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Subject[PATCH 15/15] powerpc/powernv: provide a console flush operation for opal hvc driver
Date
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>
---
arch/powerpc/include/asm/opal.h | 1 +
arch/powerpc/platforms/powernv/opal.c | 83 +++++++++++++++++----------
drivers/tty/hvc/hvc_opal.c | 2 +
3 files changed, 55 insertions(+), 31 deletions(-)

diff --git a/arch/powerpc/include/asm/opal.h b/arch/powerpc/include/asm/opal.h
index 5d7072411561..a426d2caaf9f 100644
--- a/arch/powerpc/include/asm/opal.h
+++ b/arch/powerpc/include/asm/opal.h
@@ -304,6 +304,7 @@ 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 bcdb90ada938..048bc09afc83 100644
--- 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 @@ static int __opal_put_chars(uint32_t vtermno, const char *data, int total_len, b
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 786e76a1e06d..fd306033f8d4 100644
--- 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,
--
2.17.0
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