[PATCH net-next 1/6] platform/x86: intel_pmc_core: Add IPC mailbox accessor function and add SoC register access

[Choong Yong Liang <yong.liang.choong@linux.intel.com>]

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/adl.c          |  2 +-
 drivers/platform/x86/intel/pmc/cnp.c          |  2 +-
 drivers/platform/x86/intel/pmc/core.c         | 63 ++++++++++++++++++-
 drivers/platform/x86/intel/pmc/icl.c          |  2 +-
 drivers/platform/x86/intel/pmc/mtl.c          |  2 +-
 drivers/platform/x86/intel/pmc/spt.c          |  2 +-
 drivers/platform/x86/intel/pmc/tgl.c          |  2 +-
 .../core.h => include/linux/intel_pmc_core.h  | 27 +++++++-
 9 files changed, 95 insertions(+), 8 deletions(-)
 rename drivers/platform/x86/intel/pmc/core.h => include/linux/intel_pmc_core.h (95%)

diff --git a/MAINTAINERS b/MAINTAINERS
index cb14589d14ab..bdb08a79a5f8 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -10581,6 +10581,7 @@ L:	platform-driver-x86@vger.kernel.org
 S:	Maintained
 F:	Documentation/ABI/testing/sysfs-platform-intel-pmc
 F:	drivers/platform/x86/intel/pmc/
+F:	include/linux/intel_pmc_core*
 
 INTEL PMIC GPIO DRIVERS
 M:	Andy Shevchenko <andy@kernel.org>
diff --git a/drivers/platform/x86/intel/pmc/adl.c b/drivers/platform/x86/intel/pmc/adl.c
index 5cbd40979f2a..b6a376c536c0 100644
--- a/drivers/platform/x86/intel/pmc/adl.c
+++ b/drivers/platform/x86/intel/pmc/adl.c
@@ -8,7 +8,7 @@
  *
  */
 
-#include "core.h"
+#include <linux/intel_pmc_core.h>
 
 /* Alder Lake: PGD PFET Enable Ack Status Register(s) bitmap */
 const struct pmc_bit_map adl_pfear_map[] = {
diff --git a/drivers/platform/x86/intel/pmc/cnp.c b/drivers/platform/x86/intel/pmc/cnp.c
index 7fb38815c4eb..504034cc5ec3 100644
--- a/drivers/platform/x86/intel/pmc/cnp.c
+++ b/drivers/platform/x86/intel/pmc/cnp.c
@@ -8,7 +8,7 @@
  *
  */
 
-#include "core.h"
+#include <linux/intel_pmc_core.h>
 
 /* Cannon Lake: PGD PFET Enable Ack Status Register(s) bitmap */
 const struct pmc_bit_map cnp_pfear_map[] = {
diff --git a/drivers/platform/x86/intel/pmc/core.c b/drivers/platform/x86/intel/pmc/core.c
index da6e7206d38b..0d60763c5144 100644
--- a/drivers/platform/x86/intel/pmc/core.c
+++ b/drivers/platform/x86/intel/pmc/core.c
@@ -16,6 +16,7 @@
 #include <linux/delay.h>
 #include <linux/dmi.h>
 #include <linux/io.h>
+#include <linux/intel_pmc_core.h>
 #include <linux/module.h>
 #include <linux/pci.h>
 #include <linux/slab.h>
@@ -26,7 +27,9 @@
 #include <asm/msr.h>
 #include <asm/tsc.h>
 
-#include "core.h"
+#define PMC_IPCS_PARAM_COUNT           7
+
+static const struct x86_cpu_id *pmc_cpu_id;
 
 /* Maximum number of modes supported by platfoms that has low power mode capability */
 const char *pmc_lpm_modes[] = {
@@ -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 (!pmc_cpu_id || !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_dev *pmcdev, int reg_offset)
 {
 	return readl(pmcdev->regbase + reg_offset);
@@ -1130,6 +1190,7 @@ static int pmc_core_probe(struct platform_device *pdev)
 	mutex_init(&pmcdev->lock);
 	core_init(pmcdev);
 
+	pmc_cpu_id = cpu_id;
 
 	if (lpit_read_residency_count_address(&slp_s0_addr)) {
 		pmcdev->base_addr = PMC_BASE_ADDR_DEFAULT;
diff --git a/drivers/platform/x86/intel/pmc/icl.c b/drivers/platform/x86/intel/pmc/icl.c
index 2f11b1a6daeb..f18048ff9382 100644
--- a/drivers/platform/x86/intel/pmc/icl.c
+++ b/drivers/platform/x86/intel/pmc/icl.c
@@ -8,7 +8,7 @@
  *
  */
 
-#include "core.h"
+#include <linux/intel_pmc_core.h>
 
 const struct pmc_bit_map icl_pfear_map[] = {
 	{"RES_65",		BIT(0)},
diff --git a/drivers/platform/x86/intel/pmc/mtl.c b/drivers/platform/x86/intel/pmc/mtl.c
index e8cc156412ce..7897f5fe9881 100644
--- a/drivers/platform/x86/intel/pmc/mtl.c
+++ b/drivers/platform/x86/intel/pmc/mtl.c
@@ -9,7 +9,7 @@
  */
 
 #include <linux/pci.h>
-#include "core.h"
+#include <linux/intel_pmc_core.h>
 
 const struct pmc_reg_map mtl_reg_map = {
 	.pfear_sts = ext_tgl_pfear_map,
diff --git a/drivers/platform/x86/intel/pmc/spt.c b/drivers/platform/x86/intel/pmc/spt.c
index e16982236778..95ce490cf5d6 100644
--- a/drivers/platform/x86/intel/pmc/spt.c
+++ b/drivers/platform/x86/intel/pmc/spt.c
@@ -8,7 +8,7 @@
  *
  */
 
-#include "core.h"
+#include <linux/intel_pmc_core.h>
 
 const struct pmc_bit_map spt_pll_map[] = {
 	{"MIPI PLL",			SPT_PMC_BIT_MPHY_CMN_LANE0},
diff --git a/drivers/platform/x86/intel/pmc/tgl.c b/drivers/platform/x86/intel/pmc/tgl.c
index c245ada849d0..a1719d809497 100644
--- a/drivers/platform/x86/intel/pmc/tgl.c
+++ b/drivers/platform/x86/intel/pmc/tgl.c
@@ -8,7 +8,7 @@
  *
  */
 
-#include "core.h"
+#include <linux/intel_pmc_core.h>
 
 #define ACPI_S0IX_DSM_UUID		"57a6512e-3979-4e9d-9708-ff13b2508972"
 #define ACPI_GET_LOW_MODE_REGISTERS	1
diff --git a/drivers/platform/x86/intel/pmc/core.h b/include/linux/intel_pmc_core.h
similarity index 95%
rename from drivers/platform/x86/intel/pmc/core.h
rename to include/linux/intel_pmc_core.h
index 9ca9b9746719..82810e8b92a2 100644
--- a/drivers/platform/x86/intel/pmc/core.h
+++ b/include/linux/intel_pmc_core.h
@@ -250,7 +250,16 @@ enum ppfear_regs {
 #define MTL_LPM_STATUS_OFFSET			0x1700
 #define MTL_LPM_LIVE_STATUS_OFFSET		0x175C
 
-extern const char *pmc_lpm_modes[];
+#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];
+};
 
 struct pmc_bit_map {
 	const char *name;
@@ -427,4 +436,20 @@ static const struct file_operations __name ## _fops = {			\
 	.release	= single_release,				\
 }
 
+#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 /* PMC_CORE_H */
-- 
2.25.1