diff options
Diffstat (limited to 'drivers/char/hvc_lguest.c')
| -rw-r--r-- | drivers/char/hvc_lguest.c | 177 |
1 files changed, 0 insertions, 177 deletions
diff --git a/drivers/char/hvc_lguest.c b/drivers/char/hvc_lguest.c deleted file mode 100644 index efccb215583..00000000000 --- a/drivers/char/hvc_lguest.c +++ /dev/null @@ -1,177 +0,0 @@ -/*D:300 - * The Guest console driver - * - * This is a trivial console driver: we use lguest's DMA mechanism to send - * bytes out, and register a DMA buffer to receive bytes in. It is assumed to - * be present and available from the very beginning of boot. - * - * Writing console drivers is one of the few remaining Dark Arts in Linux. - * Fortunately for us, the path of virtual consoles has been well-trodden by - * the PowerPC folks, who wrote "hvc_console.c" to generically support any - * virtual console. We use that infrastructure which only requires us to write - * the basic put_chars and get_chars functions and call the right register - * functions. - :*/ - -/*M:002 The console can be flooded: while the Guest is processing input the - * Host can send more. Buffering in the Host could alleviate this, but it is a - * difficult problem in general. :*/ -/* Copyright (C) 2006 Rusty Russell, IBM Corporation - * - * This program is free software; you can redistribute it and/or modify - * it under the terms of the GNU General Public License as published by - * the Free Software Foundation; either version 2 of the License, or - * (at your option) any later version. - * - * 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. - * - * You should have received a copy of the GNU General Public License - * along with this program; if not, write to the Free Software - * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA - */ -#include <linux/err.h> -#include <linux/init.h> -#include <linux/lguest_bus.h> -#include <asm/paravirt.h> -#include "hvc_console.h" - -/*D:340 This is our single console input buffer, with associated "struct - * lguest_dma" referring to it. Note the 0-terminated length array, and the - * use of physical address for the buffer itself. */ -static char inbuf[256]; -static struct lguest_dma cons_input = { .used_len = 0, - .addr[0] = __pa(inbuf), - .len[0] = sizeof(inbuf), - .len[1] = 0 }; - -/*D:310 The put_chars() callback is pretty straightforward. - * - * First we put the pointer and length in a "struct lguest_dma": we only have - * one pointer, so we set the second length to 0. Then we use SEND_DMA to send - * the data to (Host) buffers attached to the console key. Usually a device's - * key is a physical address within the device's memory, but because the - * console device doesn't have any associated physical memory, we use the - * LGUEST_CONSOLE_DMA_KEY constant (aka 0). */ -static int put_chars(u32 vtermno, const char *buf, int count) -{ - struct lguest_dma dma; - - /* FIXME: DMA buffers in a "struct lguest_dma" are not allowed - * to go over page boundaries. This never seems to happen, - * but if it did we'd need to fix this code. */ - dma.len[0] = count; - dma.len[1] = 0; - dma.addr[0] = __pa(buf); - - lguest_send_dma(LGUEST_CONSOLE_DMA_KEY, &dma); - /* We're expected to return the amount of data we wrote: all of it. */ - return count; -} - -/*D:350 get_chars() is the callback from the hvc_console infrastructure when - * an interrupt is received. - * - * Firstly we see if our buffer has been filled: if not, we return. The rest - * of the code deals with the fact that the hvc_console() infrastructure only - * asks us for 16 bytes at a time. We keep a "cons_offset" variable for - * partially-read buffers. */ -static int get_chars(u32 vtermno, char *buf, int count) -{ - static int cons_offset; - - /* Nothing left to see here... */ - if (!cons_input.used_len) - return 0; - - /* You want more than we have to give? Well, try wanting less! */ - if (cons_input.used_len - cons_offset < count) - count = cons_input.used_len - cons_offset; - - /* Copy across to their buffer and increment offset. */ - memcpy(buf, inbuf + cons_offset, count); - cons_offset += count; - - /* Finished? Zero offset, and reset cons_input so Host will use it - * again. */ - if (cons_offset == cons_input.used_len) { - cons_offset = 0; - cons_input.used_len = 0; - } - return count; -} -/*:*/ - -static struct hv_ops lguest_cons = { - .get_chars = get_chars, - .put_chars = put_chars, -}; - -/*D:320 Console drivers are initialized very early so boot messages can go - * out. At this stage, the console is output-only. Our driver checks we're a - * Guest, and if so hands hvc_instantiate() the console number (0), priority - * (0), and the struct hv_ops containing the put_chars() function. */ -static int __init cons_init(void) -{ - if (strcmp(pv_info.name, "lguest") != 0) - return 0; - - return hvc_instantiate(0, 0, &lguest_cons); -} -console_initcall(cons_init); - -/*D:370 To set up and manage our virtual console, we call hvc_alloc() and - * stash the result in the private pointer of the "struct lguest_device". - * Since we never remove the console device we never need this pointer again, - * but using ->private is considered good form, and you never know who's going - * to copy your driver. - * - * Once the console is set up, we bind our input buffer ready for input. */ -static int lguestcons_probe(struct lguest_device *lgdev) -{ - int err; - - /* The first argument of hvc_alloc() is the virtual console number, so - * we use zero. The second argument is the interrupt number. - * - * The third argument is a "struct hv_ops" containing the put_chars() - * and get_chars() pointers. The final argument is the output buffer - * size: we use 256 and expect the Host to have room for us to send - * that much. */ - lgdev->private = hvc_alloc(0, lgdev_irq(lgdev), &lguest_cons, 256); - if (IS_ERR(lgdev->private)) - return PTR_ERR(lgdev->private); - - /* We bind a single DMA buffer at key LGUEST_CONSOLE_DMA_KEY. - * "cons_input" is that statically-initialized global DMA buffer we saw - * above, and we also give the interrupt we want. */ - err = lguest_bind_dma(LGUEST_CONSOLE_DMA_KEY, &cons_input, 1, - lgdev_irq(lgdev)); - if (err) - printk("lguest console: failed to bind buffer.\n"); - return err; -} -/* Note the use of lgdev_irq() for the interrupt number. We tell hvc_alloc() - * to expect input when this interrupt is triggered, and then tell - * lguest_bind_dma() that is the interrupt to send us when input comes in. */ - -/*D:360 From now on the console driver follows standard Guest driver form: - * register_lguest_driver() registers the device type and probe function, and - * the probe function sets up the device. - * - * The standard "struct lguest_driver": */ -static struct lguest_driver lguestcons_drv = { - .name = "lguestcons", - .owner = THIS_MODULE, - .device_type = LGUEST_DEVICE_T_CONSOLE, - .probe = lguestcons_probe, -}; - -/* The standard init function */ -static int __init hvc_lguest_init(void) -{ - return register_lguest_driver(&lguestcons_drv); -} -module_init(hvc_lguest_init); |