[PATCH linux dev-4.7 v2] drivers/fsi: Add FSI SBEFIFO driver
Eddie James
eajames at linux.vnet.ibm.com
Fri Apr 21 06:41:33 AEST 2017
Looks good.
Reviewed-by: Eddie James <eajames at linux.vnet.ibm.com>
On 04/20/2017 01:51 PM, Brad Bishop wrote:
> IBM POWER9 processors contain some embedded hardware and software bits
> collectively referred to as the self boot engine (SBE). One role of
> the SBE is to act as a proxy that provides access to the registers of
> the POWER chip from other (embedded) systems.
>
> The POWER9 chip contains a hardware frontend for communicating with
> the SBE from remote systems called the SBEFIFO. The SBEFIFO logic
> is contained within an FSI CFAM (see Documentation/fsi) and as such
> the driver implements an FSI bus device.
>
> The SBE expects to communicate using a defined wire protocol; however,
> the driver knows nothing of the protocol and only provides raw access
> to the fifo device to userspace applications wishing to communicate with
> the SBE using the wire protocol.
>
> The SBEFIFO consists of two hardware fifos. The upstream fifo is used by
> the driver to transfer data to the SBE on the POWER chip, from the system
> hosting the driver. The downstream fifo is used by the driver to transfer
> data from the SBE on the power chip to the system hosting the driver.
>
> Signed-off-by: Brad Bishop <bradleyb at fuzziesquirrel.com>
> ---
> v2:
> Unexpand list_first_entry_or_null.
> Unexpand list_for_each_entry_safe.
> Reschedule a full 500ms later when fifos are busy.
> ---
> drivers/fsi/Kconfig | 6 +
> drivers/fsi/Makefile | 1 +
> drivers/fsi/fsi-sbefifo.c | 810 ++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 817 insertions(+)
> create mode 100644 drivers/fsi/fsi-sbefifo.c
>
> diff --git a/drivers/fsi/Kconfig b/drivers/fsi/Kconfig
> index c78b9b6e..087f239 100644
> --- a/drivers/fsi/Kconfig
> +++ b/drivers/fsi/Kconfig
> @@ -18,6 +18,12 @@ config FSI_MASTER_GPIO
> ---help---
> This option enables a FSI master driver using GPIO lines.
>
> +config FSI_SBEFIFO
> + tristate "SBEFIFO FSI client device driver"
> + depends on FSI
> + ---help---
> + This option enables an FSI based SBEFIFO device driver.
> +
> config FSI_SCOM
> tristate "SCOM FSI client device driver"
> depends on FSI
> diff --git a/drivers/fsi/Makefile b/drivers/fsi/Makefile
> index 3a106ba..edd84b2 100644
> --- a/drivers/fsi/Makefile
> +++ b/drivers/fsi/Makefile
> @@ -1,5 +1,6 @@
>
> obj-$(CONFIG_FSI) += fsi-core.o
> obj-$(CONFIG_FSI_MASTER_GPIO) += fsi-master-gpio.o
> +obj-$(CONFIG_FSI_SBEFIFO) += fsi-sbefifo.o
> obj-$(CONFIG_FSI_SCOM) += fsi-scom.o
> obj-$(CONFIG_FSI_I2C) += i2c/
> diff --git a/drivers/fsi/fsi-sbefifo.c b/drivers/fsi/fsi-sbefifo.c
> new file mode 100644
> index 0000000..c289508
> --- /dev/null
> +++ b/drivers/fsi/fsi-sbefifo.c
> @@ -0,0 +1,810 @@
> +/*
> + * Copyright (C) IBM Corporation 2017
> + *
> + * 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.
> + *
> + * This program is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERGCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/errno.h>
> +#include <linux/idr.h>
> +#include <linux/fsi.h>
> +#include <linux/list.h>
> +#include <linux/miscdevice.h>
> +#include <linux/module.h>
> +#include <linux/poll.h>
> +#include <linux/sched.h>
> +#include <linux/slab.h>
> +#include <linux/timer.h>
> +#include <linux/uaccess.h>
> +
> +/*
> + * The SBEFIFO is a pipe-like FSI device for communicating with
> + * the self boot engine on POWER processors.
> + */
> +
> +#define DEVICE_NAME "sbefifo"
> +#define FSI_ENGID_SBE 0x22
> +#define SBEFIFO_BUF_CNT 32
> +
> +#define SBEFIFO_UP 0x00 /* Up register offset */
> +#define SBEFIFO_DWN 0x40 /* Down register offset */
> +
> +#define SBEFIFO_STS 0x04
> +#define SBEFIFO_EMPTY BIT(20)
> +#define SBEFIFO_EOT_RAISE 0x08
> +#define SBEFIFO_EOT_MAGIC 0xffffffff
> +#define SBEFIFO_EOT_ACK 0x14
> +
> +struct sbefifo {
> + struct timer_list poll_timer;
> + struct fsi_device *fsi_dev;
> + struct miscdevice mdev;
> + wait_queue_head_t wait;
> + struct list_head link;
> + struct list_head xfrs;
> + struct kref kref;
> + spinlock_t lock;
> + char name[32];
> + int idx;
> + int rc;
> +};
> +
> +struct sbefifo_buf {
> + u32 buf[SBEFIFO_BUF_CNT];
> + unsigned long flags;
> +#define SBEFIFO_BUF_FULL 1
> + u32 *rpos;
> + u32 *wpos;
> +};
> +
> +struct sbefifo_xfr {
> + struct sbefifo_buf *rbuf;
> + struct sbefifo_buf *wbuf;
> + struct list_head client;
> + struct list_head xfrs;
> + unsigned long flags;
> +#define SBEFIFO_XFR_WRITE_DONE 1
> +#define SBEFIFO_XFR_RESP_PENDING 2
> +#define SBEFIFO_XFR_COMPLETE 3
> +#define SBEFIFO_XFR_CANCEL 4
> +};
> +
> +struct sbefifo_client {
> + struct sbefifo_buf rbuf;
> + struct sbefifo_buf wbuf;
> + struct list_head xfrs;
> + struct sbefifo *dev;
> + struct kref kref;
> +};
> +
> +static struct list_head sbefifo_fifos;
> +
> +static DEFINE_IDA(sbefifo_ida);
> +
> +static int sbefifo_inw(struct sbefifo *sbefifo, int reg, u32 *word)
> +{
> + return fsi_device_read(sbefifo->fsi_dev, reg, word, sizeof(*word));
> +}
> +
> +static int sbefifo_outw(struct sbefifo *sbefifo, int reg, u32 word)
> +{
> + return fsi_device_write(sbefifo->fsi_dev, reg, &word, sizeof(word));
> +}
> +
> +static int sbefifo_readw(struct sbefifo *sbefifo, u32 *word)
> +{
> + return sbefifo_inw(sbefifo, SBEFIFO_DWN, word);
> +}
> +
> +static int sbefifo_writew(struct sbefifo *sbefifo, u32 word)
> +{
> + return sbefifo_outw(sbefifo, SBEFIFO_UP, word);
> +}
> +
> +static int sbefifo_ack_eot(struct sbefifo *sbefifo)
> +{
> + u32 discard;
> + int ret;
> +
> + /* Discard the EOT word. */
> + ret = sbefifo_readw(sbefifo, &discard);
> + if (ret)
> + return ret;
> +
> + return sbefifo_outw(sbefifo, SBEFIFO_DWN | SBEFIFO_EOT_ACK,
> + SBEFIFO_EOT_MAGIC);
> +}
> +
> +static size_t sbefifo_dev_nwreadable(u32 sts)
> +{
> + static const u32 FIFO_NTRY_CNT_MSK = 0x000f0000;
> + static const unsigned int FIFO_NTRY_CNT_SHIFT = 16;
> +
> + return (sts & FIFO_NTRY_CNT_MSK) >> FIFO_NTRY_CNT_SHIFT;
> +}
> +
> +static size_t sbefifo_dev_nwwriteable(u32 sts)
> +{
> + static const size_t FIFO_DEPTH = 8;
> +
> + return FIFO_DEPTH - sbefifo_dev_nwreadable(sts);
> +}
> +
> +static void sbefifo_buf_init(struct sbefifo_buf *buf)
> +{
> + WRITE_ONCE(buf->rpos, buf->buf);
> + WRITE_ONCE(buf->wpos, buf->buf);
> +}
> +
> +static size_t sbefifo_buf_nbreadable(struct sbefifo_buf *buf)
> +{
> + size_t n;
> + u32 *rpos = READ_ONCE(buf->rpos);
> + u32 *wpos = READ_ONCE(buf->wpos);
> +
> + if (test_bit(SBEFIFO_BUF_FULL, &buf->flags))
> + n = SBEFIFO_BUF_CNT;
> + else if (rpos <= wpos)
> + n = wpos - rpos;
> + else
> + n = (buf->buf + SBEFIFO_BUF_CNT) - rpos;
> +
> + return n << 2;
> +}
> +
> +static size_t sbefifo_buf_nbwriteable(struct sbefifo_buf *buf)
> +{
> + size_t n;
> + u32 *rpos = READ_ONCE(buf->rpos);
> + u32 *wpos = READ_ONCE(buf->wpos);
> +
> + if (test_bit(SBEFIFO_BUF_FULL, &buf->flags))
> + n = 0;
> + else if (wpos < rpos)
> + n = rpos - wpos;
> + else
> + n = (buf->buf + SBEFIFO_BUF_CNT) - wpos;
> +
> + return n << 2;
> +}
> +
> +/*
> + * Update pointers and flags after doing a buffer read. Return true if the
> + * buffer is now empty;
> + */
> +static bool sbefifo_buf_readnb(struct sbefifo_buf *buf, size_t n)
> +{
> + u32 *rpos = READ_ONCE(buf->rpos);
> + u32 *wpos = READ_ONCE(buf->wpos);
> +
> + if (n)
> + clear_bit(SBEFIFO_BUF_FULL, &buf->flags);
> +
> + rpos += (n >> 2);
> + if (rpos == buf->buf + SBEFIFO_BUF_CNT)
> + rpos = buf->buf;
> +
> + WRITE_ONCE(buf->rpos, rpos);
> + return rpos == wpos;
> +}
> +
> +/*
> + * Update pointers and flags after doing a buffer write. Return true if the
> + * buffer is now full.
> + */
> +static bool sbefifo_buf_wrotenb(struct sbefifo_buf *buf, size_t n)
> +{
> + u32 *rpos = READ_ONCE(buf->rpos);
> + u32 *wpos = READ_ONCE(buf->wpos);
> +
> + wpos += (n >> 2);
> + if (wpos == buf->buf + SBEFIFO_BUF_CNT)
> + wpos = buf->buf;
> + if (wpos == rpos)
> + set_bit(SBEFIFO_BUF_FULL, &buf->flags);
> +
> + WRITE_ONCE(buf->wpos, wpos);
> + return rpos == wpos;
> +}
> +
> +static void sbefifo_free(struct kref *kref)
> +{
> + struct sbefifo *sbefifo;
> +
> + sbefifo = container_of(kref, struct sbefifo, kref);
> + kfree(sbefifo);
> +}
> +
> +static void sbefifo_get(struct sbefifo *sbefifo)
> +{
> + kref_get(&sbefifo->kref);
> +}
> +
> +static void sbefifo_put(struct sbefifo *sbefifo)
> +{
> + kref_put(&sbefifo->kref, sbefifo_free);
> +}
> +
> +static struct sbefifo_xfr *sbefifo_enq_xfr(struct sbefifo_client *client)
> +{
> + struct sbefifo *sbefifo = client->dev;
> + struct sbefifo_xfr *xfr;
> +
> + xfr = kzalloc(sizeof(*xfr), GFP_KERNEL);
> + if (!xfr)
> + return NULL;
> +
> + xfr->rbuf = &client->rbuf;
> + xfr->wbuf = &client->wbuf;
> + list_add_tail(&xfr->xfrs, &sbefifo->xfrs);
> + list_add_tail(&xfr->client, &client->xfrs);
> +
> + return xfr;
> +}
> +
> +static struct sbefifo_xfr *sbefifo_client_next_xfr(
> + struct sbefifo_client *client)
> +{
> + if (list_empty(&client->xfrs))
> + return NULL;
> +
> + return container_of(client->xfrs.next, struct sbefifo_xfr,
> + client);
> +}
> +
> +static bool sbefifo_xfr_rsp_pending(struct sbefifo_client *client)
> +{
> + struct sbefifo_xfr *xfr;
> +
> + xfr = sbefifo_client_next_xfr(client);
> + if (xfr && test_bit(SBEFIFO_XFR_RESP_PENDING, &xfr->flags))
> + return true;
> +
> + return false;
> +}
> +
> +static struct sbefifo_client *sbefifo_new_client(struct sbefifo *sbefifo)
> +{
> + struct sbefifo_client *client;
> +
> + client = kzalloc(sizeof(*client), GFP_KERNEL);
> + if (!client)
> + return NULL;
> +
> + kref_init(&client->kref);
> + client->dev = sbefifo;
> + sbefifo_buf_init(&client->rbuf);
> + sbefifo_buf_init(&client->wbuf);
> + INIT_LIST_HEAD(&client->xfrs);
> +
> + sbefifo_get(sbefifo);
> +
> + return client;
> +}
> +
> +static void sbefifo_client_release(struct kref *kref)
> +{
> + struct sbefifo_client *client;
> + struct sbefifo_xfr *xfr;
> +
> + client = container_of(kref, struct sbefifo_client, kref);
> + list_for_each_entry(xfr, &client->xfrs, client) {
> + /*
> + * The client left with pending or running xfrs.
> + * Cancel them.
> + */
> + set_bit(SBEFIFO_XFR_CANCEL, &xfr->flags);
> + sbefifo_get(client->dev);
> + if (mod_timer(&client->dev->poll_timer, jiffies))
> + sbefifo_put(client->dev);
> + }
> +
> + sbefifo_put(client->dev);
> + kfree(client);
> +}
> +
> +static void sbefifo_get_client(struct sbefifo_client *client)
> +{
> + kref_get(&client->kref);
> +}
> +
> +static void sbefifo_put_client(struct sbefifo_client *client)
> +{
> + kref_put(&client->kref, sbefifo_client_release);
> +}
> +
> +static struct sbefifo_xfr *sbefifo_next_xfr(struct sbefifo *sbefifo)
> +{
> + struct sbefifo_xfr *xfr, *tmp;
> +
> + list_for_each_entry_safe(xfr, tmp, &sbefifo->xfrs, xfrs) {
> + if (unlikely(test_bit(SBEFIFO_XFR_CANCEL, &xfr->flags))) {
> + /* Discard cancelled transfers. */
> + list_del(&xfr->xfrs);
> + kfree(xfr);
> + continue;
> + }
> + return xfr;
> + }
> +
> + return NULL;
> +}
> +
> +static void sbefifo_poll_timer(unsigned long data)
> +{
> + static const unsigned long EOT_MASK = 0x000000ff;
> + struct sbefifo *sbefifo = (void *)data;
> + struct sbefifo_buf *rbuf, *wbuf;
> + struct sbefifo_xfr *xfr = NULL;
> + struct sbefifo_buf drain;
> + size_t devn, bufn;
> + int eot = 0;
> + int ret = 0;
> + u32 sts;
> + int i;
> +
> + spin_lock(&sbefifo->lock);
> + xfr = list_first_entry_or_null(&sbefifo->xfrs, struct sbefifo_xfr,
> + xfrs);
> + if (!xfr)
> + goto out_unlock;
> +
> + rbuf = xfr->rbuf;
> + wbuf = xfr->wbuf;
> +
> + if (unlikely(test_bit(SBEFIFO_XFR_CANCEL, &xfr->flags))) {
> + /* The client left. */
> + rbuf = &drain;
> + wbuf = &drain;
> + sbefifo_buf_init(&drain);
> + if (!test_bit(SBEFIFO_XFR_RESP_PENDING, &xfr->flags))
> + set_bit(SBEFIFO_XFR_WRITE_DONE, &xfr->flags);
> + }
> +
> + /* Drain the write buffer. */
> + while ((bufn = sbefifo_buf_nbreadable(wbuf))) {
> + ret = sbefifo_inw(sbefifo, SBEFIFO_UP | SBEFIFO_STS,
> + &sts);
> + if (ret)
> + goto out;
> +
> + devn = sbefifo_dev_nwwriteable(sts);
> + if (devn == 0) {
> + /* No open slot for write. Reschedule. */
> + sbefifo->poll_timer.expires = jiffies +
> + msecs_to_jiffies(500);
> + add_timer(&sbefifo->poll_timer);
> + goto out_unlock;
> + }
> +
> + devn = min_t(size_t, devn, bufn >> 2);
> + for (i = 0; i < devn; i++) {
> + ret = sbefifo_writew(sbefifo, *wbuf->rpos);
> + if (ret)
> + goto out;
> +
> + sbefifo_buf_readnb(wbuf, 1 << 2);
> + }
> + }
> +
> + /* Send EOT if the writer is finished. */
> + if (test_and_clear_bit(SBEFIFO_XFR_WRITE_DONE, &xfr->flags)) {
> + ret = sbefifo_outw(sbefifo,
> + SBEFIFO_UP | SBEFIFO_EOT_RAISE,
> + SBEFIFO_EOT_MAGIC);
> + if (ret)
> + goto out;
> +
> + /* Inform reschedules that the writer is finished. */
> + set_bit(SBEFIFO_XFR_RESP_PENDING, &xfr->flags);
> + }
> +
> + /* Nothing left to do if the writer is not finished. */
> + if (!test_bit(SBEFIFO_XFR_RESP_PENDING, &xfr->flags))
> + goto out;
> +
> + /* Fill the read buffer. */
> + while ((bufn = sbefifo_buf_nbwriteable(rbuf))) {
> + ret = sbefifo_inw(sbefifo, SBEFIFO_DWN | SBEFIFO_STS, &sts);
> + if (ret)
> + goto out;
> +
> + devn = sbefifo_dev_nwreadable(sts);
> + if (devn == 0) {
> + /* No data yet. Reschedule. */
> + sbefifo->poll_timer.expires = jiffies +
> + msecs_to_jiffies(500);
> + add_timer(&sbefifo->poll_timer);
> + goto out_unlock;
> + }
> +
> + /* Fill. The EOT word is discarded. */
> + devn = min_t(size_t, devn, bufn >> 2);
> + eot = (sts & EOT_MASK) != 0;
> + if (eot)
> + devn--;
> +
> + for (i = 0; i < devn; i++) {
> + ret = sbefifo_readw(sbefifo, rbuf->wpos);
> + if (ret)
> + goto out;
> +
> + if (likely(!test_bit(SBEFIFO_XFR_CANCEL, &xfr->flags)))
> + sbefifo_buf_wrotenb(rbuf, 1 << 2);
> + }
> +
> + if (eot) {
> + ret = sbefifo_ack_eot(sbefifo);
> + if (ret)
> + goto out;
> +
> + set_bit(SBEFIFO_XFR_COMPLETE, &xfr->flags);
> + list_del(&xfr->xfrs);
> + if (unlikely(test_bit(SBEFIFO_XFR_CANCEL,
> + &xfr->flags)))
> + kfree(xfr);
> + break;
> + }
> + }
> +
> +out:
> + if (unlikely(ret)) {
> + sbefifo->rc = ret;
> + dev_err(&sbefifo->fsi_dev->dev,
> + "Fatal bus access failure: %d\n", ret);
> + list_for_each_entry(xfr, &sbefifo->xfrs, xfrs)
> + kfree(xfr);
> + INIT_LIST_HEAD(&sbefifo->xfrs);
> +
> + } else if (eot && sbefifo_next_xfr(sbefifo)) {
> + sbefifo_get(sbefifo);
> + sbefifo->poll_timer.expires = jiffies;
> + add_timer(&sbefifo->poll_timer);
> + }
> +
> + sbefifo_put(sbefifo);
> + wake_up(&sbefifo->wait);
> +
> +out_unlock:
> + spin_unlock(&sbefifo->lock);
> +}
> +
> +static int sbefifo_open(struct inode *inode, struct file *file)
> +{
> + struct sbefifo *sbefifo = container_of(file->private_data,
> + struct sbefifo, mdev);
> + struct sbefifo_client *client;
> + int ret;
> +
> + ret = READ_ONCE(sbefifo->rc);
> + if (ret)
> + return ret;
> +
> + client = sbefifo_new_client(sbefifo);
> + if (!client)
> + return -ENOMEM;
> +
> + file->private_data = client;
> +
> + return 0;
> +}
> +
> +static unsigned int sbefifo_poll(struct file *file, poll_table *wait)
> +{
> + struct sbefifo_client *client = file->private_data;
> + struct sbefifo *sbefifo = client->dev;
> + unsigned int mask = 0;
> +
> + poll_wait(file, &sbefifo->wait, wait);
> +
> + if (READ_ONCE(sbefifo->rc))
> + mask |= POLLERR;
> +
> + if (sbefifo_buf_nbreadable(&client->rbuf))
> + mask |= POLLIN;
> +
> + if (sbefifo_buf_nbwriteable(&client->wbuf))
> + mask |= POLLOUT;
> +
> + return mask;
> +}
> +
> +static ssize_t sbefifo_read(struct file *file, char __user *buf,
> + size_t len, loff_t *offset)
> +{
> + struct sbefifo_client *client = file->private_data;
> + struct sbefifo *sbefifo = client->dev;
> + struct sbefifo_xfr *xfr;
> + ssize_t ret = 0;
> + size_t n;
> +
> + WARN_ON(*offset);
> +
> + if (!access_ok(VERIFY_WRITE, buf, len))
> + return -EFAULT;
> +
> + if ((len >> 2) << 2 != len)
> + return -EINVAL;
> +
> + if ((file->f_flags & O_NONBLOCK) && !sbefifo_xfr_rsp_pending(client))
> + return -EAGAIN;
> +
> + sbefifo_get_client(client);
> + if (wait_event_interruptible(sbefifo->wait,
> + (ret = READ_ONCE(sbefifo->rc)) ||
> + (n = sbefifo_buf_nbreadable(
> + &client->rbuf)))) {
> + sbefifo_put_client(client);
> + return -ERESTARTSYS;
> + }
> + if (ret) {
> + INIT_LIST_HEAD(&client->xfrs);
> + sbefifo_put_client(client);
> + return ret;
> + }
> +
> + n = min_t(size_t, n, len);
> +
> + if (copy_to_user(buf, READ_ONCE(client->rbuf.rpos), n)) {
> + sbefifo_put_client(client);
> + return -EFAULT;
> + }
> +
> + if (sbefifo_buf_readnb(&client->rbuf, n)) {
> + xfr = sbefifo_client_next_xfr(client);
> + if (!test_bit(SBEFIFO_XFR_COMPLETE, &xfr->flags)) {
> + /*
> + * Fill the read buffer back up.
> + */
> + sbefifo_get(sbefifo);
> + if (mod_timer(&client->dev->poll_timer, jiffies))
> + sbefifo_put(sbefifo);
> + } else {
> + kfree(xfr);
> + list_del(&xfr->client);
> + wake_up(&sbefifo->wait);
> + }
> + }
> +
> + sbefifo_put_client(client);
> +
> + return n;
> +}
> +
> +static ssize_t sbefifo_write(struct file *file, const char __user *buf,
> + size_t len, loff_t *offset)
> +{
> + struct sbefifo_client *client = file->private_data;
> + struct sbefifo *sbefifo = client->dev;
> + struct sbefifo_xfr *xfr;
> + ssize_t ret = 0;
> + size_t n;
> +
> + WARN_ON(*offset);
> +
> + if (!access_ok(VERIFY_READ, buf, len))
> + return -EFAULT;
> +
> + if ((len >> 2) << 2 != len)
> + return -EINVAL;
> +
> + if (!len)
> + return 0;
> +
> + n = sbefifo_buf_nbwriteable(&client->wbuf);
> +
> + spin_lock_irq(&sbefifo->lock);
> + xfr = sbefifo_next_xfr(sbefifo);
> +
> + if ((file->f_flags & O_NONBLOCK) && xfr && n < len) {
> + spin_unlock_irq(&sbefifo->lock);
> + return -EAGAIN;
> + }
> +
> + xfr = sbefifo_enq_xfr(client);
> + if (!xfr) {
> + spin_unlock_irq(&sbefifo->lock);
> + return -ENOMEM;
> + }
> + spin_unlock_irq(&sbefifo->lock);
> +
> + sbefifo_get_client(client);
> +
> + /*
> + * Partial writes are not really allowed in that EOT is sent exactly
> + * once per write.
> + */
> + while (len) {
> + if (wait_event_interruptible(sbefifo->wait,
> + READ_ONCE(sbefifo->rc) ||
> + (sbefifo_client_next_xfr(client) == xfr &&
> + (n = sbefifo_buf_nbwriteable(
> + &client->wbuf))))) {
> + set_bit(SBEFIFO_XFR_CANCEL, &xfr->flags);
> + sbefifo_get(sbefifo);
> + if (mod_timer(&sbefifo->poll_timer, jiffies))
> + sbefifo_put(sbefifo);
> +
> + sbefifo_put_client(client);
> + return -ERESTARTSYS;
> + }
> + if (sbefifo->rc) {
> + INIT_LIST_HEAD(&client->xfrs);
> + sbefifo_put_client(client);
> + return sbefifo->rc;
> + }
> +
> + n = min_t(size_t, n, len);
> +
> + if (copy_from_user(READ_ONCE(client->wbuf.wpos), buf, n)) {
> + set_bit(SBEFIFO_XFR_CANCEL, &xfr->flags);
> + sbefifo_get(sbefifo);
> + if (mod_timer(&sbefifo->poll_timer, jiffies))
> + sbefifo_put(sbefifo);
> + sbefifo_put_client(client);
> + return -EFAULT;
> + }
> +
> + sbefifo_buf_wrotenb(&client->wbuf, n);
> + len -= n;
> + buf += n;
> + ret += n;
> +
> + /*
> + * Drain the write buffer.
> + */
> + sbefifo_get(sbefifo);
> + if (mod_timer(&client->dev->poll_timer, jiffies))
> + sbefifo_put(sbefifo);
> + }
> +
> + set_bit(SBEFIFO_XFR_WRITE_DONE, &xfr->flags);
> + sbefifo_put_client(client);
> +
> + return ret;
> +}
> +
> +static int sbefifo_release(struct inode *inode, struct file *file)
> +{
> + struct sbefifo_client *client = file->private_data;
> + struct sbefifo *sbefifo = client->dev;
> +
> + sbefifo_put_client(client);
> +
> + return READ_ONCE(sbefifo->rc);
> +}
> +
> +static const struct file_operations sbefifo_fops = {
> + .owner = THIS_MODULE,
> + .open = sbefifo_open,
> + .read = sbefifo_read,
> + .write = sbefifo_write,
> + .poll = sbefifo_poll,
> + .release = sbefifo_release,
> +};
> +
> +static int sbefifo_probe(struct device *dev)
> +{
> + struct fsi_device *fsi_dev = to_fsi_dev(dev);
> + struct sbefifo *sbefifo;
> + u32 sts;
> + int ret;
> +
> + dev_info(dev, "Found sbefifo device\n");
> + sbefifo = kzalloc(sizeof(*sbefifo), GFP_KERNEL);
> + if (!sbefifo)
> + return -ENOMEM;
> +
> + sbefifo->fsi_dev = fsi_dev;
> +
> + ret = sbefifo_inw(sbefifo,
> + SBEFIFO_UP | SBEFIFO_STS, &sts);
> + if (ret)
> + return ret;
> + if (!(sts & SBEFIFO_EMPTY)) {
> + dev_err(&sbefifo->fsi_dev->dev,
> + "Found data in upstream fifo\n");
> + return -EIO;
> + }
> +
> + ret = sbefifo_inw(sbefifo, SBEFIFO_DWN | SBEFIFO_STS, &sts);
> + if (ret)
> + return ret;
> + if (!(sts & SBEFIFO_EMPTY)) {
> + dev_err(&sbefifo->fsi_dev->dev,
> + "Found data in downstream fifo\n");
> + return -EIO;
> + }
> +
> + sbefifo->mdev.minor = MISC_DYNAMIC_MINOR;
> + sbefifo->mdev.fops = &sbefifo_fops;
> + sbefifo->mdev.name = sbefifo->name;
> + sbefifo->mdev.parent = dev;
> + spin_lock_init(&sbefifo->lock);
> + kref_init(&sbefifo->kref);
> +
> + sbefifo->idx = ida_simple_get(&sbefifo_ida, 1, INT_MAX, GFP_KERNEL);
> + snprintf(sbefifo->name, sizeof(sbefifo->name), "sbefifo%d",
> + sbefifo->idx);
> + init_waitqueue_head(&sbefifo->wait);
> + INIT_LIST_HEAD(&sbefifo->xfrs);
> +
> + /* This bit of silicon doesn't offer any interrupts... */
> + setup_timer(&sbefifo->poll_timer, sbefifo_poll_timer,
> + (unsigned long)sbefifo);
> +
> + list_add(&sbefifo->link, &sbefifo_fifos);
> + return misc_register(&sbefifo->mdev);
> +}
> +
> +static int sbefifo_remove(struct device *dev)
> +{
> + struct fsi_device *fsi_dev = to_fsi_dev(dev);
> + struct sbefifo *sbefifo, *sbefifo_tmp;
> + struct sbefifo_xfr *xfr;
> +
> + list_for_each_entry_safe(sbefifo, sbefifo_tmp, &sbefifo_fifos, link) {
> + if (sbefifo->fsi_dev != fsi_dev)
> + continue;
> + misc_deregister(&sbefifo->mdev);
> + list_del(&sbefifo->link);
> + ida_simple_remove(&sbefifo_ida, sbefifo->idx);
> +
> + if (del_timer_sync(&sbefifo->poll_timer))
> + sbefifo_put(sbefifo);
> +
> + spin_lock(&sbefifo->lock);
> + list_for_each_entry(xfr, &sbefifo->xfrs, xfrs)
> + kfree(xfr);
> + spin_unlock(&sbefifo->lock);
> +
> + WRITE_ONCE(sbefifo->rc, -ENODEV);
> +
> + wake_up(&sbefifo->wait);
> + sbefifo_put(sbefifo);
> + }
> +
> + return 0;
> +}
> +
> +static struct fsi_device_id sbefifo_ids[] = {
> + {
> + .engine_type = FSI_ENGID_SBE,
> + .version = FSI_VERSION_ANY,
> + },
> + { 0 }
> +};
> +
> +static struct fsi_driver sbefifo_drv = {
> + .id_table = sbefifo_ids,
> + .drv = {
> + .name = DEVICE_NAME,
> + .bus = &fsi_bus_type,
> + .probe = sbefifo_probe,
> + .remove = sbefifo_remove,
> + }
> +};
> +
> +static int sbefifo_init(void)
> +{
> + INIT_LIST_HEAD(&sbefifo_fifos);
> + return fsi_driver_register(&sbefifo_drv);
> +}
> +
> +static void sbefifo_exit(void)
> +{
> + fsi_driver_unregister(&sbefifo_drv);
> +}
> +
> +module_init(sbefifo_init);
> +module_exit(sbefifo_exit);
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Brad Bishop <bradleyb at fuzziesquirrel.com>");
> +MODULE_DESCRIPTION("Linux device interface to the POWER self boot engine");
More information about the openbmc
mailing list