From 8e3f9da608f14cfebac2659d8dd8737b79d01308 Mon Sep 17 00:00:00 2001 From: Sudeep Holla Date: Wed, 13 Oct 2021 10:11:27 +0100 Subject: [PATCH] firmware: arm_ffa: Handle compatibility with different firmware versions The driver currently just support v1.0 of Arm FFA specification. It also expects the firmware implementation to match the same and bail out if it doesn't match. This is causing issue when running with higher version of firmware implementation(e.g. v1.1 which will released soon). In order to support compatibility with different firmware versions, let us add additional checks and find the compatible version the driver can work with. Link: https://lore.kernel.org/r/20211013091127.990992-1-sudeep.holla@arm.com Reviewed-by: Jens Wiklander Signed-off-by: Sudeep Holla --- drivers/firmware/arm_ffa/driver.c | 37 ++++++++++++++++++++++++++----- 1 file changed, 32 insertions(+), 5 deletions(-) diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c index c9fb56afbcb4..6e0c883ab708 100644 --- a/drivers/firmware/arm_ffa/driver.c +++ b/drivers/firmware/arm_ffa/driver.c @@ -167,6 +167,28 @@ struct ffa_drv_info { static struct ffa_drv_info *drv_info; +/* + * The driver must be able to support all the versions from the earliest + * supported FFA_MIN_VERSION to the latest supported FFA_DRIVER_VERSION. + * The specification states that if firmware supports a FFA implementation + * that is incompatible with and at a greater version number than specified + * by the caller(FFA_DRIVER_VERSION passed as parameter to FFA_VERSION), + * it must return the NOT_SUPPORTED error code. + */ +static u32 ffa_compatible_version_find(u32 version) +{ + u32 compat_version; + u16 major = MAJOR_VERSION(version), minor = MINOR_VERSION(version); + u16 drv_major = MAJOR_VERSION(FFA_DRIVER_VERSION); + u16 drv_minor = MINOR_VERSION(FFA_DRIVER_VERSION); + + if ((major < drv_major) || (major == drv_major && minor <= drv_minor)) + return version; + + pr_info("Firmware version higher than driver version, downgrading\n"); + return FFA_DRIVER_VERSION; +} + static int ffa_version_check(u32 *version) { ffa_value_t ver; @@ -180,15 +202,20 @@ static int ffa_version_check(u32 *version) return -EOPNOTSUPP; } - if (ver.a0 < FFA_MIN_VERSION || ver.a0 > FFA_DRIVER_VERSION) { - pr_err("Incompatible version %d.%d found\n", - MAJOR_VERSION(ver.a0), MINOR_VERSION(ver.a0)); + if (ver.a0 < FFA_MIN_VERSION) { + pr_err("Incompatible v%d.%d! Earliest supported v%d.%d\n", + MAJOR_VERSION(ver.a0), MINOR_VERSION(ver.a0), + MAJOR_VERSION(FFA_MIN_VERSION), + MINOR_VERSION(FFA_MIN_VERSION)); return -EINVAL; } - *version = ver.a0; - pr_info("Version %d.%d found\n", MAJOR_VERSION(ver.a0), + pr_info("Driver version %d.%d\n", MAJOR_VERSION(FFA_DRIVER_VERSION), + MINOR_VERSION(FFA_DRIVER_VERSION)); + pr_info("Firmware version %d.%d found\n", MAJOR_VERSION(ver.a0), MINOR_VERSION(ver.a0)); + *version = ffa_compatible_version_find(ver.a0); + return 0; }