Commit 17cc1dd4 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

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 <benh@kernel.crashing.org>
Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent ac4ac788

arch/powerpc/include/asm/opal.h

+1 −0
Original line number Diff line number Diff line
@@ -305,6 +305,7 @@ 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_console(uint32_t vtermno);



extern void hvc_opal_init_early(void);

arch/powerpc/platforms/powernv/opal.c

+27 −10
Original line number Diff line number Diff line
@@ -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;
@@ -354,10 +354,7 @@ 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.

	 */

	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) {
@@ -391,13 +388,17 @@ int opal_put_chars(uint32_t vtermno, const char *data, int total_len) 


	written = be64_to_cpu(olen);

	if (written < total_len) {

		if (atomic) {

			/* Should not happen */

		pr_warn("atomic console write returned partial len=%d written=%d\n", total_len, written);

			pr_warn("atomic console write returned partial "

				"len=%d written=%d\n", total_len, written);

		}

		if (!written)

			written = -EAGAIN;

	}



out:

	if (atomic)

		spin_unlock_irqrestore(&opal_write_lock, flags);



	/* In the -EAGAIN case, callers loop, so we have to flush the console
@@ -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;

drivers/tty/hvc/hvc_opal.c

+13 −5
Original line number Diff line number Diff line
@@ -183,9 +183,15 @@ static int hvc_opal_probe(struct platform_device *dev) 
			return -ENOMEM;

		pv->proto = proto;

		hvc_opal_privs[termno] = pv;

		if (proto == HV_PROTOCOL_HVSI)

			hvsilib_init(&pv->hvsi, opal_get_chars, opal_put_chars,

		if (proto == HV_PROTOCOL_HVSI) {

			/*

			 * We want put_chars to be atomic to avoid mangling of

			 * hvsi packets.

			 */

			hvsilib_init(&pv->hvsi,

				     opal_get_chars, opal_put_chars_atomic,

				     termno, 0);

		}



		/* Instanciate now to establish a mapping index==vtermno */

		hvc_instantiate(termno, termno, ops);
@@ -375,8 +381,9 @@ void __init hvc_opal_init_early(void) 
	else if (of_device_is_compatible(stdout_node,"ibm,opal-console-hvsi")) {

		hvc_opal_boot_priv.proto = HV_PROTOCOL_HVSI;

		ops = &hvc_opal_hvsi_ops;

		hvsilib_init(&hvc_opal_boot_priv.hvsi, opal_get_chars,

			     opal_put_chars, index, 1);

		hvsilib_init(&hvc_opal_boot_priv.hvsi,

			     opal_get_chars, opal_put_chars_atomic,

			     index, 1);

		/* HVSI, perform the handshake now */

		hvsilib_establish(&hvc_opal_boot_priv.hvsi);

		pr_devel("hvc_opal: Found HVSI console\n");
@@ -408,7 +415,8 @@ void __init udbg_init_debug_opal_hvsi(void) 
	hvc_opal_privs[index] = &hvc_opal_boot_priv;

	hvc_opal_boot_termno = index;

	udbg_init_opal_common();

	hvsilib_init(&hvc_opal_boot_priv.hvsi, opal_get_chars, opal_put_chars,

	hvsilib_init(&hvc_opal_boot_priv.hvsi,

		     opal_get_chars, opal_put_chars_atomic,

		     index, 1);

	hvsilib_establish(&hvc_opal_boot_priv.hvsi);

}

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