[PATCH] powerpc: hvc_console updates

These are some updates from both Ryan and Arnd for the hvc_console
driver:

The main point is to enable the inclusion of a console driver
for rtas, which is currrently needed for the cell platform.

Also shuffle around some data-type declarations and moves some
functions out of include/asm-ppc64/hvconsole.h and into a new
drivers/char/hvc_console.h file.

Signed-off-by: "Ryan S. Arnold" <rsa@us.ibm.com>
Signed-off-by: Arnd Bergmann <abergman@de.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

7 files changed, 128 insertions, 59 deletions

diff --git a/arch/powerpc/platforms/pseries/hvconsole.c b/arch/powerpc/platforms/pseries/hvconsole.c
index 138e128a3886..ba6befd96636 100644
--- a/arch/powerpc/platforms/pseries/hvconsole.c
+++ b/arch/powerpc/platforms/pseries/hvconsole.c
@@ -62,6 +62,11 @@ int hvc_put_chars(uint32_t vtermno, const char *buf, int count)
         unsigned long *lbuf = (unsigned long *) buf;
         long ret;
 
+
+        /* hcall will ret H_PARAMETER if 'count' exceeds firmware max.*/
+        if (count > MAX_VIO_PUT_CHARS)
+                count = MAX_VIO_PUT_CHARS;
+
         ret = plpar_hcall_norets(H_PUT_TERM_CHAR, vtermno, count, lbuf[0],
                                  lbuf[1]);
         if (ret == H_Success)
diff --git a/drivers/char/Kconfig b/drivers/char/Kconfig
index facc3f1d9e37..831419381cf5 100644
--- a/drivers/char/Kconfig
+++ b/drivers/char/Kconfig
@@ -561,9 +561,19 @@ config TIPAR
 
           If unsure, say N.
 
+config HVC_DRIVER
+        bool
+        help
+          Users of pSeries machines that want to utilize the hvc console front-end
+          module for their backend console driver should select this option.
+          It will automatically be selected if one of the back-end console drivers
+          is selected.
+
+
 config HVC_CONSOLE
         bool "pSeries Hypervisor Virtual Console support"
         depends on PPC_PSERIES
+        select HVC_DRIVER
         help
           pSeries machines when partitioned support a hypervisor virtual
           console. This driver allows each pSeries partition to have a console
diff --git a/drivers/char/Makefile b/drivers/char/Makefile
index b2a11245fa95..e6c03335fd6a 100644
--- a/drivers/char/Makefile
+++ b/drivers/char/Makefile
@@ -41,7 +41,8 @@ obj-$(CONFIG_N_HDLC)		+= n_hdlc.o
 obj-$(CONFIG_AMIGA_BUILTIN_SERIAL) += amiserial.o
 obj-$(CONFIG_SX)                += sx.o generic_serial.o
 obj-$(CONFIG_RIO)               += rio/ generic_serial.o
-obj-$(CONFIG_HVC_CONSOLE)       += hvc_console.o hvc_vio.o hvsi.o
+obj-$(CONFIG_HVC_DRIVER)        += hvc_console.o
+obj-$(CONFIG_HVC_CONSOLE)       += hvc_vio.o hvsi.o
 obj-$(CONFIG_RAW_DRIVER)        += raw.o
 obj-$(CONFIG_SGI_SNSC)          += snsc.o snsc_event.o
 obj-$(CONFIG_MMTIMER)           += mmtimer.o
diff --git a/drivers/char/hvc_console.c b/drivers/char/hvc_console.c
index a94c5b0cac52..2b6a56b2bf35 100644
--- a/drivers/char/hvc_console.c
+++ b/drivers/char/hvc_console.c
@@ -39,8 +39,10 @@
 #include <linux/sched.h>
 #include <linux/spinlock.h>
 #include <linux/delay.h>
+
 #include <asm/uaccess.h>
-#include <asm/hvconsole.h>
+
+#include "hvc_console.h"
 
 #define HVC_MAJOR       229
 #define HVC_MINOR       0
@@ -54,17 +56,14 @@
 #define HVC_CLOSE_WAIT (HZ/100) /* 1/10 of a second */
 
 /*
- * The Linux TTY code does not support dynamic addition of tty derived devices
- * so we need to know how many tty devices we might need when space is allocated
- * for the tty device.  Since this driver supports hotplug of vty adapters we
- * need to make sure we have enough allocated.
+ * These sizes are most efficient for vio, because they are the
+ * native transfer size. We could make them selectable in the
+ * future to better deal with backends that want other buffer sizes.
  */
-#define HVC_ALLOC_TTY_ADAPTERS  8
-
 #define N_OUTBUF        16
 #define N_INBUF         16
 
-#define __ALIGNED__     __attribute__((__aligned__(8)))
+#define __ALIGNED__ __attribute__((__aligned__(sizeof(long))))
 
 static struct tty_driver *hvc_driver;
 static struct task_struct *hvc_task;
@@ -154,7 +153,7 @@ static uint32_t vtermnos[MAX_NR_HVC_CONSOLES] =
 
 void hvc_console_print(struct console *co, const char *b, unsigned count)
 {
-        char c[16] __ALIGNED__;
+        char c[N_OUTBUF] __ALIGNED__;
         unsigned i = 0, n = 0;
         int r, donecr = 0, index = co->index;
 
@@ -473,8 +472,10 @@ static void hvc_push(struct hvc_struct *hp)
 
         n = hp->ops->put_chars(hp->vtermno, hp->outbuf, hp->n_outbuf);
         if (n <= 0) {
-                if (n == 0)
+                if (n == 0) {
+                        hp->do_wakeup = 1;
                         return;
+                }
                 /* throw away output on error; this happens when
                    there is no session connected to the vterm. */
                 hp->n_outbuf = 0;
@@ -486,12 +487,19 @@ static void hvc_push(struct hvc_struct *hp)
                 hp->do_wakeup = 1;
 }
 
-static inline int __hvc_write_kernel(struct hvc_struct *hp,
-                                   const unsigned char *buf, int count)
+static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
 {
+        struct hvc_struct *hp = tty->driver_data;
         unsigned long flags;
         int rsize, written = 0;
 
+        /* This write was probably executed during a tty close. */
+        if (!hp)
+                return -EPIPE;
+
+        if (hp->count <= 0)
+                return -EIO;
+
         spin_lock_irqsave(&hp->lock, flags);
 
         /* Push pending writes */
@@ -510,26 +518,8 @@ static inline int __hvc_write_kernel(struct hvc_struct *hp,
         }
         spin_unlock_irqrestore(&hp->lock, flags);
 
-        return written;
-}
-static int hvc_write(struct tty_struct *tty, const unsigned char *buf, int count)
-{
-        struct hvc_struct *hp = tty->driver_data;
-        int written;
-
-        /* This write was probably executed during a tty close. */
-        if (!hp)
-                return -EPIPE;
-
-        if (hp->count <= 0)
-                return -EIO;
-
-        written = __hvc_write_kernel(hp, buf, count);
-
         /*
          * Racy, but harmless, kick thread if there is still pending data.
-         * There really is nothing wrong with kicking the thread, even if there
-         * is no buffered data.
          */
         if (hp->n_outbuf)
                 hvc_kick();
@@ -614,6 +604,13 @@ static int hvc_poll(struct hvc_struct *hp)
                                 spin_unlock_irqrestore(&hp->lock, flags);
                                 tty_hangup(tty);
                                 spin_lock_irqsave(&hp->lock, flags);
+                        } else if ( n == -EAGAIN ) {
+                                /*
+                                 * Some back-ends can only ensure a certain min
+                                 * num of bytes read, which may be > 'count'.
+                                 * Let the tty clear the flip buff to make room.
+                                 */
+                                poll_mask |= HVC_POLL_READ;
                         }
                         break;
                 }
@@ -635,16 +632,7 @@ static int hvc_poll(struct hvc_struct *hp)
                         tty_insert_flip_char(tty, buf[i], 0);
                 }
 
-                /*
-                 * Account for the total amount read in one loop, and if above
-                 * 64 bytes, we do a quick schedule loop to let the tty grok
-                 * the data and eventually throttle us.
-                 */
                 read_total += n;
-                if (read_total >= 64) {
-                        poll_mask |= HVC_POLL_QUICK;
-                        break;
-                }
         }
  throttled:
         /* Wakeup write queue if necessary */
@@ -767,7 +755,8 @@ struct hvc_struct __devinit *hvc_alloc(uint32_t vtermno, int irq,
          * see if this vterm id matches one registered for console.
          */
         for (i=0; i < MAX_NR_HVC_CONSOLES; i++)
-                if (vtermnos[i] == hp->vtermno)
+                if (vtermnos[i] == hp->vtermno &&
+                    cons_ops[i] == hp->ops)
                         break;
 
         /* no matching slot, just use a counter */
diff --git a/drivers/char/hvc_console.h b/drivers/char/hvc_console.h
new file mode 100644
index 000000000000..96b7401319c1
--- /dev/null
+++ b/drivers/char/hvc_console.h
@@ -0,0 +1,63 @@
+/*
+ * hvc_console.h
+ * Copyright (C) 2005 IBM Corporation
+ *
+ * Author(s):
+ *      Ryan S. Arnold <rsa@us.ibm.com>
+ *
+ * hvc_console header information:
+ *      moved here from include/asm-powerpc/hvconsole.h
+ *      and drivers/char/hvc_console.c
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
+ */
+
+#ifndef HVC_CONSOLE_H
+#define HVC_CONSOLE_H
+
+/*
+ * This is the max number of console adapters that can/will be found as
+ * console devices on first stage console init.  Any number beyond this range
+ * can't be used as a console device but is still a valid tty device.
+ */
+#define MAX_NR_HVC_CONSOLES     16
+
+/*
+ * The Linux TTY code does not support dynamic addition of tty derived devices
+ * so we need to know how many tty devices we might need when space is allocated
+ * for the tty device.  Since this driver supports hotplug of vty adapters we
+ * need to make sure we have enough allocated.
+ */
+#define HVC_ALLOC_TTY_ADAPTERS  8
+
+
+/* implemented by a low level driver */
+struct hv_ops {
+        int (*get_chars)(uint32_t vtermno, char *buf, int count);
+        int (*put_chars)(uint32_t vtermno, const char *buf, int count);
+};
+
+struct hvc_struct;
+
+/* Register a vterm and a slot index for use as a console (console_init) */
+extern int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops);
+
+/* register a vterm for hvc tty operation (module_init or hotplug add) */
+extern struct hvc_struct * __devinit hvc_alloc(uint32_t vtermno, int irq,
+                                                 struct hv_ops *ops);
+/* remove a vterm from hvc tty operation (modele_exit or hotplug remove) */
+extern int __devexit hvc_remove(struct hvc_struct *hp);
+
+#endif // HVC_CONSOLE_H
diff --git a/drivers/char/hvc_vio.c b/drivers/char/hvc_vio.c
index f5212eb2b41d..9add81ceb440 100644
--- a/drivers/char/hvc_vio.c
+++ b/drivers/char/hvc_vio.c
@@ -31,10 +31,13 @@
 
 #include <linux/types.h>
 #include <linux/init.h>
+
 #include <asm/hvconsole.h>
 #include <asm/vio.h>
 #include <asm/prom.h>
 
+#include "hvc_console.h"
+
 char hvc_driver_name[] = "hvc_console";
 
 static struct vio_device_id hvc_driver_table[] __devinitdata = {
@@ -48,6 +51,14 @@ static int filtered_get_chars(uint32_t vtermno, char *buf, int count)
         unsigned long got;
         int i;
 
+        /*
+         * 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;
+
         got = hvc_get_chars(vtermno, buf, count);
 
         /*
diff --git a/include/asm-powerpc/hvconsole.h b/include/asm-powerpc/hvconsole.h
index 34daf7b9b62f..35ea69e8121f 100644
--- a/include/asm-powerpc/hvconsole.h
+++ b/include/asm-powerpc/hvconsole.h
@@ -24,28 +24,18 @@
 #ifdef __KERNEL__
 
 /*
- * This is the max number of console adapters that can/will be found as
- * console devices on first stage console init.  Any number beyond this range
- * can't be used as a console device but is still a valid tty device.
+ * PSeries firmware will only send/recv up to 16 bytes of character data per
+ * hcall.
  */
-#define MAX_NR_HVC_CONSOLES     16
+#define MAX_VIO_PUT_CHARS       16
+#define SIZE_VIO_GET_CHARS      16
 
-/* implemented by a low level driver */
-struct hv_ops {
-        int (*get_chars)(uint32_t vtermno, char *buf, int count);
-        int (*put_chars)(uint32_t vtermno, const char *buf, int count);
-};
+/*
+ * Vio firmware always attempts to fetch MAX_VIO_GET_CHARS chars.  The 'count'
+ * parm is included to conform to put_chars() function pointer template
+ */
 extern int hvc_get_chars(uint32_t vtermno, char *buf, int count);
 extern int hvc_put_chars(uint32_t vtermno, const char *buf, int count);
 
-struct hvc_struct;
-
-/* Register a vterm and a slot index for use as a console (console_init) */
-extern int hvc_instantiate(uint32_t vtermno, int index, struct hv_ops *ops);
-/* register a vterm for hvc tty operation (module_init or hotplug add) */
-extern struct hvc_struct * __devinit hvc_alloc(uint32_t vtermno, int irq,
-                                                 struct hv_ops *ops);
-/* remove a vterm from hvc tty operation (modele_exit or hotplug remove) */
-extern int __devexit hvc_remove(struct hvc_struct *hp);
 #endif /* __KERNEL__ */
 #endif /* _PPC64_HVCONSOLE_H */