drivers/ipmi: Add chip ops

* Add chips ops for IPMI KCS.
* Get IPMI version over KCS.
* Generates ACPI SPMI table for IPMI KCS.
* Generates SMBIOS type 38 for IPMI KCS.
* Generates ACPI SPMI device for IPMI KCS on LPC device.
* Add documentation

To use this driver on BMC that support KCS on I/O:

1. Add an entry to the devicetree.cb:

 chip drivers/ipmi
    device pnp ca2.0 on end         # IPMI KCS
 end

2. Select IPMI_KCS in Kconfig.
3. (Optional) enable LPC I/O decode for the given address.

Tested on Wedge100s.

Change-Id: I73cbd2058ccdc5395baf244f31345a85eb0047d7
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/33255
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

2 files changed, 54 insertions, 0 deletions

diff --git a/Documentation/drivers/index.md b/Documentation/drivers/index.md
new file mode 100644
index 0000000000..642ae1a5f3
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+++ b/Documentation/drivers/index.md
@@ -0,0 +1,7 @@
+# Platform indenpendend drivers documentation
+
+The drivers can be found in `src/drivers`. They are intended for onboard
+and plugin devices, significantly reducing integration complexity and
+they allow to easily reuse existing code accross platforms.
+
+* [IPMI KCS](ipmi_kcs.md)
diff --git a/Documentation/drivers/ipmi_kcs.md b/Documentation/drivers/ipmi_kcs.md
new file mode 100644
index 0000000000..f6f0fb986a
--- /dev/null
+++ b/Documentation/drivers/ipmi_kcs.md
@@ -0,0 +1,47 @@
+# IPMI KCS driver
+
+The driver can be found in `src/drivers/ipmi/`. It works with BMC that provide
+a KCS I/O interface as specified in the [IPMI] standard.
+
+The driver detects the IPMI version, reserves the I/O space in coreboot's
+resource allocator and writes the required ACPI and SMBIOS tables.
+
+## For developers
+
+To use the driver, select the `IPMI_KCS` Kconfig and add the following PNP
+device under the LPC bridge device (in example for the KCS at 0xca2):
+
+```
+ chip drivers/ipmi
+   device pnp ca2.0 on end         # IPMI KCS
+ end
+```
+
+**Note:** The I/O base address needs to be aligned to 2.
+
+The following registers can be set:
+
+* `have_nv_storage`
+  * Boolean
+  * If true `nv_storage_device_address` will be added to SMBIOS type 38.
+* `nv_storage_device_address`
+  * Integer
+  * The NV storage address as defined in SMBIOS spec for type 38.
+* `bmc_i2c_address`
+  * Integer
+  * The i2c address of the BMC. zero if not applicable.
+* `have_apic`
+  * Boolean
+  * If true the `apic_interrupt` will be added to SPMI table.
+* `apic_interrupt`
+  * Integer
+  * The APIC interrupt used to notify about a change on the KCS.
+* `have_gpe`
+  * Boolean
+  * If true the `gpe_interrupt` will be added to SPMI table.
+* `gpe_interrupt`
+  * Integer
+  * The bit in GPE (SCI) used to notify about a change on the KCS.
+
+
+[IPMI]: https://www.intel.com/content/dam/www/public/us/en/documents/product-briefs/ipmi-second-gen-interface-spec-v2-rev1-1.pdf