[PATCH 3/8] nvdimm acpi: introduce _FIT

[Xiao Guangrong <guangrong.xiao@linux.intel.com>]

_FIT is required for hotplug support, guest will inquire the updated
device info from it if a hotplug event is received

As FIT buffer is not completely mapped into guest address space, so a
new function, Read FIT whose function index is 0xFFFFFFFF, is reserved
by QEMU to read the piece of FIT buffer. The buffer is concatenated
before _FIT return

Refer to docs/specs/acpi-nvdimm.txt for detailed design

Signed-off-by: Xiao Guangrong <guangrong.xiao@linux.intel.com>
---
 hw/acpi/nvdimm.c | 82 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 82 insertions(+)

diff --git a/hw/acpi/nvdimm.c b/hw/acpi/nvdimm.c
index 0e2b9f0..4bbd1e7 100644
--- a/hw/acpi/nvdimm.c
+++ b/hw/acpi/nvdimm.c
@@ -886,6 +886,87 @@ static void nvdimm_build_device_dsm(Aml *dev, uint32_t handle)
     aml_append(dev, method);
 }
 
+static void nvdimm_build_fit(Aml *dev)
+{
+    Aml *method, *pkg, *buf, *buf_size, *offset, *call_result;
+    Aml *whilectx, *ifcond, *ifctx, *fit;
+
+    buf = aml_local(0);
+    buf_size = aml_local(1);
+    fit = aml_local(2);
+
+    /* build helper function, RFIT. */
+    method = aml_method("RFIT", 1, AML_NOTSERIALIZED);
+    aml_append(method, aml_create_dword_field(aml_buffer(4, NULL),
+                                              aml_int(0), "OFST"));
+
+    /* prepare input package. */
+    pkg = aml_package(1);
+    aml_append(method, aml_store(aml_arg(0), aml_name("OFST")));
+    aml_append(pkg, aml_name("OFST"));
+
+    /* call Read_FIT function. */
+    call_result = aml_call5(NVDIMM_COMMON_DSM,
+                            aml_touuid("2F10E7A4-9E91-11E4-89D3-123B93F75CBA"
+                            /* UUID for NVDIMM Root Device */),
+                            aml_int(1) /* Revision 1 */,
+                            aml_int(0xFFFFFFFF) /* Read FIT. */,
+                            pkg, aml_int(0) /* for root device. */);
+    aml_append(method, aml_store(call_result, buf));
+
+    /* handle _DSM result. */
+    aml_append(method, aml_create_dword_field(buf,
+               aml_int(0) /* offset at byte 0 */, "STAU"));
+
+     /* if something is wrong during _DSM. */
+    ifcond = aml_equal(aml_int(0 /* Success */), aml_name("STAU"));
+    ifctx = aml_if(aml_lnot(ifcond));
+    aml_append(ifctx, aml_return(aml_buffer(0, NULL)));
+    aml_append(method, ifctx);
+
+    aml_append(method, aml_store(aml_sizeof(buf), buf_size));
+    aml_append(method, aml_subtract(buf_size,
+                                    aml_int(4) /* the size of "STAU" */,
+                                    buf_size));
+
+    /* if we read the end of fit. */
+    ifctx = aml_if(aml_equal(buf_size, aml_int(0)));
+    aml_append(ifctx, aml_return(aml_buffer(0, NULL)));
+    aml_append(method, ifctx);
+
+    aml_append(method, aml_store(aml_shiftleft(buf_size, aml_int(3)),
+                                 buf_size));
+    aml_append(method, aml_create_field(buf,
+                            aml_int(4 * BITS_PER_BYTE), /* offset at byte 4.*/
+                            buf_size, "BUFF"));
+    aml_append(method, aml_return(aml_name("BUFF")));
+    aml_append(dev, method);
+
+    /* build _FIT. */
+    method = aml_method("_FIT", 0, AML_NOTSERIALIZED);
+    offset = aml_local(3);
+
+    aml_append(method, aml_store(aml_buffer(0, NULL), fit));
+    aml_append(method, aml_store(aml_int(0), offset));
+
+    whilectx = aml_while(aml_int(1));
+    aml_append(whilectx, aml_store(aml_call1("RFIT", offset), buf));
+    aml_append(whilectx, aml_store(aml_sizeof(buf), buf_size));
+
+    /* finish fit read if no data is read out. */
+    ifctx = aml_if(aml_equal(buf_size, aml_int(0)));
+    aml_append(ifctx, aml_return(fit));
+    aml_append(whilectx, ifctx);
+
+    /* update the offset. */
+    aml_append(whilectx, aml_add(offset, buf_size, offset));
+    /* append the data we read out to the fit buffer. */
+    aml_append(whilectx, aml_concatenate(fit, buf, fit));
+    aml_append(method, whilectx);
+
+    aml_append(dev, method);
+}
+
 static void nvdimm_build_nvdimm_devices(Aml *root_dev, uint32_t ram_slots)
 {
     uint32_t slot;
@@ -1001,6 +1082,7 @@ static void nvdimm_build_ssdt(GArray *table_offsets, GArray *table_data,
 
     /* 0 is reserved for root device. */
     nvdimm_build_device_dsm(dev, 0);
+    nvdimm_build_fit(dev);
 
     nvdimm_build_nvdimm_devices(dev, ram_slots);
 
-- 
1.8.3.1