Commit 19df9abd authored by Anton Blanchard's avatar Anton Blanchard Committed by Benjamin Herrenschmidt
Browse files

powerpc/pseries: Fix hvterm_raw_get_chars to accept < 16 chars, fixing xmon 



commit 4d2bb3f5 (powerpc/pseries: Re-implement HVSI as part of
hvc_vio) changed udbg_getc to be based on hvterm_raw_get_chars.
Unfortunately hvterm_raw_get_chars returns -EAGAIN if you ask
for anything less than 16 characters. As a result xmon no longer
accepts input and prints a stream of junk to the screen.

The recent change highlights a problem that xmon on pseries VIO
has had all along, that it can drop input characters. The issue
is the hypervisor call does not take a count argument and can
return up to 16 characters.

This patch adds a per vterm buffer that we copy input data into
and give it out as requested.

Signed-off-by: default avatarAnton Blanchard <anton@samba.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 88962934

drivers/tty/hvc/hvc_vio.c

+37 −21
Original line number Diff line number Diff line
@@ -71,41 +71,53 @@ struct hvterm_priv { 
	u32			termno;	/* HV term number */

	hv_protocol_t		proto;	/* Raw data or HVSI packets */

	struct hvsi_priv	hvsi;	/* HVSI specific data */

	spinlock_t		buf_lock;

	char			buf[SIZE_VIO_GET_CHARS];

	int			left;

	int			offset;

};

static struct hvterm_priv *hvterm_privs[MAX_NR_HVC_CONSOLES];



/* For early boot console */

static struct hvterm_priv hvterm_priv0;



static int hvterm_raw_get_chars(uint32_t vtermno, char *buf, int count)

{

	struct hvterm_priv *pv = hvterm_privs[vtermno];

	unsigned long got, i;

	unsigned long i;

	unsigned long flags;

	int got;



	if (WARN_ON(!pv))

		return 0;



	/*

	 * Vio firmware will read up to SIZE_VIO_GET_CHARS at its own discretion

	 * so we play safe and avoid the situation where got > count which could

	 * overload the flip buffer.

	 */

	if (count < SIZE_VIO_GET_CHARS)

		return -EAGAIN;

	spin_lock_irqsave(&pv->buf_lock, flags);



	got = hvc_get_chars(pv->termno, buf, count);

	if (pv->left == 0) {

		pv->offset = 0;

		pv->left = hvc_get_chars(pv->termno, pv->buf, count);



		/*

		 * Work around a HV bug where it gives us a null

		 * after every \r.  -- paulus

		 */

	for (i = 1; i < got; ++i) {

		if (buf[i] == 0 && buf[i-1] == '\r') {

			--got;

			if (i < got)

				memmove(&buf[i], &buf[i+1], got - i);

		for (i = 1; i < pv->left; ++i) {

			if (pv->buf[i] == 0 && pv->buf[i-1] == '\r') {

				--pv->left;

				if (i < pv->left) {

					memmove(&pv->buf[i], &pv->buf[i+1],

						pv->left - i);

				}

			}

		}

	}



	got = min(count, pv->left);

	memcpy(buf, &pv->buf[pv->offset], got);

	pv->offset += got;

	pv->left -= got;



	spin_unlock_irqrestore(&pv->buf_lock, flags);



	return got;

}
@@ -266,6 +278,7 @@ static int __devinit hvc_vio_probe(struct vio_dev *vdev, 
			return -ENOMEM;

		pv->termno = vdev->unit_address;

		pv->proto = proto;

		spin_lock_init(&pv->buf_lock);

		hvterm_privs[termno] = pv;

		hvsilib_init(&pv->hvsi, hvc_get_chars, hvc_put_chars,

			     pv->termno, 0);
@@ -406,6 +419,7 @@ void __init hvc_vio_init_early(void) 
	if (termno == NULL)

		goto out;

	hvterm_priv0.termno = *termno;

	spin_lock_init(&hvterm_priv0.buf_lock);

	hvterm_privs[0] = &hvterm_priv0;



	/* Check the protocol */
@@ -447,6 +461,7 @@ void __init udbg_init_debug_lpar(void) 
	hvterm_privs[0] = &hvterm_priv0;

	hvterm_priv0.termno = 0;

	hvterm_priv0.proto = HV_PROTOCOL_RAW;

	spin_lock_init(&hvterm_priv0.buf_lock)

	udbg_putc = udbg_hvc_putc;

	udbg_getc = udbg_hvc_getc;

	udbg_getc_poll = udbg_hvc_getc_poll;
@@ -459,6 +474,7 @@ void __init udbg_init_debug_lpar_hvsi(void) 
	hvterm_privs[0] = &hvterm_priv0;

	hvterm_priv0.termno = CONFIG_PPC_EARLY_DEBUG_HVSI_VTERMNO;

	hvterm_priv0.proto = HV_PROTOCOL_HVSI;

	spin_lock_init(&hvterm_priv0.buf_lock)

	udbg_putc = udbg_hvc_putc;

	udbg_getc = udbg_hvc_getc;

	udbg_getc_poll = udbg_hvc_getc_poll;

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