// SPDX-License-Identifier: GPL-2.0
/*
* Intel Speed Select Interface: Mbox via PCI Interface
* Copyright (c) 2019, Intel Corporation.
* All rights reserved.
*
* Author: Srinivas Pandruvada <[email protected]>
*/
#include <linux/cpufeature.h>
#include <linux/module.h>
#include <linux/pci.h>
#include <linux/sched/signal.h>
#include <linux/uaccess.h>
#include <uapi/linux/isst_if.h>
#include "isst_if_common.h"
#define PUNIT_MAILBOX_DATA 0xA0
#define PUNIT_MAILBOX_INTERFACE 0xA4
#define PUNIT_MAILBOX_BUSY_BIT 31
/*
* The average time to complete mailbox commands is less than 40us. Most of
* the commands complete in few micro seconds. But the same firmware handles
* requests from all power management features.
* We can create a scenario where we flood the firmware with requests then
* the mailbox response can be delayed for 100s of micro seconds. So define
* two timeouts. One for average case and one for long.
* If the firmware is taking more than average, just call cond_resched().
*/
#define OS_MAILBOX_TIMEOUT_AVG_US 40
#define OS_MAILBOX_TIMEOUT_MAX_US 1000
struct isst_if_device {
struct mutex mutex;
};
static int isst_if_mbox_cmd(struct pci_dev *pdev,
struct isst_if_mbox_cmd *mbox_cmd)
{
s64 tm_delta = 0;
ktime_t tm;
u32 data;
int ret;
/* Poll for rb bit == 0 */
tm = ktime_get();
do {
ret = pci_read_config_dword(pdev, PUNIT_MAILBOX_INTERFACE,
&data);
if (ret)
return ret;
if (data & BIT_ULL(PUNIT_MAILBOX_BUSY_BIT)) {
ret = -EBUSY;
tm_delta = ktime_us_delta(ktime_get(), tm);
if (tm_delta > OS_MAILBOX_TIMEOUT_AVG_US)
cond_resched();
continue;
}
ret = 0;
break;
} while (tm_delta < OS_MAILBOX_TIMEOUT_MAX_US);
if (ret)
return ret;
/* Write DATA register */
ret = pci_write_config_dword(pdev, PUNIT_MAILBOX_DATA,
mbox_cmd->req_data);
if (ret)
return ret;
/* Write command register */
data = BIT_ULL(PUNIT_MAILBOX_BUSY_BIT) |
(mbox_cmd->parameter & GENMASK_ULL(13, 0)) << 16 |
(mbox_cmd->sub_command << 8) |
mbox_cmd->command;
ret = pci_write_config_dword(pdev, PUNIT_MAILBOX_INTERFACE, data);
if (ret)
return ret;
/* Poll for rb bit == 0 */
tm_delta = 0;
tm = ktime_get();
do {
ret = pci_read_config_dword(pdev, PUNIT_MAILBOX_INTERFACE,
&data);
if (ret)
return ret;
if (data & BIT_ULL(PUNIT_MAILBOX_BUSY_BIT)) {
ret = -EBUSY;
tm_delta = ktime_us_delta(ktime_get(), tm);
if (tm_delta > OS_MAILBOX_TIMEOUT_AVG_US)
cond_resched();
continue;
}
if (data & 0xff)
return -ENXIO;
ret = pci_read_config_dword(pdev, PUNIT_MAILBOX_DATA, &data);
if (ret)
return ret;
mbox_cmd->resp_data = data;
ret = 0;
break;
} while (tm_delta < OS_MAILBOX_TIMEOUT_MAX_US);
return ret;
}
static long isst_if_mbox_proc_cmd(u8 *cmd_ptr, int *write_only, int resume)
{
struct isst_if_mbox_cmd *mbox_cmd;
struct isst_if_device *punit_dev;
struct pci_dev *pdev;
int ret;
mbox_cmd = (struct isst_if_mbox_cmd *)cmd_ptr;
if (isst_if_mbox_cmd_invalid(mbox_cmd))
return -EINVAL;
if (isst_if_mbox_cmd_set_req(mbox_cmd) && !capable(CAP_SYS_ADMIN))
return -EPERM;
pdev = isst_if_get_pci_dev(mbox_cmd->logical_cpu, 1, 30, 1);
if (!pdev)
return -EINVAL;
punit_dev = pci_get_drvdata(pdev);
if (!punit_dev)
return -EINVAL;
/*
* Basically we are allowing one complete mailbox transaction on
* a mapped PCI device at a time.
*/
mutex_lock(&punit_dev->mutex);
ret = isst_if_mbox_cmd(pdev, mbox_cmd);
if (!ret && !resume && isst_if_mbox_cmd_set_req(mbox_cmd))
ret = isst_store_cmd(mbox_cmd->command,
mbox_cmd->sub_command,
mbox_cmd->logical_cpu, 1,
mbox_cmd->parameter,
mbox_cmd->req_data);
mutex_unlock(&punit_dev->mutex);
if (ret)
return ret;
*write_only = 0;
return 0;
}
static const struct pci_device_id isst_if_mbox_ids[] = {
{ PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_CFG_MBOX_DEVID_0)},
{ PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_CFG_MBOX_DEVID_1)},
{ 0 },
};
MODULE_DEVICE_TABLE(pci, isst_if_mbox_ids);
static int isst_if_mbox_probe(struct pci_dev *pdev,
const struct pci_device_id *ent)
{
struct isst_if_device *punit_dev;
struct isst_if_cmd_cb cb;
int ret;
punit_dev = devm_kzalloc(&pdev->dev, sizeof(*punit_dev), GFP_KERNEL);
if (!punit_dev)
return -ENOMEM;
ret = pcim_enable_device(pdev);
if (ret)
return ret;
mutex_init(&punit_dev->mutex);
pci_set_drvdata(pdev, punit_dev);
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)
mutex_destroy(&punit_dev->mutex);
return ret;
}
static void isst_if_mbox_remove(struct pci_dev *pdev)
{
struct isst_if_device *punit_dev;
punit_dev = pci_get_drvdata(pdev);
isst_if_cdev_unregister(ISST_IF_DEV_MBOX);
mutex_destroy(&punit_dev->mutex);
}
static int __maybe_unused isst_if_resume(struct device *device)
{
isst_resume_common();
return 0;
}
static SIMPLE_DEV_PM_OPS(isst_if_pm_ops, NULL, isst_if_resume);
static struct pci_driver isst_if_pci_driver = {
.name = "isst_if_mbox_pci",
.id_table = isst_if_mbox_ids,
.probe = isst_if_mbox_probe,
.remove = isst_if_mbox_remove,
.driver.pm = &isst_if_pm_ops,
};
module_pci_driver(isst_if_pci_driver);
MODULE_LICENSE("GPL v2");
MODULE_DESCRIPTION("Intel speed select interface pci mailbox driver");
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