[POWERPC] Xserve cpu-meter driver

This is a small driver for the Xserve G5 CPU-meter blue LEDs on the
front-panel. It might work on the Xserve G4 as well though that was
not tested. It's pretty basic and could use some improvements if
somebody cares doing them. :)

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

4 files changed, 627 insertions, 1 deletions

diff --git a/drivers/macintosh/Kconfig b/drivers/macintosh/Kconfig
index 7f8477d..92ccee8 100644
--- a/drivers/macintosh/Kconfig
+++ b/drivers/macintosh/Kconfig
@@ -228,4 +228,11 @@ config ANSLCD
 	tristate "Support for ANS LCD display"
 	depends on ADB_CUDA && PPC_PMAC
 
+config PMAC_RACKMETER
+	tristate "Support for Apple XServe front panel LEDs"
+	depends on PPC_PMAC
+	help
+	  This driver procides some support to control the front panel
+          blue LEDs "vu-meter" of the XServer macs.
+
 endmenu
diff --git a/drivers/macintosh/Makefile b/drivers/macintosh/Makefile
index b53d45f..2dfc3f4 100644
--- a/drivers/macintosh/Makefile
+++ b/drivers/macintosh/Makefile
@@ -42,3 +42,4 @@ obj-$(CONFIG_WINDFARM_PM112)	+= windfarm_pm112.o windfarm_smu_sat.o \
 				   windfarm_smu_sensors.o \
 				   windfarm_max6690_sensor.o \
 				   windfarm_lm75_sensor.o windfarm_pid.o
+obj-$(CONFIG_PMAC_RACKMETER)	+= rack-meter.o
diff --git a/drivers/macintosh/rack-meter.c b/drivers/macintosh/rack-meter.c
new file mode 100644
index 0000000..f1b6f56
--- /dev/null
+++ b/drivers/macintosh/rack-meter.c
@@ -0,0 +1,612 @@
+/*
+ * RackMac vu-meter driver
+ *
+ * (c) Copyright 2006 Benjamin Herrenschmidt, IBM Corp.
+ *                    <benh@kernel.crashing.org>
+ *
+ * Released under the term of the GNU GPL v2.
+ *
+ * Support the CPU-meter LEDs of the Xserve G5
+ *
+ * TODO: Implement PWM to do variable intensity and provide userland
+ * interface for fun. Also, the CPU-meter could be made nicer by being
+ * a bit less "immediate" but giving instead a more average load over
+ * time. Patches welcome :-)
+ *
+ */
+#undef DEBUG
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include <linux/dma-mapping.h>
+#include <linux/kernel_stat.h>
+
+#include <asm/io.h>
+#include <asm/prom.h>
+#include <asm/machdep.h>
+#include <asm/pmac_feature.h>
+#include <asm/dbdma.h>
+#include <asm/dbdma.h>
+#include <asm/macio.h>
+#include <asm/keylargo.h>
+
+/* Number of samples in a sample buffer */
+#define SAMPLE_COUNT		256
+
+/* CPU meter sampling rate in ms */
+#define CPU_SAMPLING_RATE	250
+
+struct rackmeter_dma {
+	struct dbdma_cmd	cmd[4]			____cacheline_aligned;
+	u32			mark			____cacheline_aligned;
+	u32			buf1[SAMPLE_COUNT]	____cacheline_aligned;
+	u32			buf2[SAMPLE_COUNT]	____cacheline_aligned;
+} ____cacheline_aligned;
+
+struct rackmeter_cpu {
+	struct work_struct	sniffer;
+	cputime64_t		prev_wall;
+	cputime64_t		prev_idle;
+	int			zero;
+} ____cacheline_aligned;
+
+struct rackmeter {
+	struct macio_dev		*mdev;
+	unsigned int			irq;
+	struct device_node		*i2s;
+	u8				*ubuf;
+	struct dbdma_regs __iomem	*dma_regs;
+	void __iomem			*i2s_regs;
+	dma_addr_t			dma_buf_p;
+	struct rackmeter_dma		*dma_buf_v;
+	int				stale_irq;
+	struct rackmeter_cpu		cpu[2];
+	int				paused;
+	struct mutex			sem;
+};
+
+/* To be set as a tunable */
+static int rackmeter_ignore_nice;
+
+/* This GPIO is whacked by the OS X driver when initializing */
+#define RACKMETER_MAGIC_GPIO	0x78
+
+/* This is copied from cpufreq_ondemand, maybe we should put it in
+ * a common header somewhere
+ */
+static inline cputime64_t get_cpu_idle_time(unsigned int cpu)
+{
+	cputime64_t retval;
+
+	retval = cputime64_add(kstat_cpu(cpu).cpustat.idle,
+			kstat_cpu(cpu).cpustat.iowait);
+
+	if (rackmeter_ignore_nice)
+		retval = cputime64_add(retval, kstat_cpu(cpu).cpustat.nice);
+
+	return retval;
+}
+
+static void rackmeter_setup_i2s(struct rackmeter *rm)
+{
+	struct macio_chip *macio = rm->mdev->bus->chip;
+
+	/* First whack magic GPIO */
+	pmac_call_feature(PMAC_FTR_WRITE_GPIO, NULL, RACKMETER_MAGIC_GPIO, 5);
+
+
+	/* Call feature code to enable the sound channel and the proper
+	 * clock sources
+	 */
+	pmac_call_feature(PMAC_FTR_SOUND_CHIP_ENABLE, rm->i2s, 0, 1);
+
+	/* Power i2s and stop i2s clock. We whack MacIO FCRs directly for now.
+	 * This is a bit racy, thus we should add new platform functions to
+	 * handle that. snd-aoa needs that too
+	 */
+	MACIO_BIS(KEYLARGO_FCR1, KL1_I2S0_ENABLE);
+	MACIO_BIC(KEYLARGO_FCR1, KL1_I2S0_CLK_ENABLE_BIT);
+	(void)MACIO_IN32(KEYLARGO_FCR1);
+	udelay(10);
+
+	/* Then setup i2s. For now, we use the same magic value that
+	 * the OS X driver seems to use. We might want to play around
+	 * with the clock divisors later
+	 */
+	out_le32(rm->i2s_regs + 0x10, 0x01fa0000);
+	(void)in_le32(rm->i2s_regs + 0x10);
+	udelay(10);
+
+	/* Fully restart i2s*/
+	MACIO_BIS(KEYLARGO_FCR1, KL1_I2S0_CELL_ENABLE |
+		  KL1_I2S0_CLK_ENABLE_BIT);
+	(void)MACIO_IN32(KEYLARGO_FCR1);
+	udelay(10);
+}
+
+static void rackmeter_set_default_pattern(struct rackmeter *rm)
+{
+	int i;
+
+	for (i = 0; i < 16; i++) {
+		if (i < 8)
+			rm->ubuf[i] = (i & 1) * 255;
+		else
+			rm->ubuf[i] = ((~i) & 1) * 255;
+	}
+}
+
+static void rackmeter_do_pause(struct rackmeter *rm, int pause)
+{
+	struct rackmeter_dma *rdma = rm->dma_buf_v;
+
+	pr_debug("rackmeter: %s\n", pause ? "paused" : "started");
+
+	rm->paused = pause;
+	if (pause) {
+		DBDMA_DO_STOP(rm->dma_regs);
+		return;
+	}
+	memset(rdma->buf1, 0, SAMPLE_COUNT & sizeof(u32));
+	memset(rdma->buf2, 0, SAMPLE_COUNT & sizeof(u32));
+
+	rm->dma_buf_v->mark = 0;
+
+	mb();
+	out_le32(&rm->dma_regs->cmdptr_hi, 0);
+	out_le32(&rm->dma_regs->cmdptr, rm->dma_buf_p);
+	out_le32(&rm->dma_regs->control, (RUN << 16) | RUN);
+}
+
+static void rackmeter_setup_dbdma(struct rackmeter *rm)
+{
+	struct rackmeter_dma *db = rm->dma_buf_v;
+	struct dbdma_cmd *cmd = db->cmd;
+
+	/* Make sure dbdma is reset */
+	DBDMA_DO_RESET(rm->dma_regs);
+
+	pr_debug("rackmeter: mark offset=0x%lx\n",
+		 offsetof(struct rackmeter_dma, mark));
+	pr_debug("rackmeter: buf1 offset=0x%lx\n",
+		 offsetof(struct rackmeter_dma, buf1));
+	pr_debug("rackmeter: buf2 offset=0x%lx\n",
+		 offsetof(struct rackmeter_dma, buf2));
+
+	/* Prepare 4 dbdma commands for the 2 buffers */
+	memset(cmd, 0, 4 * sizeof(struct dbdma_cmd));
+	st_le16(&cmd->req_count, 4);
+	st_le16(&cmd->command, STORE_WORD | INTR_ALWAYS | KEY_SYSTEM);
+	st_le32(&cmd->phy_addr, rm->dma_buf_p +
+		offsetof(struct rackmeter_dma, mark));
+	st_le32(&cmd->cmd_dep, 0x02000000);
+	cmd++;
+
+	st_le16(&cmd->req_count, SAMPLE_COUNT * 4);
+	st_le16(&cmd->command, OUTPUT_MORE);
+	st_le32(&cmd->phy_addr, rm->dma_buf_p +
+		offsetof(struct rackmeter_dma, buf1));
+	cmd++;
+
+	st_le16(&cmd->req_count, 4);
+	st_le16(&cmd->command, STORE_WORD | INTR_ALWAYS | KEY_SYSTEM);
+	st_le32(&cmd->phy_addr, rm->dma_buf_p +
+		offsetof(struct rackmeter_dma, mark));
+	st_le32(&cmd->cmd_dep, 0x01000000);
+	cmd++;
+
+	st_le16(&cmd->req_count, SAMPLE_COUNT * 4);
+	st_le16(&cmd->command, OUTPUT_MORE | BR_ALWAYS);
+	st_le32(&cmd->phy_addr, rm->dma_buf_p +
+		offsetof(struct rackmeter_dma, buf2));
+	st_le32(&cmd->cmd_dep, rm->dma_buf_p);
+
+	rackmeter_do_pause(rm, 0);
+}
+
+static void rackmeter_do_timer(void *data)
+{
+	struct rackmeter *rm = data;
+	unsigned int cpu = smp_processor_id();
+	struct rackmeter_cpu *rcpu = &rm->cpu[cpu];
+	cputime64_t cur_jiffies, total_idle_ticks;
+	unsigned int total_ticks, idle_ticks;
+	int i, offset, load, cumm, pause;
+
+	cur_jiffies = jiffies64_to_cputime64(get_jiffies_64());
+	total_ticks = (unsigned int)cputime64_sub(cur_jiffies,
+						  rcpu->prev_wall);
+	rcpu->prev_wall = cur_jiffies;
+
+	total_idle_ticks = get_cpu_idle_time(cpu);
+	idle_ticks = (unsigned int) cputime64_sub(total_idle_ticks,
+				rcpu->prev_idle);
+	rcpu->prev_idle = total_idle_ticks;
+
+	/* We do a very dumb calculation to update the LEDs for now,
+	 * we'll do better once we have actual PWM implemented
+	 */
+	load = (9 * (total_ticks - idle_ticks)) / total_ticks;
+
+	offset = cpu << 3;
+	cumm = 0;
+	for (i = 0; i < 8; i++) {
+		u8 ub = (load > i) ? 0xff : 0;
+		rm->ubuf[i + offset] = ub;
+		cumm |= ub;
+	}
+	rcpu->zero = (cumm == 0);
+
+	/* Now check if LEDs are all 0, we can stop DMA */
+	pause = (rm->cpu[0].zero && rm->cpu[1].zero);
+	if (pause != rm->paused) {
+		mutex_lock(&rm->sem);
+		pause = (rm->cpu[0].zero && rm->cpu[1].zero);
+		rackmeter_do_pause(rm, pause);
+		mutex_unlock(&rm->sem);
+	}
+	schedule_delayed_work_on(cpu, &rcpu->sniffer,
+				 msecs_to_jiffies(CPU_SAMPLING_RATE));
+}
+
+static void __devinit rackmeter_init_cpu_sniffer(struct rackmeter *rm)
+{
+	unsigned int cpu;
+
+	/* This driver works only with 1 or 2 CPUs numbered 0 and 1,
+	 * but that's really all we have on Apple Xserve. It doesn't
+	 * play very nice with CPU hotplug neither but we don't do that
+	 * on those machines yet
+	 */
+
+	INIT_WORK(&rm->cpu[0].sniffer, rackmeter_do_timer, rm);
+	INIT_WORK(&rm->cpu[1].sniffer, rackmeter_do_timer, rm);
+
+	for_each_online_cpu(cpu) {
+		struct rackmeter_cpu *rcpu;
+
+		if (cpu > 1)
+			continue;
+		rcpu = &rm->cpu[cpu];;
+		rcpu->prev_idle = get_cpu_idle_time(cpu);
+		rcpu->prev_wall = jiffies64_to_cputime64(get_jiffies_64());
+		schedule_delayed_work_on(cpu, &rm->cpu[cpu].sniffer,
+					 msecs_to_jiffies(CPU_SAMPLING_RATE));
+	}
+}
+
+static void __devexit rackmeter_stop_cpu_sniffer(struct rackmeter *rm)
+{
+	cancel_rearming_delayed_work(&rm->cpu[0].sniffer);
+	cancel_rearming_delayed_work(&rm->cpu[1].sniffer);
+}
+
+static int rackmeter_setup(struct rackmeter *rm)
+{
+	pr_debug("rackmeter: setting up i2s..\n");
+	rackmeter_setup_i2s(rm);
+
+	pr_debug("rackmeter: setting up default pattern..\n");
+	rackmeter_set_default_pattern(rm);
+
+	pr_debug("rackmeter: setting up dbdma..\n");
+	rackmeter_setup_dbdma(rm);
+
+	pr_debug("rackmeter: start CPU measurements..\n");
+	rackmeter_init_cpu_sniffer(rm);
+
+	printk(KERN_INFO "RackMeter initialized\n");
+
+	return 0;
+}
+
+/*  XXX FIXME: No PWM yet, this is 0/1 */
+static u32 rackmeter_calc_sample(struct rackmeter *rm, unsigned int index)
+{
+	int led;
+	u32 sample = 0;
+
+	for (led = 0; led < 16; led++) {
+		sample >>= 1;
+		sample |= ((rm->ubuf[led] >= 0x80) << 15);
+	}
+	return (sample << 17) | (sample >> 15);
+}
+
+static irqreturn_t rackmeter_irq(int irq, void *arg)
+{
+	struct rackmeter *rm = arg;
+	struct rackmeter_dma *db = rm->dma_buf_v;
+	unsigned int mark, i;
+	u32 *buf;
+
+	/* Flush PCI buffers with an MMIO read. Maybe we could actually
+	 * check the status one day ... in case things go wrong, though
+	 * this never happened to me
+	 */
+	(void)in_le32(&rm->dma_regs->status);
+
+	/* Make sure the CPU gets us in order */
+	rmb();
+
+	/* Read mark */
+	mark = db->mark;
+	if (mark != 1 && mark != 2) {
+		printk(KERN_WARNING "rackmeter: Incorrect DMA mark 0x%08x\n",
+		       mark);
+		/* We allow for 3 errors like that (stale DBDMA irqs) */
+		if (++rm->stale_irq > 3) {
+			printk(KERN_ERR "rackmeter: Too many errors,"
+			       " stopping DMA\n");
+			DBDMA_DO_RESET(rm->dma_regs);
+		}
+		return IRQ_HANDLED;
+	}
+
+	/* Next buffer we need to fill is mark value */
+	buf = mark == 1 ? db->buf1 : db->buf2;
+
+	/* Fill it now. This routine converts the 8 bits depth sample array
+	 * into the PWM bitmap for each LED.
+	 */
+	for (i = 0; i < SAMPLE_COUNT; i++)
+		buf[i] = rackmeter_calc_sample(rm, i);
+
+
+	return IRQ_HANDLED;
+}
+
+static int __devinit rackmeter_probe(struct macio_dev* mdev,
+				     const struct of_device_id *match)
+{
+	struct device_node *i2s = NULL, *np = NULL;
+	struct rackmeter *rm = NULL;
+	struct resource ri2s, rdma;
+	int rc = -ENODEV;
+
+	pr_debug("rackmeter_probe()\n");
+
+	/* Get i2s-a node */
+	while ((i2s = of_get_next_child(mdev->ofdev.node, i2s)) != NULL)
+	       if (strcmp(i2s->name, "i2s-a") == 0)
+		       break;
+	if (i2s == NULL) {
+		pr_debug("  i2s-a child not found\n");
+		goto bail;
+	}
+	/* Get lightshow or virtual sound */
+	while ((np = of_get_next_child(i2s, np)) != NULL) {
+	       if (strcmp(np->name, "lightshow") == 0)
+		       break;
+	       if ((strcmp(np->name, "sound") == 0) &&
+		   get_property(np, "virtual", NULL) != NULL)
+		       break;
+	}
+	if (np == NULL) {
+		pr_debug("  lightshow or sound+virtual child not found\n");
+		goto bail;
+	}
+
+	/* Create and initialize our instance data */
+	rm = kzalloc(sizeof(struct rackmeter), GFP_KERNEL);
+	if (rm == NULL) {
+		printk(KERN_ERR "rackmeter: failed to allocate memory !\n");
+		rc = -ENOMEM;
+		goto bail_release;
+	}
+	rm->mdev = mdev;
+	rm->i2s = i2s;
+	mutex_init(&rm->sem);
+	dev_set_drvdata(&mdev->ofdev.dev, rm);
+	/* Check resources availability. We need at least resource 0 and 1 */
+#if 0 /* Use that when i2s-a is finally an mdev per-se */
+	if (macio_resource_count(mdev) < 2 || macio_irq_count(mdev) < 2) {
+		printk(KERN_ERR
+		       "rackmeter: found match but lacks resources: %s"
+		       " (%d resources, %d interrupts)\n",
+		       mdev->ofdev.node->full_name);
+		rc = -ENXIO;
+		goto bail_free;
+	}
+	if (macio_request_resources(mdev, "rackmeter")) {
+		printk(KERN_ERR
+		       "rackmeter: failed to request resources: %s\n",
+		       mdev->ofdev.node->full_name);
+		rc = -EBUSY;
+		goto bail_free;
+	}
+	rm->irq = macio_irq(mdev, 1);
+#else
+	rm->irq = irq_of_parse_and_map(i2s, 1);
+	if (rm->irq == NO_IRQ ||
+	    of_address_to_resource(i2s, 0, &ri2s) ||
+	    of_address_to_resource(i2s, 1, &rdma)) {
+		printk(KERN_ERR
+		       "rackmeter: found match but lacks resources: %s",
+		       mdev->ofdev.node->full_name);
+		rc = -ENXIO;
+		goto bail_free;
+	}
+#endif
+
+	pr_debug("  i2s @0x%08x\n", (unsigned int)ri2s.start);
+	pr_debug("  dma @0x%08x\n", (unsigned int)rdma.start);
+	pr_debug("  irq %d\n", rm->irq);
+
+	rm->ubuf = (u8 *)__get_free_page(GFP_KERNEL);
+	if (rm->ubuf == NULL) {
+		printk(KERN_ERR
+		       "rackmeter: failed to allocate samples page !\n");
+		rc = -ENOMEM;
+		goto bail_release;
+	}
+
+	rm->dma_buf_v = dma_alloc_coherent(&macio_get_pci_dev(mdev)->dev,
+					   sizeof(struct rackmeter_dma),
+					   &rm->dma_buf_p, GFP_KERNEL);
+	if (rm->dma_buf_v == NULL) {
+		printk(KERN_ERR
+		       "rackmeter: failed to allocate dma buffer !\n");
+		rc = -ENOMEM;
+		goto bail_free_samples;
+	}
+#if 0
+	rm->i2s_regs = ioremap(macio_resource_start(mdev, 0), 0x1000);
+#else
+	rm->i2s_regs = ioremap(ri2s.start, 0x1000);
+#endif
+	if (rm->i2s_regs == NULL) {
+		printk(KERN_ERR
+		       "rackmeter: failed to map i2s registers !\n");
+		rc = -ENXIO;
+		goto bail_free_dma;
+	}
+#if 0
+	rm->dma_regs = ioremap(macio_resource_start(mdev, 1), 0x100);
+#else
+	rm->dma_regs = ioremap(rdma.start, 0x100);
+#endif
+	if (rm->dma_regs == NULL) {
+		printk(KERN_ERR
+		       "rackmeter: failed to map dma registers !\n");
+		rc = -ENXIO;
+		goto bail_unmap_i2s;
+	}
+
+	rc = rackmeter_setup(rm);
+	if (rc) {
+		printk(KERN_ERR
+		       "rackmeter: failed to initialize !\n");
+		rc = -ENXIO;
+		goto bail_unmap_dma;
+	}
+
+	rc = request_irq(rm->irq, rackmeter_irq, 0, "rackmeter", rm);
+	if (rc != 0) {
+		printk(KERN_ERR
+		       "rackmeter: failed to request interrupt !\n");
+		goto bail_stop_dma;
+	}
+	of_node_put(np);
+	return 0;
+
+ bail_stop_dma:
+	DBDMA_DO_RESET(rm->dma_regs);
+ bail_unmap_dma:
+	iounmap(rm->dma_regs);
+ bail_unmap_i2s:
+	iounmap(rm->i2s_regs);
+ bail_free_dma:
+	dma_free_coherent(&macio_get_pci_dev(mdev)->dev,
+			  sizeof(struct rackmeter_dma),
+			  rm->dma_buf_v, rm->dma_buf_p);
+ bail_free_samples:
+	free_page((unsigned long)rm->ubuf);
+ bail_release:
+#if 0
+	macio_release_resources(mdev);
+#endif
+ bail_free:
+	kfree(rm);
+ bail:
+	of_node_put(i2s);
+	of_node_put(np);
+	dev_set_drvdata(&mdev->ofdev.dev, NULL);
+	return rc;
+}
+
+static int __devexit rackmeter_remove(struct macio_dev* mdev)
+{
+	struct rackmeter *rm = dev_get_drvdata(&mdev->ofdev.dev);
+
+	/* Stop CPU sniffer timer & work queues */
+	rackmeter_stop_cpu_sniffer(rm);
+
+	/* Clear reference to private data */
+	dev_set_drvdata(&mdev->ofdev.dev, NULL);
+
+	/* Stop/reset dbdma */
+	DBDMA_DO_RESET(rm->dma_regs);
+
+	/* Release the IRQ */
+	free_irq(rm->irq, rm);
+
+	/* Unmap registers */
+	iounmap(rm->dma_regs);
+	iounmap(rm->i2s_regs);
+
+	/* Free DMA */
+	dma_free_coherent(&macio_get_pci_dev(mdev)->dev,
+			  sizeof(struct rackmeter_dma),
+			  rm->dma_buf_v, rm->dma_buf_p);
+
+	/* Free samples */
+	free_page((unsigned long)rm->ubuf);
+
+#if 0
+	/* Release resources */
+	macio_release_resources(mdev);
+#endif
+
+	/* Get rid of me */
+	kfree(rm);
+
+	return 0;
+}
+
+static int rackmeter_shutdown(struct macio_dev* mdev)
+{
+	struct rackmeter *rm = dev_get_drvdata(&mdev->ofdev.dev);
+
+	if (rm == NULL)
+		return -ENODEV;
+
+	/* Stop CPU sniffer timer & work queues */
+	rackmeter_stop_cpu_sniffer(rm);
+
+	/* Stop/reset dbdma */
+	DBDMA_DO_RESET(rm->dma_regs);
+
+	return 0;
+}
+
+static struct of_device_id rackmeter_match[] = {
+	{ .name = "i2s" },
+	{ }
+};
+
+static struct macio_driver rackmeter_drv = {
+	.name = "rackmeter",
+	.owner = THIS_MODULE,
+	.match_table = rackmeter_match,
+	.probe = rackmeter_probe,
+	.remove = rackmeter_remove,
+	.shutdown = rackmeter_shutdown,
+};
+
+
+static int __init rackmeter_init(void)
+{
+	pr_debug("rackmeter_init()\n");
+
+	return macio_register_driver(&rackmeter_drv);
+}
+
+static void __exit rackmeter_exit(void)
+{
+	pr_debug("rackmeter_exit()\n");
+
+	macio_unregister_driver(&rackmeter_drv);
+}
+
+module_init(rackmeter_init);
+module_exit(rackmeter_exit);
+
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Benjamin Herrenschmidt <benh@kernel.crashing.org>");
+MODULE_DESCRIPTION("RackMeter: Support vu-meter on XServe front panel");
diff --git a/include/asm-powerpc/dbdma.h b/include/asm-powerpc/dbdma.h
index 8973565..e23f07e 100644
--- a/include/asm-powerpc/dbdma.h
+++ b/include/asm-powerpc/dbdma.h
@@ -95,7 +95,13 @@ struct dbdma_cmd {
 #define DBDMA_DO_STOP(regs) do {				\
 	out_le32(&((regs)->control), (RUN|FLUSH)<<16);		\
 	while(in_le32(&((regs)->status)) & (ACTIVE|FLUSH))	\
-		;						\
+		; \
+} while(0)
+
+#define DBDMA_DO_RESET(regs) do {				\
+	out_le32(&((regs)->control), (ACTIVE|DEAD|WAKE|FLUSH|PAUSE|RUN)<<16);\
+	while(in_le32(&((regs)->status)) & (RUN)) \
+		; \
 } while(0)
 
 #endif /* _ASM_DBDMA_H_ */