Consider a case when we have several similar boards but leds & buttons connected differently. Some of leds uses gpio, other pwm, third gpio over spi bitbang. Also different board may have different gpio hogs. And last but not least: board type stored inside a ubi volume.
We want a single u-boot image that will support all these boards (we are not using SPL). So we need runtime dtb switching. We can't use MULTI_DTB_FIT and DTB_RESELECT because they tries to switch dtb too early when flash & ubi drivers are not loaded/activated. The following code do runtime switching ret = fdtdec_resetup(&rescan); if (!ret && rescan){ dm_uninit(); dm_init_and_scan(false); } but it have several nasty issues * additional code required to reinitialize console otherwise board will hang. * MTD subsystem is not cleared, we need to remove mtd partition before switching to new dtb * spi-nand flash will be named "spi-nand1" instead of "spi-nand0", thus flash becomes unusable * some drivers are unable to deinitialize properly (ex: network driver will not release mdio interface) * some memory will leak, because most of drivers assumes that it will never be unloaded To avoid this nasty issues the following hack was implemented * Full DM and console reinitialization was skipped * Only missed device/subdevice added from new dtb during device scan. * Some driver renames their devices. As result we can't use device names to match old device node with a new one. The special field was added to struct udevice for this purposes. * Driver must be binded to the old device one more time to add missed subdevices. * uclass must be post_bind to the old device one more time to add missed subdevices. * We can't use old dtb anymore, so replace old device node with a new one for existing devices. The following restrictions are present: * initial dtb MUST be a subset of a new one * old devices will NOT be reinitialised * no devices will be deleted or deactivated * only new devices will be added Typical usage: ret = fdtdec_resetup(&rescan); if (!ret && rescan) dm_rescan(); The code was tested with: gpio, gpio_hog, leds, buttons. Signed-off-by: Mikhail Kshevetskiy <mikhail.kshevets...@iopsys.eu> --- drivers/core/device.c | 31 +++++++++++++++++++++++++++++++ drivers/core/root.c | 15 +++++++++++++++ dts/Kconfig | 8 ++++++++ include/dm/device.h | 3 +++ include/dm/root.h | 23 +++++++++++++++++++++++ 5 files changed, 80 insertions(+) diff --git a/drivers/core/device.c b/drivers/core/device.c index bf7f261cbce..4f575ca82e7 100644 --- a/drivers/core/device.c +++ b/drivers/core/device.c @@ -62,6 +62,34 @@ static int device_bind_common(struct udevice *parent, const struct driver *drv, return ret; } +#if CONFIG_IS_ENABLED(MULTI_DTB_FIT_RESCAN) + if (parent) { + struct list_head *entry; + ofnode dev_node; + + list_for_each(entry, &parent->child_head) { + dev = list_entry(entry, struct udevice, sibling_node); + dev_node = dev_ofnode(dev); + if ((dev->driver == drv) && (dev->uclass == uc) && + (dev->driver_data == driver_data) && + (strcmp(dev->node_name, ofnode_get_name(node)) == 0)) + { + ret = 0; + dev_set_ofnode(dev, node); + if (drv->bind) + ret = drv->bind(dev); + + if (!ret && uc->uc_drv->post_bind) + ret = uc->uc_drv->post_bind(dev); + + if (!ret && devp) + *devp = dev; + return ret; + } + } + } +#endif + dev = calloc(1, sizeof(struct udevice)); if (!dev) return -ENOMEM; @@ -75,6 +103,9 @@ static int device_bind_common(struct udevice *parent, const struct driver *drv, dev_set_plat(dev, plat); dev->driver_data = driver_data; dev->name = name; +#if CONFIG_IS_ENABLED(MULTI_DTB_FIT_RESCAN) + dev->node_name = name; +#endif dev_set_ofnode(dev, node); dev->parent = parent; dev->driver = drv; diff --git a/drivers/core/root.c b/drivers/core/root.c index d4ae652bcfb..4bf1ff80636 100644 --- a/drivers/core/root.c +++ b/drivers/core/root.c @@ -340,6 +340,21 @@ static int dm_scan(bool pre_reloc_only) return dm_probe_devices(gd->dm_root, pre_reloc_only); } +#if CONFIG_IS_ENABLED(MULTI_DTB_FIT_RESCAN) +int dm_rescan(void) +{ + int ret; + + ret = dm_extended_scan(false); + if (ret) { + debug("dm_extended_scan() failed: %d\n", ret); + return ret; + } + + return dm_probe_devices(gd->dm_root, false); +} +#endif + int dm_init_and_scan(bool pre_reloc_only) { int ret; diff --git a/dts/Kconfig b/dts/Kconfig index 6883a000a05..ab486b21fe2 100644 --- a/dts/Kconfig +++ b/dts/Kconfig @@ -292,6 +292,14 @@ config DTB_RESELECT config allows boards to implement a function at a later point during boot to switch to the "correct" dtb. +config MULTI_DTB_FIT_RESCAN + bool "Support switching dtb without drivers unloading (experimental)" + depends on MULTI_DTB_FIT + help + This configs adds possibility to switch from initial (minimal) dtb + to a "correct" one without devices/drivers unloading (ex: board type + required to switch dtb stored in ubi volume) + config MULTI_DTB_FIT bool "Support embedding several DTBs in a FIT image for u-boot" help diff --git a/include/dm/device.h b/include/dm/device.h index add67f9ec06..409b1c4861a 100644 --- a/include/dm/device.h +++ b/include/dm/device.h @@ -170,6 +170,9 @@ enum { struct udevice { const struct driver *driver; const char *name; +#if CONFIG_IS_ENABLED(MULTI_DTB_FIT_RESCAN) + const char *node_name; +#endif void *plat_; void *parent_plat_; void *uclass_plat_; diff --git a/include/dm/root.h b/include/dm/root.h index b2f30a842f5..dcab28f6c47 100644 --- a/include/dm/root.h +++ b/include/dm/root.h @@ -155,6 +155,29 @@ int dm_init(bool of_live); */ int dm_uninit(void); +#if CONFIG_IS_ENABLED(MULTI_DTB_FIT_RESCAN) +/** + * dm_rescan - Rescan ftd and add missed DM devices (experimental) + * + * This function can be used for switching from initial (minimal) dtb + * to a "correct" one without devices/drivers unloading. + * + * Restrictions: + * - initial dtb MUST be a subset of a new one + * - old devices will NOT be reinitialised + * - no devices will be deleted or deactivated + * - only new devices will be added + * + * Typical usage: + * ret = fdtdec_resetup(&rescan); + * if (!ret && rescan) + * dm_rescan(); + * + * Return: 0 if OK, -ve on error + */ +int dm_rescan(void); +#endif + #if CONFIG_IS_ENABLED(DM_DEVICE_REMOVE) /** * dm_remove_devices_flags - Call remove function of all drivers with -- 2.43.0