// SPDX-License-Identifier: GPL-2.0+
/*
* Copyright (c) 2015-2016, IBM Corporation.
*/
#include <linux/atomic.h>
#include <linux/bt-bmc.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/io.h>
#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/timer.h>
/*
* This is a BMC device used to communicate to the host
*/
#define DEVICE_NAME "ipmi-bt-host"
#define BT_IO_BASE 0xe4
#define BT_IRQ 10
#define BT_CR0 0x0
#define BT_CR0_IO_BASE 16
#define BT_CR0_IRQ 12
#define BT_CR0_EN_CLR_SLV_RDP 0x8
#define BT_CR0_EN_CLR_SLV_WRP 0x4
#define BT_CR0_ENABLE_IBT 0x1
#define BT_CR1 0x4
#define BT_CR1_IRQ_H2B 0x01
#define BT_CR1_IRQ_HBUSY 0x40
#define BT_CR2 0x8
#define BT_CR2_IRQ_H2B 0x01
#define BT_CR2_IRQ_HBUSY 0x40
#define BT_CR3 0xc
#define BT_CTRL 0x10
#define BT_CTRL_B_BUSY 0x80
#define BT_CTRL_H_BUSY 0x40
#define BT_CTRL_OEM0 0x20
#define BT_CTRL_SMS_ATN 0x10
#define BT_CTRL_B2H_ATN 0x08
#define BT_CTRL_H2B_ATN 0x04
#define BT_CTRL_CLR_RD_PTR 0x02
#define BT_CTRL_CLR_WR_PTR 0x01
#define BT_BMC2HOST 0x14
#define BT_INTMASK 0x18
#define BT_INTMASK_B2H_IRQEN 0x01
#define BT_INTMASK_B2H_IRQ 0x02
#define BT_INTMASK_BMC_HWRST 0x80
#define BT_BMC_BUFFER_SIZE 256
struct bt_bmc {
struct device dev;
struct miscdevice miscdev;
void __iomem *base;
int irq;
wait_queue_head_t queue;
struct timer_list poll_timer;
struct mutex mutex;
};
static atomic_t open_count = ATOMIC_INIT(0);
static u8 bt_inb(struct bt_bmc *bt_bmc, int reg)
{
return readb(bt_bmc->base + reg);
}
static void bt_outb(struct bt_bmc *bt_bmc, u8 data, int reg)
{
writeb(data, bt_bmc->base + reg);
}
static void clr_rd_ptr(struct bt_bmc *bt_bmc)
{
bt_outb(bt_bmc, BT_CTRL_CLR_RD_PTR, BT_CTRL);
}
static void clr_wr_ptr(struct bt_bmc *bt_bmc)
{
bt_outb(bt_bmc, BT_CTRL_CLR_WR_PTR, BT_CTRL);
}
static void clr_h2b_atn(struct bt_bmc *bt_bmc)
{
bt_outb(bt_bmc, BT_CTRL_H2B_ATN, BT_CTRL);
}
static void set_b_busy(struct bt_bmc *bt_bmc)
{
if (!(bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_B_BUSY))
bt_outb(bt_bmc, BT_CTRL_B_BUSY, BT_CTRL);
}
static void clr_b_busy(struct bt_bmc *bt_bmc)
{
if (bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_B_BUSY)
bt_outb(bt_bmc, BT_CTRL_B_BUSY, BT_CTRL);
}
static void set_b2h_atn(struct bt_bmc *bt_bmc)
{
bt_outb(bt_bmc, BT_CTRL_B2H_ATN, BT_CTRL);
}
static u8 bt_read(struct bt_bmc *bt_bmc)
{
return bt_inb(bt_bmc, BT_BMC2HOST);
}
static ssize_t bt_readn(struct bt_bmc *bt_bmc, u8 *buf, size_t n)
{
int i;
for (i = 0; i < n; i++)
buf[i] = bt_read(bt_bmc);
return n;
}
static void bt_write(struct bt_bmc *bt_bmc, u8 c)
{
bt_outb(bt_bmc, c, BT_BMC2HOST);
}
static ssize_t bt_writen(struct bt_bmc *bt_bmc, u8 *buf, size_t n)
{
int i;
for (i = 0; i < n; i++)
bt_write(bt_bmc, buf[i]);
return n;
}
static void set_sms_atn(struct bt_bmc *bt_bmc)
{
bt_outb(bt_bmc, BT_CTRL_SMS_ATN, BT_CTRL);
}
static struct bt_bmc *file_bt_bmc(struct file *file)
{
return container_of(file->private_data, struct bt_bmc, miscdev);
}
static int bt_bmc_open(struct inode *inode, struct file *file)
{
struct bt_bmc *bt_bmc = file_bt_bmc(file);
if (atomic_inc_return(&open_count) == 1) {
clr_b_busy(bt_bmc);
return 0;
}
atomic_dec(&open_count);
return -EBUSY;
}
/*
* The BT (Block Transfer) interface means that entire messages are
* buffered by the host before a notification is sent to the BMC that
* there is data to be read. The first byte is the length and the
* message data follows. The read operation just tries to capture the
* whole before returning it to userspace.
*
* BT Message format :
*
* Byte 1 Byte 2 Byte 3 Byte 4 Byte 5:N
* Length NetFn/LUN Seq Cmd Data
*
*/
static ssize_t bt_bmc_read(struct file *file, char __user *buf,
size_t count, loff_t *ppos)
{
struct bt_bmc *bt_bmc = file_bt_bmc(file);
u8 len;
int len_byte = 1;
u8 kbuffer[BT_BMC_BUFFER_SIZE];
ssize_t ret = 0;
ssize_t nread;
WARN_ON(*ppos);
if (wait_event_interruptible(bt_bmc->queue,
bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_H2B_ATN))
return -ERESTARTSYS;
mutex_lock(&bt_bmc->mutex);
if (unlikely(!(bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_H2B_ATN))) {
ret = -EIO;
goto out_unlock;
}
set_b_busy(bt_bmc);
clr_h2b_atn(bt_bmc);
clr_rd_ptr(bt_bmc);
/*
* The BT frames start with the message length, which does not
* include the length byte.
*/
kbuffer[0] = bt_read(bt_bmc);
len = kbuffer[0];
/* We pass the length back to userspace as well */
if (len + 1 > count)
len = count - 1;
while (len) {
nread = min_t(ssize_t, len, sizeof(kbuffer) - len_byte);
bt_readn(bt_bmc, kbuffer + len_byte, nread);
if (copy_to_user(buf, kbuffer, nread + len_byte)) {
ret = -EFAULT;
break;
}
len -= nread;
buf += nread + len_byte;
ret += nread + len_byte;
len_byte = 0;
}
clr_b_busy(bt_bmc);
out_unlock:
mutex_unlock(&bt_bmc->mutex);
return ret;
}
/*
* BT Message response format :
*
* Byte 1 Byte 2 Byte 3 Byte 4 Byte 5 Byte 6:N
* Length NetFn/LUN Seq Cmd Code Data
*/
static ssize_t bt_bmc_write(struct file *file, const char __user *buf,
size_t count, loff_t *ppos)
{
struct bt_bmc *bt_bmc = file_bt_bmc(file);
u8 kbuffer[BT_BMC_BUFFER_SIZE];
ssize_t ret = 0;
ssize_t nwritten;
/*
* send a minimum response size
*/
if (count < 5)
return -EINVAL;
WARN_ON(*ppos);
/*
* There's no interrupt for clearing bmc busy so we have to
* poll
*/
if (wait_event_interruptible(bt_bmc->queue,
!(bt_inb(bt_bmc, BT_CTRL) &
(BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN))))
return -ERESTARTSYS;
mutex_lock(&bt_bmc->mutex);
if (unlikely(bt_inb(bt_bmc, BT_CTRL) &
(BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN))) {
ret = -EIO;
goto out_unlock;
}
clr_wr_ptr(bt_bmc);
while (count) {
nwritten = min_t(ssize_t, count, sizeof(kbuffer));
if (copy_from_user(&kbuffer, buf, nwritten)) {
ret = -EFAULT;
break;
}
bt_writen(bt_bmc, kbuffer, nwritten);
count -= nwritten;
buf += nwritten;
ret += nwritten;
}
set_b2h_atn(bt_bmc);
out_unlock:
mutex_unlock(&bt_bmc->mutex);
return ret;
}
static long bt_bmc_ioctl(struct file *file, unsigned int cmd,
unsigned long param)
{
struct bt_bmc *bt_bmc = file_bt_bmc(file);
switch (cmd) {
case BT_BMC_IOCTL_SMS_ATN:
set_sms_atn(bt_bmc);
return 0;
}
return -EINVAL;
}
static int bt_bmc_release(struct inode *inode, struct file *file)
{
struct bt_bmc *bt_bmc = file_bt_bmc(file);
atomic_dec(&open_count);
set_b_busy(bt_bmc);
return 0;
}
static __poll_t bt_bmc_poll(struct file *file, poll_table *wait)
{
struct bt_bmc *bt_bmc = file_bt_bmc(file);
__poll_t mask = 0;
u8 ctrl;
poll_wait(file, &bt_bmc->queue, wait);
ctrl = bt_inb(bt_bmc, BT_CTRL);
if (ctrl & BT_CTRL_H2B_ATN)
mask |= EPOLLIN;
if (!(ctrl & (BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN)))
mask |= EPOLLOUT;
return mask;
}
static const struct file_operations bt_bmc_fops = {
.owner = THIS_MODULE,
.open = bt_bmc_open,
.read = bt_bmc_read,
.write = bt_bmc_write,
.release = bt_bmc_release,
.poll = bt_bmc_poll,
.unlocked_ioctl = bt_bmc_ioctl,
};
static void poll_timer(struct timer_list *t)
{
struct bt_bmc *bt_bmc = from_timer(bt_bmc, t, poll_timer);
bt_bmc->poll_timer.expires += msecs_to_jiffies(500);
wake_up(&bt_bmc->queue);
add_timer(&bt_bmc->poll_timer);
}
static irqreturn_t bt_bmc_irq(int irq, void *arg)
{
struct bt_bmc *bt_bmc = arg;
u32 reg;
reg = readl(bt_bmc->base + BT_CR2);
reg &= BT_CR2_IRQ_H2B | BT_CR2_IRQ_HBUSY;
if (!reg)
return IRQ_NONE;
/* ack pending IRQs */
writel(reg, bt_bmc->base + BT_CR2);
wake_up(&bt_bmc->queue);
return IRQ_HANDLED;
}
static int bt_bmc_config_irq(struct bt_bmc *bt_bmc,
struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
int rc;
u32 reg;
bt_bmc->irq = platform_get_irq_optional(pdev, 0);
if (bt_bmc->irq < 0)
return bt_bmc->irq;
rc = devm_request_irq(dev, bt_bmc->irq, bt_bmc_irq, IRQF_SHARED,
DEVICE_NAME, bt_bmc);
if (rc < 0) {
dev_warn(dev, "Unable to request IRQ %d\n", bt_bmc->irq);
bt_bmc->irq = rc;
return rc;
}
/*
* Configure IRQs on the bmc clearing the H2B and HBUSY bits;
* H2B will be asserted when the bmc has data for us; HBUSY
* will be cleared (along with B2H) when we can write the next
* message to the BT buffer
*/
reg = readl(bt_bmc->base + BT_CR1);
reg |= BT_CR1_IRQ_H2B | BT_CR1_IRQ_HBUSY;
writel(reg, bt_bmc->base + BT_CR1);
return 0;
}
static int bt_bmc_probe(struct platform_device *pdev)
{
struct bt_bmc *bt_bmc;
struct device *dev;
int rc;
dev = &pdev->dev;
dev_info(dev, "Found bt bmc device\n");
bt_bmc = devm_kzalloc(dev, sizeof(*bt_bmc), GFP_KERNEL);
if (!bt_bmc)
return -ENOMEM;
dev_set_drvdata(&pdev->dev, bt_bmc);
bt_bmc->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(bt_bmc->base))
return PTR_ERR(bt_bmc->base);
mutex_init(&bt_bmc->mutex);
init_waitqueue_head(&bt_bmc->queue);
bt_bmc->miscdev.minor = MISC_DYNAMIC_MINOR;
bt_bmc->miscdev.name = DEVICE_NAME;
bt_bmc->miscdev.fops = &bt_bmc_fops;
bt_bmc->miscdev.parent = dev;
rc = misc_register(&bt_bmc->miscdev);
if (rc) {
dev_err(dev, "Unable to register misc device\n");
return rc;
}
bt_bmc_config_irq(bt_bmc, pdev);
if (bt_bmc->irq >= 0) {
dev_info(dev, "Using IRQ %d\n", bt_bmc->irq);
} else {
dev_info(dev, "No IRQ; using timer\n");
timer_setup(&bt_bmc->poll_timer, poll_timer, 0);
bt_bmc->poll_timer.expires = jiffies + msecs_to_jiffies(10);
add_timer(&bt_bmc->poll_timer);
}
writel((BT_IO_BASE << BT_CR0_IO_BASE) |
(BT_IRQ << BT_CR0_IRQ) |
BT_CR0_EN_CLR_SLV_RDP |
BT_CR0_EN_CLR_SLV_WRP |
BT_CR0_ENABLE_IBT,
bt_bmc->base + BT_CR0);
clr_b_busy(bt_bmc);
return 0;
}
static int bt_bmc_remove(struct platform_device *pdev)
{
struct bt_bmc *bt_bmc = dev_get_drvdata(&pdev->dev);
misc_deregister(&bt_bmc->miscdev);
if (bt_bmc->irq < 0)
del_timer_sync(&bt_bmc->poll_timer);
return 0;
}
static const struct of_device_id bt_bmc_match[] = {
{ .compatible = "aspeed,ast2400-ibt-bmc" },
{ .compatible = "aspeed,ast2500-ibt-bmc" },
{ .compatible = "aspeed,ast2600-ibt-bmc" },
{ },
};
static struct platform_driver bt_bmc_driver = {
.driver = {
.name = DEVICE_NAME,
.of_match_table = bt_bmc_match,
},
.probe = bt_bmc_probe,
.remove = bt_bmc_remove,
};
module_platform_driver(bt_bmc_driver);
MODULE_DEVICE_TABLE(of, bt_bmc_match);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Alistair Popple <alistair@popple.id.au>");
MODULE_DESCRIPTION("Linux device interface to the IPMI BT interface");
