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Grygorii Strashko
10e7473d60
The commit 3e322bef8b ("xen/arm: firmware: Add SCMI over SMC calls
handling layer") introduces simple driver which forwards SCMI over SMC
calls from hwdom/dom0 to EL3 firmware (TF-A) with a single SCMI OSPM agent
support. While it is working gracefully for hwdom/dom0 use case it doesn't
cover "thin Dom0 with guest domain, which serves as Driver domain"
use-case. In this case HW need to be enable in Driver domain and dom0 is
performing only control functions.
The EL3 SCMI firmware (TF-A) with a single SCMI OSPM agent support is
pretty generic case for the default vendors SDK and new platforms.
This patch enables passthrough of SCMI SMC single agent interface to the
one guest domain serving as Driver domain.
Configure Dom0 to enable SCMI passthrough:
- dom0: add scmi-smc-passthrough to the Xen Command Line
Enabled SCMI passthrough for guest using toolstack in the following way:
- domD: xl.cfg add "arm_sci" option as below
arm_sci = "type=scmi_smc"
- domD: xl.cfg enable access to the "arm,scmi-shmem"
iomem = [
"47ff0,1@22001",
]
- domD: add SCMI nodes to the Driver domain partial device tree as in the
below example:
passthrough {
scmi_shm_0: sram@22001000 {
compatible = "arm,scmi-shmem";
reg = <0x0 0x22001000 0x0 0x1000>;
};
firmware {
compatible = "simple-bus";
scmi: scmi {
compatible = "arm,scmi-smc";
shmem = <&scmi_shm_0>;
...
}
}
}
dom0less case configuration:
- add "xen,sci_type" property for required DomU ("xen,domain") node
xen,sci_type="scmi_smc"
- add scmi nodes to the Driver domain partial device tree the same way
as above and enable access to the "arm,scmi-shmem" according to
dom0less documentation. For example:
scmi_shm_0: sram@22001000 {
compatible = "arm,scmi-shmem";
reg = <0x00 0x22001000 0x00 0x1000>;
-> xen,reg = <0x0 0x47ff0000 0x0 0x1000 0x0 0x22001000>;
-> xen,force-assign-without-iommu;
};
The SCMI SMC single agent interface can be enabled for one and only one
domain. In general, the configuration is similar to any other HW
passthrough, except explicitly enabling SCMI with "arm_sci" xl.cfg option.
Note that "arm,scmi-smc" and "arm,scmi-shmem" nodes will be removed from
dom0/hwdom DT when "scmi-smc-passthrough" cmdline parameter was provided.
Signed-off-by: Grygorii Strashko <grygorii_strashko@epam.com>
Signed-off-by: Oleksii Moisieiev <oleksii_moisieiev@epam.com>
Acked-by: Anthony PERARD <anthony.perard@vates.tech> # tools