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Date: Wed, 23 Aug 2017 23:38:06 -0700
From: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
To: Michael Ellerman <mpe@...erman.id.au>
Cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
mikey@...ling.org, stewart@...ux.vnet.ibm.com, apopple@....ibm.com,
hbabu@...ibm.com, oohall@...il.com, linuxppc-dev@...abs.org,
<linux-kernel@...r.kernel.org>
Subject: [PATCH v7 10/12] powerpc/vas: Define vas_win_close() interface
Define the vas_win_close() interface which should be used to close a
send or receive windows.
While the hardware configurations required to open send and receive windows
differ, the configuration to close a window is the same for both. So we use
a single interface to close the window.
Signed-off-by: Sukadev Bhattiprolu <sukadev@...ux.vnet.ibm.com>
---
Changelog[v4]:
- Drop the poll for credits return (we can set the required credit,
but cannot really find the available credit at a point in time)
- Export the symbol
Changelog[v3]:
- Fix order of parameters in GET_FIELD().
- Update references and sequence for closing/quiescing a window.
---
arch/powerpc/include/asm/vas.h | 7 ++
arch/powerpc/platforms/powernv/vas-window.c | 99 +++++++++++++++++++++++++++--
2 files changed, 101 insertions(+), 5 deletions(-)
diff --git a/arch/powerpc/include/asm/vas.h b/arch/powerpc/include/asm/vas.h
index 0701a08..3478ac8 100644
--- a/arch/powerpc/include/asm/vas.h
+++ b/arch/powerpc/include/asm/vas.h
@@ -109,4 +109,11 @@ extern void vas_init_rx_win_attr(struct vas_rx_win_attr *rxattr,
extern struct vas_window *vas_rx_win_open(int vasid, enum vas_cop_type cop,
struct vas_rx_win_attr *attr);
+/*
+ * Close the send or receive window identified by @win. For receive windows
+ * return -EAGAIN if there are active send windows attached to this receive
+ * window.
+ */
+int vas_win_close(struct vas_window *win);
+
#endif /* _MISC_VAS_H */
diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c
index 2dd4b63..24288dd 100644
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -139,7 +139,7 @@ static void unmap_region(void *addr, uint64_t start, int len)
/*
* Unmap the paste address region for a window.
*/
-void unmap_paste_region(struct vas_window *window)
+static void unmap_paste_region(struct vas_window *window)
{
int len;
uint64_t busaddr_start;
@@ -535,7 +535,7 @@ int vas_assign_window_id(struct ida *ida)
return winid;
}
-void vas_window_free(struct vas_window *window)
+static void vas_window_free(struct vas_window *window)
{
int winid = window->winid;
struct vas_instance *vinst = window->vinst;
@@ -572,6 +572,14 @@ static struct vas_window *vas_window_alloc(struct vas_instance *vinst)
return ERR_PTR(-ENOMEM);
}
+static void put_rx_win(struct vas_window *rxwin)
+{
+ /* Better not be a send window! */
+ WARN_ON_ONCE(rxwin->tx_win);
+
+ atomic_dec(&rxwin->num_txwins);
+}
+
/*
* Find the user space receive window given the @pswid.
* - We must have a valid vasid and it must belong to this instance.
@@ -664,7 +672,7 @@ static void set_vinst_win(struct vas_instance *vinst,
* Clear this window from the table(s) of windows for this VAS instance.
* See also function header of set_vinst_win().
*/
-void clear_vinst_win(struct vas_window *window)
+static void clear_vinst_win(struct vas_window *window)
{
int id = window->winid;
struct vas_instance *vinst = window->vinst;
@@ -879,11 +887,92 @@ struct vas_window *vas_rx_win_open(int vasid, enum vas_cop_type cop,
}
EXPORT_SYMBOL_GPL(vas_rx_win_open);
-/* stub for now */
+static void poll_window_busy_state(struct vas_window *window)
+{
+ int busy;
+ uint64_t val;
+
+retry:
+ /*
+ * Poll Window Busy flag
+ */
+ val = read_hvwc_reg(window, VREG(WIN_STATUS));
+ busy = GET_FIELD(VAS_WIN_BUSY, val);
+ if (busy) {
+ val = 0;
+ schedule_timeout(2000);
+ goto retry;
+ }
+}
+
+static void poll_window_castout(struct vas_window *window)
+{
+ int cached;
+ uint64_t val;
+
+ /* Cast window context out of the cache */
+retry:
+ val = read_hvwc_reg(window, VREG(WIN_CTX_CACHING_CTL));
+ cached = GET_FIELD(VAS_WIN_CACHE_STATUS, val);
+ if (cached) {
+ val = 0ULL;
+ val = SET_FIELD(VAS_CASTOUT_REQ, val, 1);
+ val = SET_FIELD(VAS_PUSH_TO_MEM, val, 0);
+ write_hvwc_reg(window, VREG(WIN_CTX_CACHING_CTL), val);
+
+ schedule_timeout(2000);
+ goto retry;
+ }
+}
+
+/*
+ * Close a window.
+ *
+ * See Section 1.12.1 of VAS workbook v1.05 for details on closing window:
+ * - Disable new paste operations (unmap paste address)
+ * - Poll for the "Window Busy" bit to be cleared
+ * - Clear the Open/Enable bit for the Window.
+ * - Poll for return of window Credits (implies FIFO empty for Rx win?)
+ * - Unpin and cast window context out of cache
+ *
+ * Besides the hardware, kernel has some bookkeeping of course.
+ */
int vas_win_close(struct vas_window *window)
{
- return -1;
+ uint64_t val;
+
+ if (!window)
+ return 0;
+
+ if (!window->tx_win && atomic_read(&window->num_txwins) != 0) {
+ pr_devel("VAS: Attempting to close an active Rx window!\n");
+ WARN_ON_ONCE(1);
+ return -EAGAIN;
+ }
+
+ unmap_paste_region(window);
+
+ clear_vinst_win(window);
+
+ poll_window_busy_state(window);
+
+ /* Unpin window from cache and close it */
+ val = read_hvwc_reg(window, VREG(WINCTL));
+ val = SET_FIELD(VAS_WINCTL_PIN, val, 0);
+ val = SET_FIELD(VAS_WINCTL_OPEN, val, 0);
+ write_hvwc_reg(window, VREG(WINCTL), val);
+
+ poll_window_castout(window);
+
+ /* if send window, drop reference to matching receive window */
+ if (window->tx_win)
+ put_rx_win(window->rxwin);
+
+ vas_window_free(window);
+
+ return 0;
}
+EXPORT_SYMBOL_GPL(vas_win_close);
/*
* Return a system-wide unique window id for the window @win.
--
2.7.4
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