From c97db7cc7778e34a53b42d58c766f0ec0e30d580 Mon Sep 17 00:00:00 2001 From: Arnd Bergmann Date: Wed, 21 Sep 2016 14:57:19 +0800 Subject: [PATCH] base: soc: Introduce soc_device_match() interface We keep running into cases where device drivers want to know the exact version of the a SoC they are currently running on. In the past, this has usually been done through a vendor specific API that can be called by a driver, or by directly accessing some kind of version register that is not part of the device itself but that belongs to a global register area of the chip. Common reasons for doing this include: - A machine is not using devicetree or similar for passing data about on-chip devices, but just announces their presence using boot-time platform devices, and the machine code itself does not care about the revision. - There is existing firmware or boot loaders with existing DT binaries with generic compatible strings that do not identify the particular revision of each device, but the driver knows which SoC revisions include which part. - A prerelease version of a chip has some quirks and we are using the same version of the bootloader and the DT blob on both the prerelease and the final version. An update of the DT binding seems inappropriate because that would involve maintaining multiple copies of the dts and/or bootloader. This patch introduces the soc_device_match() interface that is meant to work like of_match_node() but instead of identifying the version of a device, it identifies the SoC itself using a vendor-agnostic interface. Unlike of_match_node(), we do not do an exact string compare but instead use glob_match() to allow wildcards in strings. Signed-off-by: Arnd Bergmann Signed-off-by: Yangbo Lu Signed-off-by: Geert Uytterhoeven Acked-by: Greg Kroah-Hartman --- drivers/base/Kconfig | 1 + drivers/base/soc.c | 66 +++++++++++++++++++++++++++++++++++++++++ include/linux/sys_soc.h | 3 ++ 3 files changed, 70 insertions(+) diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index fdf44cac08e6..991b21e1f89b 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -235,6 +235,7 @@ config GENERIC_CPU_AUTOPROBE config SOC_BUS bool + select GLOB source "drivers/base/regmap/Kconfig" diff --git a/drivers/base/soc.c b/drivers/base/soc.c index 028cef377fd4..04ee597fc3a3 100644 --- a/drivers/base/soc.c +++ b/drivers/base/soc.c @@ -13,6 +13,7 @@ #include #include #include +#include static DEFINE_IDA(soc_ida); @@ -168,3 +169,68 @@ static int __init soc_bus_register(void) return bus_register(&soc_bus_type); } core_initcall(soc_bus_register); + +static int soc_device_match_one(struct device *dev, void *arg) +{ + struct soc_device *soc_dev = container_of(dev, struct soc_device, dev); + const struct soc_device_attribute *match = arg; + + if (match->machine && + !glob_match(match->machine, soc_dev->attr->machine)) + return 0; + + if (match->family && + !glob_match(match->family, soc_dev->attr->family)) + return 0; + + if (match->revision && + !glob_match(match->revision, soc_dev->attr->revision)) + return 0; + + if (match->soc_id && + !glob_match(match->soc_id, soc_dev->attr->soc_id)) + return 0; + + return 1; +} + +/* + * soc_device_match - identify the SoC in the machine + * @matches: zero-terminated array of possible matches + * + * returns the first matching entry of the argument array, or NULL + * if none of them match. + * + * This function is meant as a helper in place of of_match_node() + * in cases where either no device tree is available or the information + * in a device node is insufficient to identify a particular variant + * by its compatible strings or other properties. For new devices, + * the DT binding should always provide unique compatible strings + * that allow the use of of_match_node() instead. + * + * The calling function can use the .data entry of the + * soc_device_attribute to pass a structure or function pointer for + * each entry. + */ +const struct soc_device_attribute *soc_device_match( + const struct soc_device_attribute *matches) +{ + int ret = 0; + + if (!matches) + return NULL; + + while (!ret) { + if (!(matches->machine || matches->family || + matches->revision || matches->soc_id)) + break; + ret = bus_for_each_dev(&soc_bus_type, NULL, (void *)matches, + soc_device_match_one); + if (!ret) + matches++; + else + return matches; + } + return NULL; +} +EXPORT_SYMBOL_GPL(soc_device_match); diff --git a/include/linux/sys_soc.h b/include/linux/sys_soc.h index 2739ccb69571..9f5eb06f9fd8 100644 --- a/include/linux/sys_soc.h +++ b/include/linux/sys_soc.h @@ -13,6 +13,7 @@ struct soc_device_attribute { const char *family; const char *revision; const char *soc_id; + const void *data; }; /** @@ -34,4 +35,6 @@ void soc_device_unregister(struct soc_device *soc_dev); */ struct device *soc_device_to_device(struct soc_device *soc); +const struct soc_device_attribute *soc_device_match( + const struct soc_device_attribute *matches); #endif /* __SOC_BUS_H */