[PATCH] serial: mxser.c - Cleanup opmode shiftbit calculation

[Michal Kadlic <michal.kadlic@xxxxxxxxx>]

Replace opmode shiftbit calculations with stored value per port (mxser_port.opmode_shift) .  Preload value in mxser_probe routine.

Signed-off-by: Michal Kadlic <michal.kadlic@xxxxxxxxx>

---

Mxser driver uses a packed opmode register ( 2bits per port) to switch between RS232,RS485 and RS422 mode. Shiftbit variable is calculated in several places to determine correct bits per port.

Reasons for change:

1. Code cleanup - remove calculations scattered in code
2. ARCH_MOXART could use mxser.c in the future but it uses different bit offsets, so each calculation would need an #ifdef.

---

diff -purN old/drivers/tty/mxser.c new/drivers/tty/mxser.c
--- old/drivers/tty/mxser.c        2016-06-15 13:22:50.000000000 +0200
+++ new/drivers/tty/mxser.c        2016-06-15 13:33:23.000000000 +0200
@@ -256,6 +256,8 @@ struct mxser_port {
         int xmit_cnt;
         int closing;
 
+        unsigned char opmode_shift; /* Position of opmode bits in opmode register */
+
         struct ktermios normal_termios;
 
         struct mxser_mon mon_data;
@@ -1622,7 +1624,7 @@ static int mxser_ioctl_special(unsigned
                                         me->fifo[p] = 1;
 
                                 if (ip->board->chip_flag == MOXA_MUST_MU860_HWID) {
-                                        opmode = inb(ip->opmode_ioaddr)>>((p % 4) * 2);
+                                        opmode = inb(ip->opmode_ioaddr) >> ip->opmode_shift;
                                         opmode &= OP_MODE_MASK;
                                 } else {
                                         opmode = RS232_MODE;
@@ -1677,16 +1679,12 @@ static int mxser_ioctl(struct tty_struct
                 return mxser_ioctl_special(cmd, argp);
 
         if (cmd == MOXA_SET_OP_MODE || cmd == MOXA_GET_OP_MODE) {
-                int p;
                 unsigned long opmode;
-                static unsigned char ModeMask[] = { 0xfc, 0xf3, 0xcf, 0x3f };
-                int shiftbit;
                 unsigned char val, mask;
 
                 if (info->board->chip_flag != MOXA_MUST_MU860_HWID)
                         return -EFAULT;
 
-                p = tty->index % 4;
                 if (cmd == MOXA_SET_OP_MODE) {
                         if (get_user(opmode, (int __user *) argp))
                                 return -EFAULT;
@@ -1695,19 +1693,17 @@ static int mxser_ioctl(struct tty_struct
                                         opmode != RS422_MODE &&
                                         opmode != RS485_4WIRE_MODE)
                                 return -EFAULT;
-                        mask = ModeMask[p];
-                        shiftbit = p * 2;
+                        mask = ~ ( OP_MODE_MASK << info->opmode_shift );
+
                         spin_lock_irq(&info->slock);
                         val = inb(info->opmode_ioaddr);
                         val &= mask;
-                        val |= (opmode << shiftbit);
+                        val |= (opmode << info->opmode_shift);
                         outb(val, info->opmode_ioaddr);
+
                         spin_unlock_irq(&info->slock);
                 } else {
-                        shiftbit = p * 2;
-                        spin_lock_irq(&info->slock);
-                        opmode = inb(info->opmode_ioaddr) >> shiftbit;
-                        spin_unlock_irq(&info->slock);
+                        opmode = inb(info->opmode_ioaddr) >> info->opmode_shift;
                         opmode &= OP_MODE_MASK;
                         if (put_user(opmode, (int __user *)argp))
                                 return -EFAULT;
@@ -2633,9 +2629,12 @@ static int mxser_probe(struct pci_dev *p
                                 brd->ports[i].opmode_ioaddr = ioaddress + 4;
                         else
                                 brd->ports[i].opmode_ioaddr = ioaddress + 0x0c;
+                        /* opmode is packed , 2 bits per port, 4 ports per register */
+                        brd->ports[i].opmode_shift = (i % 4) * 2;
                 }
                 outb(0, ioaddress + 4);        /* default set to RS232 mode */
-                outb(0, ioaddress + 0x0c);        /* default set to RS232 mode */
+                if (brd->info->nports > 4)
+                        outb(0, ioaddress + 0x0c);        /* default set to RS232 mode */
         }
 
         for (i = 0; i < brd->info->nports; i++) {
--
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