隨着在presentation on Free Electrons和ALSA driver tutorial找到的信息，都是由@Mali提到的，我終於成功地建立我的簡單的驅動程序。我將發佈下面的代碼，也許它對其他人有用。它直接基於Linux內核源代碼中的sound/drivers/dummy.c驅動程序。其中很重要的一點是，從
snd_pcm_lib_preallocate_pages_for_all(pcm,
SNDRV_DMA_TYPE_CONTINUOUS,
snd_dma_continuous_data(GFP_KERNEL),
0, 64*1024);
改變snd_card_fmplayer_pcm緩衝區預分配到
snd_pcm_lib_preallocate_pages_for_all(pcm,
SNDRV_DMA_TYPE_DEV, /* This type is veeery important! */
NULL,
MAX_BUFFER_SIZE, MAX_BUFFER_SIZE);
沒有這個變化，駕駛員基本工作，但播放數據幾乎類似於實際樣本，似乎是由緩存效應引起的。
該模塊仍然需要內核定時器（無論是系統時間還是高分辨率定時器），因爲硬件未配置爲在播放時生成中斷。如果它被用於某些嚴重的應用程序，這應該是固定的。
再見，
菲利普
/*
* ALSA soundcard kernel module to access the fmplayer FPGA core.
*
* This code is mostly based on the ALSA dummy soundcard in
* sound/drivers/dummy.c written by Jaroslav Kysela <[email protected]>
*
* 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/init.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/jiffies.h>
#include <linux/slab.h>
#include <linux/time.h>
#include <linux/wait.h>
#include <linux/hrtimer.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/control.h>
#include <sound/tlv.h>
#include <sound/pcm.h>
#include <sound/rawmidi.h>
#include <sound/info.h>
#include <sound/initval.h>
#include <linux/io.h>
#include <linux/delay.h>
#include <asm/io.h>
#include <linux/dma-mapping.h>
MODULE_AUTHOR("Philipp Burch <[email protected]>");
MODULE_DESCRIPTION("FM player sound card");
MODULE_LICENSE("GPL");
MODULE_SUPPORTED_DEVICE("{{ALSA,fmplayer}}");
// FPGA core -------------------------------------------------------------------
// Slave register address map (byte address offsets):
// 0x00 RW STAT_CTRL
// Bit 0: Set to enable the block. If cleared, the output is forced
// to all-zeros.
// 0x04 RW MEMSTART
// Starting address of the sample memory (16-bit aligned). A write
// to this register resets and disables the player. When read,
// this register contains the address from where the next
// sample will be read. It can be used as progress information,
// so that one half of the memory can be overwritten by new
// data after it has been played.
// 0x08 RW MEMEND
// Last address of the sample memory, after which the address
// counter wraps back to MEMSTART.
// 0x0c RW SAMPRATE
// Update value for the sampling rate DDS. This should be
// selected according to the nominal sampling rate of the
// data to play.
#define REG_BASE 0xc0003000
#define REGNUM_RW_STAT_CTRL 0
#define REGNUM_RW_MEMSTART 1
#define REGNUM_RW_MEMEND 2
#define REGNUM_RW_SAMPRATE 3
#define REG_SIZE_BYTES 32
#define DDS_CLK_FREQ 100000000
#define DDS_WIDTH 32ULL
// -----------------------------------------------------------------------------
#define MAX_PCM_DEVICES 1
#define MAX_PCM_SUBSTREAMS 1
#define MAX_MIDI_DEVICES 0
/* defaults */
#define MAX_BUFFER_SIZE (64*1024)
#define MIN_PERIOD_SIZE 64
#define MAX_PERIOD_SIZE 1024
#define USE_FORMATS (SNDRV_PCM_FMTBIT_S16_LE)
#define USE_RATE (SNDRV_PCM_RATE_CONTINUOUS | SNDRV_PCM_RATE_8000_48000)
#define USE_RATE_MIN 1000
#define USE_RATE_MAX 192000
#define USE_CHANNELS_MIN 2
#define USE_CHANNELS_MAX 2
#define USE_PERIODS_MIN 2
#define USE_PERIODS_MAX 1024
static int index[SNDRV_CARDS] = SNDRV_DEFAULT_IDX; /* Index 0-MAX */
static char *id[SNDRV_CARDS] = SNDRV_DEFAULT_STR; /* ID for this card */
static bool enable[SNDRV_CARDS] = {1, [1 ... (SNDRV_CARDS - 1)] = 0};
#ifdef CONFIG_HIGH_RES_TIMERS
static bool hrtimer = 1;
#endif
module_param_array(index, int, NULL, 0444);
MODULE_PARM_DESC(index, "Index value for fmplayer.");
module_param_array(id, charp, NULL, 0444);
MODULE_PARM_DESC(id, "ID string for fmplayer.");
module_param_array(enable, bool, NULL, 0444);
MODULE_PARM_DESC(enable, "Enable this fmplayer.");
#ifdef CONFIG_HIGH_RES_TIMERS
module_param(hrtimer, bool, 0644);
MODULE_PARM_DESC(hrtimer, "Use hrtimer as the timer source.");
#endif
static struct platform_device *devices[SNDRV_CARDS];
struct fmplayer_timer_ops {
int (*create)(struct snd_pcm_substream *);
void (*free)(struct snd_pcm_substream *);
int (*prepare)(struct snd_pcm_substream *);
int (*start)(struct snd_pcm_substream *);
int (*stop)(struct snd_pcm_substream *);
snd_pcm_uframes_t (*pointer)(struct snd_pcm_substream *);
};
struct snd_fmplayer {
struct snd_card *card;
struct fmplayer_model *model;
struct snd_pcm *pcm;
struct snd_pcm_hardware pcm_hw;
spinlock_t mixer_lock;
u32 *iomem;
struct snd_kcontrol *cd_volume_ctl;
struct snd_kcontrol *cd_switch_ctl;
const struct fmplayer_timer_ops *timer_ops;
};
/*
* system timer interface
*/
struct fmplayer_systimer_pcm {
spinlock_t lock;
struct timer_list timer;
unsigned long base_time;
unsigned int frac_pos; /* fractional sample position (based HZ) */
unsigned int frac_period_rest;
unsigned int frac_buffer_size; /* buffer_size * HZ */
unsigned int frac_period_size; /* period_size * HZ */
unsigned int rate;
int elapsed;
struct snd_pcm_substream *substream;
};
static void fmplayer_systimer_rearm(struct fmplayer_systimer_pcm *dpcm)
{
mod_timer(&dpcm->timer, jiffies +
(dpcm->frac_period_rest + dpcm->rate - 1)/dpcm->rate);
}
static void fmplayer_systimer_update(struct fmplayer_systimer_pcm *dpcm)
{
unsigned long delta;
delta = jiffies - dpcm->base_time;
if (!delta)
return;
dpcm->base_time += delta;
delta *= dpcm->rate;
dpcm->frac_pos += delta;
while (dpcm->frac_pos >= dpcm->frac_buffer_size)
dpcm->frac_pos -= dpcm->frac_buffer_size;
while (dpcm->frac_period_rest <= delta) {
dpcm->elapsed++;
dpcm->frac_period_rest += dpcm->frac_period_size;
}
dpcm->frac_period_rest -= delta;
}
static int fmplayer_systimer_start(struct snd_pcm_substream *substream)
{
struct fmplayer_systimer_pcm *dpcm = substream->runtime->private_data;
spin_lock(&dpcm->lock);
dpcm->base_time = jiffies;
fmplayer_systimer_rearm(dpcm);
spin_unlock(&dpcm->lock);
return 0;
}
static int fmplayer_systimer_stop(struct snd_pcm_substream *substream)
{
struct fmplayer_systimer_pcm *dpcm = substream->runtime->private_data;
spin_lock(&dpcm->lock);
del_timer(&dpcm->timer);
spin_unlock(&dpcm->lock);
return 0;
}
static int fmplayer_systimer_prepare(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct fmplayer_systimer_pcm *dpcm = runtime->private_data;
dpcm->frac_pos = 0;
dpcm->rate = runtime->rate;
dpcm->frac_buffer_size = runtime->buffer_size * HZ;
dpcm->frac_period_size = runtime->period_size * HZ;
dpcm->frac_period_rest = dpcm->frac_period_size;
dpcm->elapsed = 0;
return 0;
}
static void fmplayer_systimer_callback(unsigned long data)
{
struct fmplayer_systimer_pcm *dpcm = (struct fmplayer_systimer_pcm *)data;
unsigned long flags;
int elapsed = 0;
spin_lock_irqsave(&dpcm->lock, flags);
fmplayer_systimer_update(dpcm);
fmplayer_systimer_rearm(dpcm);
elapsed = dpcm->elapsed;
dpcm->elapsed = 0;
spin_unlock_irqrestore(&dpcm->lock, flags);
if (elapsed)
snd_pcm_period_elapsed(dpcm->substream);
}
static snd_pcm_uframes_t
fmplayer_systimer_pointer(struct snd_pcm_substream *substream)
{
struct fmplayer_systimer_pcm *dpcm = substream->runtime->private_data;
snd_pcm_uframes_t pos;
spin_lock(&dpcm->lock);
fmplayer_systimer_update(dpcm);
pos = dpcm->frac_pos/HZ;
spin_unlock(&dpcm->lock);
return pos;
}
static int fmplayer_systimer_create(struct snd_pcm_substream *substream)
{
struct fmplayer_systimer_pcm *dpcm;
dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
if (!dpcm)
return -ENOMEM;
substream->runtime->private_data = dpcm;
setup_timer(&dpcm->timer, fmplayer_systimer_callback,
(unsigned long) dpcm);
spin_lock_init(&dpcm->lock);
dpcm->substream = substream;
return 0;
}
static void fmplayer_systimer_free(struct snd_pcm_substream *substream)
{
kfree(substream->runtime->private_data);
}
static struct fmplayer_timer_ops fmplayer_systimer_ops = {
.create = fmplayer_systimer_create,
.free = fmplayer_systimer_free,
.prepare = fmplayer_systimer_prepare,
.start = fmplayer_systimer_start,
.stop = fmplayer_systimer_stop,
.pointer = fmplayer_systimer_pointer,
};
#ifdef CONFIG_HIGH_RES_TIMERS
/*
* hrtimer interface
*/
struct fmplayer_hrtimer_pcm {
ktime_t base_time;
ktime_t period_time;
atomic_t running;
struct hrtimer timer;
struct tasklet_struct tasklet;
struct snd_pcm_substream *substream;
};
static void fmplayer_hrtimer_pcm_elapsed(unsigned long priv)
{
struct fmplayer_hrtimer_pcm *dpcm = (struct fmplayer_hrtimer_pcm *)priv;
if (atomic_read(&dpcm->running))
snd_pcm_period_elapsed(dpcm->substream);
}
static enum hrtimer_restart fmplayer_hrtimer_callback(struct hrtimer *timer)
{
struct fmplayer_hrtimer_pcm *dpcm;
dpcm = container_of(timer, struct fmplayer_hrtimer_pcm, timer);
if (!atomic_read(&dpcm->running))
return HRTIMER_NORESTART;
tasklet_schedule(&dpcm->tasklet);
hrtimer_forward_now(timer, dpcm->period_time);
return HRTIMER_RESTART;
}
static int fmplayer_hrtimer_start(struct snd_pcm_substream *substream)
{
struct fmplayer_hrtimer_pcm *dpcm = substream->runtime->private_data;
dpcm->base_time = hrtimer_cb_get_time(&dpcm->timer);
hrtimer_start(&dpcm->timer, dpcm->period_time, HRTIMER_MODE_REL);
atomic_set(&dpcm->running, 1);
return 0;
}
static int fmplayer_hrtimer_stop(struct snd_pcm_substream *substream)
{
struct fmplayer_hrtimer_pcm *dpcm = substream->runtime->private_data;
atomic_set(&dpcm->running, 0);
hrtimer_cancel(&dpcm->timer);
return 0;
}
static inline void fmplayer_hrtimer_sync(struct fmplayer_hrtimer_pcm *dpcm)
{
tasklet_kill(&dpcm->tasklet);
}
static snd_pcm_uframes_t
fmplayer_hrtimer_pointer(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct fmplayer_hrtimer_pcm *dpcm = runtime->private_data;
u64 delta;
u32 pos;
delta = ktime_us_delta(hrtimer_cb_get_time(&dpcm->timer),
dpcm->base_time);
delta = div_u64(delta * runtime->rate + 999999, 1000000);
div_u64_rem(delta, runtime->buffer_size, &pos);
return pos;
}
static int fmplayer_hrtimer_prepare(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct fmplayer_hrtimer_pcm *dpcm = runtime->private_data;
unsigned int period, rate;
long sec;
unsigned long nsecs;
fmplayer_hrtimer_sync(dpcm);
period = runtime->period_size;
rate = runtime->rate;
sec = period/rate;
period %= rate;
nsecs = div_u64((u64)period * 1000000000UL + rate - 1, rate);
dpcm->period_time = ktime_set(sec, nsecs);
return 0;
}
static int fmplayer_hrtimer_create(struct snd_pcm_substream *substream)
{
struct fmplayer_hrtimer_pcm *dpcm;
dpcm = kzalloc(sizeof(*dpcm), GFP_KERNEL);
if (!dpcm)
return -ENOMEM;
substream->runtime->private_data = dpcm;
hrtimer_init(&dpcm->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
dpcm->timer.function = fmplayer_hrtimer_callback;
dpcm->substream = substream;
atomic_set(&dpcm->running, 0);
tasklet_init(&dpcm->tasklet, fmplayer_hrtimer_pcm_elapsed,
(unsigned long)dpcm);
return 0;
}
static void fmplayer_hrtimer_free(struct snd_pcm_substream *substream)
{
struct fmplayer_hrtimer_pcm *dpcm = substream->runtime->private_data;
fmplayer_hrtimer_sync(dpcm);
kfree(dpcm);
}
static struct fmplayer_timer_ops fmplayer_hrtimer_ops = {
.create = fmplayer_hrtimer_create,
.free = fmplayer_hrtimer_free,
.prepare = fmplayer_hrtimer_prepare,
.start = fmplayer_hrtimer_start,
.stop = fmplayer_hrtimer_stop,
.pointer = fmplayer_hrtimer_pointer,
};
#endif /* CONFIG_HIGH_RES_TIMERS */
/*
* PCM interface
*/
static int fmplayer_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
struct snd_fmplayer *fmplayer = snd_pcm_substream_chip(substream);
switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
case SNDRV_PCM_TRIGGER_RESUME:
iowrite32(1, &(fmplayer->iomem[REGNUM_RW_STAT_CTRL]));
return fmplayer->timer_ops->start(substream);
case SNDRV_PCM_TRIGGER_STOP:
case SNDRV_PCM_TRIGGER_SUSPEND:
iowrite32(0, &(fmplayer->iomem[REGNUM_RW_STAT_CTRL]));
return fmplayer->timer_ops->stop(substream);
}
return -EINVAL;
}
static int fmplayer_pcm_prepare(struct snd_pcm_substream *substream)
{
struct snd_fmplayer *fmplayer = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
u64 extrate = (u64)(runtime->rate) << DDS_WIDTH;
u32 dds_val = (u32)div_u64(extrate, (u64)(DDS_CLK_FREQ));
u32 dma_startaddr = runtime->dma_addr;
u32 dma_endaddr = dma_startaddr + (runtime->buffer_size-1)*4;
/* Configure the sample rate. */
iowrite32(dds_val, &(fmplayer->iomem[REGNUM_RW_SAMPRATE]));
/* Configure the DMA addresses. */
iowrite32(dma_startaddr, &(fmplayer->iomem[REGNUM_RW_MEMSTART]));
iowrite32(dma_endaddr, &(fmplayer->iomem[REGNUM_RW_MEMEND]));
printk(KERN_DEBUG "DMA range: 0x%08x .. 0x%08x\n", dma_startaddr, dma_endaddr);
printk(KERN_DEBUG "DMA size: %d bytes\n", runtime->dma_bytes);
printk(KERN_DEBUG "Buffer size: %d frames\n", (int)runtime->buffer_size);
printk(KERN_DEBUG "Using %d periods of %d frames\n",
runtime->periods, (int)runtime->period_size);
printk(KERN_DEBUG "Rate: %d Hz\n", runtime->rate);
printk(KERN_DEBUG "Channels: %d\n", runtime->channels);
printk(KERN_DEBUG "%d bits/sample, %d bits/frame\n",
runtime->sample_bits, runtime->frame_bits);
printk(KERN_DEBUG "Access: %d\n", runtime->access);
printk(KERN_DEBUG "Format: %d\n", runtime->format);
printk(KERN_DEBUG "Subformat: 0x%08x\n", runtime->subformat);
return fmplayer->timer_ops->prepare(substream);
}
static snd_pcm_uframes_t fmplayer_pcm_pointer(struct snd_pcm_substream *substream)
{
struct snd_fmplayer *fmplayer = snd_pcm_substream_chip(substream);
u32 dma_startaddr = substream->runtime->dma_addr;
u32 dma_curraddr = ioread32(&(fmplayer->iomem[REGNUM_RW_MEMSTART]));
return (dma_curraddr - dma_startaddr)/4;
}
static struct snd_pcm_hardware fmplayer_pcm_hardware = {
.info = (SNDRV_PCM_INFO_MMAP |
SNDRV_PCM_INFO_INTERLEAVED |
SNDRV_PCM_INFO_MMAP_VALID),
.formats = USE_FORMATS,
.rates = USE_RATE,
.rate_min = USE_RATE_MIN,
.rate_max = USE_RATE_MAX,
.channels_min = USE_CHANNELS_MIN,
.channels_max = USE_CHANNELS_MAX,
.buffer_bytes_max = MAX_BUFFER_SIZE,
.period_bytes_min = MIN_PERIOD_SIZE,
.period_bytes_max = MAX_PERIOD_SIZE,
.periods_min = USE_PERIODS_MIN,
.periods_max = USE_PERIODS_MAX,
.fifo_size = 0,
};
static int fmplayer_pcm_hw_params(struct snd_pcm_substream *substream,
struct snd_pcm_hw_params *hw_params)
{
return snd_pcm_lib_malloc_pages(substream, params_buffer_bytes(hw_params));
}
static int fmplayer_pcm_hw_free(struct snd_pcm_substream *substream)
{
struct snd_fmplayer *fmplayer = snd_pcm_substream_chip(substream);
/* Make sure that no more memory is accessed by the DMA. */
iowrite32(0, &(fmplayer->iomem[REGNUM_RW_STAT_CTRL]));
return snd_pcm_lib_free_pages(substream);
}
static int fmplayer_pcm_open(struct snd_pcm_substream *substream)
{
struct snd_fmplayer *fmplayer = snd_pcm_substream_chip(substream);
struct snd_pcm_runtime *runtime = substream->runtime;
int err;
fmplayer->timer_ops = &fmplayer_systimer_ops;
#ifdef CONFIG_HIGH_RES_TIMERS
if (hrtimer)
fmplayer->timer_ops = &fmplayer_hrtimer_ops;
#endif
err = fmplayer->timer_ops->create(substream);
if (err < 0)
return err;
runtime->hw = fmplayer->pcm_hw;
return 0;
}
static int fmplayer_pcm_close(struct snd_pcm_substream *substream)
{
struct snd_fmplayer *fmplayer = snd_pcm_substream_chip(substream);
fmplayer->timer_ops->free(substream);
return 0;
}
static struct snd_pcm_ops fmplayer_pcm_ops = {
.open = fmplayer_pcm_open,
.close = fmplayer_pcm_close,
.ioctl = snd_pcm_lib_ioctl,
.hw_params = fmplayer_pcm_hw_params,
.hw_free = fmplayer_pcm_hw_free,
.prepare = fmplayer_pcm_prepare,
.trigger = fmplayer_pcm_trigger,
.pointer = fmplayer_pcm_pointer,
};
static int snd_card_fmplayer_pcm(struct snd_fmplayer *fmplayer, int device,
int substreams)
{
struct snd_pcm *pcm;
int err;
err = snd_pcm_new(fmplayer->card, "FM player PCM", device,
substreams, substreams, &pcm);
if (err < 0)
return err;
fmplayer->pcm = pcm;
snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &fmplayer_pcm_ops);
snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, NULL);
pcm->private_data = fmplayer;
pcm->info_flags = 0;
strcpy(pcm->name, "FM player PCM");
snd_pcm_lib_preallocate_pages_for_all(pcm,
SNDRV_DMA_TYPE_DEV, /* This type is veeery important! */
NULL,
MAX_BUFFER_SIZE, MAX_BUFFER_SIZE);
return 0;
}
static int snd_fmplayer_probe(struct platform_device *devptr)
{
struct snd_card *card;
struct snd_fmplayer *fmplayer;
struct resource *res;
int err;
int dev = devptr->id;
err = snd_card_new(&devptr->dev, index[dev], id[dev], THIS_MODULE,
sizeof(struct snd_fmplayer), &card);
if (err < 0)
return err;
fmplayer = card->private_data;
fmplayer->card = card;
/* Allocate and remap I/O memory for hardware (FPGA) connection. */
res = request_mem_region(REG_BASE, REG_SIZE_BYTES, "fmplayer");
if (res == NULL) {
snd_card_free(card);
return -ENOMEM;
}
fmplayer->iomem = ioremap(REG_BASE, REG_SIZE_BYTES);
if (fmplayer->iomem == NULL) {
release_mem_region(REG_BASE, REG_SIZE_BYTES);
snd_card_free(card);
return -ENOMEM;
}
err = snd_card_fmplayer_pcm(fmplayer, 0, 1);
if (err < 0)
goto __nodev;
fmplayer->pcm_hw = fmplayer_pcm_hardware;
strcpy(card->driver, "fmplayer");
strcpy(card->shortname, "fmplayer");
sprintf(card->longname, "fmplayer %i", dev + 1);
err = snd_card_register(card);
if (err == 0) {
platform_set_drvdata(devptr, card);
return 0;
}
__nodev:
snd_card_free(card);
return err;
}
static int snd_fmplayer_remove(struct platform_device *devptr)
{
/* Release and unmap the I/O memory. */
struct snd_card *card = platform_get_drvdata(devptr);
if (card != NULL) {
struct snd_fmplayer *fmplayer = card->private_data;
if (fmplayer != NULL) {
/* Make sure that the driver is stopped. */
iowrite32(0, &(fmplayer->iomem[REGNUM_RW_STAT_CTRL]));
iounmap(fmplayer->iomem);
release_mem_region(REG_BASE, REG_SIZE_BYTES);
}
}
snd_card_free(platform_get_drvdata(devptr));
return 0;
}
#define SND_FMPLAYER_DRIVER "snd_fmplayer"
static struct platform_driver snd_fmplayer_driver = {
.probe = snd_fmplayer_probe,
.remove = snd_fmplayer_remove,
.driver = {
.name = SND_FMPLAYER_DRIVER,
.pm = NULL,
},
};
static void snd_fmplayer_unregister_all(void)
{
int i;
for (i = 0; i < ARRAY_SIZE(devices); ++i)
platform_device_unregister(devices[i]);
platform_driver_unregister(&snd_fmplayer_driver);
}
static int __init alsa_card_fmplayer_init(void)
{
int i, cards, err;
err = platform_driver_register(&snd_fmplayer_driver);
if (err < 0)
return err;
cards = 0;
for (i = 0; i < SNDRV_CARDS; i++) {
struct platform_device *device;
if (! enable[i])
continue;
device = platform_device_register_simple(SND_FMPLAYER_DRIVER,
i, NULL, 0);
if (IS_ERR(device))
continue;
if (!platform_get_drvdata(device)) {
platform_device_unregister(device);
continue;
}
devices[i] = device;
cards++;
}
if (!cards) {
#ifdef MODULE
printk(KERN_ERR "FM player soundcard not found or device busy\n");
#endif
snd_fmplayer_unregister_all();
return -ENODEV;
}
return 0;
}
static void __exit alsa_card_fmplayer_exit(void)
{
snd_fmplayer_unregister_all();
}
module_init(alsa_card_fmplayer_init)
module_exit(alsa_card_fmplayer_exit)
感謝，這正是我一直在尋找！當然，我仍然對其他意見和建議開放，但我想我會與我現在擁有的:)相處:) –
我不能再做更多的事情，祝你好運:) – Mali
明白了！再次感謝:) –