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![David Howells](/assets/img/avatar_default.png)
Maintain a per-CPU global "struct pt_regs *" variable which can be used instead of passing regs around manually through all ~1800 interrupt handlers in the Linux kernel. The regs pointer is used in few places, but it potentially costs both stack space and code to pass it around. On the FRV arch, removing the regs parameter from all the genirq function results in a 20% speed up of the IRQ exit path (ie: from leaving timer_interrupt() to leaving do_IRQ()). Where appropriate, an arch may override the generic storage facility and do something different with the variable. On FRV, for instance, the address is maintained in GR28 at all times inside the kernel as part of general exception handling. Having looked over the code, it appears that the parameter may be handed down through up to twenty or so layers of functions. Consider a USB character device attached to a USB hub, attached to a USB controller that posts its interrupts through a cascaded auxiliary interrupt controller. A character device driver may want to pass regs to the sysrq handler through the input layer which adds another few layers of parameter passing. I've build this code with allyesconfig for x86_64 and i386. I've runtested the main part of the code on FRV and i386, though I can't test most of the drivers. I've also done partial conversion for powerpc and MIPS - these at least compile with minimal configurations. This will affect all archs. Mostly the changes should be relatively easy. Take do_IRQ(), store the regs pointer at the beginning, saving the old one: struct pt_regs *old_regs = set_irq_regs(regs); And put the old one back at the end: set_irq_regs(old_regs); Don't pass regs through to generic_handle_irq() or __do_IRQ(). In timer_interrupt(), this sort of change will be necessary: - update_process_times(user_mode(regs)); - profile_tick(CPU_PROFILING, regs); + update_process_times(user_mode(get_irq_regs())); + profile_tick(CPU_PROFILING); I'd like to move update_process_times()'s use of get_irq_regs() into itself, except that i386, alone of the archs, uses something other than user_mode(). Some notes on the interrupt handling in the drivers: (*) input_dev() is now gone entirely. The regs pointer is no longer stored in the input_dev struct. (*) finish_unlinks() in drivers/usb/host/ohci-q.c needs checking. It does something different depending on whether it's been supplied with a regs pointer or not. (*) Various IRQ handler function pointers have been moved to type irq_handler_t. Signed-Off-By: David Howells <dhowells@redhat.com> (cherry picked from 1b16e7ac850969f38b375e511e3fa2f474a33867 commit)
526 lines
10 KiB
C
526 lines
10 KiB
C
/* sunhv.c: Serial driver for SUN4V hypervisor console.
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*
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* Copyright (C) 2006 David S. Miller (davem@davemloft.net)
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*/
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#include <linux/module.h>
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#include <linux/kernel.h>
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#include <linux/errno.h>
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#include <linux/tty.h>
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#include <linux/tty_flip.h>
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#include <linux/major.h>
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#include <linux/circ_buf.h>
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#include <linux/serial.h>
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#include <linux/sysrq.h>
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#include <linux/console.h>
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#include <linux/spinlock.h>
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#include <linux/slab.h>
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#include <linux/delay.h>
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#include <linux/init.h>
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#include <asm/hypervisor.h>
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#include <asm/spitfire.h>
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#include <asm/prom.h>
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#include <asm/of_device.h>
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#include <asm/irq.h>
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#if defined(CONFIG_MAGIC_SYSRQ)
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#define SUPPORT_SYSRQ
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#endif
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#include <linux/serial_core.h>
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#include "suncore.h"
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#define CON_BREAK ((long)-1)
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#define CON_HUP ((long)-2)
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static inline long hypervisor_con_getchar(long *status)
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{
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register unsigned long func asm("%o5");
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register unsigned long arg0 asm("%o0");
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register unsigned long arg1 asm("%o1");
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func = HV_FAST_CONS_GETCHAR;
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arg0 = 0;
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arg1 = 0;
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__asm__ __volatile__("ta %6"
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: "=&r" (func), "=&r" (arg0), "=&r" (arg1)
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: "0" (func), "1" (arg0), "2" (arg1),
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"i" (HV_FAST_TRAP));
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*status = arg0;
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return (long) arg1;
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}
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static inline long hypervisor_con_putchar(long ch)
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{
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register unsigned long func asm("%o5");
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register unsigned long arg0 asm("%o0");
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func = HV_FAST_CONS_PUTCHAR;
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arg0 = ch;
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__asm__ __volatile__("ta %4"
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: "=&r" (func), "=&r" (arg0)
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: "0" (func), "1" (arg0), "i" (HV_FAST_TRAP));
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return (long) arg0;
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}
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#define IGNORE_BREAK 0x1
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#define IGNORE_ALL 0x2
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static int hung_up = 0;
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static struct tty_struct *receive_chars(struct uart_port *port)
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{
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struct tty_struct *tty = NULL;
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int saw_console_brk = 0;
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int limit = 10000;
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if (port->info != NULL) /* Unopened serial console */
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tty = port->info->tty;
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while (limit-- > 0) {
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long status;
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long c = hypervisor_con_getchar(&status);
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unsigned char flag;
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if (status == HV_EWOULDBLOCK)
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break;
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if (c == CON_BREAK) {
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if (uart_handle_break(port))
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continue;
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saw_console_brk = 1;
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c = 0;
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}
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if (c == CON_HUP) {
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hung_up = 1;
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uart_handle_dcd_change(port, 0);
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} else if (hung_up) {
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hung_up = 0;
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uart_handle_dcd_change(port, 1);
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}
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if (tty == NULL) {
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uart_handle_sysrq_char(port, c);
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continue;
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}
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flag = TTY_NORMAL;
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port->icount.rx++;
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if (c == CON_BREAK) {
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port->icount.brk++;
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if (uart_handle_break(port))
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continue;
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flag = TTY_BREAK;
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}
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if (uart_handle_sysrq_char(port, c))
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continue;
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if ((port->ignore_status_mask & IGNORE_ALL) ||
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((port->ignore_status_mask & IGNORE_BREAK) &&
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(c == CON_BREAK)))
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continue;
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tty_insert_flip_char(tty, c, flag);
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}
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if (saw_console_brk)
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sun_do_break();
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return tty;
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}
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static void transmit_chars(struct uart_port *port)
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{
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struct circ_buf *xmit;
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if (!port->info)
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return;
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xmit = &port->info->xmit;
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if (uart_circ_empty(xmit) || uart_tx_stopped(port))
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return;
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while (!uart_circ_empty(xmit)) {
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long status = hypervisor_con_putchar(xmit->buf[xmit->tail]);
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if (status != HV_EOK)
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break;
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xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
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port->icount.tx++;
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}
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if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
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uart_write_wakeup(port);
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}
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static irqreturn_t sunhv_interrupt(int irq, void *dev_id)
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{
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struct uart_port *port = dev_id;
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struct tty_struct *tty;
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unsigned long flags;
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spin_lock_irqsave(&port->lock, flags);
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tty = receive_chars(port);
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transmit_chars(port);
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spin_unlock_irqrestore(&port->lock, flags);
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if (tty)
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tty_flip_buffer_push(tty);
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return IRQ_HANDLED;
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}
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/* port->lock is not held. */
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static unsigned int sunhv_tx_empty(struct uart_port *port)
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{
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/* Transmitter is always empty for us. If the circ buffer
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* is non-empty or there is an x_char pending, our caller
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* will do the right thing and ignore what we return here.
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*/
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return TIOCSER_TEMT;
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}
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/* port->lock held by caller. */
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static void sunhv_set_mctrl(struct uart_port *port, unsigned int mctrl)
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{
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return;
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}
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/* port->lock is held by caller and interrupts are disabled. */
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static unsigned int sunhv_get_mctrl(struct uart_port *port)
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{
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return TIOCM_DSR | TIOCM_CAR | TIOCM_CTS;
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}
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/* port->lock held by caller. */
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static void sunhv_stop_tx(struct uart_port *port)
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{
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return;
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}
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/* port->lock held by caller. */
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static void sunhv_start_tx(struct uart_port *port)
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{
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struct circ_buf *xmit = &port->info->xmit;
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while (!uart_circ_empty(xmit)) {
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long status = hypervisor_con_putchar(xmit->buf[xmit->tail]);
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if (status != HV_EOK)
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break;
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xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
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port->icount.tx++;
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}
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}
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/* port->lock is not held. */
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static void sunhv_send_xchar(struct uart_port *port, char ch)
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{
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unsigned long flags;
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int limit = 10000;
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spin_lock_irqsave(&port->lock, flags);
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while (limit-- > 0) {
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long status = hypervisor_con_putchar(ch);
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if (status == HV_EOK)
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break;
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}
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spin_unlock_irqrestore(&port->lock, flags);
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}
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/* port->lock held by caller. */
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static void sunhv_stop_rx(struct uart_port *port)
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{
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}
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/* port->lock held by caller. */
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static void sunhv_enable_ms(struct uart_port *port)
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{
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}
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/* port->lock is not held. */
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static void sunhv_break_ctl(struct uart_port *port, int break_state)
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{
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if (break_state) {
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unsigned long flags;
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int limit = 1000000;
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spin_lock_irqsave(&port->lock, flags);
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while (limit-- > 0) {
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long status = hypervisor_con_putchar(CON_BREAK);
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if (status == HV_EOK)
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break;
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udelay(2);
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}
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spin_unlock_irqrestore(&port->lock, flags);
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}
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}
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/* port->lock is not held. */
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static int sunhv_startup(struct uart_port *port)
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{
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return 0;
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}
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/* port->lock is not held. */
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static void sunhv_shutdown(struct uart_port *port)
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{
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}
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/* port->lock is not held. */
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static void sunhv_set_termios(struct uart_port *port, struct termios *termios,
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struct termios *old)
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{
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unsigned int baud = uart_get_baud_rate(port, termios, old, 0, 4000000);
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unsigned int quot = uart_get_divisor(port, baud);
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unsigned int iflag, cflag;
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unsigned long flags;
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spin_lock_irqsave(&port->lock, flags);
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iflag = termios->c_iflag;
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cflag = termios->c_cflag;
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port->ignore_status_mask = 0;
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if (iflag & IGNBRK)
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port->ignore_status_mask |= IGNORE_BREAK;
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if ((cflag & CREAD) == 0)
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port->ignore_status_mask |= IGNORE_ALL;
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/* XXX */
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uart_update_timeout(port, cflag,
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(port->uartclk / (16 * quot)));
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spin_unlock_irqrestore(&port->lock, flags);
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}
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static const char *sunhv_type(struct uart_port *port)
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{
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return "SUN4V HCONS";
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}
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static void sunhv_release_port(struct uart_port *port)
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{
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}
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static int sunhv_request_port(struct uart_port *port)
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{
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return 0;
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}
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static void sunhv_config_port(struct uart_port *port, int flags)
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{
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}
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static int sunhv_verify_port(struct uart_port *port, struct serial_struct *ser)
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{
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return -EINVAL;
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}
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static struct uart_ops sunhv_pops = {
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.tx_empty = sunhv_tx_empty,
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.set_mctrl = sunhv_set_mctrl,
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.get_mctrl = sunhv_get_mctrl,
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.stop_tx = sunhv_stop_tx,
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.start_tx = sunhv_start_tx,
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.send_xchar = sunhv_send_xchar,
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.stop_rx = sunhv_stop_rx,
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.enable_ms = sunhv_enable_ms,
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.break_ctl = sunhv_break_ctl,
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.startup = sunhv_startup,
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.shutdown = sunhv_shutdown,
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.set_termios = sunhv_set_termios,
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.type = sunhv_type,
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.release_port = sunhv_release_port,
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.request_port = sunhv_request_port,
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.config_port = sunhv_config_port,
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.verify_port = sunhv_verify_port,
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};
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static struct uart_driver sunhv_reg = {
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.owner = THIS_MODULE,
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.driver_name = "serial",
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.dev_name = "ttyS",
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.major = TTY_MAJOR,
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};
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static struct uart_port *sunhv_port;
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static inline void sunhv_console_putchar(struct uart_port *port, char c)
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{
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unsigned long flags;
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int limit = 1000000;
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spin_lock_irqsave(&port->lock, flags);
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while (limit-- > 0) {
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long status = hypervisor_con_putchar(c);
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if (status == HV_EOK)
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break;
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udelay(2);
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}
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spin_unlock_irqrestore(&port->lock, flags);
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}
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static void sunhv_console_write(struct console *con, const char *s, unsigned n)
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{
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struct uart_port *port = sunhv_port;
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int i;
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for (i = 0; i < n; i++) {
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if (*s == '\n')
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sunhv_console_putchar(port, '\r');
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sunhv_console_putchar(port, *s++);
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}
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}
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static struct console sunhv_console = {
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.name = "ttyHV",
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.write = sunhv_console_write,
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.device = uart_console_device,
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.flags = CON_PRINTBUFFER,
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.index = -1,
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.data = &sunhv_reg,
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};
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static inline struct console *SUNHV_CONSOLE(void)
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{
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if (con_is_present())
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return NULL;
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sunhv_console.index = 0;
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return &sunhv_console;
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}
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static int __devinit hv_probe(struct of_device *op, const struct of_device_id *match)
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{
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struct uart_port *port;
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int err;
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if (op->irqs[0] == 0xffffffff)
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return -ENODEV;
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port = kzalloc(sizeof(struct uart_port), GFP_KERNEL);
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if (unlikely(!port))
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return -ENOMEM;
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sunhv_port = port;
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port->line = 0;
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port->ops = &sunhv_pops;
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port->type = PORT_SUNHV;
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port->uartclk = ( 29491200 / 16 ); /* arbitrary */
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port->membase = (unsigned char __iomem *) __pa(port);
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port->irq = op->irqs[0];
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port->dev = &op->dev;
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sunhv_reg.minor = sunserial_current_minor;
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sunhv_reg.nr = 1;
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err = uart_register_driver(&sunhv_reg);
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if (err)
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goto out_free_port;
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sunhv_reg.tty_driver->name_base = sunhv_reg.minor - 64;
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sunserial_current_minor += 1;
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sunhv_reg.cons = SUNHV_CONSOLE();
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err = uart_add_one_port(&sunhv_reg, port);
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if (err)
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goto out_unregister_driver;
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err = request_irq(port->irq, sunhv_interrupt, 0, "hvcons", port);
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if (err)
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goto out_remove_port;
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dev_set_drvdata(&op->dev, port);
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return 0;
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out_remove_port:
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uart_remove_one_port(&sunhv_reg, port);
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out_unregister_driver:
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sunserial_current_minor -= 1;
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uart_unregister_driver(&sunhv_reg);
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out_free_port:
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kfree(port);
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sunhv_port = NULL;
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return err;
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}
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static int __devexit hv_remove(struct of_device *dev)
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{
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struct uart_port *port = dev_get_drvdata(&dev->dev);
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free_irq(port->irq, port);
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uart_remove_one_port(&sunhv_reg, port);
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sunserial_current_minor -= 1;
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uart_unregister_driver(&sunhv_reg);
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kfree(port);
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sunhv_port = NULL;
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dev_set_drvdata(&dev->dev, NULL);
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return 0;
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}
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static struct of_device_id hv_match[] = {
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{
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.name = "console",
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.compatible = "qcn",
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},
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{},
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};
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MODULE_DEVICE_TABLE(of, hv_match);
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static struct of_platform_driver hv_driver = {
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.name = "hv",
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.match_table = hv_match,
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.probe = hv_probe,
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.remove = __devexit_p(hv_remove),
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};
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static int __init sunhv_init(void)
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{
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if (tlb_type != hypervisor)
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return -ENODEV;
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return of_register_driver(&hv_driver, &of_bus_type);
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}
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static void __exit sunhv_exit(void)
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|
{
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of_unregister_driver(&hv_driver);
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}
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|
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module_init(sunhv_init);
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module_exit(sunhv_exit);
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|
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MODULE_AUTHOR("David S. Miller");
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MODULE_DESCRIPTION("SUN4V Hypervisor console driver");
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MODULE_VERSION("2.0");
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MODULE_LICENSE("GPL");
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