[PATCH net-next v2 1/5] platform/x86: intel_pmc_core: Add IPC mailbox accessor function and add SoC register access

Choong Yong Liang
2023-08-04T08:47:24Z

From: "David E. Box" <david.e.box@linux.intel.com>

- Exports intel_pmc_core_ipc() for host access to the PMC IPC mailbox
- Add support to use IPC command allows host to access SoC registers
through PMC firmware that are otherwise inaccessible to the host due to
security policies.

Signed-off-by: David E. Box <david.e.box@linux.intel.com>
Signed-off-by: Chao Qin <chao.qin@intel.com>
Signed-off-by: Choong Yong Liang <yong.liang.choong@linux.intel.com>
---
MAINTAINERS | 1 +
drivers/platform/x86/intel/pmc/core.c | 60 +++++++++++++++++++
.../linux/platform_data/x86/intel_pmc_core.h | 41 +++++++++++++
3 files changed, 102 insertions(+)
create mode 100644 include/linux/platform_data/x86/intel_pmc_core.h

diff --git a/MAINTAINERS b/MAINTAINERS
index 069e176d607a..8a034dee9da9 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10648,6 +10648,7 @@ L: platform-driver-x86@vger.kernel.org
S: Maintained
F: Documentation/ABI/testing/sysfs-platform-intel-pmc
F: drivers/platform/x86/intel/pmc/
+F: linux/platform_data/x86/intel_pmc_core.h

INTEL PMIC GPIO DRIVERS
M: Andy Shevchenko <andy@kernel.org>
diff --git a/drivers/platform/x86/intel/pmc/core.c b/drivers/platform/x86/intel/pmc/core.c
index 5a36b3f77bc5..6fb1b0f453d8 100644
--- a/drivers/platform/x86/intel/pmc/core.c
+++ b/drivers/platform/x86/intel/pmc/core.c
@@ -20,6 +20,7 @@
#include <linux/pci.h>
#include <linux/slab.h>
#include <linux/suspend.h>
+#include <linux/platform_data/x86/intel_pmc_core.h>

#include <asm/cpu_device_id.h>
#include <asm/intel-family.h>
@@ -28,6 +29,8 @@

#include "core.h"

+#define PMC_IPCS_PARAM_COUNT 7
+
/* Maximum number of modes supported by platfoms that has low power mode capability */
const char *pmc_lpm_modes[] = {
"S0i2.0",
@@ -53,6 +56,63 @@ const struct pmc_bit_map msr_map[] = {
{}
};

+int intel_pmc_core_ipc(struct pmc_ipc_cmd *ipc_cmd, u32 *rbuf)
+{
+ struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+ union acpi_object params[PMC_IPCS_PARAM_COUNT] = {
+ {.type = ACPI_TYPE_INTEGER,},
+ {.type = ACPI_TYPE_INTEGER,},
+ {.type = ACPI_TYPE_INTEGER,},
+ {.type = ACPI_TYPE_INTEGER,},
+ {.type = ACPI_TYPE_INTEGER,},
+ {.type = ACPI_TYPE_INTEGER,},
+ {.type = ACPI_TYPE_INTEGER,},
+ };
+ struct acpi_object_list arg_list = { PMC_IPCS_PARAM_COUNT, params };
+ union acpi_object *obj;
+ int status;
+
+ if (!ipc_cmd || !rbuf)
+ return -EINVAL;
+
+ /*
+ * 0: IPC Command
+ * 1: IPC Sub Command
+ * 2: Size
+ * 3-6: Write Buffer for offset
+ */
+ params[0].integer.value = ipc_cmd->cmd;
+ params[1].integer.value = ipc_cmd->sub_cmd;
+ params[2].integer.value = ipc_cmd->size;
+ params[3].integer.value = ipc_cmd->wbuf[0];
+ params[4].integer.value = ipc_cmd->wbuf[1];
+ params[5].integer.value = ipc_cmd->wbuf[2];
+ params[6].integer.value = ipc_cmd->wbuf[3];
+
+ status = acpi_evaluate_object(NULL, "\\IPCS", &arg_list, &buffer);
+ if (ACPI_FAILURE(status))
+ return -ENODEV;
+
+ obj = buffer.pointer;
+ /* Check if the number of elements in package is 5 */
+ if (obj && obj->type == ACPI_TYPE_PACKAGE && obj->package.count == 5) {
+ const union acpi_object *objs = obj->package.elements;
+
+ if ((u8)objs[0].integer.value != 0)
+ return -EINVAL;
+
+ rbuf[0] = objs[1].integer.value;
+ rbuf[1] = objs[2].integer.value;
+ rbuf[2] = objs[3].integer.value;
+ rbuf[3] = objs[4].integer.value;
+ } else {
+ return -EINVAL;
+ }
+
+ return 0;
+}
+EXPORT_SYMBOL(intel_pmc_core_ipc);
+
static inline u32 pmc_core_reg_read(struct pmc *pmc, int reg_offset)
{
return readl(pmc->regbase + reg_offset);
diff --git a/include/linux/platform_data/x86/intel_pmc_core.h b/include/linux/platform_data/x86/intel_pmc_core.h
new file mode 100644
index 000000000000..9bb3394fedcf
--- /dev/null
+++ b/include/linux/platform_data/x86/intel_pmc_core.h
@@ -0,0 +1,41 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Intel Core SoC Power Management Controller Header File
+ *
+ * Copyright (c) 2023, Intel Corporation.
+ * All Rights Reserved.
+ *
+ * Authors: Choong Yong Liang <yong.liang.choong@linux.intel.com>
+ * David E. Box <david.e.box@linux.intel.com>
+ */
+#ifndef INTEL_PMC_CORE_H
+#define INTEL_PMC_CORE_H
+
+#define IPC_SOC_REGISTER_ACCESS 0xAA
+#define IPC_SOC_SUB_CMD_READ 0x00
+#define IPC_SOC_SUB_CMD_WRITE 0x01
+
+struct pmc_ipc_cmd {
+ u32 cmd;
+ u32 sub_cmd;
+ u32 size;
+ u32 wbuf[4];
+};
+
+#if IS_ENABLED(CONFIG_INTEL_PMC_CORE)
+/**
+ * intel_pmc_core_ipc() - PMC IPC Mailbox accessor
+ * @ipc_cmd: struct pmc_ipc_cmd prepared with input to send
+ * @rbuf: Allocated u32[4] array for returned IPC data
+ *
+ * Return: 0 on success. Non-zero on mailbox error
+ */
+int intel_pmc_core_ipc(struct pmc_ipc_cmd *ipc_cmd, u32 *rbuf);
+#else
+static inline int intel_pmc_core_ipc(struct pmc_ipc_cmd *ipc_cmd, u32 *rbuf)
+{
+ return -ENODEV;
+}
+#endif /* CONFIG_INTEL_PMC_CORE */
+
+#endif /* INTEL_PMC_CORE_H */
--
2.25.1