driver: add PPI support in tpm driver

The Physical Presence Interface enables the OS and the BIOS to cooperate and
provides a simple and straightforward platform user experience for
administering the TPM without sacrificing security.

V2: separate the patch out in a separate source file,
    add #ifdef CONFIG_ACPI so it compiles out on ppc,
    use standard error instead of ACPI error as return code of show/store fns.
V3: move #ifdef CONFIG_ACPI from .c file to .h file.
V4: move tpm_ppi code from tpm module to tpm_bios module.
V5: modify sys_add_ppi() so that ppi_attr_grp doesn't need to be exported

Signed-off-by: Xiaoyan Zhang <xiaoyan.zhang@intel.com>
Signed-off-by: Kent Yoder <key@linux.vnet.ibm.com>

4 files changed, 475 insertions, 1 deletions

diff --git a/drivers/char/tpm/Makefile b/drivers/char/tpm/Makefile
index 9080cc44e3c4..5b3fc8bc6c13 100644
--- a/drivers/char/tpm/Makefile
+++ b/drivers/char/tpm/Makefile
@@ -4,7 +4,7 @@
 obj-$(CONFIG_TCG_TPM) += tpm.o
 ifdef CONFIG_ACPI
         obj-$(CONFIG_TCG_TPM) += tpm_bios.o
-        tpm_bios-objs += tpm_eventlog.o tpm_acpi.o
+        tpm_bios-objs += tpm_eventlog.o tpm_acpi.o tpm_ppi.o
 else
 ifdef CONFIG_TCG_IBMVTPM
         obj-$(CONFIG_TCG_TPM) += tpm_bios.o
diff --git a/drivers/char/tpm/tpm.c b/drivers/char/tpm/tpm.c
index 0a75638e3e56..39526c053158 100644
--- a/drivers/char/tpm/tpm.c
+++ b/drivers/char/tpm/tpm.c
@@ -1476,6 +1476,11 @@ struct tpm_chip *tpm_register_hardware(struct device *dev,
                 goto put_device;
         }
 
+        if (sys_add_ppi(&dev->kobj)) {
+                misc_deregister(&chip->vendor.miscdev);
+                goto put_device;
+        }
+
         chip->bios_dir = tpm_bios_log_setup(devname);
 
         /* Make chip available */
diff --git a/drivers/char/tpm/tpm.h b/drivers/char/tpm/tpm.h
index f1af73821101..02c266aa2bf7 100644
--- a/drivers/char/tpm/tpm.h
+++ b/drivers/char/tpm/tpm.h
@@ -327,3 +327,12 @@ extern int tpm_pm_suspend(struct device *);
 extern int tpm_pm_resume(struct device *);
 extern int wait_for_tpm_stat(struct tpm_chip *, u8, unsigned long,
                              wait_queue_head_t *);
+
+#ifdef CONFIG_ACPI
+extern ssize_t sys_add_ppi(struct kobject *parent);
+#else
+static inline ssize_t sys_add_ppi(struct kobject *parent)
+{
+        return 0;
+}
+#endif
diff --git a/drivers/char/tpm/tpm_ppi.c b/drivers/char/tpm/tpm_ppi.c
new file mode 100644
index 000000000000..440fa1c2d301
--- /dev/null
+++ b/drivers/char/tpm/tpm_ppi.c
@@ -0,0 +1,460 @@
+#include <linux/acpi.h>
+#include <acpi/acpi_drivers.h>
+#include "tpm.h"
+
+static const u8 tpm_ppi_uuid[] = {
+        0xA6, 0xFA, 0xDD, 0x3D,
+        0x1B, 0x36,
+        0xB4, 0x4E,
+        0xA4, 0x24,
+        0x8D, 0x10, 0x08, 0x9D, 0x16, 0x53
+};
+static char *tpm_device_name = "TPM";
+
+#define TPM_PPI_REVISION_ID     1
+#define TPM_PPI_FN_VERSION      1
+#define TPM_PPI_FN_SUBREQ       2
+#define TPM_PPI_FN_GETREQ       3
+#define TPM_PPI_FN_GETACT       4
+#define TPM_PPI_FN_GETRSP       5
+#define TPM_PPI_FN_SUBREQ2      7
+#define TPM_PPI_FN_GETOPR       8
+#define PPI_TPM_REQ_MAX         22
+#define PPI_VS_REQ_START        128
+#define PPI_VS_REQ_END          255
+#define PPI_VERSION_LEN         3
+
+static acpi_status ppi_callback(acpi_handle handle, u32 level, void *context,
+                                void **return_value)
+{
+        acpi_status status;
+        struct acpi_buffer buffer = { ACPI_ALLOCATE_BUFFER, NULL };
+        status = acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
+        if (strstr(buffer.pointer, context) != NULL) {
+                *return_value = handle;
+                kfree(buffer.pointer);
+                return AE_CTRL_TERMINATE;
+        }
+        return AE_OK;
+}
+
+static inline void ppi_assign_params(union acpi_object params[4],
+                                     u64 function_num)
+{
+        params[0].type = ACPI_TYPE_BUFFER;
+        params[0].buffer.length = sizeof(tpm_ppi_uuid);
+        params[0].buffer.pointer = (char *)tpm_ppi_uuid;
+        params[1].type = ACPI_TYPE_INTEGER;
+        params[1].integer.value = TPM_PPI_REVISION_ID;
+        params[2].type = ACPI_TYPE_INTEGER;
+        params[2].integer.value = function_num;
+        params[3].type = ACPI_TYPE_PACKAGE;
+        params[3].package.count = 0;
+        params[3].package.elements = NULL;
+}
+
+ssize_t tpm_show_ppi_version(struct device *dev, struct device_attribute *attr,
+                             char *buf)
+{
+        acpi_handle handle;
+        acpi_status status;
+        struct acpi_object_list input;
+        struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+        union acpi_object params[4];
+        union acpi_object *obj;
+
+        input.count = 4;
+        ppi_assign_params(params, TPM_PPI_FN_VERSION);
+        input.pointer = params;
+        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+                                     ACPI_UINT32_MAX, ppi_callback, NULL,
+                                     tpm_device_name, &handle);
+        if (ACPI_FAILURE(status))
+                return -ENXIO;
+
+        status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
+                                         ACPI_TYPE_STRING);
+        if (ACPI_FAILURE(status))
+                return -ENOMEM;
+        obj = (union acpi_object *)output.pointer;
+        status = scnprintf(buf, PAGE_SIZE, "%s\n", obj->string.pointer);
+        kfree(output.pointer);
+        return status;
+}
+
+ssize_t tpm_show_ppi_request(struct device *dev,
+                             struct device_attribute *attr,
+                             char *buf)
+{
+        acpi_handle handle;
+        acpi_status status;
+        struct acpi_object_list input;
+        struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+        union acpi_object params[4];
+        union acpi_object *ret_obj;
+
+        input.count = 4;
+        ppi_assign_params(params, TPM_PPI_FN_GETREQ);
+        input.pointer = params;
+        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+                                     ACPI_UINT32_MAX, ppi_callback, NULL,
+                                     tpm_device_name, &handle);
+        if (ACPI_FAILURE(status))
+                return -ENXIO;
+
+        status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
+                                            ACPI_TYPE_PACKAGE);
+        if (ACPI_FAILURE(status))
+                return -ENOMEM;
+        /*
+         * output.pointer should be of package type, including two integers.
+         * The first is function return code, 0 means success and 1 means
+         * error. The second is pending TPM operation requested by the OS, 0
+         * means none and >0 means operation value.
+         */
+        ret_obj = ((union acpi_object *)output.pointer)->package.elements;
+        if (ret_obj->type == ACPI_TYPE_INTEGER) {
+                if (ret_obj->integer.value) {
+                        status = -EFAULT;
+                        goto cleanup;
+                }
+                ret_obj++;
+                if (ret_obj->type == ACPI_TYPE_INTEGER)
+                        status = scnprintf(buf, PAGE_SIZE, "%llu\n",
+                                           ret_obj->integer.value);
+                else
+                        status = -EINVAL;
+        } else {
+                status = -EINVAL;
+        }
+cleanup:
+        kfree(output.pointer);
+        return status;
+}
+
+ssize_t tpm_store_ppi_request(struct device *dev,
+                              struct device_attribute *attr,
+                              const char *buf, size_t count)
+{
+        char version[PPI_VERSION_LEN + 1];
+        acpi_handle handle;
+        acpi_status status;
+        struct acpi_object_list input;
+        struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+        union acpi_object params[4];
+        union acpi_object obj;
+        u32 req;
+        u64 ret;
+
+        input.count = 4;
+        ppi_assign_params(params, TPM_PPI_FN_VERSION);
+        input.pointer = params;
+        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+                                     ACPI_UINT32_MAX, ppi_callback, NULL,
+                                     tpm_device_name, &handle);
+        if (ACPI_FAILURE(status))
+                return -ENXIO;
+
+        status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
+                                            ACPI_TYPE_STRING);
+        if (ACPI_FAILURE(status))
+                return -ENOMEM;
+        strncpy(version,
+                ((union acpi_object *)output.pointer)->string.pointer,
+                PPI_VERSION_LEN);
+        kfree(output.pointer);
+        output.length = ACPI_ALLOCATE_BUFFER;
+        output.pointer = NULL;
+        /*
+         * the function to submit TPM operation request to pre-os environment
+         * is updated with function index from SUBREQ to SUBREQ2 since PPI
+         * version 1.1
+         */
+        if (strcmp(version, "1.1") == -1)
+                params[2].integer.value = TPM_PPI_FN_SUBREQ;
+        else
+                params[2].integer.value = TPM_PPI_FN_SUBREQ2;
+        /*
+         * PPI spec defines params[3].type as ACPI_TYPE_PACKAGE. Some BIOS
+         * accept buffer/string/integer type, but some BIOS accept buffer/
+         * string/package type. For PPI version 1.0 and 1.1, use buffer type
+         * for compatibility, and use package type since 1.2 according to spec.
+         */
+        if (strcmp(version, "1.2") == -1) {
+                params[3].type = ACPI_TYPE_BUFFER;
+                params[3].buffer.length = sizeof(req);
+                sscanf(buf, "%d", &req);
+                params[3].buffer.pointer = (char *)&req;
+        } else {
+                params[3].package.count = 1;
+                obj.type = ACPI_TYPE_INTEGER;
+                sscanf(buf, "%llu", &obj.integer.value);
+                params[3].package.elements = &obj;
+        }
+
+        status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
+                                            ACPI_TYPE_INTEGER);
+        if (ACPI_FAILURE(status))
+                return -ENOMEM;
+        ret = ((union acpi_object *)output.pointer)->integer.value;
+        if (ret == 0)
+                status = (acpi_status)count;
+        else if (ret == 1)
+                status = -EPERM;
+        else
+                status = -EFAULT;
+        kfree(output.pointer);
+        return status;
+}
+
+ssize_t tpm_show_ppi_transition_action(struct device *dev,
+                                       struct device_attribute *attr,
+                                       char *buf)
+{
+        char version[PPI_VERSION_LEN + 1];
+        acpi_handle handle;
+        acpi_status status;
+        struct acpi_object_list input;
+        struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+        union acpi_object params[4];
+        u32 ret;
+        char *info[] = {
+                "None",
+                "Shutdown",
+                "Reboot",
+                "OS Vendor-specific",
+                "Error",
+        };
+        input.count = 4;
+        ppi_assign_params(params, TPM_PPI_FN_VERSION);
+        input.pointer = params;
+        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+                                     ACPI_UINT32_MAX, ppi_callback, NULL,
+                                     tpm_device_name, &handle);
+        if (ACPI_FAILURE(status))
+                return -ENXIO;
+
+        status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
+                                            ACPI_TYPE_STRING);
+        if (ACPI_FAILURE(status))
+                return -ENOMEM;
+        strncpy(version,
+                ((union acpi_object *)output.pointer)->string.pointer,
+                PPI_VERSION_LEN);
+        /*
+         * PPI spec defines params[3].type as empty package, but some platforms
+         * (e.g. Capella with PPI 1.0) need integer/string/buffer type, so for
+         * compatibility, define params[3].type as buffer, if PPI version < 1.2
+         */
+        if (strcmp(version, "1.2") == -1) {
+                params[3].type = ACPI_TYPE_BUFFER;
+                params[3].buffer.length =  0;
+                params[3].buffer.pointer = NULL;
+        }
+        params[2].integer.value = TPM_PPI_FN_GETACT;
+        kfree(output.pointer);
+        output.length = ACPI_ALLOCATE_BUFFER;
+        output.pointer = NULL;
+        status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
+                                            ACPI_TYPE_INTEGER);
+        if (ACPI_FAILURE(status))
+                return -ENOMEM;
+        ret = ((union acpi_object *)output.pointer)->integer.value;
+        if (ret < ARRAY_SIZE(info) - 1)
+                status = scnprintf(buf, PAGE_SIZE, "%d: %s\n", ret, info[ret]);
+        else
+                status = scnprintf(buf, PAGE_SIZE, "%d: %s\n", ret,
+                                   info[ARRAY_SIZE(info)-1]);
+        kfree(output.pointer);
+        return status;
+}
+
+ssize_t tpm_show_ppi_response(struct device *dev,
+                              struct device_attribute *attr,
+                              char *buf)
+{
+        acpi_handle handle;
+        acpi_status status;
+        struct acpi_object_list input;
+        struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+        union acpi_object params[4];
+        union acpi_object *ret_obj;
+        u64 req;
+
+        input.count = 4;
+        ppi_assign_params(params, TPM_PPI_FN_GETRSP);
+        input.pointer = params;
+        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+                                     ACPI_UINT32_MAX, ppi_callback, NULL,
+                                     tpm_device_name, &handle);
+        if (ACPI_FAILURE(status))
+                return -ENXIO;
+
+        status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
+                                            ACPI_TYPE_PACKAGE);
+        if (ACPI_FAILURE(status))
+                return -ENOMEM;
+        /*
+         * parameter output.pointer should be of package type, including
+         * 3 integers. The first means function return code, the second means
+         * most recent TPM operation request, and the last means response to
+         * the most recent TPM operation request. Only if the first is 0, and
+         * the second integer is not 0, the response makes sense.
+         */
+        ret_obj = ((union acpi_object *)output.pointer)->package.elements;
+        if (ret_obj->type != ACPI_TYPE_INTEGER) {
+                status = -EINVAL;
+                goto cleanup;
+        }
+        if (ret_obj->integer.value) {
+                status = -EFAULT;
+                goto cleanup;
+        }
+        ret_obj++;
+        if (ret_obj->type != ACPI_TYPE_INTEGER) {
+                status = -EINVAL;
+                goto cleanup;
+        }
+        if (ret_obj->integer.value) {
+                req = ret_obj->integer.value;
+                ret_obj++;
+                if (ret_obj->type != ACPI_TYPE_INTEGER) {
+                        status = -EINVAL;
+                        goto cleanup;
+                }
+                if (ret_obj->integer.value == 0)
+                        status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
+                                           "0: Success");
+                else if (ret_obj->integer.value == 0xFFFFFFF0)
+                        status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
+                                           "0xFFFFFFF0: User Abort");
+                else if (ret_obj->integer.value == 0xFFFFFFF1)
+                        status = scnprintf(buf, PAGE_SIZE, "%llu %s\n", req,
+                                           "0xFFFFFFF1: BIOS Failure");
+                else if (ret_obj->integer.value >= 1 &&
+                         ret_obj->integer.value <= 0x00000FFF)
+                        status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
+                                           req, ret_obj->integer.value,
+                                           "Corresponding TPM error");
+                else
+                        status = scnprintf(buf, PAGE_SIZE, "%llu %llu: %s\n",
+                                           req, ret_obj->integer.value,
+                                           "Error");
+        } else {
+                status = scnprintf(buf, PAGE_SIZE, "%llu: %s\n",
+                                   ret_obj->integer.value, "No Recent Request");
+        }
+cleanup:
+        kfree(output.pointer);
+        return status;
+}
+
+static ssize_t show_ppi_operations(char *buf, u32 start, u32 end)
+{
+        char *str = buf;
+        char version[PPI_VERSION_LEN];
+        acpi_handle handle;
+        acpi_status status;
+        struct acpi_object_list input;
+        struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER, NULL };
+        union acpi_object params[4];
+        union acpi_object obj;
+        int i;
+        u32 ret;
+        char *info[] = {
+                "Not implemented",
+                "BIOS only",
+                "Blocked for OS by BIOS",
+                "User required",
+                "User not required",
+        };
+        input.count = 4;
+        ppi_assign_params(params, TPM_PPI_FN_VERSION);
+        input.pointer = params;
+        status = acpi_walk_namespace(ACPI_TYPE_DEVICE, ACPI_ROOT_OBJECT,
+                                     ACPI_UINT32_MAX, ppi_callback, NULL,
+                                     tpm_device_name, &handle);
+        if (ACPI_FAILURE(status))
+                return -ENXIO;
+
+        status = acpi_evaluate_object_typed(handle, "_DSM", &input, &output,
+                                         ACPI_TYPE_STRING);
+        if (ACPI_FAILURE(status))
+                return -ENOMEM;
+
+        strncpy(version,
+                ((union acpi_object *)output.pointer)->string.pointer,
+                PPI_VERSION_LEN);
+        kfree(output.pointer);
+        output.length = ACPI_ALLOCATE_BUFFER;
+        output.pointer = NULL;
+        if (strcmp(version, "1.2") == -1)
+                return -EPERM;
+
+        params[2].integer.value = TPM_PPI_FN_GETOPR;
+        params[3].package.count = 1;
+        obj.type = ACPI_TYPE_INTEGER;
+        params[3].package.elements = &obj;
+        for (i = start; i <= end; i++) {
+                obj.integer.value = i;
+                status = acpi_evaluate_object_typed(handle, "_DSM",
+                         &input, &output, ACPI_TYPE_INTEGER);
+                if (ACPI_FAILURE(status))
+                        return -ENOMEM;
+
+                ret = ((union acpi_object *)output.pointer)->integer.value;
+                if (ret > 0 && ret < ARRAY_SIZE(info))
+                        str += scnprintf(str, PAGE_SIZE, "%d %d: %s\n",
+                                         i, ret, info[ret]);
+                kfree(output.pointer);
+                output.length = ACPI_ALLOCATE_BUFFER;
+                output.pointer = NULL;
+        }
+        return str - buf;
+}
+
+ssize_t tpm_show_ppi_tcg_operations(struct device *dev,
+                                   struct device_attribute *attr, char *buf)
+{
+        return show_ppi_operations(buf, 0, PPI_TPM_REQ_MAX);
+}
+
+ssize_t tpm_show_ppi_vs_operations(struct device *dev,
+                                  struct device_attribute *attr, char *buf)
+{
+        return show_ppi_operations(buf, PPI_VS_REQ_START, PPI_VS_REQ_END);
+}
+
+static DEVICE_ATTR(version, S_IRUGO, tpm_show_ppi_version, NULL);
+static DEVICE_ATTR(request, S_IRUGO | S_IWUSR | S_IWGRP,
+                   tpm_show_ppi_request, tpm_store_ppi_request);
+static DEVICE_ATTR(transition_action, S_IRUGO,
+                   tpm_show_ppi_transition_action, NULL);
+static DEVICE_ATTR(response, S_IRUGO, tpm_show_ppi_response, NULL);
+static DEVICE_ATTR(tcg_operations, S_IRUGO, tpm_show_ppi_tcg_operations, NULL);
+static DEVICE_ATTR(vs_operations, S_IRUGO, tpm_show_ppi_vs_operations, NULL);
+
+static struct attribute *ppi_attrs[] = {
+        &dev_attr_version.attr,
+        &dev_attr_request.attr,
+        &dev_attr_transition_action.attr,
+        &dev_attr_response.attr,
+        &dev_attr_tcg_operations.attr,
+        &dev_attr_vs_operations.attr, NULL,
+};
+static struct attribute_group ppi_attr_grp = {
+        .attrs = ppi_attrs
+};
+
+ssize_t sys_add_ppi(struct kobject *parent)
+{
+        struct kobject *ppi;
+        ppi = kobject_create_and_add("ppi", parent);
+        if (sysfs_create_group(ppi, &ppi_attr_grp))
+                return -EFAULT;
+        else
+                return 0;
+}
+EXPORT_SYMBOL_GPL(sys_add_ppi);
+
+MODULE_LICENSE("GPL");