creates the qib_diag.c file.

Signed-off-by: Ralph Campbell <ralph.campb...@qlogic.com>
---

 drivers/infiniband/hw/qib/qib_diag.c |  894 ++++++++++++++++++++++++++++++++++
 1 files changed, 894 insertions(+), 0 deletions(-)
 create mode 100644 drivers/infiniband/hw/qib/qib_diag.c

diff --git a/drivers/infiniband/hw/qib/qib_diag.c 
b/drivers/infiniband/hw/qib/qib_diag.c
new file mode 100644
index 0000000..ca98dd5
--- /dev/null
+++ b/drivers/infiniband/hw/qib/qib_diag.c
@@ -0,0 +1,894 @@
+/*
+ * Copyright (c) 2010 QLogic Corporation. All rights reserved.
+ * Copyright (c) 2006, 2007, 2008, 2009 QLogic Corporation. All rights 
reserved.
+ * Copyright (c) 2003, 2004, 2005, 2006 PathScale, Inc. All rights reserved.
+ *
+ * This software is available to you under a choice of one of two
+ * licenses.  You may choose to be licensed under the terms of the GNU
+ * General Public License (GPL) Version 2, available from the file
+ * COPYING in the main directory of this source tree, or the
+ * OpenIB.org BSD license below:
+ *
+ *     Redistribution and use in source and binary forms, with or
+ *     without modification, are permitted provided that the following
+ *     conditions are met:
+ *
+ *      - Redistributions of source code must retain the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer.
+ *
+ *      - Redistributions in binary form must reproduce the above
+ *        copyright notice, this list of conditions and the following
+ *        disclaimer in the documentation and/or other materials
+ *        provided with the distribution.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+/*
+ * This file contains support for diagnostic functions.  It is accessed by
+ * opening the qib_diag device, normally minor number 129.  Diagnostic use
+ * of the QLogic_IB chip may render the chip or board unusable until the
+ * driver is unloaded, or in some cases, until the system is rebooted.
+ *
+ * Accesses to the chip through this interface are not similar to going
+ * through the /sys/bus/pci resource mmap interface.
+ */
+
+#include <linux/io.h>
+#include <linux/pci.h>
+#include <linux/poll.h>
+#include <linux/vmalloc.h>
+#include <linux/fs.h>
+#include <linux/uaccess.h>
+
+#include "qib.h"
+#include "qib_common.h"
+
+/*
+ * Each client that opens the diag device must read then write
+ * offset 0, to prevent lossage from random cat or od. diag_state
+ * sequences this "handshake".
+ */
+enum diag_state { UNUSED = 0, OPENED, INIT, READY };
+
+/* State for an individual client. PID so children cannot abuse handshake */
+static struct qib_diag_client {
+       struct qib_diag_client *next;
+       struct qib_devdata *dd;
+       pid_t pid;
+       enum diag_state state;
+} *client_pool;
+
+/*
+ * Get a client struct. Recycled if possible, else kmalloc.
+ * Must be called with qib_mutex held
+ */
+static struct qib_diag_client *get_client(struct qib_devdata *dd)
+{
+       struct qib_diag_client *dc;
+
+       dc = client_pool;
+       if (dc)
+               /* got from pool remove it and use */
+               client_pool = dc->next;
+       else
+               /* None in pool, alloc and init */
+               dc = kmalloc(sizeof *dc, GFP_KERNEL);
+
+       if (dc) {
+               dc->next = NULL;
+               dc->dd = dd;
+               dc->pid = current->pid;
+               dc->state = OPENED;
+       }
+       return dc;
+}
+
+/*
+ * Return to pool. Must be called with qib_mutex held
+ */
+static void return_client(struct qib_diag_client *dc)
+{
+       struct qib_devdata *dd = dc->dd;
+       struct qib_diag_client *tdc, *rdc;
+
+       rdc = NULL;
+       if (dc == dd->diag_client) {
+               dd->diag_client = dc->next;
+               rdc = dc;
+       } else {
+               tdc = dc->dd->diag_client;
+               while (tdc) {
+                       if (dc == tdc->next) {
+                               tdc->next = dc->next;
+                               rdc = dc;
+                               break;
+                       }
+                       tdc = tdc->next;
+               }
+       }
+       if (rdc) {
+               rdc->state = UNUSED;
+               rdc->dd = NULL;
+               rdc->pid = 0;
+               rdc->next = client_pool;
+               client_pool = rdc;
+       }
+}
+
+static int qib_diag_open(struct inode *in, struct file *fp);
+static int qib_diag_release(struct inode *in, struct file *fp);
+static ssize_t qib_diag_read(struct file *fp, char __user *data,
+                            size_t count, loff_t *off);
+static ssize_t qib_diag_write(struct file *fp, const char __user *data,
+                             size_t count, loff_t *off);
+
+static const struct file_operations diag_file_ops = {
+       .owner = THIS_MODULE,
+       .write = qib_diag_write,
+       .read = qib_diag_read,
+       .open = qib_diag_open,
+       .release = qib_diag_release
+};
+
+static atomic_t diagpkt_count = ATOMIC_INIT(0);
+static struct cdev *diagpkt_cdev;
+static struct device *diagpkt_device;
+
+static ssize_t qib_diagpkt_write(struct file *fp, const char __user *data,
+                                size_t count, loff_t *off);
+
+static const struct file_operations diagpkt_file_ops = {
+       .owner = THIS_MODULE,
+       .write = qib_diagpkt_write,
+};
+
+int qib_diag_add(struct qib_devdata *dd)
+{
+       char name[16];
+       int ret = 0;
+
+       if (atomic_inc_return(&diagpkt_count) == 1) {
+               ret = qib_cdev_init(QIB_DIAGPKT_MINOR, "ipath_diagpkt",
+                                   &diagpkt_file_ops, &diagpkt_cdev,
+                                   &diagpkt_device);
+               if (ret)
+                       goto done;
+       }
+
+       snprintf(name, sizeof(name), "ipath_diag%d", dd->unit);
+       ret = qib_cdev_init(QIB_DIAG_MINOR_BASE + dd->unit, name,
+                           &diag_file_ops, &dd->diag_cdev,
+                           &dd->diag_device);
+done:
+       return ret;
+}
+
+static void qib_unregister_observers(struct qib_devdata *dd);
+
+void qib_diag_remove(struct qib_devdata *dd)
+{
+       struct qib_diag_client *dc;
+
+       if (atomic_dec_and_test(&diagpkt_count))
+               qib_cdev_cleanup(&diagpkt_cdev, &diagpkt_device);
+
+       qib_cdev_cleanup(&dd->diag_cdev, &dd->diag_device);
+
+       /*
+        * Return all diag_clients of this device. There should be none,
+        * as we are "guaranteed" that no clients are still open
+        */
+       while (dd->diag_client)
+               return_client(dd->diag_client);
+
+       /* Now clean up all unused client structs */
+       while (client_pool) {
+               dc = client_pool;
+               client_pool = dc->next;
+               kfree(dc);
+       }
+       /* Clean up observer list */
+       qib_unregister_observers(dd);
+}
+
+/* qib_remap_ioaddr32 - remap an offset into chip address space to __iomem *
+ *
+ * @dd: the qlogic_ib device
+ * @offs: the offset in chip-space
+ * @cntp: Pointer to max (byte) count for transfer starting at offset
+ * This returns a u32 __iomem * so it can be used for both 64 and 32-bit
+ * mapping. It is needed because with the use of PAT for control of
+ * write-combining, the logically contiguous address-space of the chip
+ * may be split into virtually non-contiguous spaces, with different
+ * attributes, which are them mapped to contiguous physical space
+ * based from the first BAR.
+ *
+ * The code below makes the same assumptions as were made in
+ * init_chip_wc_pat() (qib_init.c), copied here:
+ * Assumes chip address space looks like:
+ *             - kregs + sregs + cregs + uregs (in any order)
+ *             - piobufs (2K and 4K bufs in either order)
+ *     or:
+ *             - kregs + sregs + cregs (in any order)
+ *             - piobufs (2K and 4K bufs in either order)
+ *             - uregs
+ *
+ * If cntp is non-NULL, returns how many bytes from offset can be accessed
+ * Returns 0 if the offset is not mapped.
+ */
+static u32 __iomem *qib_remap_ioaddr32(struct qib_devdata *dd, u32 offset,
+                                      u32 *cntp)
+{
+       u32 kreglen;
+       u32 snd_bottom, snd_lim = 0;
+       u32 __iomem *krb32 = (u32 __iomem *)dd->kregbase;
+       u32 __iomem *map = NULL;
+       u32 cnt = 0;
+
+       /* First, simplest case, offset is within the first map. */
+       kreglen = (dd->kregend - dd->kregbase) * sizeof(u64);
+       if (offset < kreglen) {
+               map = krb32 + (offset / sizeof(u32));
+               cnt = kreglen - offset;
+               goto mapped;
+       }
+
+       /*
+        * Next check for user regs, the next most common case,
+        * and a cheap check because if they are not in the first map
+        * they are last in chip.
+        */
+       if (dd->userbase) {
+               /* If user regs mapped, they are after send, so set limit. */
+               u32 ulim = (dd->cfgctxts * dd->ureg_align) + dd->uregbase;
+               snd_lim = dd->uregbase;
+               krb32 = (u32 __iomem *)dd->userbase;
+               if (offset >= dd->uregbase && offset < ulim) {
+                       map = krb32 + (offset - dd->uregbase) / sizeof(u32);
+                       cnt = ulim - offset;
+                       goto mapped;
+               }
+       }
+
+       /*
+        * Lastly, check for offset within Send Buffers.
+        * This is gnarly because struct devdata is deliberately vague
+        * about things like 7322 VL15 buffers, and we are not in
+        * chip-specific code here, so should not make many assumptions.
+        * The one we _do_ make is that the only chip that has more sndbufs
+        * than we admit is the 7322, and it has userregs above that, so
+        * we know the snd_lim.
+        */
+       /* Assume 2K buffers are first. */
+       snd_bottom = dd->pio2k_bufbase;
+       if (snd_lim == 0) {
+               u32 tot2k = dd->piobcnt2k * ALIGN(dd->piosize2k, dd->palign);
+               snd_lim = snd_bottom + tot2k;
+       }
+       /* If 4k buffers exist, account for them by bumping
+        * appropriate limit.
+        */
+       if (dd->piobcnt4k) {
+               u32 tot4k = dd->piobcnt4k * dd->align4k;
+               u32 offs4k = dd->piobufbase >> 32;
+               if (snd_bottom > offs4k)
+                       snd_bottom = offs4k;
+               else {
+                       /* 4k above 2k. Bump snd_lim, if needed*/
+                       if (!dd->userbase)
+                               snd_lim = offs4k + tot4k;
+               }
+       }
+       /*
+        * Judgement call: can we ignore the space between SendBuffs and
+        * UserRegs, where we would like to see vl15 buffs, but not more?
+        */
+       if (offset >= snd_bottom && offset < snd_lim) {
+               offset -= snd_bottom;
+               map = (u32 __iomem *)dd->piobase + (offset / sizeof(u32));
+               cnt = snd_lim - offset;
+       }
+
+mapped:
+       if (cntp)
+               *cntp = cnt;
+       return map;
+}
+
+/*
+ * qib_read_umem64 - read a 64-bit quantity from the chip into user space
+ * @dd: the qlogic_ib device
+ * @uaddr: the location to store the data in user memory
+ * @regoffs: the offset from BAR0 (_NOT_ full pointer, anymore)
+ * @count: number of bytes to copy (multiple of 32 bits)
+ *
+ * This function also localizes all chip memory accesses.
+ * The copy should be written such that we read full cacheline packets
+ * from the chip.  This is usually used for a single qword
+ *
+ * NOTE:  This assumes the chip address is 64-bit aligned.
+ */
+static int qib_read_umem64(struct qib_devdata *dd, void __user *uaddr,
+                          u32 regoffs, size_t count)
+{
+       const u64 __iomem *reg_addr;
+       const u64 __iomem *reg_end;
+       u32 limit;
+       int ret;
+
+       reg_addr = (const u64 __iomem *)qib_remap_ioaddr32(dd, regoffs, &limit);
+       if (reg_addr == NULL || limit == 0 || !(dd->flags & QIB_PRESENT)) {
+               ret = -EINVAL;
+               goto bail;
+       }
+       if (count >= limit)
+               count = limit;
+       reg_end = reg_addr + (count / sizeof(u64));
+
+       /* not very efficient, but it works for now */
+       while (reg_addr < reg_end) {
+               u64 data = readq(reg_addr);
+
+               if (copy_to_user(uaddr, &data, sizeof(u64))) {
+                       ret = -EFAULT;
+                       goto bail;
+               }
+               reg_addr++;
+               uaddr += sizeof(u64);
+       }
+       ret = 0;
+bail:
+       return ret;
+}
+
+/*
+ * qib_write_umem64 - write a 64-bit quantity to the chip from user space
+ * @dd: the qlogic_ib device
+ * @regoffs: the offset from BAR0 (_NOT_ full pointer, anymore)
+ * @uaddr: the source of the data in user memory
+ * @count: the number of bytes to copy (multiple of 32 bits)
+ *
+ * This is usually used for a single qword
+ * NOTE:  This assumes the chip address is 64-bit aligned.
+ */
+
+static int qib_write_umem64(struct qib_devdata *dd, u32 regoffs,
+                           const void __user *uaddr, size_t count)
+{
+       u64 __iomem *reg_addr;
+       const u64 __iomem *reg_end;
+       u32 limit;
+       int ret;
+
+       reg_addr = (u64 __iomem *)qib_remap_ioaddr32(dd, regoffs, &limit);
+       if (reg_addr == NULL || limit == 0 || !(dd->flags & QIB_PRESENT)) {
+               ret = -EINVAL;
+               goto bail;
+       }
+       if (count >= limit)
+               count = limit;
+       reg_end = reg_addr + (count / sizeof(u64));
+
+       /* not very efficient, but it works for now */
+       while (reg_addr < reg_end) {
+               u64 data;
+               if (copy_from_user(&data, uaddr, sizeof(data))) {
+                       ret = -EFAULT;
+                       goto bail;
+               }
+               writeq(data, reg_addr);
+
+               reg_addr++;
+               uaddr += sizeof(u64);
+       }
+       ret = 0;
+bail:
+       return ret;
+}
+
+/*
+ * qib_read_umem32 - read a 32-bit quantity from the chip into user space
+ * @dd: the qlogic_ib device
+ * @uaddr: the location to store the data in user memory
+ * @regoffs: the offset from BAR0 (_NOT_ full pointer, anymore)
+ * @count: number of bytes to copy
+ *
+ * read 32 bit values, not 64 bit; for memories that only
+ * support 32 bit reads; usually a single dword.
+ */
+static int qib_read_umem32(struct qib_devdata *dd, void __user *uaddr,
+                          u32 regoffs, size_t count)
+{
+       const u32 __iomem *reg_addr;
+       const u32 __iomem *reg_end;
+       u32 limit;
+       int ret;
+
+       reg_addr = qib_remap_ioaddr32(dd, regoffs, &limit);
+       if (reg_addr == NULL || limit == 0 || !(dd->flags & QIB_PRESENT)) {
+               ret = -EINVAL;
+               goto bail;
+       }
+       if (count >= limit)
+               count = limit;
+       reg_end = reg_addr + (count / sizeof(u32));
+
+       /* not very efficient, but it works for now */
+       while (reg_addr < reg_end) {
+               u32 data = readl(reg_addr);
+
+               if (copy_to_user(uaddr, &data, sizeof(data))) {
+                       ret = -EFAULT;
+                       goto bail;
+               }
+
+               reg_addr++;
+               uaddr += sizeof(u32);
+
+       }
+       ret = 0;
+bail:
+       return ret;
+}
+
+/*
+ * qib_write_umem32 - write a 32-bit quantity to the chip from user space
+ * @dd: the qlogic_ib device
+ * @regoffs: the offset from BAR0 (_NOT_ full pointer, anymore)
+ * @uaddr: the source of the data in user memory
+ * @count: number of bytes to copy
+ *
+ * write 32 bit values, not 64 bit; for memories that only
+ * support 32 bit write; usually a single dword.
+ */
+
+static int qib_write_umem32(struct qib_devdata *dd, u32 regoffs,
+                           const void __user *uaddr, size_t count)
+{
+       u32 __iomem *reg_addr;
+       const u32 __iomem *reg_end;
+       u32 limit;
+       int ret;
+
+       reg_addr = qib_remap_ioaddr32(dd, regoffs, &limit);
+       if (reg_addr == NULL || limit == 0 || !(dd->flags & QIB_PRESENT)) {
+               ret = -EINVAL;
+               goto bail;
+       }
+       if (count >= limit)
+               count = limit;
+       reg_end = reg_addr + (count / sizeof(u32));
+
+       while (reg_addr < reg_end) {
+               u32 data;
+
+               if (copy_from_user(&data, uaddr, sizeof(data))) {
+                       ret = -EFAULT;
+                       goto bail;
+               }
+               writel(data, reg_addr);
+
+               reg_addr++;
+               uaddr += sizeof(u32);
+       }
+       ret = 0;
+bail:
+       return ret;
+}
+
+static int qib_diag_open(struct inode *in, struct file *fp)
+{
+       int unit = iminor(in) - QIB_DIAG_MINOR_BASE;
+       struct qib_devdata *dd;
+       struct qib_diag_client *dc;
+       int ret;
+
+       mutex_lock(&qib_mutex);
+
+       dd = qib_lookup(unit);
+
+       if (dd == NULL || !(dd->flags & QIB_PRESENT) ||
+           !dd->kregbase) {
+               ret = -ENODEV;
+               goto bail;
+       }
+
+       dc = get_client(dd);
+       if (!dc) {
+               ret = -ENOMEM;
+               goto bail;
+       }
+       dc->next = dd->diag_client;
+       dd->diag_client = dc;
+       fp->private_data = dc;
+       ret = 0;
+bail:
+       mutex_unlock(&qib_mutex);
+
+       return ret;
+}
+
+/**
+ * qib_diagpkt_write - write an IB packet
+ * @fp: the diag data device file pointer
+ * @data: qib_diag_pkt structure saying where to get the packet
+ * @count: size of data to write
+ * @off: unused by this code
+ */
+static ssize_t qib_diagpkt_write(struct file *fp,
+                                const char __user *data,
+                                size_t count, loff_t *off)
+{
+       u32 __iomem *piobuf;
+       u32 plen, clen, pbufn;
+       struct qib_diag_xpkt dp;
+       u32 *tmpbuf = NULL;
+       struct qib_devdata *dd;
+       struct qib_pportdata *ppd;
+       ssize_t ret = 0;
+
+       if (count != sizeof(dp)) {
+               ret = -EINVAL;
+               goto bail;
+       }
+       if (copy_from_user(&dp, data, sizeof(dp))) {
+               ret = -EFAULT;
+               goto bail;
+       }
+
+       dd = qib_lookup(dp.unit);
+       if (!dd || !(dd->flags & QIB_PRESENT) || !dd->kregbase) {
+               ret = -ENODEV;
+               goto bail;
+       }
+       if (!(dd->flags & QIB_INITTED)) {
+               /* no hardware, freeze, etc. */
+               ret = -ENODEV;
+               goto bail;
+       }
+
+       if (dp.version != _DIAG_XPKT_VERS) {
+               qib_dev_err(dd, "Invalid version %u for diagpkt_write\n",
+                           dp.version);
+               ret = -EINVAL;
+               goto bail;
+       }
+       /* send count must be an exact number of dwords */
+       if (dp.len & 3) {
+               ret = -EINVAL;
+               goto bail;
+       }
+       if (!dp.port || dp.port > dd->num_pports) {
+               ret = -EINVAL;
+               goto bail;
+       }
+       ppd = &dd->pport[dp.port - 1];
+
+       /* need total length before first word written */
+       /* +1 word is for the qword padding */
+       plen = sizeof(u32) + dp.len;
+       clen = dp.len >> 2;
+
+       if ((plen + 4) > ppd->ibmaxlen) {
+               ret = -EINVAL;
+               goto bail;      /* before writing pbc */
+       }
+       tmpbuf = vmalloc(plen);
+       if (!tmpbuf) {
+               qib_devinfo(dd->pcidev, "Unable to allocate tmp buffer, "
+                        "failing\n");
+               ret = -ENOMEM;
+               goto bail;
+       }
+
+       if (copy_from_user(tmpbuf,
+                          (const void __user *) (unsigned long) dp.data,
+                          dp.len)) {
+               ret = -EFAULT;
+               goto bail;
+       }
+
+       plen >>= 2;             /* in dwords */
+
+       if (dp.pbc_wd == 0)
+               dp.pbc_wd = plen;
+
+       piobuf = dd->f_getsendbuf(ppd, dp.pbc_wd, &pbufn);
+       if (!piobuf) {
+               ret = -EBUSY;
+               goto bail;
+       }
+       /* disarm it just to be extra sure */
+       dd->f_sendctrl(dd->pport, QIB_SENDCTRL_DISARM_BUF(pbufn));
+
+       /* disable header check on pbufn for this packet */
+       dd->f_txchk_change(dd, pbufn, 1, TXCHK_CHG_TYPE_DIS1, NULL);
+
+       writeq(dp.pbc_wd, piobuf);
+       /*
+        * Copy all but the trigger word, then flush, so it's written
+        * to chip before trigger word, then write trigger word, then
+        * flush again, so packet is sent.
+        */
+       if (dd->flags & QIB_PIO_FLUSH_WC) {
+               qib_flush_wc();
+               qib_pio_copy(piobuf + 2, tmpbuf, clen - 1);
+               qib_flush_wc();
+               __raw_writel(tmpbuf[clen - 1], piobuf + clen + 1);
+       } else
+               qib_pio_copy(piobuf + 2, tmpbuf, clen);
+
+       if (dd->flags & QIB_USE_SPCL_TRIG) {
+               u32 spcl_off = (pbufn >= dd->piobcnt2k) ? 2047 : 1023;
+
+               qib_flush_wc();
+               __raw_writel(0xaebecede, piobuf + spcl_off);
+       }
+
+       /*
+        * Ensure buffer is written to the chip, then re-enable
+        * header checks (if supported by chip).  The txchk
+        * code will ensure seen by chip before returning.
+        */
+       qib_flush_wc();
+       qib_sendbuf_done(dd, pbufn);
+       dd->f_txchk_change(dd, pbufn, 1, TXCHK_CHG_TYPE_ENAB1, NULL);
+
+       ret = sizeof(dp);
+
+bail:
+       vfree(tmpbuf);
+       return ret;
+}
+
+static int qib_diag_release(struct inode *in, struct file *fp)
+{
+       mutex_lock(&qib_mutex);
+       return_client(fp->private_data);
+       fp->private_data = NULL;
+       mutex_unlock(&qib_mutex);
+       return 0;
+}
+
+/*
+ * Chip-specific code calls to register its interest in
+ * a specific range.
+ */
+struct diag_observer_list_elt {
+       struct diag_observer_list_elt *next;
+       const struct diag_observer *op;
+};
+
+int qib_register_observer(struct qib_devdata *dd,
+                         const struct diag_observer *op)
+{
+       struct diag_observer_list_elt *olp;
+       int ret = -EINVAL;
+
+       if (!dd || !op)
+               goto bail;
+       ret = -ENOMEM;
+       olp = vmalloc(sizeof *olp);
+       if (!olp) {
+               printk(KERN_ERR QIB_DRV_NAME ": vmalloc for observer failed\n");
+               goto bail;
+       }
+       if (olp) {
+               unsigned long flags;
+
+               spin_lock_irqsave(&dd->qib_diag_trans_lock, flags);
+               olp->op = op;
+               olp->next = dd->diag_observer_list;
+               dd->diag_observer_list = olp;
+               spin_unlock_irqrestore(&dd->qib_diag_trans_lock, flags);
+               ret = 0;
+       }
+bail:
+       return ret;
+}
+
+/* Remove all registered observers when device is closed */
+static void qib_unregister_observers(struct qib_devdata *dd)
+{
+       struct diag_observer_list_elt *olp;
+       unsigned long flags;
+
+       spin_lock_irqsave(&dd->qib_diag_trans_lock, flags);
+       olp = dd->diag_observer_list;
+       while (olp) {
+               /* Pop one observer, let go of lock */
+               dd->diag_observer_list = olp->next;
+               spin_unlock_irqrestore(&dd->qib_diag_trans_lock, flags);
+               vfree(olp);
+               /* try again. */
+               spin_lock_irqsave(&dd->qib_diag_trans_lock, flags);
+               olp = dd->diag_observer_list;
+       }
+       spin_unlock_irqrestore(&dd->qib_diag_trans_lock, flags);
+}
+
+/*
+ * Find the observer, if any, for the specified address. Initial implementation
+ * is simple stack of observers. This must be called with diag transaction
+ * lock held.
+ */
+static const struct diag_observer *diag_get_observer(struct qib_devdata *dd,
+                                                    u32 addr)
+{
+       struct diag_observer_list_elt *olp;
+       const struct diag_observer *op = NULL;
+
+       olp = dd->diag_observer_list;
+       while (olp) {
+               op = olp->op;
+               if (addr >= op->bottom && addr <= op->top)
+                       break;
+               olp = olp->next;
+       }
+       if (!olp)
+               op = NULL;
+
+       return op;
+}
+
+static ssize_t qib_diag_read(struct file *fp, char __user *data,
+                            size_t count, loff_t *off)
+{
+       struct qib_diag_client *dc = fp->private_data;
+       struct qib_devdata *dd = dc->dd;
+       void __iomem *kreg_base;
+       ssize_t ret;
+
+       if (dc->pid != current->pid) {
+               ret = -EPERM;
+               goto bail;
+       }
+
+       kreg_base = dd->kregbase;
+
+       if (count == 0)
+               ret = 0;
+       else if ((count % 4) || (*off % 4))
+               /* address or length is not 32-bit aligned, hence invalid */
+               ret = -EINVAL;
+       else if (dc->state < READY && (*off || count != 8))
+               ret = -EINVAL;  /* prevent cat /dev/qib_diag* */
+       else {
+               unsigned long flags;
+               u64 data64 = 0;
+               int use_32;
+               const struct diag_observer *op;
+
+               use_32 = (count % 8) || (*off % 8);
+               ret = -1;
+               spin_lock_irqsave(&dd->qib_diag_trans_lock, flags);
+               /*
+                * Check for observer on this address range.
+                * we only support a single 32 or 64-bit read
+                * via observer, currently.
+                */
+               op = diag_get_observer(dd, *off);
+               if (op) {
+                       u32 offset = *off;
+                       ret = op->hook(dd, op, offset, &data64, 0, use_32);
+               }
+               /*
+                * We need to release lock before any copy_to_user(),
+                * whether implicit in qib_read_umem* or explicit below.
+                */
+               spin_unlock_irqrestore(&dd->qib_diag_trans_lock, flags);
+               if (!op) {
+                       if (use_32)
+                               /*
+                                * Address or length is not 64-bit aligned;
+                                * do 32-bit rd
+                                */
+                               ret = qib_read_umem32(dd, data, (u32) *off,
+                                                     count);
+                       else
+                               ret = qib_read_umem64(dd, data, (u32) *off,
+                                                     count);
+               } else if (ret == count) {
+                       /* Below finishes case where observer existed */
+                       ret = copy_to_user(data, &data64, use_32 ?
+                                          sizeof(u32) : sizeof(u64));
+                       if (ret)
+                               ret = -EFAULT;
+               }
+       }
+
+       if (ret >= 0) {
+               *off += count;
+               ret = count;
+               if (dc->state == OPENED)
+                       dc->state = INIT;
+       }
+bail:
+       return ret;
+}
+
+static ssize_t qib_diag_write(struct file *fp, const char __user *data,
+                             size_t count, loff_t *off)
+{
+       struct qib_diag_client *dc = fp->private_data;
+       struct qib_devdata *dd = dc->dd;
+       void __iomem *kreg_base;
+       ssize_t ret;
+
+       if (dc->pid != current->pid) {
+               ret = -EPERM;
+               goto bail;
+       }
+
+       kreg_base = dd->kregbase;
+
+       if (count == 0)
+               ret = 0;
+       else if ((count % 4) || (*off % 4))
+               /* address or length is not 32-bit aligned, hence invalid */
+               ret = -EINVAL;
+       else if (dc->state < READY &&
+               ((*off || count != 8) || dc->state != INIT))
+               /* No writes except second-step of init seq */
+               ret = -EINVAL;  /* before any other write allowed */
+       else {
+               unsigned long flags;
+               const struct diag_observer *op = NULL;
+               int use_32 =  (count % 8) || (*off % 8);
+
+               /*
+                * Check for observer on this address range.
+                * We only support a single 32 or 64-bit write
+                * via observer, currently. This helps, because
+                * we would otherwise have to jump through hoops
+                * to make "diag transaction" meaningful when we
+                * cannot do a copy_from_user while holding the lock.
+                */
+               if (count == 4 || count == 8) {
+                       u64 data64;
+                       u32 offset = *off;
+                       ret = copy_from_user(&data64, data, count);
+                       if (ret) {
+                               ret = -EFAULT;
+                               goto bail;
+                       }
+                       spin_lock_irqsave(&dd->qib_diag_trans_lock, flags);
+                       op = diag_get_observer(dd, *off);
+                       if (op)
+                               ret = op->hook(dd, op, offset, &data64, ~0Ull,
+                                              use_32);
+                       spin_unlock_irqrestore(&dd->qib_diag_trans_lock, flags);
+               }
+
+               if (!op) {
+                       if (use_32)
+                               /*
+                                * Address or length is not 64-bit aligned;
+                                * do 32-bit write
+                                */
+                               ret = qib_write_umem32(dd, (u32) *off, data,
+                                                      count);
+                       else
+                               ret = qib_write_umem64(dd, (u32) *off, data,
+                                                      count);
+               }
+       }
+
+       if (ret >= 0) {
+               *off += count;
+               ret = count;
+               if (dc->state == INIT)
+                       dc->state = READY; /* all read/write OK now */
+       }
+bail:
+       return ret;
+}

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