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 */