platform/x86: Add AMD system management interface

Recent Fam19h EPYC server line of processors from AMD support system
management functionality via HSMP (Host System Management Port) interface.

The Host System Management Port (HSMP) is an interface to provide
OS-level software with access to system management functions via a
set of mailbox registers.

More details on the interface can be found in chapter
"7 Host System Management Port (HSMP)" of the following PPR
https://www.amd.com/system/files/TechDocs/55898_B1_pub_0.50.zip

This patch adds new amd_hsmp module under the drivers/platforms/x86/
which creates miscdevice with an IOCTL interface to the user space.
/dev/hsmp is for running the hsmp mailbox commands.
Signed-off-by: Suma Hegde <suma.hegde@amd.com>
Signed-off-by: Naveen Krishna Chatradhi <nchatrad@amd.com>
Reviewed-by: Carlos Bilbao <carlos.bilbao@amd.com>
Acked-by: Song Liu <song@kernel.org>
Reviewed-by: Nathan Fontenot <nathan.fontenot@amd.com>
Link: https://lore.kernel.org/r/20220222050501.18789-1-nchatrad@amd.comReviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

Documentation/userspace-api/ioctl/ioctl-number.rst

@@ -372,6 +372,8 @@ Code  Seq#    Include File                                           Comments
                                                                      <mailto:thomas@winischhofer.net>
 0xF6  all                                                            LTTng Linux Trace Toolkit Next Generation
                                                                      <mailto:mathieu.desnoyers@efficios.com>
+0xF8  all    arch/x86/include/uapi/asm/amd_hsmp.h                    AMD HSMP EPYC system management interface driver
+                                                                     <mailto:nchatrad@amd.com>
 0xFD  all    linux/dm-ioctl.h
 0xFE  all    linux/isst_if.h
 ====  =====  ======================================================= ================================================================

MAINTAINERS

@@ -988,6 +988,16 @@ L:	platform-driver-x86@vger.kernel.org
 S:	Maintained
 F:	drivers/platform/x86/amd-pmc.*
 
+AMD HSMP DRIVER
+M:	Naveen Krishna Chatradhi <naveenkrishna.chatradhi@amd.com>
+R:	Carlos Bilbao <carlos.bilbao@amd.com>
+L:	platform-driver-x86@vger.kernel.org
+S:	Maintained
+F:	Documentation/x86/amd_hsmp.rst
+F:	arch/x86/include/asm/amd_hsmp.h
+F:	arch/x86/include/uapi/asm/amd_hsmp.h
+F:	drivers/platform/x86/amd_hsmp.c
+
 AMD POWERPLAY AND SWSMU
 M:	Evan Quan <evan.quan@amd.com>
 L:	amd-gfx@lists.freedesktop.org

arch/x86/include/asm/amd_hsmp.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+
+#ifndef _ASM_X86_AMD_HSMP_H_
+#define _ASM_X86_AMD_HSMP_H_
+
+#include <uapi/asm/amd_hsmp.h>
+
+#if IS_ENABLED(CONFIG_AMD_HSMP)
+int hsmp_send_message(struct hsmp_message *msg);
+#else
+static inline int hsmp_send_message(struct hsmp_message *msg)
+{
+	return -ENODEV;
+}
+#endif
+#endif /*_ASM_X86_AMD_HSMP_H_*/

arch/x86/include/uapi/asm/amd_hsmp.h

+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+
+#ifndef _UAPI_ASM_X86_AMD_HSMP_H_
+#define _UAPI_ASM_X86_AMD_HSMP_H_
+
+#include <linux/types.h>
+
+#pragma pack(4)
+
+#define HSMP_MAX_MSG_LEN 8
+
+/*
+ * HSMP Messages supported
+ */
+enum hsmp_message_ids {
+	HSMP_TEST = 1,			/* 01h Increments input value by 1 */
+	HSMP_GET_SMU_VER,		/* 02h SMU FW version */
+	HSMP_GET_PROTO_VER,		/* 03h HSMP interface version */
+	HSMP_GET_SOCKET_POWER,		/* 04h average package power consumption */
+	HSMP_SET_SOCKET_POWER_LIMIT,	/* 05h Set the socket power limit */
+	HSMP_GET_SOCKET_POWER_LIMIT,	/* 06h Get current socket power limit */
+	HSMP_GET_SOCKET_POWER_LIMIT_MAX,/* 07h Get maximum socket power value */
+	HSMP_SET_BOOST_LIMIT,		/* 08h Set a core maximum frequency limit */
+	HSMP_SET_BOOST_LIMIT_SOCKET,	/* 09h Set socket maximum frequency level */
+	HSMP_GET_BOOST_LIMIT,		/* 0Ah Get current frequency limit */
+	HSMP_GET_PROC_HOT,		/* 0Bh Get PROCHOT status */
+	HSMP_SET_XGMI_LINK_WIDTH,	/* 0Ch Set max and min width of xGMI Link */
+	HSMP_SET_DF_PSTATE,		/* 0Dh Alter APEnable/Disable messages behavior */
+	HSMP_SET_AUTO_DF_PSTATE,	/* 0Eh Enable DF P-State Performance Boost algorithm */
+	HSMP_GET_FCLK_MCLK,		/* 0Fh Get FCLK and MEMCLK for current socket */
+	HSMP_GET_CCLK_THROTTLE_LIMIT,	/* 10h Get CCLK frequency limit in socket */
+	HSMP_GET_C0_PERCENT,		/* 11h Get average C0 residency in socket */
+	HSMP_SET_NBIO_DPM_LEVEL,	/* 12h Set max/min LCLK DPM Level for a given NBIO */
+					/* 13h Reserved */
+	HSMP_GET_DDR_BANDWIDTH = 0x14,	/* 14h Get theoretical maximum and current DDR Bandwidth */
+	HSMP_GET_TEMP_MONITOR,		/* 15h Get per-DIMM temperature and refresh rates */
+	HSMP_MSG_ID_MAX,
+};
+
+struct hsmp_message {
+	__u32	msg_id;			/* Message ID */
+	__u16	num_args;		/* Number of input argument words in message */
+	__u16	response_sz;		/* Number of expected output/response words */
+	__u32	args[HSMP_MAX_MSG_LEN];	/* argument/response buffer */
+	__u16	sock_ind;		/* socket number */
+};
+
+enum hsmp_msg_type {
+	HSMP_RSVD = -1,
+	HSMP_SET  = 0,
+	HSMP_GET  = 1,
+};
+
+struct hsmp_msg_desc {
+	int num_args;
+	int response_sz;
+	enum hsmp_msg_type type;
+};
+
+/*
+ * User may use these comments as reference, please find the
+ * supported list of messages and message definition in the
+ * HSMP chapter of respective family/model PPR.
+ *
+ * Not supported messages would return -ENOMSG.
+ */
+static const struct hsmp_msg_desc hsmp_msg_desc_table[] = {
+	/* RESERVED */
+	{0, 0, HSMP_RSVD},
+
+	/*
+	 * HSMP_TEST, num_args = 1, response_sz = 1
+	 * input:  args[0] = xx
+	 * output: args[0] = xx + 1
+	 */
+	{1, 1, HSMP_GET},
+
+	/*
+	 * HSMP_GET_SMU_VER, num_args = 0, response_sz = 1
+	 * output: args[0] = smu fw ver
+	 */
+	{0, 1, HSMP_GET},
+
+	/*
+	 * HSMP_GET_PROTO_VER, num_args = 0, response_sz = 1
+	 * output: args[0] = proto version
+	 */
+	{0, 1, HSMP_GET},
+
+	/*
+	 * HSMP_GET_SOCKET_POWER, num_args = 0, response_sz = 1
+	 * output: args[0] = socket power in mWatts
+	 */
+	{0, 1, HSMP_GET},
+
+	/*
+	 * HSMP_SET_SOCKET_POWER_LIMIT, num_args = 1, response_sz = 0
+	 * input: args[0] = power limit value in mWatts
+	 */
+	{1, 0, HSMP_SET},
+
+	/*
+	 * HSMP_GET_SOCKET_POWER_LIMIT, num_args = 0, response_sz = 1
+	 * output: args[0] = socket power limit value in mWatts
+	 */
+	{0, 1, HSMP_GET},
+
+	/*
+	 * HSMP_GET_SOCKET_POWER_LIMIT_MAX, num_args = 0, response_sz = 1
+	 * output: args[0] = maximuam socket power limit in mWatts
+	 */
+	{0, 1, HSMP_GET},
+
+	/*
+	 * HSMP_SET_BOOST_LIMIT, num_args = 1, response_sz = 0
+	 * input: args[0] = apic id[31:16] + boost limit value in MHz[15:0]
+	 */
+	{1, 0, HSMP_SET},
+
+	/*
+	 * HSMP_SET_BOOST_LIMIT_SOCKET, num_args = 1, response_sz = 0
+	 * input: args[0] = boost limit value in MHz
+	 */
+	{1, 0, HSMP_SET},
+
+	/*
+	 * HSMP_GET_BOOST_LIMIT, num_args = 1, response_sz = 1
+	 * input: args[0] = apic id
+	 * output: args[0] = boost limit value in MHz
+	 */
+	{1, 1, HSMP_GET},
+
+	/*
+	 * HSMP_GET_PROC_HOT, num_args = 0, response_sz = 1
+	 * output: args[0] = proc hot status
+	 */
+	{0, 1, HSMP_GET},
+
+	/*
+	 * HSMP_SET_XGMI_LINK_WIDTH, num_args = 1, response_sz = 0
+	 * input: args[0] = min link width[15:8] + max link width[7:0]
+	 */
+	{1, 0, HSMP_SET},
+
+	/*
+	 * HSMP_SET_DF_PSTATE, num_args = 1, response_sz = 0
+	 * input: args[0] = df pstate[7:0]
+	 */
+	{1, 0, HSMP_SET},
+
+	/* HSMP_SET_AUTO_DF_PSTATE, num_args = 0, response_sz = 0 */
+	{0, 0, HSMP_SET},
+
+	/*
+	 * HSMP_GET_FCLK_MCLK, num_args = 0, response_sz = 2
+	 * output: args[0] = fclk in MHz, args[1] = mclk in MHz
+	 */
+	{0, 2, HSMP_GET},
+
+	/*
+	 * HSMP_GET_CCLK_THROTTLE_LIMIT, num_args = 0, response_sz = 1
+	 * output: args[0] = core clock in MHz
+	 */
+	{0, 1, HSMP_GET},
+
+	/*
+	 * HSMP_GET_C0_PERCENT, num_args = 0, response_sz = 1
+	 * output: args[0] = average c0 residency
+	 */
+	{0, 1, HSMP_GET},
+
+	/*
+	 * HSMP_SET_NBIO_DPM_LEVEL, num_args = 1, response_sz = 0
+	 * input: args[0] = nbioid[23:16] + max dpm level[15:8] + min dpm level[7:0]
+	 */
+	{1, 0, HSMP_SET},
+
+	/* RESERVED message */
+	{0, 0, HSMP_RSVD},
+
+	/*
+	 * HSMP_GET_DDR_BANDWIDTH, num_args = 0, response_sz = 1
+	 * output: args[0] = max bw in Gbps[31:20] + utilised bw in Gbps[19:8] +
+	 * bw in percentage[7:0]
+	 */
+	{0, 1, HSMP_GET},
+
+	/*
+	 * HSMP_GET_TEMP_MONITOR, num_args = 0, response_sz = 1
+	 * output: args[0] = temperature in degree celsius. [15:8] integer part +
+	 * [7:5] fractional part
+	 */
+	{0, 1, HSMP_GET},
+};
+
+/* Reset to default packing */
+#pragma pack()
+
+/* Define unique ioctl command for hsmp msgs using generic _IOWR */
+#define HSMP_BASE_IOCTL_NR	0xF8
+#define HSMP_IOCTL_CMD		_IOWR(HSMP_BASE_IOCTL_NR, 0, struct hsmp_message)
+
+#endif /*_ASM_X86_AMD_HSMP_H_*/

drivers/platform/x86/Kconfig

@@ -210,6 +210,19 @@ config AMD_PMC
 	  If you choose to compile this driver as a module the module will be
 	  called amd-pmc.
 
+config AMD_HSMP
+	tristate "AMD HSMP Driver"
+	depends on AMD_NB && X86_64
+	help
+	  The driver provides a way for user space tools to monitor and manage
+	  system management functionality on EPYC server CPUs from AMD.
+
+	  Host System Management Port (HSMP) interface is a mailbox interface
+	  between the x86 core and the System Management Unit (SMU) firmware.
+
+	  If you choose to compile this driver as a module the module will be
+	  called amd_hsmp.
+
 config ADV_SWBUTTON
 	tristate "Advantech ACPI Software Button Driver"
 	depends on ACPI && INPUT

drivers/platform/x86/Makefile

@@ -24,6 +24,7 @@ obj-$(CONFIG_ACER_WMI)		+= acer-wmi.o
 
 # AMD
 obj-$(CONFIG_AMD_PMC)		+= amd-pmc.o
+obj-$(CONFIG_AMD_HSMP)		+= amd_hsmp.o
 
 # Advantech
 obj-$(CONFIG_ADV_SWBUTTON)	+= adv_swbutton.o