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    Subject[PATCH v6 11/17] powerpc/vas: Define vas_win_close() interface
    Date
    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>
    ---
    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 a3778d7..e1c5376 100644
    --- a/arch/powerpc/include/asm/vas.h
    +++ b/arch/powerpc/include/asm/vas.h
    @@ -91,4 +91,11 @@ 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 dfa7e67..9704a3b 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;
    @@ -609,6 +609,14 @@ static bool valid_permissions(struct vas_window *rxwin)
    return rc;
    }

    +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.
    *
    @@ -710,7 +718,7 @@ 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;
    @@ -925,11 +933,92 @@ 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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