sound: oss: sh_dac_audio timer fixes.
Magnus Damm [Fri, 15 May 2009 03:07:17 +0000 (12:07 +0900)]
This patch modifies sh_dac_audio in the following ways:

- use high resolution timer instead of TMU1
- fix cpu/dac.h include
- add future rewrite comment

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>

sound/oss/Kconfig
sound/oss/sh_dac_audio.c

index 1ca7427..bcf2a06 100644 (file)
@@ -561,7 +561,7 @@ endif       # SOUND_OSS
 
 config SOUND_SH_DAC_AUDIO
        tristate "SuperH DAC audio support"
-       depends on CPU_SH3
+       depends on CPU_SH3 && HIGH_RES_TIMERS
 
 config SOUND_SH_DAC_AUDIO_CHANNEL
        int "DAC channel"
index 78cfb66..b2ed875 100644 (file)
 #include <linux/sound.h>
 #include <linux/soundcard.h>
 #include <linux/interrupt.h>
+#include <linux/hrtimer.h>
 #include <asm/io.h>
 #include <asm/uaccess.h>
 #include <asm/irq.h>
 #include <asm/delay.h>
 #include <asm/clock.h>
-#include <asm/cpu/dac.h>
-#include <asm/cpu/timer.h>
+#include <cpu/dac.h>
 #include <asm/machvec.h>
 #include <mach/hp6xx.h>
 #include <asm/hd64461.h>
 
 #define MODNAME "sh_dac_audio"
 
-#define TMU_TOCR_INIT  0x00
-
-#define TMU1_TCR_INIT  0x0020  /* Clock/4, rising edge; interrupt on */
-#define TMU1_TSTR_INIT  0x02   /* Bit to turn on TMU1 */
-
 #define BUFFER_SIZE 48000
 
 static int rate;
 static int empty;
 static char *data_buffer, *buffer_begin, *buffer_end;
 static int in_use, device_major;
+static struct hrtimer hrtimer;
+static ktime_t wakeups_per_second;
 
 static void dac_audio_start_timer(void)
 {
-       u8 tstr;
-
-       tstr = ctrl_inb(TMU_TSTR);
-       tstr |= TMU1_TSTR_INIT;
-       ctrl_outb(tstr, TMU_TSTR);
+       hrtimer_start(&hrtimer, wakeups_per_second, HRTIMER_MODE_REL);
 }
 
 static void dac_audio_stop_timer(void)
 {
-       u8 tstr;
-
-       tstr = ctrl_inb(TMU_TSTR);
-       tstr &= ~TMU1_TSTR_INIT;
-       ctrl_outb(tstr, TMU_TSTR);
+       hrtimer_cancel(&hrtimer);
 }
 
 static void dac_audio_reset(void)
@@ -77,38 +66,30 @@ static void dac_audio_sync(void)
 static void dac_audio_start(void)
 {
        if (mach_is_hp6xx()) {
-               u16 v = inw(HD64461_GPADR);
+               u16 v = __raw_readw(HD64461_GPADR);
                v &= ~HD64461_GPADR_SPEAKER;
-               outw(v, HD64461_GPADR);
+               __raw_writew(v, HD64461_GPADR);
        }
 
        sh_dac_enable(CONFIG_SOUND_SH_DAC_AUDIO_CHANNEL);
-       ctrl_outw(TMU1_TCR_INIT, TMU1_TCR);
 }
 static void dac_audio_stop(void)
 {
        dac_audio_stop_timer();
 
        if (mach_is_hp6xx()) {
-               u16 v = inw(HD64461_GPADR);
+               u16 v = __raw_readw(HD64461_GPADR);
                v |= HD64461_GPADR_SPEAKER;
-               outw(v, HD64461_GPADR);
+               __raw_writew(v, HD64461_GPADR);
        }
 
-       sh_dac_output(0, CONFIG_SOUND_SH_DAC_AUDIO_CHANNEL);
+       sh_dac_output(0, CONFIG_SOUND_SH_DAC_AUDIO_CHANNEL);
        sh_dac_disable(CONFIG_SOUND_SH_DAC_AUDIO_CHANNEL);
 }
 
 static void dac_audio_set_rate(void)
 {
-       unsigned long interval;
-       struct clk *clk;
-
-       clk = clk_get(NULL, "module_clk");
-       interval = (clk_get_rate(clk) / 4) / rate;
-       clk_put(clk);
-       ctrl_outl(interval, TMU1_TCOR);
-       ctrl_outl(interval, TMU1_TCNT);
+       wakeups_per_second = ktime_set(0, 1000000000 / rate);
 }
 
 static int dac_audio_ioctl(struct inode *inode, struct file *file,
@@ -265,32 +246,26 @@ const struct file_operations dac_audio_fops = {
       .release =       dac_audio_release,
 };
 
-static irqreturn_t timer1_interrupt(int irq, void *dev)
+static enum hrtimer_restart sh_dac_audio_timer(struct hrtimer *handle)
 {
-       unsigned long timer_status;
-
-       timer_status = ctrl_inw(TMU1_TCR);
-       timer_status &= ~0x100;
-       ctrl_outw(timer_status, TMU1_TCR);
-
        if (!empty) {
                sh_dac_output(*buffer_begin, CONFIG_SOUND_SH_DAC_AUDIO_CHANNEL);
                buffer_begin++;
 
                if (buffer_begin == data_buffer + BUFFER_SIZE)
                        buffer_begin = data_buffer;
-               if (buffer_begin == buffer_end) {
+               if (buffer_begin == buffer_end)
                        empty = 1;
-                       dac_audio_stop_timer();
-               }
        }
-       return IRQ_HANDLED;
+
+       if (!empty)
+               hrtimer_start(&hrtimer, wakeups_per_second, HRTIMER_MODE_REL);
+
+       return HRTIMER_NORESTART;
 }
 
 static int __init dac_audio_init(void)
 {
-       int retval;
-
        if ((device_major = register_sound_dsp(&dac_audio_fops, -1)) < 0) {
                printk(KERN_ERR "Cannot register dsp device");
                return device_major;
@@ -306,21 +281,25 @@ static int __init dac_audio_init(void)
        rate = 8000;
        dac_audio_set_rate();
 
-       retval =
-           request_irq(TIMER1_IRQ, timer1_interrupt, IRQF_DISABLED, MODNAME, 0);
-       if (retval < 0) {
-               printk(KERN_ERR "sh_dac_audio: IRQ %d request failed\n",
-                      TIMER1_IRQ);
-               return retval;
-       }
+       /* Today: High Resolution Timer driven DAC playback.
+        * The timer callback gets called once per sample. Ouch.
+        *
+        * Future: A much better approach would be to use the
+        * SH7720 CMT+DMAC+DAC hardware combination like this:
+        * - Program sample rate using CMT0 or CMT1
+        * - Program DMAC to use CMT for timing and output to DAC
+        * - Play sound using DMAC, let CPU sleep.
+        * - While at it, rewrite this driver to use ALSA.
+        */
+
+       hrtimer_init(&hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
+       hrtimer.function = sh_dac_audio_timer;
 
        return 0;
 }
 
 static void __exit dac_audio_exit(void)
 {
-       free_irq(TIMER1_IRQ, 0);
-
        unregister_sound_dsp(device_major);
        kfree((void *)data_buffer);
 }