[POWERPC] Optionally use new device number for pmac_zilog

This adds the option for the pmac_zilog driver to use the major/minor
numbers recently allocated specifically for it (/dev/ttyPZn) instead
of the /dev/ttySn numbers.  The advantage of doing this is that it
allows the pmac_zilog and 8250 drivers to coexist.  The disadvantage
of doing this is that it is a user-visible ABI change and it will
break existing working setups on powermacs, and could be confusing to
users.

Signed-off-by: David Woodhouse <dwmw2@infradead.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

2 files changed, 40 insertions, 5 deletions

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 81b52b7cca21..d6ae38e55d01 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -986,6 +986,31 @@ config SERIAL_PMACZILOG
           PowerMac machines.
           Say Y or M if you want to be able to these serial ports.
 
+config SERIAL_PMACZILOG_TTYS
+        bool "Use ttySn device nodes for Zilog z85c30"
+        depends on SERIAL_PMACZILOG
+        help
+          The pmac_zilog driver for the z85C30 chip on many powermacs
+          historically used the device numbers for /dev/ttySn.  The
+          8250 serial port driver also uses these numbers, which means
+          the two drivers being unable to coexist; you could not use
+          both z85C30 and 8250 type ports at the same time.
+
+          If this option is not selected, the pmac_zilog driver will
+          use the device numbers allocated for /dev/ttyPZn.  This allows
+          the pmac_zilog and 8250 drivers to co-exist, but may cause
+          existing userspace setups to break.  Programs that need to
+          access the built-in serial ports on powermacs will need to
+          be reconfigured to use /dev/ttyPZn instead of /dev/ttySn.
+
+          If you enable this option, any z85c30 ports in the system will
+          be registered as ttyS0 onwards as in the past, and you will be
+          unable to use the 8250 module for PCMCIA or other 16C550-style
+          UARTs.
+
+          Say N unless you need the z85c30 ports on your powermac
+          to appear as /dev/ttySn.
+
 config SERIAL_PMACZILOG_CONSOLE
         bool "Console on PowerMac z85c30 serial port"
         depends on SERIAL_PMACZILOG=y
diff --git a/drivers/serial/pmac_zilog.c b/drivers/serial/pmac_zilog.c
index f793ac212672..794bd0f50d73 100644
--- a/drivers/serial/pmac_zilog.c
+++ b/drivers/serial/pmac_zilog.c
@@ -88,6 +88,16 @@ MODULE_LICENSE("GPL");
 
 #define PWRDBG(fmt, arg...)     printk(KERN_DEBUG fmt , ## arg)
 
+#ifdef CONFIG_SERIAL_PMACZILOG_TTYS
+#define PMACZILOG_MAJOR         TTY_MAJOR
+#define PMACZILOG_MINOR         64
+#define PMACZILOG_NAME          "ttyS"
+#else
+#define PMACZILOG_MAJOR         204
+#define PMACZILOG_MINOR         192
+#define PMACZILOG_NAME          "ttyPZ"
+#endif
+
 
 /*
  * For the sake of early serial console, we can do a pre-probe
@@ -99,9 +109,10 @@ static DEFINE_MUTEX(pmz_irq_mutex);
 
 static struct uart_driver pmz_uart_reg = {
         .owner          =       THIS_MODULE,
-        .driver_name    =       "ttyS",
-        .dev_name       =       "ttyS",
-        .major          =       TTY_MAJOR,
+        .driver_name    =       PMACZILOG_NAME,
+        .dev_name       =       PMACZILOG_NAME,
+        .major          =       PMACZILOG_MAJOR,
+        .minor          =       PMACZILOG_MINOR,
 };
 
 
@@ -1778,7 +1789,7 @@ static void pmz_console_write(struct console *con, const char *s, unsigned int c
 static int __init pmz_console_setup(struct console *co, char *options);
 
 static struct console pmz_console = {
-        .name   =       "ttyS",
+        .name   =       PMACZILOG_NAME,
         .write  =       pmz_console_write,
         .device =       uart_console_device,
         .setup  =       pmz_console_setup,
@@ -1802,7 +1813,6 @@ static int __init pmz_register(void)
         
         pmz_uart_reg.nr = pmz_ports_count;
         pmz_uart_reg.cons = PMACZILOG_CONSOLE;
-        pmz_uart_reg.minor = 64;
 
         /*
          * Register this driver with the serial core