diff options
Diffstat (limited to 'drivers/platform/goldfish/goldfish_pipe.c')
| -rw-r--r-- | drivers/platform/goldfish/goldfish_pipe.c | 611 |
1 files changed, 611 insertions, 0 deletions
diff --git a/drivers/platform/goldfish/goldfish_pipe.c b/drivers/platform/goldfish/goldfish_pipe.c new file mode 100644 index 000000000000..58dae1f1fdd4 --- /dev/null +++ b/drivers/platform/goldfish/goldfish_pipe.c @@ -0,0 +1,611 @@ +/* + * Copyright (C) 2011 Google, Inc. + * Copyright (C) 2012 Intel, Inc. + * Copyright (C) 2013 Intel, Inc. + * + * This software is licensed under the terms of the GNU General Public + * License version 2, as published by the Free Software Foundation, and + * may be copied, distributed, and modified under those terms. + * + * 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. + * + */ + +/* This source file contains the implementation of a special device driver + * that intends to provide a *very* fast communication channel between the + * guest system and the QEMU emulator. + * + * Usage from the guest is simply the following (error handling simplified): + * + * int fd = open("/dev/qemu_pipe",O_RDWR); + * .... write() or read() through the pipe. + * + * This driver doesn't deal with the exact protocol used during the session. + * It is intended to be as simple as something like: + * + * // do this _just_ after opening the fd to connect to a specific + * // emulator service. + * const char* msg = "<pipename>"; + * if (write(fd, msg, strlen(msg)+1) < 0) { + * ... could not connect to <pipename> service + * close(fd); + * } + * + * // after this, simply read() and write() to communicate with the + * // service. Exact protocol details left as an exercise to the reader. + * + * This driver is very fast because it doesn't copy any data through + * intermediate buffers, since the emulator is capable of translating + * guest user addresses into host ones. + * + * Note that we must however ensure that each user page involved in the + * exchange is properly mapped during a transfer. + */ + +#include <linux/module.h> +#include <linux/interrupt.h> +#include <linux/kernel.h> +#include <linux/spinlock.h> +#include <linux/miscdevice.h> +#include <linux/platform_device.h> +#include <linux/poll.h> +#include <linux/sched.h> +#include <linux/bitops.h> +#include <linux/slab.h> +#include <linux/io.h> + +/* + * IMPORTANT: The following constants must match the ones used and defined + * in external/qemu/hw/goldfish_pipe.c in the Android source tree. + */ + +/* pipe device registers */ +#define PIPE_REG_COMMAND 0x00 /* write: value = command */ +#define PIPE_REG_STATUS 0x04 /* read */ +#define PIPE_REG_CHANNEL 0x08 /* read/write: channel id */ +#define PIPE_REG_SIZE 0x0c /* read/write: buffer size */ +#define PIPE_REG_ADDRESS 0x10 /* write: physical address */ +#define PIPE_REG_WAKES 0x14 /* read: wake flags */ +#define PIPE_REG_PARAMS_ADDR_LOW 0x18 /* read/write: batch data address */ +#define PIPE_REG_PARAMS_ADDR_HIGH 0x1c /* read/write: batch data address */ +#define PIPE_REG_ACCESS_PARAMS 0x20 /* write: batch access */ + +/* list of commands for PIPE_REG_COMMAND */ +#define CMD_OPEN 1 /* open new channel */ +#define CMD_CLOSE 2 /* close channel (from guest) */ +#define CMD_POLL 3 /* poll read/write status */ + +/* List of bitflags returned in status of CMD_POLL command */ +#define PIPE_POLL_IN (1 << 0) +#define PIPE_POLL_OUT (1 << 1) +#define PIPE_POLL_HUP (1 << 2) + +/* The following commands are related to write operations */ +#define CMD_WRITE_BUFFER 4 /* send a user buffer to the emulator */ +#define CMD_WAKE_ON_WRITE 5 /* tell the emulator to wake us when writing + is possible */ + +/* The following commands are related to read operations, they must be + * listed in the same order than the corresponding write ones, since we + * will use (CMD_READ_BUFFER - CMD_WRITE_BUFFER) as a special offset + * in goldfish_pipe_read_write() below. + */ +#define CMD_READ_BUFFER 6 /* receive a user buffer from the emulator */ +#define CMD_WAKE_ON_READ 7 /* tell the emulator to wake us when reading + * is possible */ + +/* Possible status values used to signal errors - see goldfish_pipe_error_convert */ +#define PIPE_ERROR_INVAL -1 +#define PIPE_ERROR_AGAIN -2 +#define PIPE_ERROR_NOMEM -3 +#define PIPE_ERROR_IO -4 + +/* Bit-flags used to signal events from the emulator */ +#define PIPE_WAKE_CLOSED (1 << 0) /* emulator closed pipe */ +#define PIPE_WAKE_READ (1 << 1) /* pipe can now be read from */ +#define PIPE_WAKE_WRITE (1 << 2) /* pipe can now be written to */ + +struct access_params { + u32 channel; + u32 size; + u32 address; + u32 cmd; + u32 result; + /* reserved for future extension */ + u32 flags; +}; + +/* The global driver data. Holds a reference to the i/o page used to + * communicate with the emulator, and a wake queue for blocked tasks + * waiting to be awoken. + */ +struct goldfish_pipe_dev { + spinlock_t lock; + unsigned char __iomem *base; + struct access_params *aps; + int irq; +}; + +static struct goldfish_pipe_dev pipe_dev[1]; + +/* This data type models a given pipe instance */ +struct goldfish_pipe { + struct goldfish_pipe_dev *dev; + struct mutex lock; + unsigned long flags; + wait_queue_head_t wake_queue; +}; + + +/* Bit flags for the 'flags' field */ +enum { + BIT_CLOSED_ON_HOST = 0, /* pipe closed by host */ + BIT_WAKE_ON_WRITE = 1, /* want to be woken on writes */ + BIT_WAKE_ON_READ = 2, /* want to be woken on reads */ +}; + + +static u32 goldfish_cmd_status(struct goldfish_pipe *pipe, u32 cmd) +{ + unsigned long flags; + u32 status; + struct goldfish_pipe_dev *dev = pipe->dev; + + spin_lock_irqsave(&dev->lock, flags); + writel((u32)pipe, dev->base + PIPE_REG_CHANNEL); + writel(cmd, dev->base + PIPE_REG_COMMAND); + status = readl(dev->base + PIPE_REG_STATUS); + spin_unlock_irqrestore(&dev->lock, flags); + return status; +} + +static void goldfish_cmd(struct goldfish_pipe *pipe, u32 cmd) +{ + unsigned long flags; + struct goldfish_pipe_dev *dev = pipe->dev; + + spin_lock_irqsave(&dev->lock, flags); + writel((u32)pipe, dev->base + PIPE_REG_CHANNEL); + writel(cmd, dev->base + PIPE_REG_COMMAND); + spin_unlock_irqrestore(&dev->lock, flags); +} + +/* This function converts an error code returned by the emulator through + * the PIPE_REG_STATUS i/o register into a valid negative errno value. + */ +static int goldfish_pipe_error_convert(int status) +{ + switch (status) { + case PIPE_ERROR_AGAIN: + return -EAGAIN; + case PIPE_ERROR_NOMEM: + return -ENOMEM; + case PIPE_ERROR_IO: + return -EIO; + default: + return -EINVAL; + } +} + +/* + * Notice: QEMU will return 0 for un-known register access, indicating + * param_acess is supported or not + */ +static int valid_batchbuffer_addr(struct goldfish_pipe_dev *dev, + struct access_params *aps) +{ + u32 aph, apl; + u64 paddr; + aph = readl(dev->base + PIPE_REG_PARAMS_ADDR_HIGH); + apl = readl(dev->base + PIPE_REG_PARAMS_ADDR_LOW); + + paddr = ((u64)aph << 32) | apl; + if (paddr != (__pa(aps))) + return 0; + return 1; +} + +/* 0 on success */ +static int setup_access_params_addr(struct platform_device *pdev, + struct goldfish_pipe_dev *dev) +{ + u64 paddr; + struct access_params *aps; + + aps = devm_kzalloc(&pdev->dev, sizeof(struct access_params), GFP_KERNEL); + if (!aps) + return -1; + + /* FIXME */ + paddr = __pa(aps); + writel((u32)(paddr >> 32), dev->base + PIPE_REG_PARAMS_ADDR_HIGH); + writel((u32)paddr, dev->base + PIPE_REG_PARAMS_ADDR_LOW); + + if (valid_batchbuffer_addr(dev, aps)) { + dev->aps = aps; + return 0; + } else + return -1; +} + +/* A value that will not be set by qemu emulator */ +#define INITIAL_BATCH_RESULT (0xdeadbeaf) +static int access_with_param(struct goldfish_pipe_dev *dev, const int cmd, + unsigned long address, unsigned long avail, + struct goldfish_pipe *pipe, int *status) +{ + struct access_params *aps = dev->aps; + + if (aps == NULL) + return -1; + + aps->result = INITIAL_BATCH_RESULT; + aps->channel = (unsigned long)pipe; + aps->size = avail; + aps->address = address; + aps->cmd = cmd; + writel(cmd, dev->base + PIPE_REG_ACCESS_PARAMS); + /* + * If the aps->result has not changed, that means + * that the batch command failed + */ + if (aps->result == INITIAL_BATCH_RESULT) + return -1; + *status = aps->result; + return 0; +} + +/* This function is used for both reading from and writing to a given + * pipe. + */ +static ssize_t goldfish_pipe_read_write(struct file *filp, char __user *buffer, + size_t bufflen, int is_write) +{ + unsigned long irq_flags; + struct goldfish_pipe *pipe = filp->private_data; + struct goldfish_pipe_dev *dev = pipe->dev; + const int cmd_offset = is_write ? 0 + : (CMD_READ_BUFFER - CMD_WRITE_BUFFER); + unsigned long address, address_end; + int ret = 0; + + /* If the emulator already closed the pipe, no need to go further */ + if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags)) + return -EIO; + + /* Null reads or writes succeeds */ + if (unlikely(bufflen) == 0) + return 0; + + /* Check the buffer range for access */ + if (!access_ok(is_write ? VERIFY_WRITE : VERIFY_READ, + buffer, bufflen)) + return -EFAULT; + + /* Serialize access to the pipe */ + if (mutex_lock_interruptible(&pipe->lock)) + return -ERESTARTSYS; + + address = (unsigned long)(void *)buffer; + address_end = address + bufflen; + + while (address < address_end) { + unsigned long page_end = (address & PAGE_MASK) + PAGE_SIZE; + unsigned long next = page_end < address_end ? page_end + : address_end; + unsigned long avail = next - address; + int status, wakeBit; + + /* Ensure that the corresponding page is properly mapped */ + if (is_write) { + char c; + /* Ensure that the page is mapped and readable */ + if (__get_user(c, (char __user *)address)) { + if (!ret) + ret = -EFAULT; + break; + } + } else { + /* Ensure that the page is mapped and writable */ + if (__put_user(0, (char __user *)address)) { + if (!ret) + ret = -EFAULT; + break; + } + } + + /* Now, try to transfer the bytes in the current page */ + spin_lock_irqsave(&dev->lock, irq_flags); + if (access_with_param(dev, CMD_WRITE_BUFFER + cmd_offset, + address, avail, pipe, &status)) { + writel((u32)pipe, dev->base + PIPE_REG_CHANNEL); + writel(avail, dev->base + PIPE_REG_SIZE); + writel(address, dev->base + PIPE_REG_ADDRESS); + writel(CMD_WRITE_BUFFER + cmd_offset, + dev->base + PIPE_REG_COMMAND); + status = readl(dev->base + PIPE_REG_STATUS); + } + spin_unlock_irqrestore(&dev->lock, irq_flags); + + if (status > 0) { /* Correct transfer */ + ret += status; + address += status; + continue; + } + + if (status == 0) /* EOF */ + break; + + /* An error occured. If we already transfered stuff, just + * return with its count. We expect the next call to return + * an error code */ + if (ret > 0) + break; + + /* If the error is not PIPE_ERROR_AGAIN, or if we are not in + * non-blocking mode, just return the error code. + */ + if (status != PIPE_ERROR_AGAIN || + (filp->f_flags & O_NONBLOCK) != 0) { + ret = goldfish_pipe_error_convert(status); + break; + } + + /* We will have to wait until more data/space is available. + * First, mark the pipe as waiting for a specific wake signal. + */ + wakeBit = is_write ? BIT_WAKE_ON_WRITE : BIT_WAKE_ON_READ; + set_bit(wakeBit, &pipe->flags); + + /* Tell the emulator we're going to wait for a wake event */ + goldfish_cmd(pipe, CMD_WAKE_ON_WRITE + cmd_offset); + + /* Unlock the pipe, then wait for the wake signal */ + mutex_unlock(&pipe->lock); + + while (test_bit(wakeBit, &pipe->flags)) { + if (wait_event_interruptible( + pipe->wake_queue, + !test_bit(wakeBit, &pipe->flags))) + return -ERESTARTSYS; + + if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags)) + return -EIO; + } + + /* Try to re-acquire the lock */ + if (mutex_lock_interruptible(&pipe->lock)) + return -ERESTARTSYS; + + /* Try the transfer again */ + continue; + } + mutex_unlock(&pipe->lock); + return ret; +} + +static ssize_t goldfish_pipe_read(struct file *filp, char __user *buffer, + size_t bufflen, loff_t *ppos) +{ + return goldfish_pipe_read_write(filp, buffer, bufflen, 0); +} + +static ssize_t goldfish_pipe_write(struct file *filp, + const char __user *buffer, size_t bufflen, + loff_t *ppos) +{ + return goldfish_pipe_read_write(filp, (char __user *)buffer, + bufflen, 1); +} + + +static unsigned int goldfish_pipe_poll(struct file *filp, poll_table *wait) +{ + struct goldfish_pipe *pipe = filp->private_data; + unsigned int mask = 0; + int status; + + mutex_lock(&pipe->lock); + + poll_wait(filp, &pipe->wake_queue, wait); + + status = goldfish_cmd_status(pipe, CMD_POLL); + + mutex_unlock(&pipe->lock); + + if (status & PIPE_POLL_IN) + mask |= POLLIN | POLLRDNORM; + + if (status & PIPE_POLL_OUT) + mask |= POLLOUT | POLLWRNORM; + + if (status & PIPE_POLL_HUP) + mask |= POLLHUP; + + if (test_bit(BIT_CLOSED_ON_HOST, &pipe->flags)) + mask |= POLLERR; + + return mask; +} + +static irqreturn_t goldfish_pipe_interrupt(int irq, void *dev_id) +{ + struct goldfish_pipe_dev *dev = dev_id; + unsigned long irq_flags; + int count = 0; + + /* We're going to read from the emulator a list of (channel,flags) + * pairs corresponding to the wake events that occured on each + * blocked pipe (i.e. channel). + */ + spin_lock_irqsave(&dev->lock, irq_flags); + for (;;) { + /* First read the channel, 0 means the end of the list */ + struct goldfish_pipe *pipe; + unsigned long wakes; + unsigned long channel = readl(dev->base + PIPE_REG_CHANNEL); + + if (channel == 0) + break; + + /* Convert channel to struct pipe pointer + read wake flags */ + wakes = readl(dev->base + PIPE_REG_WAKES); + pipe = (struct goldfish_pipe *)(ptrdiff_t)channel; + + /* Did the emulator just closed a pipe? */ + if (wakes & PIPE_WAKE_CLOSED) { + set_bit(BIT_CLOSED_ON_HOST, &pipe->flags); + wakes |= PIPE_WAKE_READ | PIPE_WAKE_WRITE; + } + if (wakes & PIPE_WAKE_READ) + clear_bit(BIT_WAKE_ON_READ, &pipe->flags); + if (wakes & PIPE_WAKE_WRITE) + clear_bit(BIT_WAKE_ON_WRITE, &pipe->flags); + + wake_up_interruptible(&pipe->wake_queue); + count++; + } + spin_unlock_irqrestore(&dev->lock, irq_flags); + + return (count == 0) ? IRQ_NONE : IRQ_HANDLED; +} + +/** + * goldfish_pipe_open - open a channel to the AVD + * @inode: inode of device + * @file: file struct of opener + * + * Create a new pipe link between the emulator and the use application. + * Each new request produces a new pipe. + * + * Note: we use the pipe ID as a mux. All goldfish emulations are 32bit + * right now so this is fine. A move to 64bit will need this addressing + */ +static int goldfish_pipe_open(struct inode *inode, struct file *file) +{ + struct goldfish_pipe *pipe; + struct goldfish_pipe_dev *dev = pipe_dev; + int32_t status; + + /* Allocate new pipe kernel object */ + pipe = kzalloc(sizeof(*pipe), GFP_KERNEL); + if (pipe == NULL) + return -ENOMEM; + + pipe->dev = dev; + mutex_init(&pipe->lock); + init_waitqueue_head(&pipe->wake_queue); + + /* + * Now, tell the emulator we're opening a new pipe. We use the + * pipe object's address as the channel identifier for simplicity. + */ + + status = goldfish_cmd_status(pipe, CMD_OPEN); + if (status < 0) { + kfree(pipe); + return status; + } + + /* All is done, save the pipe into the file's private data field */ + file->private_data = pipe; + return 0; +} + +static int goldfish_pipe_release(struct inode *inode, struct file *filp) +{ + struct goldfish_pipe *pipe = filp->private_data; + + /* The guest is closing the channel, so tell the emulator right now */ + goldfish_cmd(pipe, CMD_CLOSE); + kfree(pipe); + filp->private_data = NULL; + return 0; +} + +static const struct file_operations goldfish_pipe_fops = { + .owner = THIS_MODULE, + .read = goldfish_pipe_read, + .write = goldfish_pipe_write, + .poll = goldfish_pipe_poll, + .open = goldfish_pipe_open, + .release = goldfish_pipe_release, +}; + +static struct miscdevice goldfish_pipe_device = { + .minor = MISC_DYNAMIC_MINOR, + .name = "goldfish_pipe", + .fops = &goldfish_pipe_fops, +}; + +static int goldfish_pipe_probe(struct platform_device *pdev) +{ + int err; + struct resource *r; + struct goldfish_pipe_dev *dev = pipe_dev; + + /* not thread safe, but this should not happen */ + WARN_ON(dev->base != NULL); + + spin_lock_init(&dev->lock); + + r = platform_get_resource(pdev, IORESOURCE_MEM, 0); + if (r == NULL || resource_size(r) < PAGE_SIZE) { + dev_err(&pdev->dev, "can't allocate i/o page\n"); + return -EINVAL; + } + dev->base = devm_ioremap(&pdev->dev, r->start, PAGE_SIZE); + if (dev->base == NULL) { + dev_err(&pdev->dev, "ioremap failed\n"); + return -EINVAL; + } + + r = platform_get_resource(pdev, IORESOURCE_IRQ, 0); + if (r == NULL) { + err = -EINVAL; + goto error; + } + dev->irq = r->start; + + err = devm_request_irq(&pdev->dev, dev->irq, goldfish_pipe_interrupt, + IRQF_SHARED, "goldfish_pipe", dev); + if (err) { + dev_err(&pdev->dev, "unable to allocate IRQ\n"); + goto error; + } + + err = misc_register(&goldfish_pipe_device); + if (err) { + dev_err(&pdev->dev, "unable to register device\n"); + goto error; + } + setup_access_params_addr(pdev, dev); + return 0; + +error: + dev->base = NULL; + return err; +} + +static int goldfish_pipe_remove(struct platform_device *pdev) +{ + struct goldfish_pipe_dev *dev = pipe_dev; + misc_deregister(&goldfish_pipe_device); + dev->base = NULL; + return 0; +} + +static struct platform_driver goldfish_pipe = { + .probe = goldfish_pipe_probe, + .remove = goldfish_pipe_remove, + .driver = { + .name = "goldfish_pipe" + } +}; + +module_platform_driver(goldfish_pipe); +MODULE_AUTHOR("David Turner <digit@google.com>"); +MODULE_LICENSE("GPL"); |