fsi: scom: Major overhaul

This was too hard to split ... this adds a number of features
to the SCOM user interface:

 - Support for indirect SCOMs

 - read()/write() interface now handle errors and retries

 - New ioctl() "raw" interface for use by debuggers

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Reviewed-by: Eddie James <eajames@linux.vnet.ibm.com>
Reviewed-by: Alistair Popple <alistair@popple.id.au>

1 files changed, 58 insertions, 0 deletions

diff --git a/include/uapi/linux/fsi.h b/include/uapi/linux/fsi.h
new file mode 100644
index 000000000000..da577ecd90e7
--- /dev/null
+++ b/include/uapi/linux/fsi.h
@@ -0,0 +1,58 @@
+/* SPDX-License-Identifier: GPL-2.0+ WITH Linux-syscall-note */
+#ifndef _UAPI_LINUX_FSI_H
+#define _UAPI_LINUX_FSI_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+
+/*
+ * /dev/scom "raw" ioctl interface
+ *
+ * The driver supports a high level "read/write" interface which
+ * handles retries and converts the status to Linux error codes,
+ * however low level tools an debugger need to access the "raw"
+ * HW status information and interpret it themselves, so this
+ * ioctl interface is also provided for their use case.
+ */
+
+/* Structure for SCOM read/write */
+struct scom_access {
+        __u64   addr;           /* SCOM address, supports indirect */
+        __u64   data;           /* SCOM data (in for write, out for read) */
+        __u64   mask;           /* Data mask for writes */
+        __u32   intf_errors;    /* Interface error flags */
+#define SCOM_INTF_ERR_PARITY            0x00000001 /* Parity error */
+#define SCOM_INTF_ERR_PROTECTION        0x00000002 /* Blocked by secure boot */
+#define SCOM_INTF_ERR_ABORT             0x00000004 /* PIB reset during access */
+#define SCOM_INTF_ERR_UNKNOWN           0x80000000 /* Unknown error */
+        /*
+         * Note: Any other bit set in intf_errors need to be considered as an
+         * error. Future implementations may define new error conditions. The
+         * pib_status below is only valid if intf_errors is 0.
+         */
+        __u8    pib_status;     /* 3-bit PIB status */
+#define SCOM_PIB_SUCCESS        0       /* Access successful */
+#define SCOM_PIB_BLOCKED        1       /* PIB blocked, pls retry */
+#define SCOM_PIB_OFFLINE        2       /* Chiplet offline */
+#define SCOM_PIB_PARTIAL        3       /* Partial good */
+#define SCOM_PIB_BAD_ADDR       4       /* Invalid address */
+#define SCOM_PIB_CLK_ERR        5       /* Clock error */
+#define SCOM_PIB_PARITY_ERR     6       /* Parity error on the PIB bus */
+#define SCOM_PIB_TIMEOUT        7       /* Bus timeout */
+        __u8    pad;
+};
+
+/* Flags for SCOM check */
+#define SCOM_CHECK_SUPPORTED    0x00000001      /* Interface supported */
+#define SCOM_CHECK_PROTECTED    0x00000002      /* Interface blocked by secure boot */
+
+/* Flags for SCOM reset */
+#define SCOM_RESET_INTF         0x00000001      /* Reset interface */
+#define SCOM_RESET_PIB          0x00000002      /* Reset PIB */
+
+#define FSI_SCOM_CHECK  _IOR('s', 0x00, __u32)
+#define FSI_SCOM_READ   _IOWR('s', 0x01, struct scom_access)
+#define FSI_SCOM_WRITE  _IOWR('s', 0x02, struct scom_access)
+#define FSI_SCOM_RESET  _IOW('s', 0x03, __u32)
+
+#endif /* _UAPI_LINUX_FSI_H */