From 17cc1dd4924391b54fb179d0868b89dc96f2ee80 Mon Sep 17 00:00:00 2001 From: Nicholas Piggin Date: Tue, 1 May 2018 00:55:51 +1000 Subject: powerpc/powernv: implement opal_put_chars_atomic The RAW console does not need writes to be atomic, so relax opal_put_chars to be able to do partial writes, and implement an _atomic variant which does not take a spinlock. This API is used in xmon, so the less locking that is used, the better chance there is that a crash can be debugged. Cc: Benjamin Herrenschmidt Signed-off-by: Nicholas Piggin Signed-off-by: Michael Ellerman --- arch/powerpc/platforms/powernv/opal.c | 37 +++++++++++++++++++++++++---------- 1 file changed, 27 insertions(+), 10 deletions(-) (limited to 'arch/powerpc/platforms/powernv') diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c index cf02e602237a..6405b6f20193 100644 --- a/arch/powerpc/platforms/powernv/opal.c +++ b/arch/powerpc/platforms/powernv/opal.c @@ -344,9 +344,9 @@ int opal_get_chars(uint32_t vtermno, char *buf, int count) return 0; } -int opal_put_chars(uint32_t vtermno, const char *data, int total_len) +static int __opal_put_chars(uint32_t vtermno, const char *data, int total_len, bool atomic) { - unsigned long flags; + unsigned long flags = 0 /* shut up gcc */; int written; __be64 olen; s64 rc; @@ -354,11 +354,8 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len) if (!opal.entry) return -ENODEV; - /* We want put_chars to be atomic to avoid mangling of hvsi - * packets. To do that, we first test for room and return - * -EAGAIN if there isn't enough. - */ - spin_lock_irqsave(&opal_write_lock, flags); + if (atomic) + spin_lock_irqsave(&opal_write_lock, flags); rc = opal_console_write_buffer_space(vtermno, &olen); if (rc || be64_to_cpu(olen) < total_len) { /* Closed -> drop characters */ @@ -391,14 +388,18 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len) written = be64_to_cpu(olen); if (written < total_len) { - /* Should not happen */ - pr_warn("atomic console write returned partial len=%d written=%d\n", total_len, written); + if (atomic) { + /* Should not happen */ + pr_warn("atomic console write returned partial " + "len=%d written=%d\n", total_len, written); + } if (!written) written = -EAGAIN; } out: - spin_unlock_irqrestore(&opal_write_lock, flags); + 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 @@ -412,6 +413,22 @@ out: return written; } +int opal_put_chars(uint32_t vtermno, const char *data, int total_len) +{ + return __opal_put_chars(vtermno, data, total_len, false); +} + +/* + * opal_put_chars_atomic will not perform partial-writes. Data will be + * atomically written to the terminal or not at all. This is not strictly + * true at the moment because console space can race with OPAL's console + * writes. + */ +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) { s64 rc; -- cgit v1.2.3