gpiolib. Instead it just loops through its child nodes and directly registers the gpio* nodes with gpiolib. Drivers that follow case 2 cause problems with fw_devlink=on. This is because fw_devlink will prevent bazz from probing until there's a struct device that has gpio0 as its fwnode (because bazz lists gpio0 as a GPIO supplier). Once the struct device is available, fw_devlink will create a device link with gpio0 device as the supplier and bazz device as the consumer. After this point, since the gpio0 device will never bind to a driver, the device link will prevent bazz device from ever probing. Finding and refactoring all the instances of drivers that follow case 2 will cause a lot of code churn and it is not something that can be done in one shot. In some instances it might not even be possible to refactor them cleanly. Examples of such instances are [1] [2]. This patch works around this problem and avoids all the code churn by simply setting the fwnode of the gpio_device and creating a stub driver to bind to the gpio_device. This allows all the consumers to continue probing when the driver follows case 2. [1] - https://lore.kernel.org/lkml/20201014191235.7f71fcb4@xhacker.debian/ [2] - https://lore.kernel.org/lkml/e28e1f38d87c12a3c714a6573beba6e1@kernel.org/ Fixes: e590474768f1 ("driver core: Set fw_devlink=on by default") Cc: Marc Zyngier Cc: Jisheng Zhang Cc: Kever Yang Reviewed-by: Linus Walleij Acked-by: Bartosz Golaszewski Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20210122193600.1415639-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpio/gpiolib-of.c | 11 +++++++++++ drivers/gpio/gpiolib-of.h | 5 +++++ drivers/gpio/gpiolib.c | 38 +++++++++++++++++++++++++++++++------- 3 files changed, 47 insertions(+), 7 deletions(-) (limited to 'drivers/gpio') diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c index b4a71119a4b0..baf0153b7bca 100644 --- a/drivers/gpio/gpiolib-of.c +++ b/drivers/gpio/gpiolib-of.c @@ -1039,3 +1039,14 @@ void of_gpiochip_remove(struct gpio_chip *chip) { of_node_put(chip->of_node); } + +void of_gpio_dev_init(struct gpio_chip *gc, struct gpio_device *gdev) +{ + /* If the gpiochip has an assigned OF node this takes precedence */ + if (gc->of_node) + gdev->dev.of_node = gc->of_node; + else + gc->of_node = gdev->dev.of_node; + if (gdev->dev.of_node) + gdev->dev.fwnode = of_fwnode_handle(gdev->dev.of_node); +} diff --git a/drivers/gpio/gpiolib-of.h b/drivers/gpio/gpiolib-of.h index ed26664f1537..8af2bc899aab 100644 --- a/drivers/gpio/gpiolib-of.h +++ b/drivers/gpio/gpiolib-of.h @@ -15,6 +15,7 @@ int of_gpiochip_add(struct gpio_chip *gc); void of_gpiochip_remove(struct gpio_chip *gc); int of_gpio_get_count(struct device *dev, const char *con_id); bool of_gpio_need_valid_mask(const struct gpio_chip *gc); +void of_gpio_dev_init(struct gpio_chip *gc, struct gpio_device *gdev); #else static inline struct gpio_desc *of_find_gpio(struct device *dev, const char *con_id, @@ -33,6 +34,10 @@ static inline bool of_gpio_need_valid_mask(const struct gpio_chip *gc) { return false; } +static inline void of_gpio_dev_init(struct gpio_chip *gc, + struct gpio_device *gdev) +{ +} #endif /* CONFIG_OF_GPIO */ extern struct notifier_block gpio_of_notifier; diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index b78a634cca24..8e0564c50840 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -590,13 +590,7 @@ int gpiochip_add_data_with_key(struct gpio_chip *gc, void *data, gdev->dev.of_node = gc->parent->of_node; } -#ifdef CONFIG_OF_GPIO - /* If the gpiochip has an assigned OF node this takes precedence */ - if (gc->of_node) - gdev->dev.of_node = gc->of_node; - else - gc->of_node = gdev->dev.of_node; -#endif + of_gpio_dev_init(gc, gdev); gdev->id = ida_alloc(&gpio_ida, GFP_KERNEL); if (gdev->id < 0) { @@ -4205,6 +4199,29 @@ void gpiod_put_array(struct gpio_descs *descs) } EXPORT_SYMBOL_GPL(gpiod_put_array); +static int gpio_stub_drv_probe(struct device *dev) +{ + /* + * The DT node of some GPIO chips have a "compatible" property, but + * never have a struct device added and probed by a driver to register + * the GPIO chip with gpiolib. In such cases, fw_devlink=on will cause + * the consumers of the GPIO chip to get probe deferred forever because + * they will be waiting for a device associated with the GPIO chip + * firmware node to get added and bound to a driver. + * + * To allow these consumers to probe, we associate the struct + * gpio_device of the GPIO chip with the firmware node and then simply + * bind it to this stub driver. + */ + return 0; +} + +static struct device_driver gpio_stub_drv = { + .name = "gpio_stub_drv", + .bus = &gpio_bus_type, + .probe = gpio_stub_drv_probe, +}; + static int __init gpiolib_dev_init(void) { int ret; @@ -4216,9 +4233,16 @@ static int __init gpiolib_dev_init(void) return ret; } + if (driver_register(&gpio_stub_drv) < 0) { + pr_err("gpiolib: could not register GPIO stub driver\n"); + bus_unregister(&gpio_bus_type); + return ret; + } + ret = alloc_chrdev_region(&gpio_devt, 0, GPIO_DEV_MAX, GPIOCHIP_NAME); if (ret < 0) { pr_err("gpiolib: failed to allocate char dev region\n"); + driver_unregister(&gpio_stub_drv); bus_unregister(&gpio_bus_type); return ret; } -- cgit v1.2.3 From ced2af419528611bac9ffebb8e51aa59a8e9fca3 Mon Sep 17 00:00:00 2001 From: Saravana Kannan Date: Thu, 4 Feb 2021 18:07:30 -0800 Subject: gpiolib: Don't probe gpio_device if it's not the primary device Dmitry reported[1] boot error messages caused by commit 4731210c09f5 ("gpiolib: Bind gpio_device to a driver to enable fw_devlink=on by default"). gpio-1022 (cpu-pwr-req-hog): hogged as input max77620-pinctrl max77620-pinctrl: pin gpio4 already requested by max77620-pinctrl; cannot claim for gpiochip1 max77620-pinctrl max77620-pinctrl: pin-4 (gpiochip1) status -22 max77620-pinctrl max77620-pinctrl: could not request pin 4 (gpio4) from group gpio4 on device max77620-pinctrl gpio_stub_drv gpiochip1: Error applying setting, reverse things back gpio_stub_drv: probe of gpiochip1 failed with error -22 This happens because when we try to probe a device, driver core calls into pinctrl to set up the pins. However, if the GPIO DT node already has a proper device created and probed, trying to probe the gpio_device with a stub driver makes the pins be claimed twice. pinctrl doesn't like this and throws an error. So, this patch makes sure the gpio_stub_drv doesn't match with a gpio_device if it's not the primary device for the fwnode. [1] - https://lore.kernel.org/lkml/544ad0e4-0954-274c-8e77-866aaa5661a8@gmail.com/ Fixes: 4731210c09f5 ("gpiolib: Bind gpio_device to a driver to enable fw_devlink=on by default") Tested-by: Dmitry Osipenko Tested-by: Geert Uytterhoeven Acked-by: Bartosz Golaszewski Signed-off-by: Saravana Kannan Link: https://lore.kernel.org/r/20210205020730.1746354-1-saravanak@google.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpio/gpiolib.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'drivers/gpio') diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 8e0564c50840..8ad679a928b0 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -56,8 +56,10 @@ static DEFINE_IDA(gpio_ida); static dev_t gpio_devt; #define GPIO_DEV_MAX 256 /* 256 GPIO chip devices supported */ +static int gpio_bus_match(struct device *dev, struct device_driver *drv); static struct bus_type gpio_bus_type = { .name = "gpio", + .match = gpio_bus_match, }; /* @@ -4199,6 +4201,18 @@ void gpiod_put_array(struct gpio_descs *descs) } EXPORT_SYMBOL_GPL(gpiod_put_array); + +static int gpio_bus_match(struct device *dev, struct device_driver *drv) +{ + /* + * Only match if the fwnode doesn't already have a proper struct device + * created for it. + */ + if (dev->fwnode && dev->fwnode->dev != dev) + return 0; + return 1; +} + static int gpio_stub_drv_probe(struct device *dev) { /* -- cgit v1.2.3