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![Miodrag Dinic](/assets/img/avatar_default.png)
Implement tty r/w operations using streaming DMA. Goldfish tty for Ranchu platforms has been modified to use streaming DMA mappings for read/write operations. This change eliminates the need for snooping through the TLB in QEMU using cpu_get_phys_page_debug() which does not guarantee that it will return the valid va -> pa mapping. The streaming DMA mapping is implemented using dma_map_single() per transfer, while dma_unmap_single() is used for unmapping right after the DMA transfer. Using DMA API is the proper way for handling r/w transfers and makes this driver more portable, thus effectively eliminating the need for virt_to_page() and page_to_phys() conversions. This change does not affect the old style Goldfish tty behaviour which is still used by the Goldfish emulator. Version register has been added and probed to see which platform is running this driver. Reading from the new register GOLDFISH_TTY_REG_VERSION using the Goldfish emulator will return 0 and driver will work with virtual addresses. Whereas if run on Ranchu it returns 1, and thus DMA is used. (Goldfish and Ranchu are code names for the first and the second generation of virtual boards used by Android emulator.) Signed-off-by: Miodrag Dinic <miodrag.dinic@imgtec.com> Signed-off-by: Goran Ferenc <goran.ferenc@imgtec.com> Signed-off-by: Aleksandar Markovic <aleksandar.markovic@imgtec.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
461 lines
12 KiB
C
461 lines
12 KiB
C
/*
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* Copyright (C) 2007 Google, Inc.
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* Copyright (C) 2012 Intel, Inc.
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*
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* This software is licensed under the terms of the GNU General Public
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* License version 2, as published by the Free Software Foundation, and
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* may be copied, distributed, and modified under those terms.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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*/
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#include <linux/console.h>
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#include <linux/interrupt.h>
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#include <linux/platform_device.h>
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#include <linux/tty.h>
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#include <linux/tty_flip.h>
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#include <linux/slab.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/goldfish.h>
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#include <linux/mm.h>
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#include <linux/dma-mapping.h>
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/* Goldfish tty register's offsets */
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#define GOLDFISH_TTY_REG_BYTES_READY 0x04
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#define GOLDFISH_TTY_REG_CMD 0x08
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#define GOLDFISH_TTY_REG_DATA_PTR 0x10
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#define GOLDFISH_TTY_REG_DATA_LEN 0x14
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#define GOLDFISH_TTY_REG_DATA_PTR_HIGH 0x18
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#define GOLDFISH_TTY_REG_VERSION 0x20
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/* Goldfish tty commands */
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#define GOLDFISH_TTY_CMD_INT_DISABLE 0
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#define GOLDFISH_TTY_CMD_INT_ENABLE 1
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#define GOLDFISH_TTY_CMD_WRITE_BUFFER 2
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#define GOLDFISH_TTY_CMD_READ_BUFFER 3
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struct goldfish_tty {
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struct tty_port port;
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spinlock_t lock;
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void __iomem *base;
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u32 irq;
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int opencount;
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struct console console;
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u32 version;
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struct device *dev;
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};
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static DEFINE_MUTEX(goldfish_tty_lock);
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static struct tty_driver *goldfish_tty_driver;
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static u32 goldfish_tty_line_count = 8;
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static u32 goldfish_tty_current_line_count;
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static struct goldfish_tty *goldfish_ttys;
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static void do_rw_io(struct goldfish_tty *qtty,
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unsigned long address,
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unsigned int count,
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int is_write)
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{
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unsigned long irq_flags;
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void __iomem *base = qtty->base;
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spin_lock_irqsave(&qtty->lock, irq_flags);
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gf_write_ptr((void *)address, base + GOLDFISH_TTY_REG_DATA_PTR,
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base + GOLDFISH_TTY_REG_DATA_PTR_HIGH);
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writel(count, base + GOLDFISH_TTY_REG_DATA_LEN);
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if (is_write)
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writel(GOLDFISH_TTY_CMD_WRITE_BUFFER,
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base + GOLDFISH_TTY_REG_CMD);
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else
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writel(GOLDFISH_TTY_CMD_READ_BUFFER,
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base + GOLDFISH_TTY_REG_CMD);
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spin_unlock_irqrestore(&qtty->lock, irq_flags);
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}
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static void goldfish_tty_rw(struct goldfish_tty *qtty,
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unsigned long addr,
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unsigned int count,
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int is_write)
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{
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dma_addr_t dma_handle;
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enum dma_data_direction dma_dir;
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dma_dir = (is_write ? DMA_TO_DEVICE : DMA_FROM_DEVICE);
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if (qtty->version > 0) {
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/*
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* Goldfish TTY for Ranchu platform uses
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* physical addresses and DMA for read/write operations
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*/
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unsigned long addr_end = addr + count;
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while (addr < addr_end) {
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unsigned long pg_end = (addr & PAGE_MASK) + PAGE_SIZE;
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unsigned long next =
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pg_end < addr_end ? pg_end : addr_end;
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unsigned long avail = next - addr;
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/*
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* Map the buffer's virtual address to the DMA address
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* so the buffer can be accessed by the device.
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*/
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dma_handle = dma_map_single(qtty->dev, (void *)addr,
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avail, dma_dir);
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if (dma_mapping_error(qtty->dev, dma_handle)) {
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dev_err(qtty->dev, "tty: DMA mapping error.\n");
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return;
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}
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do_rw_io(qtty, dma_handle, avail, is_write);
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/*
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* Unmap the previously mapped region after
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* the completion of the read/write operation.
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*/
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dma_unmap_single(qtty->dev, dma_handle, avail, dma_dir);
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addr += avail;
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}
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} else {
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/*
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* Old style Goldfish TTY used on the Goldfish platform
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* uses virtual addresses.
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*/
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do_rw_io(qtty, addr, count, is_write);
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}
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}
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static void goldfish_tty_do_write(int line, const char *buf,
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unsigned int count)
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{
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struct goldfish_tty *qtty = &goldfish_ttys[line];
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unsigned long address = (unsigned long)(void *)buf;
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goldfish_tty_rw(qtty, address, count, 1);
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}
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static irqreturn_t goldfish_tty_interrupt(int irq, void *dev_id)
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{
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struct goldfish_tty *qtty = dev_id;
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void __iomem *base = qtty->base;
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unsigned long address;
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unsigned char *buf;
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u32 count;
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count = readl(base + GOLDFISH_TTY_REG_BYTES_READY);
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if (count == 0)
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return IRQ_NONE;
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count = tty_prepare_flip_string(&qtty->port, &buf, count);
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address = (unsigned long)(void *)buf;
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goldfish_tty_rw(qtty, address, count, 0);
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tty_schedule_flip(&qtty->port);
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return IRQ_HANDLED;
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}
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static int goldfish_tty_activate(struct tty_port *port, struct tty_struct *tty)
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{
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struct goldfish_tty *qtty = container_of(port, struct goldfish_tty,
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port);
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writel(GOLDFISH_TTY_CMD_INT_ENABLE, qtty->base + GOLDFISH_TTY_REG_CMD);
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return 0;
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}
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static void goldfish_tty_shutdown(struct tty_port *port)
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{
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struct goldfish_tty *qtty = container_of(port, struct goldfish_tty,
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port);
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writel(GOLDFISH_TTY_CMD_INT_DISABLE, qtty->base + GOLDFISH_TTY_REG_CMD);
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}
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static int goldfish_tty_open(struct tty_struct *tty, struct file *filp)
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{
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struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
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return tty_port_open(&qtty->port, tty, filp);
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}
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static void goldfish_tty_close(struct tty_struct *tty, struct file *filp)
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{
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tty_port_close(tty->port, tty, filp);
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}
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static void goldfish_tty_hangup(struct tty_struct *tty)
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{
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tty_port_hangup(tty->port);
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}
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static int goldfish_tty_write(struct tty_struct *tty, const unsigned char *buf,
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int count)
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{
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goldfish_tty_do_write(tty->index, buf, count);
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return count;
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}
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static int goldfish_tty_write_room(struct tty_struct *tty)
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{
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return 0x10000;
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}
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static int goldfish_tty_chars_in_buffer(struct tty_struct *tty)
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{
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struct goldfish_tty *qtty = &goldfish_ttys[tty->index];
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void __iomem *base = qtty->base;
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return readl(base + GOLDFISH_TTY_REG_BYTES_READY);
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}
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static void goldfish_tty_console_write(struct console *co, const char *b,
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unsigned count)
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{
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goldfish_tty_do_write(co->index, b, count);
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}
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static struct tty_driver *goldfish_tty_console_device(struct console *c,
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int *index)
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{
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*index = c->index;
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return goldfish_tty_driver;
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}
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static int goldfish_tty_console_setup(struct console *co, char *options)
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{
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if ((unsigned)co->index >= goldfish_tty_line_count)
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return -ENODEV;
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if (!goldfish_ttys[co->index].base)
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return -ENODEV;
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return 0;
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}
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static const struct tty_port_operations goldfish_port_ops = {
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.activate = goldfish_tty_activate,
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.shutdown = goldfish_tty_shutdown
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};
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static const struct tty_operations goldfish_tty_ops = {
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.open = goldfish_tty_open,
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.close = goldfish_tty_close,
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.hangup = goldfish_tty_hangup,
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.write = goldfish_tty_write,
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.write_room = goldfish_tty_write_room,
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.chars_in_buffer = goldfish_tty_chars_in_buffer,
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};
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static int goldfish_tty_create_driver(void)
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{
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int ret;
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struct tty_driver *tty;
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goldfish_ttys = kzalloc(sizeof(*goldfish_ttys) *
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goldfish_tty_line_count, GFP_KERNEL);
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if (goldfish_ttys == NULL) {
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ret = -ENOMEM;
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goto err_alloc_goldfish_ttys_failed;
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}
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tty = alloc_tty_driver(goldfish_tty_line_count);
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if (tty == NULL) {
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ret = -ENOMEM;
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goto err_alloc_tty_driver_failed;
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}
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tty->driver_name = "goldfish";
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tty->name = "ttyGF";
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tty->type = TTY_DRIVER_TYPE_SERIAL;
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tty->subtype = SERIAL_TYPE_NORMAL;
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tty->init_termios = tty_std_termios;
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tty->flags = TTY_DRIVER_RESET_TERMIOS | TTY_DRIVER_REAL_RAW |
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TTY_DRIVER_DYNAMIC_DEV;
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tty_set_operations(tty, &goldfish_tty_ops);
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ret = tty_register_driver(tty);
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if (ret)
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goto err_tty_register_driver_failed;
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goldfish_tty_driver = tty;
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return 0;
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err_tty_register_driver_failed:
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put_tty_driver(tty);
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err_alloc_tty_driver_failed:
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kfree(goldfish_ttys);
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goldfish_ttys = NULL;
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err_alloc_goldfish_ttys_failed:
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return ret;
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}
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static void goldfish_tty_delete_driver(void)
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{
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tty_unregister_driver(goldfish_tty_driver);
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put_tty_driver(goldfish_tty_driver);
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goldfish_tty_driver = NULL;
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kfree(goldfish_ttys);
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goldfish_ttys = NULL;
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}
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static int goldfish_tty_probe(struct platform_device *pdev)
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{
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struct goldfish_tty *qtty;
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int ret = -ENODEV;
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struct resource *r;
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struct device *ttydev;
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void __iomem *base;
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u32 irq;
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unsigned int line;
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r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
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if (!r) {
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pr_err("goldfish_tty: No MEM resource available!\n");
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return -ENOMEM;
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}
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base = ioremap(r->start, 0x1000);
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if (!base) {
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pr_err("goldfish_tty: Unable to ioremap base!\n");
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return -ENOMEM;
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}
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r = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
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if (!r) {
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pr_err("goldfish_tty: No IRQ resource available!\n");
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goto err_unmap;
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}
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irq = r->start;
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mutex_lock(&goldfish_tty_lock);
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if (pdev->id == PLATFORM_DEVID_NONE)
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line = goldfish_tty_current_line_count;
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else
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line = pdev->id;
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if (line >= goldfish_tty_line_count) {
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pr_err("goldfish_tty: Reached maximum tty number of %d.\n",
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goldfish_tty_current_line_count);
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ret = -ENOMEM;
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goto err_unlock;
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}
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if (goldfish_tty_current_line_count == 0) {
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ret = goldfish_tty_create_driver();
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if (ret)
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goto err_unlock;
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}
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goldfish_tty_current_line_count++;
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qtty = &goldfish_ttys[line];
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spin_lock_init(&qtty->lock);
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tty_port_init(&qtty->port);
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qtty->port.ops = &goldfish_port_ops;
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qtty->base = base;
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qtty->irq = irq;
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qtty->dev = &pdev->dev;
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/*
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* Goldfish TTY device used by the Goldfish emulator
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* should identify itself with 0, forcing the driver
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* to use virtual addresses. Goldfish TTY device
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* on Ranchu emulator (qemu2) returns 1 here and
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* driver will use physical addresses.
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*/
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qtty->version = readl(base + GOLDFISH_TTY_REG_VERSION);
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/*
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* Goldfish TTY device on Ranchu emulator (qemu2)
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* will use DMA for read/write IO operations.
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*/
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if (qtty->version > 0) {
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/*
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* Initialize dma_mask to 32-bits.
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*/
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if (!pdev->dev.dma_mask)
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pdev->dev.dma_mask = &pdev->dev.coherent_dma_mask;
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ret = dma_set_mask(&pdev->dev, DMA_BIT_MASK(32));
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if (ret) {
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dev_err(&pdev->dev, "No suitable DMA available.\n");
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goto err_dec_line_count;
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}
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}
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writel(GOLDFISH_TTY_CMD_INT_DISABLE, base + GOLDFISH_TTY_REG_CMD);
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ret = request_irq(irq, goldfish_tty_interrupt, IRQF_SHARED,
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"goldfish_tty", qtty);
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if (ret) {
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pr_err("goldfish_tty: No IRQ available!\n");
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goto err_dec_line_count;
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}
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ttydev = tty_port_register_device(&qtty->port, goldfish_tty_driver,
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line, &pdev->dev);
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if (IS_ERR(ttydev)) {
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ret = PTR_ERR(ttydev);
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goto err_tty_register_device_failed;
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}
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strcpy(qtty->console.name, "ttyGF");
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qtty->console.write = goldfish_tty_console_write;
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qtty->console.device = goldfish_tty_console_device;
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qtty->console.setup = goldfish_tty_console_setup;
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qtty->console.flags = CON_PRINTBUFFER;
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qtty->console.index = line;
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register_console(&qtty->console);
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platform_set_drvdata(pdev, qtty);
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mutex_unlock(&goldfish_tty_lock);
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return 0;
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err_tty_register_device_failed:
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free_irq(irq, qtty);
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err_dec_line_count:
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goldfish_tty_current_line_count--;
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if (goldfish_tty_current_line_count == 0)
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goldfish_tty_delete_driver();
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err_unlock:
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mutex_unlock(&goldfish_tty_lock);
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err_unmap:
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iounmap(base);
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return ret;
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}
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static int goldfish_tty_remove(struct platform_device *pdev)
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{
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struct goldfish_tty *qtty = platform_get_drvdata(pdev);
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mutex_lock(&goldfish_tty_lock);
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unregister_console(&qtty->console);
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tty_unregister_device(goldfish_tty_driver, qtty->console.index);
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iounmap(qtty->base);
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qtty->base = NULL;
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free_irq(qtty->irq, pdev);
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goldfish_tty_current_line_count--;
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if (goldfish_tty_current_line_count == 0)
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goldfish_tty_delete_driver();
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mutex_unlock(&goldfish_tty_lock);
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return 0;
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}
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static const struct of_device_id goldfish_tty_of_match[] = {
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{ .compatible = "google,goldfish-tty", },
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{},
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};
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MODULE_DEVICE_TABLE(of, goldfish_tty_of_match);
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static struct platform_driver goldfish_tty_platform_driver = {
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.probe = goldfish_tty_probe,
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.remove = goldfish_tty_remove,
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.driver = {
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.name = "goldfish_tty",
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.of_match_table = goldfish_tty_of_match,
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}
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};
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module_platform_driver(goldfish_tty_platform_driver);
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MODULE_LICENSE("GPL v2");
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