Subject: [PATCH] powerpc: Xserve cpu-meter LEDs

From: Benjamin Herrenschmidt <[email-masked]>
Date: Tue, 11 Jul 2006 15:04:30 +1000

This is a very preliminary driver for the front-panel CPU-meter blue
LEDs of the Xserve. I've tested it on an Xserve G5, though it should
work on the old G4 ones as well.

It's a bit rough at the moment. I want to add a proper PWM to the DMA
sample buffers in order to have a per-LED intensity value so we can make
smoother/funnier things with the LEDs (right now it's 0 or 0xff -> off
or on) and I want to add a userland interface that allows to mmap the
"user buffer" (which contains per-LED 8 bits samples containing an
intensity) in which case the in-kernel CPU-meter control would get
disabled and userland would be free to do whatever it wants.

Also, the CPU-meter thing itself is also a bit simplistic, one may want
to transform the load value through a nice curve and 
But that's a first cut and I won't have time to hack on it for some time
now (at least til end of august) so if somebody else wants to play with
it, feel free and send me patches :)

Index: linux-irq-work/drivers/macintosh/rack-meter.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-irq-work/drivers/macintosh/rack-meter.c	2006-07-11 14:58:22.000000000 +1000
@@ -0,0 +1,539 @@
+#define 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;
+} ____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];
+};
+
+/* 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_do_feature_call(PMAC_FTR_WRITE_GPIO, NULL,
+			     RACKMETER_MAGIC_GPIO, 5);
+
+
+	/* Call feature code to enable the sound channel and the proper
+	 * clock sources
+	 */
+	pmac_do_feature_call(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_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);
+
+	db->mark = 0;
+
+	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);
+
+	/* Program the DBDMA and start it */
+	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_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;
+
+	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 = (8 * (total_ticks - idle_ticks)) / total_ticks;
+
+	offset = cpu << 3;
+	for (i = 0; i < 8; i++)
+		rm->ubuf[i + offset] = (load > i) ? 0xff : 0;
+
+	schedule_delayed_work_on(cpu, &rcpu->sniffer,
+				 msecs_to_jiffies(CPU_SAMPLING_RATE));
+}
+
+static void 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
+	 */
+	for_each_online_cpu(cpu) {
+		struct rackmeter_cpu *rcpu;
+
+		if (cpu > 1)
+			continue;
+		rcpu = &rm->cpu[cpu];;
+		INIT_WORK(&rcpu->sniffer, rackmeter_do_timer, rm);
+		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 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 pt_regs *regs)
+{
+	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 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;
+	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 rackmeter_remove(struct macio_dev* mdev)
+{
+	struct rackmeter *rm = dev_get_drvdata(&mdev->ofdev.dev);
+
+	/* 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* dev)
+{
+	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 <[email-masked]>");
+MODULE_DESCRIPTION("RackMeter: Support vu-meter on XServe front panel");
Index: linux-irq-work/drivers/macintosh/Kconfig
===================================================================
--- linux-irq-work.orig/drivers/macintosh/Kconfig	2006-07-10 16:12:38.000000000 +1000
+++ linux-irq-work/drivers/macintosh/Kconfig	2006-07-10 16:45:50.000000000 +1000
@@ -218,4 +218,11 @@
 	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
Index: linux-irq-work/drivers/macintosh/Makefile
===================================================================
--- linux-irq-work.orig/drivers/macintosh/Makefile	2006-07-10 16:12:38.000000000 +1000
+++ linux-irq-work/drivers/macintosh/Makefile	2006-07-10 16:45:50.000000000 +1000
@@ -42,3 +42,4 @@
 				   windfarm_smu_sensors.o \
 				   windfarm_max6690_sensor.o \
 				   windfarm_lm75_sensor.o windfarm_pid.o
+obj-$(CONFIG_PMAC_RACKMETER)	+= rack-meter.o
Index: linux-irq-work/include/asm-powerpc/dbdma.h
===================================================================
--- linux-irq-work.orig/include/asm-powerpc/dbdma.h	2006-07-10 16:12:38.000000000 +1000
+++ linux-irq-work/include/asm-powerpc/dbdma.h	2006-07-10 16:45:50.000000000 +1000
@@ -95,7 +95,13 @@
 #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_ */