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

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commit 4d2bb3f500 (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: Anton Blanchard <anton@samba.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Anton Blanchard 2011-07-12 19:19:57 +00:00 committed by Benjamin Herrenschmidt
parent 8896293422
commit 19df9abdd3
1 changed files with 35 additions and 19 deletions
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54
drivers/tty/hvc/hvc_vio.c
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@ -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);
/*
* Work around a HV bug where it gives us a null
* after every \r. -- paulus
*/
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;