Release 4.16 samples/vfio-mdev/mtty.c
/*
* Mediated virtual PCI serial host device driver
*
* Copyright (c) 2016, NVIDIA CORPORATION. All rights reserved.
* Author: Neo Jia <cjia@nvidia.com>
* Kirti Wankhede <kwankhede@nvidia.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
* Sample driver that creates mdev device that simulates serial port over PCI
* card.
*
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/fs.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/cdev.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <linux/uuid.h>
#include <linux/vfio.h>
#include <linux/iommu.h>
#include <linux/sysfs.h>
#include <linux/ctype.h>
#include <linux/file.h>
#include <linux/mdev.h>
#include <linux/pci.h>
#include <linux/serial.h>
#include <uapi/linux/serial_reg.h>
#include <linux/eventfd.h>
/*
* #defines
*/
#define VERSION_STRING "0.1"
#define DRIVER_AUTHOR "NVIDIA Corporation"
#define MTTY_CLASS_NAME "mtty"
#define MTTY_NAME "mtty"
#define MTTY_STRING_LEN 16
#define MTTY_CONFIG_SPACE_SIZE 0xff
#define MTTY_IO_BAR_SIZE 0x8
#define MTTY_MMIO_BAR_SIZE 0x100000
#define STORE_LE16(addr, val) (*(u16 *)addr = val)
#define STORE_LE32(addr, val) (*(u32 *)addr = val)
#define MAX_FIFO_SIZE 16
#define CIRCULAR_BUF_INC_IDX(idx) (idx = (idx + 1) & (MAX_FIFO_SIZE - 1))
#define MTTY_VFIO_PCI_OFFSET_SHIFT 40
#define MTTY_VFIO_PCI_OFFSET_TO_INDEX(off) (off >> MTTY_VFIO_PCI_OFFSET_SHIFT)
#define MTTY_VFIO_PCI_INDEX_TO_OFFSET(index) \
((u64)(index) << MTTY_VFIO_PCI_OFFSET_SHIFT)
#define MTTY_VFIO_PCI_OFFSET_MASK \
(((u64)(1) << MTTY_VFIO_PCI_OFFSET_SHIFT) - 1)
#define MAX_MTTYS 24
/*
* Global Structures
*/
struct mtty_dev {
dev_t vd_devt;
struct class *vd_class;
struct cdev vd_cdev;
struct idr vd_idr;
struct device dev;
} mtty_dev;
struct mdev_region_info {
u64 start;
u64 phys_start;
u32 size;
u64 vfio_offset;
};
#if defined(DEBUG_REGS)
const char *wr_reg[] = {
"TX",
"IER",
"FCR",
"LCR",
"MCR",
"LSR",
"MSR",
"SCR"
};
const char *rd_reg[] = {
"RX",
"IER",
"IIR",
"LCR",
"MCR",
"LSR",
"MSR",
"SCR"
};
#endif
/* loop back buffer */
struct rxtx {
u8 fifo[MAX_FIFO_SIZE];
u8 head, tail;
u8 count;
};
struct serial_port {
u8 uart_reg[8]; /* 8 registers */
struct rxtx rxtx; /* loop back buffer */
bool dlab;
bool overrun;
u16 divisor;
u8 fcr; /* FIFO control register */
u8 max_fifo_size;
u8 intr_trigger_level; /* interrupt trigger level */
};
/* State of each mdev device */
struct mdev_state {
int irq_fd;
struct eventfd_ctx *intx_evtfd;
struct eventfd_ctx *msi_evtfd;
int irq_index;
u8 *vconfig;
struct mutex ops_lock;
struct mdev_device *mdev;
struct mdev_region_info region_info[VFIO_PCI_NUM_REGIONS];
u32 bar_mask[VFIO_PCI_NUM_REGIONS];
struct list_head next;
struct serial_port s[2];
struct mutex rxtx_lock;
struct vfio_device_info dev_info;
int nr_ports;
};
struct mutex mdev_list_lock;
struct list_head mdev_devices_list;
static const struct file_operations vd_fops = {
.owner = THIS_MODULE,
};
/* function prototypes */
static int mtty_trigger_interrupt(uuid_le uuid);
/* Helper functions */
static struct mdev_state *find_mdev_state_by_uuid(uuid_le uuid)
{
struct mdev_state *mds;
list_for_each_entry(mds, &mdev_devices_list, next) {
if (uuid_le_cmp(mdev_uuid(mds->mdev), uuid) == 0)
return mds;
}
return NULL;
}
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void dump_buffer(char *buf, uint32_t count)
{
#if defined(DEBUG)
int i;
pr_info("Buffer:\n");
for (i = 0; i < count; i++) {
pr_info("%2x ", *(buf + i));
if ((i + 1) % 16 == 0)
pr_info("\n");
}
#endif
}
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static void mtty_create_config_space(struct mdev_state *mdev_state)
{
/* PCI dev ID */
STORE_LE32((u32 *) &mdev_state->vconfig[0x0], 0x32534348);
/* Control: I/O+, Mem-, BusMaster- */
STORE_LE16((u16 *) &mdev_state->vconfig[0x4], 0x0001);
/* Status: capabilities list absent */
STORE_LE16((u16 *) &mdev_state->vconfig[0x6], 0x0200);
/* Rev ID */
mdev_state->vconfig[0x8] = 0x10;
/* programming interface class : 16550-compatible serial controller */
mdev_state->vconfig[0x9] = 0x02;
/* Sub class : 00 */
mdev_state->vconfig[0xa] = 0x00;
/* Base class : Simple Communication controllers */
mdev_state->vconfig[0xb] = 0x07;
/* base address registers */
/* BAR0: IO space */
STORE_LE32((u32 *) &mdev_state->vconfig[0x10], 0x000001);
mdev_state->bar_mask[0] = ~(MTTY_IO_BAR_SIZE) + 1;
if (mdev_state->nr_ports == 2) {
/* BAR1: IO space */
STORE_LE32((u32 *) &mdev_state->vconfig[0x14], 0x000001);
mdev_state->bar_mask[1] = ~(MTTY_IO_BAR_SIZE) + 1;
}
/* Subsystem ID */
STORE_LE32((u32 *) &mdev_state->vconfig[0x2c], 0x32534348);
mdev_state->vconfig[0x34] = 0x00; /* Cap Ptr */
mdev_state->vconfig[0x3d] = 0x01; /* interrupt pin (INTA#) */
/* Vendor specific data */
mdev_state->vconfig[0x40] = 0x23;
mdev_state->vconfig[0x43] = 0x80;
mdev_state->vconfig[0x44] = 0x23;
mdev_state->vconfig[0x48] = 0x23;
mdev_state->vconfig[0x4c] = 0x23;
mdev_state->vconfig[0x60] = 0x50;
mdev_state->vconfig[0x61] = 0x43;
mdev_state->vconfig[0x62] = 0x49;
mdev_state->vconfig[0x63] = 0x20;
mdev_state->vconfig[0x64] = 0x53;
mdev_state->vconfig[0x65] = 0x65;
mdev_state->vconfig[0x66] = 0x72;
mdev_state->vconfig[0x67] = 0x69;
mdev_state->vconfig[0x68] = 0x61;
mdev_state->vconfig[0x69] = 0x6c;
mdev_state->vconfig[0x6a] = 0x2f;
mdev_state->vconfig[0x6b] = 0x55;
mdev_state->vconfig[0x6c] = 0x41;
mdev_state->vconfig[0x6d] = 0x52;
mdev_state->vconfig[0x6e] = 0x54;
}
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static void handle_pci_cfg_write(struct mdev_state *mdev_state, u16 offset,
char *buf, u32 count)
{
u32 cfg_addr, bar_mask, bar_index = 0;
switch (offset) {
case 0x04: /* device control */
case 0x06: /* device status */
/* do nothing */
break;
case 0x3c: /* interrupt line */
mdev_state->vconfig[0x3c] = buf[0];
break;
case 0x3d:
/*
* Interrupt Pin is hardwired to INTA.
* This field is write protected by hardware
*/
break;
case 0x10: /* BAR0 */
case 0x14: /* BAR1 */
if (offset == 0x10)
bar_index = 0;
else if (offset == 0x14)
bar_index = 1;
if ((mdev_state->nr_ports == 1) && (bar_index == 1)) {
STORE_LE32(&mdev_state->vconfig[offset], 0);
break;
}
cfg_addr = *(u32 *)buf;
pr_info("BAR%d addr 0x%x\n", bar_index, cfg_addr);
if (cfg_addr == 0xffffffff) {
bar_mask = mdev_state->bar_mask[bar_index];
cfg_addr = (cfg_addr & bar_mask);
}
cfg_addr |= (mdev_state->vconfig[offset] & 0x3ul);
STORE_LE32(&mdev_state->vconfig[offset], cfg_addr);
break;
case 0x18: /* BAR2 */
case 0x1c: /* BAR3 */
case 0x20: /* BAR4 */
STORE_LE32(&mdev_state->vconfig[offset], 0);
break;
default:
pr_info("PCI config write @0x%x of %d bytes not handled\n",
offset, count);
break;
}
}
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static void handle_bar_write(unsigned int index, struct mdev_state *mdev_state,
u16 offset, char *buf, u32 count)
{
u8 data = *buf;
/* Handle data written by guest */
switch (offset) {
case UART_TX:
/* if DLAB set, data is LSB of divisor */
if (mdev_state->s[index].dlab) {
mdev_state->s[index].divisor |= data;
break;
}
mutex_lock(&mdev_state->rxtx_lock);
/* save in TX buffer */
if (mdev_state->s[index].rxtx.count <
mdev_state->s[index].max_fifo_size) {
mdev_state->s[index].rxtx.fifo[
mdev_state->s[index].rxtx.head] = data;
mdev_state->s[index].rxtx.count++;
CIRCULAR_BUF_INC_IDX(mdev_state->s[index].rxtx.head);
mdev_state->s[index].overrun = false;
/*
* Trigger interrupt if receive data interrupt is
* enabled and fifo reached trigger level
*/
if ((mdev_state->s[index].uart_reg[UART_IER] &
UART_IER_RDI) &&
(mdev_state->s[index].rxtx.count ==
mdev_state->s[index].intr_trigger_level)) {
/* trigger interrupt */
#if defined(DEBUG_INTR)
pr_err("Serial port %d: Fifo level trigger\n",
index);
#endif
mtty_trigger_interrupt(
mdev_uuid(mdev_state->mdev));
}
} else {
#if defined(DEBUG_INTR)
pr_err("Serial port %d: Buffer Overflow\n", index);
#endif
mdev_state->s[index].overrun = true;
/*
* Trigger interrupt if receiver line status interrupt
* is enabled
*/
if (mdev_state->s[index].uart_reg[UART_IER] &
UART_IER_RLSI)
mtty_trigger_interrupt(
mdev_uuid(mdev_state->mdev));
}
mutex_unlock(&mdev_state->rxtx_lock);
break;
case UART_IER:
/* if DLAB set, data is MSB of divisor */
if (mdev_state->s[index].dlab)
mdev_state->s[index].divisor |= (u16)data << 8;
else {
mdev_state->s[index].uart_reg[offset] = data;
mutex_lock(&mdev_state->rxtx_lock);
if ((data & UART_IER_THRI) &&
(mdev_state->s[index].rxtx.head ==
mdev_state->s[index].rxtx.tail)) {
#if defined(DEBUG_INTR)
pr_err("Serial port %d: IER_THRI write\n",
index);
#endif
mtty_trigger_interrupt(
mdev_uuid(mdev_state->mdev));
}
mutex_unlock(&mdev_state->rxtx_lock);
}
break;
case UART_FCR:
mdev_state->s[index].fcr = data;
mutex_lock(&mdev_state->rxtx_lock);
if (data & (UART_FCR_CLEAR_RCVR | UART_FCR_CLEAR_XMIT)) {
/* clear loop back FIFO */
mdev_state->s[index].rxtx.count = 0;
mdev_state->s[index].rxtx.head = 0;
mdev_state->s[index].rxtx.tail = 0;
}
mutex_unlock(&mdev_state->rxtx_lock);
switch (data & UART_FCR_TRIGGER_MASK) {
case UART_FCR_TRIGGER_1:
mdev_state->s[index].intr_trigger_level = 1;
break;
case UART_FCR_TRIGGER_4:
mdev_state->s[index].intr_trigger_level = 4;
break;
case UART_FCR_TRIGGER_8:
mdev_state->s[index].intr_trigger_level = 8;
break;
case UART_FCR_TRIGGER_14:
mdev_state->s[index].intr_trigger_level = 14;
break;
}
/*
* Set trigger level to 1 otherwise or implement timer with
* timeout of 4 characters and on expiring that timer set
* Recevice data timeout in IIR register
*/
mdev_state->s[index].intr_trigger_level = 1;
if (data & UART_FCR_ENABLE_FIFO)
mdev_state->s[index].max_fifo_size = MAX_FIFO_SIZE;
else {
mdev_state->s[index].max_fifo_size = 1;
mdev_state->s[index].intr_trigger_level = 1;
}
break;
case UART_LCR:
if (data & UART_LCR_DLAB) {
mdev_state->s[index].dlab = true;
mdev_state->s[index].divisor = 0;
} else
mdev_state->s[index].dlab = false;
mdev_state->s[index].uart_reg[offset] = data;
break;
case UART_MCR:
mdev_state->s[index].uart_reg[offset] = data;
if ((mdev_state->s[index].uart_reg[UART_IER] & UART_IER_MSI) &&
(data & UART_MCR_OUT2)) {
#if defined(DEBUG_INTR)
pr_err("Serial port %d: MCR_OUT2 write\n", index);
#endif
mtty_trigger_interrupt(mdev_uuid(mdev_state->mdev));
}
if ((mdev_state->s[index].uart_reg[UART_IER] & UART_IER_MSI) &&
(data & (UART_MCR_RTS | UART_MCR_DTR))) {
#if defined(DEBUG_INTR)
pr_err("Serial port %d: MCR RTS/DTR write\n", index);
#endif
mtty_trigger_interrupt(mdev_uuid(mdev_state->mdev));
}
break;
case UART_LSR:
case UART_MSR:
/* do nothing */
break;
case UART_SCR:
mdev_state->s[index].uart_reg[offset] = data;
break;
default:
break;
}
}
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static void handle_bar_read(unsigned int index, struct mdev_state *mdev_state,
u16 offset, char *buf, u32 count)
{
/* Handle read requests by guest */
switch (offset) {
case UART_RX:
/* if DLAB set, data is LSB of divisor */
if (mdev_state->s[index].dlab) {
*buf = (u8)mdev_state->s[index].divisor;
break;
}
mutex_lock(&mdev_state->rxtx_lock);
/* return data in tx buffer */
if (mdev_state->s[index].rxtx.head !=
mdev_state->s[index].rxtx.tail) {
*buf = mdev_state->s[index].rxtx.fifo[
mdev_state->s[index].rxtx.tail];
mdev_state->s[index].rxtx.count--;
CIRCULAR_BUF_INC_IDX(mdev_state->s[index].rxtx.tail);
}
if (mdev_state->s[index].rxtx.head ==
mdev_state->s[index].rxtx.tail) {
/*
* Trigger interrupt if tx buffer empty interrupt is
* enabled and fifo is empty
*/
#if defined(DEBUG_INTR)
pr_err("Serial port %d: Buffer Empty\n", index);
#endif
if (mdev_state->s[index].uart_reg[UART_IER] &
UART_IER_THRI)
mtty_trigger_interrupt(
mdev_uuid(mdev_state->mdev));
}
mutex_unlock(&mdev_state->rxtx_lock);
break;
case UART_IER:
if (mdev_state->s[index].dlab) {
*buf = (u8)(mdev_state->s[index].divisor >> 8);
break;
}
*buf = mdev_state->s[index].uart_reg[offset] & 0x0f;
break;
case UART_IIR:
{
u8 ier = mdev_state->s[index].uart_reg[UART_IER];
*buf = 0;
mutex_lock(&mdev_state->rxtx_lock);
/* Interrupt priority 1: Parity, overrun, framing or break */
if ((ier & UART_IER_RLSI) && mdev_state->s[index].overrun)
*buf |= UART_IIR_RLSI;
/* Interrupt priority 2: Fifo trigger level reached */
if ((ier & UART_IER_RDI) &&
(mdev_state->s[index].rxtx.count ==
mdev_state->s[index].intr_trigger_level))
*buf |= UART_IIR_RDI;
/* Interrupt priotiry 3: transmitter holding register empty */
if ((ier & UART_IER_THRI) &&
(mdev_state->s[index].rxtx.head ==
mdev_state->s[index].rxtx.tail))
*buf |= UART_IIR_THRI;
/* Interrupt priotiry 4: Modem status: CTS, DSR, RI or DCD */
if ((ier & UART_IER_MSI) &&
(mdev_state->s[index].uart_reg[UART_MCR] &
(UART_MCR_RTS | UART_MCR_DTR)))
*buf |= UART_IIR_MSI;
/* bit0: 0=> interrupt pending, 1=> no interrupt is pending */
if (*buf == 0)
*buf = UART_IIR_NO_INT;
/* set bit 6 & 7 to be 16550 compatible */
*buf |= 0xC0;
mutex_unlock(&mdev_state->rxtx_lock);
}
break;
case UART_LCR:
case UART_MCR:
*buf = mdev_state->s[index].uart_reg[offset];
break;
case UART_LSR:
{
u8 lsr = 0;
mutex_lock(&mdev_state->rxtx_lock);
/* atleast one char in FIFO */
if (mdev_state->s[index].rxtx.head !=
mdev_state->s[index].rxtx.tail)
lsr |= UART_LSR_DR;
/* if FIFO overrun */
if (mdev_state->s[index].overrun)
lsr |= UART_LSR_OE;
/* transmit FIFO empty and tramsitter empty */
if (mdev_state->s[index].rxtx.head ==
mdev_state->s[index].rxtx.tail)
lsr |= UART_LSR_TEMT | UART_LSR_THRE;
mutex_unlock(&mdev_state->rxtx_lock);
*buf = lsr;
break;
}
case UART_MSR:
*buf = UART_MSR_DSR | UART_MSR_DDSR | UART_MSR_DCD;
mutex_lock(&mdev_state->rxtx_lock);