/*
* Free all kernel contexts that are not currently in use.
* Returns 0 if all freed, else number of inuse context.
*/
static int gru_free_kernel_contexts(void)
{
struct gru_blade_state *bs;
struct gru_thread_state *kgts;
int bid, ret = 0;
for (bid = 0; bid < GRU_MAX_BLADES; bid++) {
bs = gru_base[bid];
if (!bs)
continue;
/* Ignore busy contexts. Don't want to block here. */
if (down_write_trylock(&bs->bs_kgts_sema)) {
kgts = bs->bs_kgts;
if (kgts && kgts->ts_gru)
gru_unload_context(kgts, 0);
bs->bs_kgts = NULL;
up_write(&bs->bs_kgts_sema);
kfree(kgts);
} else {
ret++;
}
}
return ret;
}
static int
process_set(struct request_state* req)
{
while (!down_write_trylock(&rwlock))
continue;
req->err = ub_cache_replace(req->key, req->len_key, req->data, req->len_data);
up_write(&rwlock);
/* TODO: this need not generate a new skb on every run, but for now it's simpler
to do it this way */
req->skb_tx = ub_skb_set_up(32);
if (req->err == 0)
ub_push_data_to_skb(req->skb_tx, "STORED\r\n", strlen("STORED\r\n"));
else if (req->err == -ENOMEM)
ub_push_data_to_skb(req->skb_tx, "NOT_STORED\r\n", strlen("NOT_STORED\r\n"));
else
{
char errstring[20];
int len_errstring = snprintf(&errstring[0], 20,
"SERVER ERROR %d\r\n", req->err);
ub_push_data_to_skb(req->skb_tx, errstring, len_errstring);
}
return 0;
}
static int wil_suspend_radio_off(struct wil6210_priv *wil)
{
int rc = 0;
bool active_ifaces;
wil_dbg_pm(wil, "suspend radio off\n");
rc = down_write_trylock(&wil->mem_lock);
if (!rc) {
wil_err(wil,
"device is busy. down_write_trylock failed, returned (0x%x)\n",
rc);
wil->suspend_stats.rejected_by_host++;
return -EBUSY;
}
set_bit(wil_status_suspending, wil->status);
up_write(&wil->mem_lock);
/* if netif up, hardware is alive, shut it down */
mutex_lock(&wil->vif_mutex);
active_ifaces = wil_has_active_ifaces(wil, true, false);
mutex_unlock(&wil->vif_mutex);
if (active_ifaces) {
rc = wil_down(wil);
if (rc) {
wil_err(wil, "wil_down : %d\n", rc);
wil->suspend_stats.r_off.failed_suspends++;
goto out;
}
}
/* Disable PCIe IRQ to prevent sporadic IRQs when PCIe is suspending */
wil_dbg_pm(wil, "Disabling PCIe IRQ before suspending\n");
wil_disable_irq(wil);
if (wil->platform_ops.suspend) {
rc = wil->platform_ops.suspend(wil->platform_handle, false);
if (rc) {
wil_enable_irq(wil);
wil->suspend_stats.r_off.failed_suspends++;
goto out;
}
}
set_bit(wil_status_suspended, wil->status);
out:
clear_bit(wil_status_suspending, wil->status);
wil_dbg_pm(wil, "suspend radio off: %d\n", rc);
return rc;
}
static ssize_t foo_store(struct kobject *kobj, struct kobj_attribute *attr,
const char *buf, size_t count)
{
/* down_write_trylock returns zero on failure */
if (!down_write_trylock(&rw_sem))
return -ERESTARTSYS;
memcpy(foo_kbuff, buf, (strlen(buf)+1));
up_write(&rw_sem);
return count;
}
static int osd_object_write_locked(const struct lu_env *env,
struct dt_object *dt)
{
struct osd_object *obj = osd_dt_obj(dt);
int rc = 1;
LASSERT(osd_invariant(obj));
if (down_write_trylock(&obj->oo_sem)) {
rc = 0;
up_write(&obj->oo_sem);
}
return rc;
}
/*
* Validate and return the priority_cached flag. We know if it's zero
* that we don't need to scan, since we immediately set it non-zero
* when we first consider a MAP_CACHE_PRIORITY mapping.
*
* We only _try_ to acquire the mmap_sem semaphore; if we can't acquire it,
* since we're in an interrupt context (servicing switch_mm) we don't
* worry about it and don't unset the "priority_cached" field.
* Presumably we'll come back later and have more luck and clear
* the value then; for now we'll just keep the cache marked for priority.
*/
static unsigned int update_priority_cached(struct mm_struct *mm)
{
if (mm->context.priority_cached && down_write_trylock(&mm->mmap_sem)) {
struct vm_area_struct *vm;
for (vm = mm->mmap; vm; vm = vm->vm_next) {
if (hv_pte_get_cached_priority(vm->vm_page_prot))
break;
}
if (vm == NULL)
mm->context.priority_cached = 0;
up_write(&mm->mmap_sem);
}
return mm->context.priority_cached;
}
struct vm_area_struct *our_vma(struct mm_struct *mm, unsigned long addr,
size_t count)
{
struct vm_area_struct *vma, *ret = NULL;
/* mmap_sem must have been held by caller. */
LASSERT(!down_write_trylock(&mm->mmap_sem));
for (vma = find_vma(mm, addr);
vma && vma->vm_start < (addr + count); vma = vma->vm_next) {
if (vma->vm_ops && vma->vm_ops == &ll_file_vm_ops &&
vma->vm_flags & VM_SHARED) {
ret = vma;
break;
}
}
return ret;
}
int __init down_write_trylock_init(void)
{
int ret;
init_rwsem( &rwsem ); //读写信号量初始化
printk("<0>after init_rwsem, count: %ld\n",rwsem.count);
if( EXEC_DOWN_READ )
down_read( &rwsem ); //读者获取读写信号量
ret = down_write_trylock( &rwsem ); //写者尝试获取读写信号量
if( ret )
{
printk("<0>after down_write_trylock, count: 0x%0lx\n",rwsem.count);
up_write( &rwsem ); //写者释放读写信号量
printk("<0>after up_write, count: %ld\n",rwsem.count);
}
else
printk("<0>down_write_trylock failed!\n");
return 0;
}
/**
* leb_write_lock - lock logical eraseblock for writing.
* @ubi: UBI device description object
* @vol_id: volume ID
* @lnum: logical eraseblock number
*
* This function locks a logical eraseblock for writing if there is no
* contention and does nothing if there is contention. Returns %0 in case of
* success, %1 in case of contention, and and a negative error code in case of
* failure.
*/
static int leb_write_trylock(struct ubi_device *ubi, int vol_id, int lnum)
{
struct ubi_ltree_entry *le;
le = ltree_add_entry(ubi, vol_id, lnum);
if (IS_ERR(le))
return PTR_ERR(le);
if (down_write_trylock(&le->mutex))
return 0;
/* Contention, cancel */
spin_lock(&ubi->ltree_lock);
le->users -= 1;
ubi_assert(le->users >= 0);
if (le->users == 0) {
rb_erase(&le->rb, &ubi->ltree);
kfree(le);
}
spin_unlock(&ubi->ltree_lock);
return 1;
}
static void ocfs2_clear_inode(struct inode *inode)
{
int status;
struct ocfs2_inode_info *oi = OCFS2_I(inode);
clear_inode(inode);
trace_ocfs2_clear_inode((unsigned long long)oi->ip_blkno,
inode->i_nlink);
mlog_bug_on_msg(OCFS2_SB(inode->i_sb) == NULL,
"Inode=%lu\n", inode->i_ino);
dquot_drop(inode);
/* To preven remote deletes we hold open lock before, now it
* is time to unlock PR and EX open locks. */
ocfs2_open_unlock(inode);
/* Do these before all the other work so that we don't bounce
* the downconvert thread while waiting to destroy the locks. */
ocfs2_mark_lockres_freeing(&oi->ip_rw_lockres);
ocfs2_mark_lockres_freeing(&oi->ip_inode_lockres);
ocfs2_mark_lockres_freeing(&oi->ip_open_lockres);
ocfs2_resv_discard(&OCFS2_SB(inode->i_sb)->osb_la_resmap,
&oi->ip_la_data_resv);
ocfs2_resv_init_once(&oi->ip_la_data_resv);
/* We very well may get a clear_inode before all an inodes
* metadata has hit disk. Of course, we can't drop any cluster
* locks until the journal has finished with it. The only
* exception here are successfully wiped inodes - their
* metadata can now be considered to be part of the system
* inodes from which it came. */
if (!(OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED))
ocfs2_checkpoint_inode(inode);
mlog_bug_on_msg(!list_empty(&oi->ip_io_markers),
"Clear inode of %llu, inode has io markers\n",
(unsigned long long)oi->ip_blkno);
ocfs2_extent_map_trunc(inode, 0);
status = ocfs2_drop_inode_locks(inode);
if (status < 0)
mlog_errno(status);
ocfs2_lock_res_free(&oi->ip_rw_lockres);
ocfs2_lock_res_free(&oi->ip_inode_lockres);
ocfs2_lock_res_free(&oi->ip_open_lockres);
ocfs2_metadata_cache_exit(INODE_CACHE(inode));
mlog_bug_on_msg(INODE_CACHE(inode)->ci_num_cached,
"Clear inode of %llu, inode has %u cache items\n",
(unsigned long long)oi->ip_blkno,
INODE_CACHE(inode)->ci_num_cached);
mlog_bug_on_msg(!(INODE_CACHE(inode)->ci_flags & OCFS2_CACHE_FL_INLINE),
"Clear inode of %llu, inode has a bad flag\n",
(unsigned long long)oi->ip_blkno);
mlog_bug_on_msg(spin_is_locked(&oi->ip_lock),
"Clear inode of %llu, inode is locked\n",
(unsigned long long)oi->ip_blkno);
mlog_bug_on_msg(!mutex_trylock(&oi->ip_io_mutex),
"Clear inode of %llu, io_mutex is locked\n",
(unsigned long long)oi->ip_blkno);
mutex_unlock(&oi->ip_io_mutex);
/*
* down_trylock() returns 0, down_write_trylock() returns 1
* kernel 1, world 0
*/
mlog_bug_on_msg(!down_write_trylock(&oi->ip_alloc_sem),
"Clear inode of %llu, alloc_sem is locked\n",
(unsigned long long)oi->ip_blkno);
up_write(&oi->ip_alloc_sem);
mlog_bug_on_msg(oi->ip_open_count,
"Clear inode of %llu has open count %d\n",
(unsigned long long)oi->ip_blkno, oi->ip_open_count);
/* Clear all other flags. */
oi->ip_flags = 0;
oi->ip_dir_start_lookup = 0;
oi->ip_blkno = 0ULL;
/*
* ip_jinode is used to track txns against this inode. We ensure that
* the journal is flushed before journal shutdown. Thus it is safe to
* have inodes get cleaned up after journal shutdown.
*/
jbd2_journal_release_jbd_inode(OCFS2_SB(inode->i_sb)->journal->j_journal,
&oi->ip_jinode);
}
void ocfs2_clear_inode(struct inode *inode)
{
int status;
struct ocfs2_inode_info *oi = OCFS2_I(inode);
mlog_entry_void();
if (!inode)
goto bail;
mlog(0, "Clearing inode: %llu, nlink = %u\n",
(unsigned long long)OCFS2_I(inode)->ip_blkno, inode->i_nlink);
mlog_bug_on_msg(OCFS2_SB(inode->i_sb) == NULL,
"Inode=%lu\n", inode->i_ino);
/* For remove delete_inode vote, we hold open lock before,
* now it is time to unlock PR and EX open locks. */
ocfs2_open_unlock(inode);
/* Do these before all the other work so that we don't bounce
* the vote thread while waiting to destroy the locks. */
ocfs2_mark_lockres_freeing(&oi->ip_rw_lockres);
ocfs2_mark_lockres_freeing(&oi->ip_meta_lockres);
ocfs2_mark_lockres_freeing(&oi->ip_data_lockres);
ocfs2_mark_lockres_freeing(&oi->ip_open_lockres);
/* We very well may get a clear_inode before all an inodes
* metadata has hit disk. Of course, we can't drop any cluster
* locks until the journal has finished with it. The only
* exception here are successfully wiped inodes - their
* metadata can now be considered to be part of the system
* inodes from which it came. */
if (!(OCFS2_I(inode)->ip_flags & OCFS2_INODE_DELETED))
ocfs2_checkpoint_inode(inode);
mlog_bug_on_msg(!list_empty(&oi->ip_io_markers),
"Clear inode of %llu, inode has io markers\n",
(unsigned long long)oi->ip_blkno);
ocfs2_extent_map_trunc(inode, 0);
status = ocfs2_drop_inode_locks(inode);
if (status < 0)
mlog_errno(status);
ocfs2_lock_res_free(&oi->ip_rw_lockres);
ocfs2_lock_res_free(&oi->ip_meta_lockres);
ocfs2_lock_res_free(&oi->ip_data_lockres);
ocfs2_lock_res_free(&oi->ip_open_lockres);
ocfs2_metadata_cache_purge(inode);
mlog_bug_on_msg(oi->ip_metadata_cache.ci_num_cached,
"Clear inode of %llu, inode has %u cache items\n",
(unsigned long long)oi->ip_blkno, oi->ip_metadata_cache.ci_num_cached);
mlog_bug_on_msg(!(oi->ip_flags & OCFS2_INODE_CACHE_INLINE),
"Clear inode of %llu, inode has a bad flag\n",
(unsigned long long)oi->ip_blkno);
mlog_bug_on_msg(spin_is_locked(&oi->ip_lock),
"Clear inode of %llu, inode is locked\n",
(unsigned long long)oi->ip_blkno);
mlog_bug_on_msg(!mutex_trylock(&oi->ip_io_mutex),
"Clear inode of %llu, io_mutex is locked\n",
(unsigned long long)oi->ip_blkno);
mutex_unlock(&oi->ip_io_mutex);
/*
* down_trylock() returns 0, down_write_trylock() returns 1
* kernel 1, world 0
*/
mlog_bug_on_msg(!down_write_trylock(&oi->ip_alloc_sem),
"Clear inode of %llu, alloc_sem is locked\n",
(unsigned long long)oi->ip_blkno);
up_write(&oi->ip_alloc_sem);
mlog_bug_on_msg(oi->ip_open_count,
"Clear inode of %llu has open count %d\n",
(unsigned long long)oi->ip_blkno, oi->ip_open_count);
/* Clear all other flags. */
oi->ip_flags = OCFS2_INODE_CACHE_INLINE;
oi->ip_created_trans = 0;
oi->ip_last_trans = 0;
oi->ip_dir_start_lookup = 0;
oi->ip_blkno = 0ULL;
bail:
mlog_exit_void();
}
static int wil_suspend_keep_radio_on(struct wil6210_priv *wil)
{
int rc = 0;
unsigned long data_comp_to;
wil_dbg_pm(wil, "suspend keep radio on\n");
/* Prevent handling of new tx and wmi commands */
rc = down_write_trylock(&wil->mem_lock);
if (!rc) {
wil_err(wil,
"device is busy. down_write_trylock failed, returned (0x%x)\n",
rc);
wil->suspend_stats.rejected_by_host++;
return -EBUSY;
}
set_bit(wil_status_suspending, wil->status);
up_write(&wil->mem_lock);
wil_pm_stop_all_net_queues(wil);
if (!wil_is_tx_idle(wil)) {
wil_dbg_pm(wil, "Pending TX data, reject suspend\n");
wil->suspend_stats.rejected_by_host++;
goto reject_suspend;
}
if (!wil->txrx_ops.is_rx_idle(wil)) {
wil_dbg_pm(wil, "Pending RX data, reject suspend\n");
wil->suspend_stats.rejected_by_host++;
goto reject_suspend;
}
if (!wil_is_wmi_idle(wil)) {
wil_dbg_pm(wil, "Pending WMI events, reject suspend\n");
wil->suspend_stats.rejected_by_host++;
goto reject_suspend;
}
/* Send WMI suspend request to the device */
rc = wmi_suspend(wil);
if (rc) {
wil_dbg_pm(wil, "wmi_suspend failed, reject suspend (%d)\n",
rc);
goto reject_suspend;
}
/* Wait for completion of the pending RX packets */
data_comp_to = jiffies + msecs_to_jiffies(WIL_DATA_COMPLETION_TO_MS);
if (test_bit(wil_status_napi_en, wil->status)) {
while (!wil->txrx_ops.is_rx_idle(wil)) {
if (time_after(jiffies, data_comp_to)) {
if (wil->txrx_ops.is_rx_idle(wil))
break;
wil_err(wil,
"TO waiting for idle RX, suspend failed\n");
wil->suspend_stats.r_on.failed_suspends++;
goto resume_after_fail;
}
wil_dbg_ratelimited(wil, "rx vring is not empty -> NAPI\n");
napi_synchronize(&wil->napi_rx);
msleep(20);
}
}
/* In case of pending WMI events, reject the suspend
* and resume the device.
* This can happen if the device sent the WMI events before
* approving the suspend.
*/
if (!wil_is_wmi_idle(wil)) {
wil_err(wil, "suspend failed due to pending WMI events\n");
wil->suspend_stats.r_on.failed_suspends++;
goto resume_after_fail;
}
wil_mask_irq(wil);
/* Disable device reset on PERST */
wil_s(wil, RGF_USER_CLKS_CTL_0, BIT_USER_CLKS_RST_PWGD);
if (wil->platform_ops.suspend) {
rc = wil->platform_ops.suspend(wil->platform_handle, true);
if (rc) {
wil_err(wil, "platform device failed to suspend (%d)\n",
rc);
wil->suspend_stats.r_on.failed_suspends++;
wil_c(wil, RGF_USER_CLKS_CTL_0, BIT_USER_CLKS_RST_PWGD);
wil_unmask_irq(wil);
goto resume_after_fail;
}
}
/* Save the current bus request to return to the same in resume */
wil->bus_request_kbps_pre_suspend = wil->bus_request_kbps;
wil6210_bus_request(wil, 0);
set_bit(wil_status_suspended, wil->status);
clear_bit(wil_status_suspending, wil->status);
return rc;
resume_after_fail:
set_bit(wil_status_resuming, wil->status);
clear_bit(wil_status_suspending, wil->status);
rc = wmi_resume(wil);
/* if resume succeeded, reject the suspend */
if (!rc) {
rc = -EBUSY;
wil_pm_wake_connected_net_queues(wil);
}
return rc;
reject_suspend:
clear_bit(wil_status_suspending, wil->status);
wil_pm_wake_connected_net_queues(wil);
return -EBUSY;
}
static long fimg2d_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
int ret = 0;
struct fimg2d_context *ctx;
struct fimg2d_platdata *pdata;
struct fimg2d_blit blit;
struct fimg2d_version ver;
struct fimg2d_image dst;
ctx = file->private_data;
if (!ctx) {
printk(KERN_ERR "[%s] missing ctx\n", __func__);
return -EFAULT;
}
switch (cmd) {
case FIMG2D_BITBLT_BLIT:
if (info->secure)
return -EFAULT;
if (copy_from_user(&blit, (void *)arg, sizeof(blit)))
return -EFAULT;
if (blit.dst)
if (copy_from_user(&dst, (void *)blit.dst, sizeof(dst)))
return -EFAULT;
#ifdef CONFIG_BUSFREQ_OPP
#if defined(CONFIG_CPU_EXYNOS4212) || defined(CONFIG_CPU_EXYNOS4412)
dev_lock(info->bus_dev, info->dev, 160160);
#endif
#endif
if ((blit.dst) && (dst.addr.type == ADDR_USER))
if (!down_write_trylock(&page_alloc_slow_rwsem))
ret = -EAGAIN;
if (ret != -EAGAIN)
ret = fimg2d_add_command(info, ctx, &blit, dst.addr.type);
if (!ret) {
fimg2d_request_bitblt(ctx);
}
#ifdef PERF_PROFILE
perf_print(ctx, blit.seq_no);
perf_clear(ctx);
#endif
if ((blit.dst) && (dst.addr.type == ADDR_USER) && ret != -EAGAIN)
up_write(&page_alloc_slow_rwsem);
#ifdef CONFIG_BUSFREQ_OPP
#if defined(CONFIG_CPU_EXYNOS4212) || defined(CONFIG_CPU_EXYNOS4412)
dev_unlock(info->bus_dev, info->dev);
#endif
#endif
break;
case FIMG2D_BITBLT_SYNC:
fimg2d_debug("FIMG2D_BITBLT_SYNC ctx: %p\n", ctx);
/* FIXME: */
break;
case FIMG2D_BITBLT_VERSION:
pdata = to_fimg2d_plat(info->dev);
ver.hw = pdata->hw_ver;
ver.sw = 0;
fimg2d_debug("fimg2d version, hw: 0x%x sw: 0x%x\n",
ver.hw, ver.sw);
if (copy_to_user((void *)arg, &ver, sizeof(ver)))
return -EFAULT;
break;
case FIMG2D_BITBLT_SECURE:
if (copy_from_user(&info->secure,
(unsigned int *)arg,
sizeof(unsigned int))) {
printk(KERN_ERR
"[%s] failed to FIMG2D_BITBLT_SECURE: copy_from_user error\n\n",
__func__);
return -EFAULT;
}
while (1) {
if (fimg2d_queue_is_empty(&info->cmd_q))
break;
mdelay(2);
}
break;
default:
printk(KERN_ERR "[%s] unknown ioctl\n", __func__);
ret = -EFAULT;
break;
}
return ret;
}
/**
* cppc_set_perf - Set a CPUs performance controls.
* @cpu: CPU for which to set performance controls.
* @perf_ctrls: ptr to cppc_perf_ctrls. See cppc_acpi.h
*
* Return: 0 for success, -ERRNO otherwise.
*/
int cppc_set_perf(int cpu, struct cppc_perf_ctrls *perf_ctrls)
{
struct cpc_desc *cpc_desc = per_cpu(cpc_desc_ptr, cpu);
struct cpc_register_resource *desired_reg;
int pcc_ss_id = per_cpu(cpu_pcc_subspace_idx, cpu);
struct cppc_pcc_data *pcc_ss_data;
int ret = 0;
if (!cpc_desc || pcc_ss_id < 0) {
pr_debug("No CPC descriptor for CPU:%d\n", cpu);
return -ENODEV;
}
pcc_ss_data = pcc_data[pcc_ss_id];
desired_reg = &cpc_desc->cpc_regs[DESIRED_PERF];
/*
* This is Phase-I where we want to write to CPC registers
* -> We want all CPUs to be able to execute this phase in parallel
*
* Since read_lock can be acquired by multiple CPUs simultaneously we
* achieve that goal here
*/
if (CPC_IN_PCC(desired_reg)) {
down_read(&pcc_ss_data->pcc_lock); /* BEGIN Phase-I */
if (pcc_ss_data->platform_owns_pcc) {
ret = check_pcc_chan(pcc_ss_id, false);
if (ret) {
up_read(&pcc_ss_data->pcc_lock);
return ret;
}
}
/*
* Update the pending_write to make sure a PCC CMD_READ will not
* arrive and steal the channel during the switch to write lock
*/
pcc_ss_data->pending_pcc_write_cmd = true;
cpc_desc->write_cmd_id = pcc_ss_data->pcc_write_cnt;
cpc_desc->write_cmd_status = 0;
}
/*
* Skip writing MIN/MAX until Linux knows how to come up with
* useful values.
*/
cpc_write(cpu, desired_reg, perf_ctrls->desired_perf);
if (CPC_IN_PCC(desired_reg))
up_read(&pcc_ss_data->pcc_lock); /* END Phase-I */
/*
* This is Phase-II where we transfer the ownership of PCC to Platform
*
* Short Summary: Basically if we think of a group of cppc_set_perf
* requests that happened in short overlapping interval. The last CPU to
* come out of Phase-I will enter Phase-II and ring the doorbell.
*
* We have the following requirements for Phase-II:
* 1. We want to execute Phase-II only when there are no CPUs
* currently executing in Phase-I
* 2. Once we start Phase-II we want to avoid all other CPUs from
* entering Phase-I.
* 3. We want only one CPU among all those who went through Phase-I
* to run phase-II
*
* If write_trylock fails to get the lock and doesn't transfer the
* PCC ownership to the platform, then one of the following will be TRUE
* 1. There is at-least one CPU in Phase-I which will later execute
* write_trylock, so the CPUs in Phase-I will be responsible for
* executing the Phase-II.
* 2. Some other CPU has beaten this CPU to successfully execute the
* write_trylock and has already acquired the write_lock. We know for a
* fact it(other CPU acquiring the write_lock) couldn't have happened
* before this CPU's Phase-I as we held the read_lock.
* 3. Some other CPU executing pcc CMD_READ has stolen the
* down_write, in which case, send_pcc_cmd will check for pending
* CMD_WRITE commands by checking the pending_pcc_write_cmd.
* So this CPU can be certain that its request will be delivered
* So in all cases, this CPU knows that its request will be delivered
* by another CPU and can return
*
* After getting the down_write we still need to check for
* pending_pcc_write_cmd to take care of the following scenario
* The thread running this code could be scheduled out between
* Phase-I and Phase-II. Before it is scheduled back on, another CPU
* could have delivered the request to Platform by triggering the
* doorbell and transferred the ownership of PCC to platform. So this
* avoids triggering an unnecessary doorbell and more importantly before
* triggering the doorbell it makes sure that the PCC channel ownership
* is still with OSPM.
* pending_pcc_write_cmd can also be cleared by a different CPU, if
* there was a pcc CMD_READ waiting on down_write and it steals the lock
* before the pcc CMD_WRITE is completed. pcc_send_cmd checks for this
* case during a CMD_READ and if there are pending writes it delivers
* the write command before servicing the read command
*/
if (CPC_IN_PCC(desired_reg)) {
if (down_write_trylock(&pcc_ss_data->pcc_lock)) {/* BEGIN Phase-II */
/* Update only if there are pending write commands */
if (pcc_ss_data->pending_pcc_write_cmd)
send_pcc_cmd(pcc_ss_id, CMD_WRITE);
up_write(&pcc_ss_data->pcc_lock); /* END Phase-II */
} else
/* Wait until pcc_write_cnt is updated by send_pcc_cmd */
wait_event(pcc_ss_data->pcc_write_wait_q,
cpc_desc->write_cmd_id != pcc_ss_data->pcc_write_cnt);
/* send_pcc_cmd updates the status in case of failure */
ret = cpc_desc->write_cmd_status;
}
return ret;
}
