powerpc/powernv/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@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/vas.h b/arch/powerpc/include/asm/vas.h
index 18c59c3..96bc24d 100644 (file)
--- a/arch/powerpc/include/asm/vas.h
+++ b/arch/powerpc/include/asm/vas.h
@@ -95,4 +95,11 @@ void vas_init_rx_win_attr(struct vas_rx_win_attr *rxattr, enum vas_cop_type cop)
 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 /* __ASM_POWERPC_VAS_H */

diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c
index 783c8c6..39aa0e4 100644 (file)
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -130,7 +130,7 @@ static void unmap_region(void *addr, u64 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;
        u64 busaddr_start;
@@ -522,7 +522,7 @@ static 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;
@@ -560,6 +560,14 @@ out_free:
        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);
+}
+
 /*
  * Get the VAS receive window associated with NX engine identified
  * by @cop and if applicable, @pswid.
@@ -627,7 +635,7 @@ 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;
@@ -839,8 +847,91 @@ 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;
+       u64 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;
+               set_current_state(TASK_UNINTERRUPTIBLE);
+               schedule_timeout(HZ);
+               goto retry;
+       }
+}
+
+static void poll_window_castout(struct vas_window *window)
+{
+       int cached;
+       u64 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);
+
+               set_current_state(TASK_UNINTERRUPTIBLE);
+               schedule_timeout(HZ);
+               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;
+       u64 val;
+
+       if (!window)
+               return 0;
+
+       if (!window->tx_win && atomic_read(&window->num_txwins) != 0) {
+               pr_devel("Attempting to close an active Rx window!\n");
+               WARN_ON_ONCE(1);
+               return -EBUSY;
+       }
+
+       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);