powerpc/powernv: provide a console flush operation for opal hvc driver

Provide the flush hv_op for the opal hvc driver. This will flush the
firmware console buffers without spinning with interrupts disabled.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linuxppc-dev@lists.ozlabs.org
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 834e7e29f1e4e0e9b948095aa8959e3f60d4be2a..ff3866473afe411f63c3d4e968ff6b574694402b 100644 (file)
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -308,6 +308,7 @@ extern void opal_configure_cores(void);
 extern int opal_get_chars(uint32_t vtermno, char *buf, int count);
 extern int opal_put_chars(uint32_t vtermno, const char *buf, int total_len);
 extern int opal_put_chars_atomic(uint32_t vtermno, const char *buf, int total_len);
+extern int opal_flush_chars(uint32_t vtermno, bool wait);
 extern int opal_flush_console(uint32_t vtermno);
 
 extern void hvc_opal_init_early(void);

diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 404c379db168cf614036293c8787c75b6b656d58..38fe4087484a61e7ead4fed3ea89db130b596b8b 100644 (file)
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -370,12 +370,8 @@ static int __opal_put_chars(uint32_t vtermno, const char *data, int total_len, b
        olen = cpu_to_be64(total_len);
        rc = opal_console_write(vtermno, &olen, data);
        if (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
-               if (rc == OPAL_BUSY_EVENT) {
-                       mdelay(OPAL_BUSY_DELAY_MS);
+               if (rc == OPAL_BUSY_EVENT)
                        opal_poll_events(NULL);
-               } else if (rc == OPAL_BUSY_EVENT) {
-                       mdelay(OPAL_BUSY_DELAY_MS);
-               }
                written = -EAGAIN;
                goto out;
        }
@@ -401,15 +397,6 @@ out:
        if (atomic)
                spin_unlock_irqrestore(&opal_write_lock, flags);
 
-       /* In the -EAGAIN case, callers loop, so we have to flush the console
-        * here in case they have interrupts off (and we don't want to wait
-        * for async flushing if we can make immediate progress here). If
-        * necessary the API could be made entirely non-flushing if the
-        * callers had a ->flush API to use.
-        */
-       if (written == -EAGAIN)
-               opal_flush_console(vtermno);
-
        return written;
 }
 
@@ -429,40 +416,74 @@ int opal_put_chars_atomic(uint32_t vtermno, const char *data, int total_len)
        return __opal_put_chars(vtermno, data, total_len, true);
 }
 
-int opal_flush_console(uint32_t vtermno)
+static s64 __opal_flush_console(uint32_t vtermno)
 {
        s64 rc;
 
        if (!opal_check_token(OPAL_CONSOLE_FLUSH)) {
                __be64 evt;
 
-               WARN_ONCE(1, "opal: OPAL_CONSOLE_FLUSH missing.\n");
                /*
                 * If OPAL_CONSOLE_FLUSH is not implemented in the firmware,
                 * the console can still be flushed by calling the polling
                 * function while it has OPAL_EVENT_CONSOLE_OUTPUT events.
                 */
-               do {
-                       opal_poll_events(&evt);
-               } while (be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_OUTPUT);
+               WARN_ONCE(1, "opal: OPAL_CONSOLE_FLUSH missing.\n");
+
+               opal_poll_events(&evt);
+               if (!(be64_to_cpu(evt) & OPAL_EVENT_CONSOLE_OUTPUT))
+                       return OPAL_SUCCESS;
+               return OPAL_BUSY;
 
-               return OPAL_SUCCESS;
+       } else {
+               rc = opal_console_flush(vtermno);
+               if (rc == OPAL_BUSY_EVENT) {
+                       opal_poll_events(NULL);
+                       rc = OPAL_BUSY;
+               }
+               return rc;
        }
 
-       do  {
-               rc = OPAL_BUSY;
-               while (rc == OPAL_BUSY || rc == OPAL_BUSY_EVENT) {
-                       rc = opal_console_flush(vtermno);
-                       if (rc == OPAL_BUSY_EVENT) {
-                               mdelay(OPAL_BUSY_DELAY_MS);
-                               opal_poll_events(NULL);
-                       } else if (rc == OPAL_BUSY) {
-                               mdelay(OPAL_BUSY_DELAY_MS);
+}
+
+/*
+ * opal_flush_console spins until the console is flushed
+ */
+int opal_flush_console(uint32_t vtermno)
+{
+       for (;;) {
+               s64 rc = __opal_flush_console(vtermno);
+
+               if (rc == OPAL_BUSY || rc == OPAL_PARTIAL) {
+                       mdelay(1);
+                       continue;
+               }
+
+               return opal_error_code(rc);
+       }
+}
+
+/*
+ * opal_flush_chars is an hvc interface that sleeps until the console is
+ * flushed if wait, otherwise it will return -EBUSY if the console has data,
+ * -EAGAIN if it has data and some of it was flushed.
+ */
+int opal_flush_chars(uint32_t vtermno, bool wait)
+{
+       for (;;) {
+               s64 rc = __opal_flush_console(vtermno);
+
+               if (rc == OPAL_BUSY || rc == OPAL_PARTIAL) {
+                       if (wait) {
+                               msleep(OPAL_BUSY_DELAY_MS);
+                               continue;
                        }
+                       if (rc == OPAL_PARTIAL)
+                               return -EAGAIN;
                }
-       } while (rc == OPAL_PARTIAL); /* More to flush */
 
-       return opal_error_code(rc);
+               return opal_error_code(rc);
+       }
 }
 
 static int opal_recover_mce(struct pt_regs *regs,

diff --git a/drivers/tty/hvc/hvc_opal.c b/drivers/tty/hvc/hvc_opal.c
index f631f8bee308846d1cab8fe73ac89e4d8953d7f7..77baf895108fac45252ed6f3ea1b8b5557cbee91 100644 (file)
--- a/drivers/tty/hvc/hvc_opal.c
+++ b/drivers/tty/hvc/hvc_opal.c
@@ -52,6 +52,7 @@ static u32 hvc_opal_boot_termno;
 static const struct hv_ops hvc_opal_raw_ops = {
        .get_chars = opal_get_chars,
        .put_chars = opal_put_chars,
+       .flush = opal_flush_chars,
        .notifier_add = notifier_add_irq,
        .notifier_del = notifier_del_irq,
        .notifier_hangup = notifier_hangup_irq,
@@ -141,6 +142,7 @@ static int hvc_opal_hvsi_tiocmset(struct hvc_struct *hp, unsigned int set,
 static const struct hv_ops hvc_opal_hvsi_ops = {
        .get_chars = hvc_opal_hvsi_get_chars,
        .put_chars = hvc_opal_hvsi_put_chars,
+       .flush = opal_flush_chars,
        .notifier_add = hvc_opal_hvsi_open,
        .notifier_del = hvc_opal_hvsi_close,
        .notifier_hangup = hvc_opal_hvsi_hangup,