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Subject[RFC v1 4/4] ipmi_bmc: bt-aspeed: port driver to IPMI BMC framework
Date
From: Benjamin Fair <benjaminfair@google.com>

The driver was handling interaction with userspace on its own. This
patch changes it to use the functionality of the ipmi_bmc framework
instead.

Note that this removes the ability for the BMC to set SMS_ATN by making
an ioctl. If this functionality is required, it can be added back in
with a later patch.

Signed-off-by: Benjamin Fair <benjaminfair@google.com>
Signed-off-by: Brendan Higgins <brendanhiggins@google.com>
---
drivers/char/ipmi_bmc/ipmi_bmc_bt_aspeed.c | 258 +++++++++--------------------
include/uapi/linux/bt-bmc.h | 18 --
2 files changed, 74 insertions(+), 202 deletions(-)
delete mode 100644 include/uapi/linux/bt-bmc.h

diff --git a/drivers/char/ipmi_bmc/ipmi_bmc_bt_aspeed.c b/drivers/char/ipmi_bmc/ipmi_bmc_bt_aspeed.c
index 70d434bc1cbf..7c8082c511ee 100644
--- a/drivers/char/ipmi_bmc/ipmi_bmc_bt_aspeed.c
+++ b/drivers/char/ipmi_bmc/ipmi_bmc_bt_aspeed.c
@@ -7,25 +7,19 @@
* 2 of the License, or (at your option) any later version.
*/

-#include <linux/atomic.h>
-#include <linux/bt-bmc.h>
#include <linux/errno.h>
#include <linux/interrupt.h>
#include <linux/io.h>
+#include <linux/ipmi_bmc.h>
#include <linux/mfd/syscon.h>
-#include <linux/miscdevice.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
-#include <linux/poll.h>
#include <linux/regmap.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 DEVICE_NAME "ipmi-bmc-bt-aspeed"

#define BT_IO_BASE 0xe4
#define BT_IRQ 10
@@ -61,18 +55,17 @@
#define BT_BMC_BUFFER_SIZE 256

struct bt_bmc {
+ struct ipmi_bmc_bus bus;
struct device dev;
- struct miscdevice miscdev;
+ struct ipmi_bmc_ctx *bmc_ctx;
+ struct bt_msg request;
struct regmap *map;
int offset;
int irq;
- wait_queue_head_t queue;
struct timer_list poll_timer;
- struct mutex mutex;
+ spinlock_t lock;
};

-static atomic_t open_count = ATOMIC_INIT(0);
-
static const struct regmap_config bt_regmap_cfg = {
.reg_bits = 32,
.val_bits = 32,
@@ -158,27 +151,28 @@ static ssize_t bt_writen(struct bt_bmc *bt_bmc, u8 *buf, size_t n)
return n;
}

+/* TODO(benjaminfair): support ioctl BT_BMC_IOCTL_SMS_ATN */
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)
+/* Called with bt_bmc->lock held */
+static bool __is_request_avail(struct bt_bmc *bt_bmc)
{
- return container_of(file->private_data, struct bt_bmc, miscdev);
+ return bt_inb(bt_bmc, BT_CTRL) & BT_CTRL_H2B_ATN;
}

-static int bt_bmc_open(struct inode *inode, struct file *file)
+static bool is_request_avail(struct bt_bmc *bt_bmc)
{
- struct bt_bmc *bt_bmc = file_bt_bmc(file);
+ unsigned long flags;
+ bool result;

- if (atomic_inc_return(&open_count) == 1) {
- clr_b_busy(bt_bmc);
- return 0;
- }
+ spin_lock_irqsave(&bt_bmc->lock, flags);
+ result = __is_request_avail(bt_bmc);
+ spin_unlock_irqrestore(&bt_bmc->lock, flags);

- atomic_dec(&open_count);
- return -EBUSY;
+ return result;
}

/*
@@ -194,67 +188,43 @@ static int bt_bmc_open(struct inode *inode, struct file *file)
* Length NetFn/LUN Seq Cmd Data
*
*/
-static ssize_t bt_bmc_read(struct file *file, char __user *buf,
- size_t count, loff_t *ppos)
+static void get_request(struct bt_bmc *bt_bmc)
{
- 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;
+ u8 *request_buf = (u8 *) &bt_bmc->request;
+ unsigned long flags;

- if (!access_ok(VERIFY_WRITE, buf, count))
- return -EFAULT;
+ spin_lock_irqsave(&bt_bmc->lock, flags);

- 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;
+ if (!__is_request_avail(bt_bmc)) {
+ spin_unlock_irqrestore(&bt_bmc->lock, flags);
+ return;
}

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;
- }
+ bt_bmc->request.len = bt_read(bt_bmc);
+ bt_readn(bt_bmc, request_buf + 1, bt_bmc->request.len);

clr_b_busy(bt_bmc);
+ ipmi_bmc_handle_request(bt_bmc->bmc_ctx, &bt_bmc->request);
+
+ spin_unlock_irqrestore(&bt_bmc->lock, flags);
+}
+
+static bool bt_bmc_is_response_open(struct ipmi_bmc_bus *bus)
+{
+ struct bt_bmc *bt_bmc = container_of(bus, struct bt_bmc, bus);
+ bool response_in_progress;
+ unsigned long flags;
+
+ spin_lock_irqsave(&bt_bmc->lock, flags);
+ response_in_progress = bt_inb(bt_bmc, BT_CTRL) & (BT_CTRL_H_BUSY |
+ BT_CTRL_B2H_ATN);
+ spin_unlock_irqrestore(&bt_bmc->lock, flags);

-out_unlock:
- mutex_unlock(&bt_bmc->mutex);
- return ret;
+ return !response_in_progress;
}

/*
@@ -263,122 +233,38 @@ static ssize_t bt_bmc_read(struct file *file, char __user *buf,
* 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)
+static int bt_bmc_send_response(struct ipmi_bmc_bus *bus,
+ struct bt_msg *bt_response)
{
- struct bt_bmc *bt_bmc = file_bt_bmc(file);
- u8 kbuffer[BT_BMC_BUFFER_SIZE];
- ssize_t ret = 0;
- ssize_t nwritten;
+ struct bt_bmc *bt_bmc = container_of(bus, struct bt_bmc, bus);
+ unsigned long flags;

- /*
- * send a minimum response size
- */
- if (count < 5)
- return -EINVAL;
-
- if (!access_ok(VERIFY_READ, buf, count))
- return -EFAULT;
-
- 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;
+ spin_lock_irqsave(&bt_bmc->lock, flags);
+ if (!bt_bmc_is_response_open(bus)) {
+ spin_unlock_irqrestore(&bt_bmc->lock, flags);
+ return -EAGAIN;
}

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;
- }
-
+ bt_writen(bt_bmc, (u8 *) bt_response, bt_msg_len(bt_response));
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);
+ spin_unlock_irqrestore(&bt_bmc->lock, flags);
return 0;
}

-static unsigned int bt_bmc_poll(struct file *file, poll_table *wait)
-{
- struct bt_bmc *bt_bmc = file_bt_bmc(file);
- unsigned int 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 |= POLLIN;
-
- if (!(ctrl & (BT_CTRL_H_BUSY | BT_CTRL_B2H_ATN)))
- mask |= POLLOUT;
-
- 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(unsigned long data)
{
struct bt_bmc *bt_bmc = (void *)data;

bt_bmc->poll_timer.expires += msecs_to_jiffies(500);
- wake_up(&bt_bmc->queue);
+
+ if (bt_bmc_is_response_open(&bt_bmc->bus))
+ ipmi_bmc_signal_response_open(bt_bmc->bmc_ctx);
+
+ if (is_request_avail(bt_bmc))
+ get_request(bt_bmc);
+
add_timer(&bt_bmc->poll_timer);
}

@@ -399,7 +285,12 @@ static irqreturn_t bt_bmc_irq(int irq, void *arg)
/* ack pending IRQs */
regmap_write(bt_bmc->map, bt_bmc->offset + BT_CR2, reg);

- wake_up(&bt_bmc->queue);
+ if (bt_bmc_is_response_open(&bt_bmc->bus))
+ ipmi_bmc_signal_response_open(bt_bmc->bmc_ctx);
+
+ if (is_request_avail(bt_bmc))
+ get_request(bt_bmc);
+
return IRQ_HANDLED;
}

@@ -474,16 +365,14 @@ static int bt_bmc_probe(struct platform_device *pdev)
return rc;
}

- mutex_init(&bt_bmc->mutex);
- init_waitqueue_head(&bt_bmc->queue);
+ spin_lock_init(&bt_bmc->lock);
+ bt_bmc->bus.send_response = bt_bmc_send_response;
+ bt_bmc->bus.is_response_open = bt_bmc_is_response_open;
+ bt_bmc->bmc_ctx = ipmi_bmc_get_global_ctx();

- 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);
+ rc = ipmi_bmc_register_bus(bt_bmc->bmc_ctx, &bt_bmc->bus);
if (rc) {
- dev_err(dev, "Unable to register misc device\n");
+ dev_err(dev, "Unable to register IPMI BMC bus\n");
return rc;
}

@@ -514,11 +403,12 @@ static int bt_bmc_probe(struct platform_device *pdev)
static int bt_bmc_remove(struct platform_device *pdev)
{
struct bt_bmc *bt_bmc = dev_get_drvdata(&pdev->dev);
+ int rc;

- misc_deregister(&bt_bmc->miscdev);
+ rc = ipmi_bmc_unregister_bus(bt_bmc->bmc_ctx, &bt_bmc->bus);
if (!bt_bmc->irq)
del_timer_sync(&bt_bmc->poll_timer);
- return 0;
+ return rc;
}

static const struct of_device_id bt_bmc_match[] = {
diff --git a/include/uapi/linux/bt-bmc.h b/include/uapi/linux/bt-bmc.h
deleted file mode 100644
index d9ec766a63d0..000000000000
--- a/include/uapi/linux/bt-bmc.h
+++ /dev/null
@@ -1,18 +0,0 @@
-/*
- * Copyright (c) 2015-2016, IBM Corporation.
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- */
-
-#ifndef _UAPI_LINUX_BT_BMC_H
-#define _UAPI_LINUX_BT_BMC_H
-
-#include <linux/ioctl.h>
-
-#define __BT_BMC_IOCTL_MAGIC 0xb1
-#define BT_BMC_IOCTL_SMS_ATN _IO(__BT_BMC_IOCTL_MAGIC, 0x00)
-
-#endif /* _UAPI_LINUX_BT_BMC_H */
--
2.14.0.rc1.383.gd1ce394fe2-goog
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