diff options
Diffstat (limited to 'drivers/platform/x86/intel_speed_select_if/isst_if_mbox_msr.c')
| -rw-r--r-- | drivers/platform/x86/intel_speed_select_if/isst_if_mbox_msr.c | 216 |
1 files changed, 216 insertions, 0 deletions
diff --git a/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_msr.c b/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_msr.c new file mode 100644 index 000000000000..89b042aecef3 --- /dev/null +++ b/drivers/platform/x86/intel_speed_select_if/isst_if_mbox_msr.c @@ -0,0 +1,216 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Intel Speed Select Interface: Mbox via MSR Interface + * Copyright (c) 2019, Intel Corporation. + * All rights reserved. + * + * Author: Srinivas Pandruvada <srinivas.pandruvada@linux.intel.com> + */ + +#include <linux/module.h> +#include <linux/cpuhotplug.h> +#include <linux/pci.h> +#include <linux/sched/signal.h> +#include <linux/slab.h> +#include <linux/suspend.h> +#include <linux/topology.h> +#include <linux/uaccess.h> +#include <uapi/linux/isst_if.h> +#include <asm/cpu_device_id.h> +#include <asm/intel-family.h> + +#include "isst_if_common.h" + +#define MSR_OS_MAILBOX_INTERFACE 0xB0 +#define MSR_OS_MAILBOX_DATA 0xB1 +#define MSR_OS_MAILBOX_BUSY_BIT 31 + +/* + * Based on experiments count is never more than 1, as the MSR overhead + * is enough to finish the command. So here this is the worst case number. + */ +#define OS_MAILBOX_RETRY_COUNT 3 + +static int isst_if_send_mbox_cmd(u8 command, u8 sub_command, u32 parameter, + u32 command_data, u32 *response_data) +{ + u32 retries; + u64 data; + int ret; + + /* Poll for rb bit == 0 */ + retries = OS_MAILBOX_RETRY_COUNT; + do { + rdmsrl(MSR_OS_MAILBOX_INTERFACE, data); + if (data & BIT_ULL(MSR_OS_MAILBOX_BUSY_BIT)) { + ret = -EBUSY; + continue; + } + ret = 0; + break; + } while (--retries); + + if (ret) + return ret; + + /* Write DATA register */ + wrmsrl(MSR_OS_MAILBOX_DATA, command_data); + + /* Write command register */ + data = BIT_ULL(MSR_OS_MAILBOX_BUSY_BIT) | + (parameter & GENMASK_ULL(13, 0)) << 16 | + (sub_command << 8) | + command; + wrmsrl(MSR_OS_MAILBOX_INTERFACE, data); + + /* Poll for rb bit == 0 */ + retries = OS_MAILBOX_RETRY_COUNT; + do { + rdmsrl(MSR_OS_MAILBOX_INTERFACE, data); + if (data & BIT_ULL(MSR_OS_MAILBOX_BUSY_BIT)) { + ret = -EBUSY; + continue; + } + + if (data & 0xff) + return -ENXIO; + + if (response_data) { + rdmsrl(MSR_OS_MAILBOX_DATA, data); + *response_data = data; + } + ret = 0; + break; + } while (--retries); + + return ret; +} + +struct msrl_action { + int err; + struct isst_if_mbox_cmd *mbox_cmd; +}; + +/* revisit, smp_call_function_single should be enough for atomic mailbox! */ +static void msrl_update_func(void *info) +{ + struct msrl_action *act = info; + + act->err = isst_if_send_mbox_cmd(act->mbox_cmd->command, + act->mbox_cmd->sub_command, + act->mbox_cmd->parameter, + act->mbox_cmd->req_data, + &act->mbox_cmd->resp_data); +} + +static long isst_if_mbox_proc_cmd(u8 *cmd_ptr, int *write_only, int resume) +{ + struct msrl_action action; + int ret; + + action.mbox_cmd = (struct isst_if_mbox_cmd *)cmd_ptr; + + if (isst_if_mbox_cmd_invalid(action.mbox_cmd)) + return -EINVAL; + + if (isst_if_mbox_cmd_set_req(action.mbox_cmd) && + !capable(CAP_SYS_ADMIN)) + return -EPERM; + + /* + * To complete mailbox command, we need to access two MSRs. + * So we don't want race to complete a mailbox transcation. + * Here smp_call ensures that msrl_update_func() has no race + * and also with wait flag, wait for completion. + * smp_call_function_single is using get_cpu() and put_cpu(). + */ + ret = smp_call_function_single(action.mbox_cmd->logical_cpu, + msrl_update_func, &action, 1); + if (ret) + return ret; + + if (!action.err && !resume && isst_if_mbox_cmd_set_req(action.mbox_cmd)) + action.err = isst_store_cmd(action.mbox_cmd->command, + action.mbox_cmd->sub_command, + action.mbox_cmd->logical_cpu, 1, + action.mbox_cmd->parameter, + action.mbox_cmd->req_data); + *write_only = 0; + + return action.err; +} + + +static int isst_pm_notify(struct notifier_block *nb, + unsigned long mode, void *_unused) +{ + switch (mode) { + case PM_POST_HIBERNATION: + case PM_POST_RESTORE: + case PM_POST_SUSPEND: + isst_resume_common(); + break; + default: + break; + } + return 0; +} + +static struct notifier_block isst_pm_nb = { + .notifier_call = isst_pm_notify, +}; + +#define ICPU(model) { X86_VENDOR_INTEL, 6, model, X86_FEATURE_ANY, } + +static const struct x86_cpu_id isst_if_cpu_ids[] = { + ICPU(INTEL_FAM6_SKYLAKE_X), + {} +}; +MODULE_DEVICE_TABLE(x86cpu, isst_if_cpu_ids); + +static int __init isst_if_mbox_init(void) +{ + struct isst_if_cmd_cb cb; + const struct x86_cpu_id *id; + u64 data; + int ret; + + id = x86_match_cpu(isst_if_cpu_ids); + if (!id) + return -ENODEV; + + /* Check presence of mailbox MSRs */ + ret = rdmsrl_safe(MSR_OS_MAILBOX_INTERFACE, &data); + if (ret) + return ret; + + ret = rdmsrl_safe(MSR_OS_MAILBOX_DATA, &data); + if (ret) + return ret; + + memset(&cb, 0, sizeof(cb)); + cb.cmd_size = sizeof(struct isst_if_mbox_cmd); + cb.offset = offsetof(struct isst_if_mbox_cmds, mbox_cmd); + cb.cmd_callback = isst_if_mbox_proc_cmd; + cb.owner = THIS_MODULE; + ret = isst_if_cdev_register(ISST_IF_DEV_MBOX, &cb); + if (ret) + return ret; + + ret = register_pm_notifier(&isst_pm_nb); + if (ret) + isst_if_cdev_unregister(ISST_IF_DEV_MBOX); + + return ret; +} +module_init(isst_if_mbox_init) + +static void __exit isst_if_mbox_exit(void) +{ + unregister_pm_notifier(&isst_pm_nb); + isst_if_cdev_unregister(ISST_IF_DEV_MBOX); +} +module_exit(isst_if_mbox_exit) + +MODULE_LICENSE("GPL v2"); +MODULE_DESCRIPTION("Intel speed select interface mailbox driver"); |