[PATCH 2/4] powerpc/pseries: Add RTAS error injection buffer infrastructure

[Narayana Murty N <nnmlinux@linux.ibm.com>]

Adds global infrastructure required by the injection engine:
 - a 1KB aligned RTAS working buffer in rtas.c
 - a spinlock to serialize buffer access
 - UAPI definitions for error-injection tokens (added to eeh.h)

Signed-off-by: Narayana Murty N <nnmlinux@linux.ibm.com>
---
 arch/powerpc/include/asm/rtas.h     | 21 +++++++++++++++++++++
 arch/powerpc/include/uapi/asm/eeh.h | 18 ++++++++++++++++++
 arch/powerpc/kernel/rtas.c          | 12 ++++++++++++
 3 files changed, 51 insertions(+)

diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h
index d046bbd5017d..82512f822c7a 100644
--- a/arch/powerpc/include/asm/rtas.h
+++ b/arch/powerpc/include/asm/rtas.h
@@ -519,6 +519,27 @@ int rtas_get_error_log_max(void);
 extern spinlock_t rtas_data_buf_lock;
 extern char rtas_data_buf[RTAS_DATA_BUF_SIZE];
 
+/*
+ * RTAS Error Injection Buffer (PAPR-compliant)
+ * ============================================
+ *
+ * 1KB aligned, zero-initialized buffer for ibm,errinjct RTAS work area.
+ * Protected by rtas_errinjct_buf_lock for concurrent access safety.
+ *
+ * PAPR Requirement: ibm,errinjct requires a caller-allocated buffer passed
+ * via physical address. Buffer must accommodate largest error type layouts:
+ * - IOA bus error (64-bit): 8x32-bit words (32 bytes)
+ * - All other types: <=4x32-bit words (16 bytes)
+ *
+ * Usage:
+ * prepare_errinjct_buffer() -> spin_lock() -> rtas_call() -> spin_unlock()
+ *
+ * Alignment: SZ_1K ensures PAPR firmware requirements and cache-line safety.
+ */
+#define RTAS_ERRINJCT_BUF_SIZE 1024
+extern spinlock_t rtas_errinjct_buf_lock;
+extern char rtas_errinjct_buf[RTAS_ERRINJCT_BUF_SIZE];
+
 /* RMO buffer reserved for user-space RTAS use */
 extern unsigned long rtas_rmo_buf;
 
diff --git a/arch/powerpc/include/uapi/asm/eeh.h b/arch/powerpc/include/uapi/asm/eeh.h
index 3b5c47ff3fc4..86645cab2827 100644
--- a/arch/powerpc/include/uapi/asm/eeh.h
+++ b/arch/powerpc/include/uapi/asm/eeh.h
@@ -41,4 +41,22 @@
 #define EEH_ERR_FUNC_DMA_WR_TARGET	19
 #define EEH_ERR_FUNC_MAX		19
 
+/* RTAS PCI Error Injection Token Types */
+#define RTAS_ERR_TYPE_FATAL                     0x1
+#define RTAS_ERR_TYPE_RECOVERED_RANDOM_EVENT    0x2
+#define RTAS_ERR_TYPE_RECOVERED_SPECIAL_EVENT   0x3
+#define RTAS_ERR_TYPE_CORRUPTED_PAGE            0x4
+#define RTAS_ERR_TYPE_CORRUPTED_SLB             0x5
+#define RTAS_ERR_TYPE_TRANSLATOR_FAILURE        0x6
+#define RTAS_ERR_TYPE_IOA_BUS_ERROR             0x7
+#define RTAS_ERR_TYPE_PLATFORM_SPECIFIC         0x8
+#define RTAS_ERR_TYPE_CORRUPTED_DCACHE_START    0x9
+#define RTAS_ERR_TYPE_CORRUPTED_DCACHE_END      0xA
+#define RTAS_ERR_TYPE_CORRUPTED_ICACHE_START    0xB
+#define RTAS_ERR_TYPE_CORRUPTED_ICACHE_END      0xC
+#define RTAS_ERR_TYPE_CORRUPTED_TLB_START       0xD
+#define RTAS_ERR_TYPE_CORRUPTED_TLB_END         0xE
+#define RTAS_ERR_TYPE_IOA_BUS_ERROR_64          0xF
+#define RTAS_ERR_TYPE_UPSTREAM_IO_ERROR         0x10
+
 #endif /* _ASM_POWERPC_EEH_H */
diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c
index 04c8438aadda..ae1cd7964bae 100644
--- a/arch/powerpc/kernel/rtas.c
+++ b/arch/powerpc/kernel/rtas.c
@@ -769,6 +769,18 @@ EXPORT_SYMBOL_GPL(rtas_data_buf);
 
 unsigned long rtas_rmo_buf;
 
+/*
+ * RTAS Error Injection Buffer - Global Definitions
+ * Global 1KB buffer and spinlock for ibm,errinjct RTAS service.
+ * Exported for pseries EEH error injection usage.
+ */
+
+DEFINE_SPINLOCK(rtas_errinjct_buf_lock);
+EXPORT_SYMBOL_GPL(rtas_errinjct_buf_lock);
+
+char rtas_errinjct_buf[1024] __aligned(SZ_1K);
+EXPORT_SYMBOL_GPL(rtas_errinjct_buf);
+
 /*
  * If non-NULL, this gets called when the kernel terminates.
  * This is done like this so rtas_flash can be a module.
-- 
2.51.1