drivers/macintosh/rack-meter.c - third_party/linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * RackMac vu-meter driver
  *
  * (c) Copyright 2006 Benjamin Herrenschmidt, IBM Corp.
  *                    <benh@kernel.crashing.org>
  *
  * 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/slab.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 <linux/of_address.h>
 #include <linux/of_irq.h>

 #include <asm/io.h>
 #include <asm/machdep.h>
 #include <asm/pmac_feature.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 delayed_work	sniffer;
 	struct rackmeter	*rm;
 	u64			prev_wall;
 	u64			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 u64 get_cpu_idle_time(unsigned int cpu)
 {
 	struct kernel_cpustat *kcpustat = &kcpustat_cpu(cpu);
 	u64 retval;

 	retval = kcpustat->cpustat[CPUTIME_IDLE] +
 		 kcpustat->cpustat[CPUTIME_IOWAIT];

 	if (rackmeter_ignore_nice)
 		retval += kcpustat_field(kcpustat, CPUTIME_NICE, cpu);

 	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, sizeof(rdma->buf1));
 	memset(rdma->buf2, 0, sizeof(rdma->buf2));

 	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%zx\n",
 		 offsetof(struct rackmeter_dma, mark));
 	pr_debug("rackmeter: buf1 offset=0x%zx\n",
 		 offsetof(struct rackmeter_dma, buf1));
 	pr_debug("rackmeter: buf2 offset=0x%zx\n",
 		 offsetof(struct rackmeter_dma, buf2));

 	/* Prepare 4 dbdma commands for the 2 buffers */
 	memset(cmd, 0, 4 * sizeof(struct dbdma_cmd));
 	cmd->req_count = cpu_to_le16(4);
 	cmd->command = cpu_to_le16(STORE_WORD | INTR_ALWAYS | KEY_SYSTEM);
 	cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
 		offsetof(struct rackmeter_dma, mark));
 	cmd->cmd_dep = cpu_to_le32(0x02000000);
 	cmd++;

 	cmd->req_count = cpu_to_le16(SAMPLE_COUNT * 4);
 	cmd->command = cpu_to_le16(OUTPUT_MORE);
 	cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
 		offsetof(struct rackmeter_dma, buf1));
 	cmd++;

 	cmd->req_count = cpu_to_le16(4);
 	cmd->command = cpu_to_le16(STORE_WORD | INTR_ALWAYS | KEY_SYSTEM);
 	cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
 		offsetof(struct rackmeter_dma, mark));
 	cmd->cmd_dep = cpu_to_le32(0x01000000);
 	cmd++;

 	cmd->req_count = cpu_to_le16(SAMPLE_COUNT * 4);
 	cmd->command = cpu_to_le16(OUTPUT_MORE | BR_ALWAYS);
 	cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
 		offsetof(struct rackmeter_dma, buf2));
 	cmd->cmd_dep = cpu_to_le32(rm->dma_buf_p);

 	rackmeter_do_pause(rm, 0);
 }

 static void rackmeter_do_timer(struct work_struct *work)
 {
 	struct rackmeter_cpu *rcpu =
 		container_of(work, struct rackmeter_cpu, sniffer.work);
 	struct rackmeter *rm = rcpu->rm;
 	unsigned int cpu = smp_processor_id();
 	u64 cur_nsecs, total_idle_nsecs;
 	u64 total_nsecs, idle_nsecs;
 	int i, offset, load, cumm, pause;

 	cur_nsecs = jiffies64_to_nsecs(get_jiffies_64());
 	total_nsecs = cur_nsecs - rcpu->prev_wall;
 	rcpu->prev_wall = cur_nsecs;

 	total_idle_nsecs = get_cpu_idle_time(cpu);
 	idle_nsecs = total_idle_nsecs - rcpu->prev_idle;
 	idle_nsecs = min(idle_nsecs, total_nsecs);
 	rcpu->prev_idle = total_idle_nsecs;

 	/* We do a very dumb calculation to update the LEDs for now,
 	 * we'll do better once we have actual PWM implemented
 	 */
 	load = div64_u64(9 * (total_nsecs - idle_nsecs), total_nsecs);

 	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 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
 	 */

 	rm->cpu[0].rm = rm;
 	INIT_DELAYED_WORK(&rm->cpu[0].sniffer, rackmeter_do_timer);
 	rm->cpu[1].rm = rm;
 	INIT_DELAYED_WORK(&rm->cpu[1].sniffer, rackmeter_do_timer);

 	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_nsecs(get_jiffies_64());
 		schedule_delayed_work_on(cpu, &rm->cpu[cpu].sniffer,
 					 msecs_to_jiffies(CPU_SAMPLING_RATE));
 	}
 }

 static void rackmeter_stop_cpu_sniffer(struct rackmeter *rm)
 {
 	cancel_delayed_work_sync(&rm->cpu[0].sniffer);
 	cancel_delayed_work_sync(&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 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 */
 	for_each_child_of_node(mdev->ofdev.dev.of_node, i2s)
 		if (of_node_name_eq(i2s, "i2s-a"))
 			break;

 	if (i2s == NULL) {
 		pr_debug("  i2s-a child not found\n");
 		goto bail;
 	}
 	/* Get lightshow or virtual sound */
 	for_each_child_of_node(i2s, np) {
 	       if (of_node_name_eq(np, "lightshow"))
 		       break;
 	       if (of_node_name_eq(np, "sound") &&
 		   of_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(*rm), 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: %pOF"
 		       " (%d resources, %d interrupts)\n",
 		       mdev->ofdev.dev.of_node);
 		rc = -ENXIO;
 		goto bail_free;
 	}
 	if (macio_request_resources(mdev, "rackmeter")) {
 		printk(KERN_ERR
 		       "rackmeter: failed to request resources: %pOF\n",
 		       mdev->ofdev.dev.of_node);
 		rc = -EBUSY;
 		goto bail_free;
 	}
 	rm->irq = macio_irq(mdev, 1);
 #else
 	rm->irq = irq_of_parse_and_map(i2s, 1);
 	if (!rm->irq ||
 	    of_address_to_resource(i2s, 0, &ri2s) ||
 	    of_address_to_resource(i2s, 1, &rdma)) {
 		printk(KERN_ERR
 		       "rackmeter: found match but lacks resources: %pOF",
 		       mdev->ofdev.dev.of_node);
 		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);

 	/* 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 const struct of_device_id rackmeter_match[] = {
 	{ .name = "i2s" },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, rackmeter_match);

 static struct macio_driver rackmeter_driver = {
 	.driver = {
 		.name = "rackmeter",
 		.owner = THIS_MODULE,
 		.of_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_driver);
 }

 static void __exit rackmeter_exit(void)
 {
 	pr_debug("rackmeter_exit()\n");

 	macio_unregister_driver(&rackmeter_driver);
 }

 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");
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* RackMac vu-meter driver
	*
	* (c) Copyright 2006 Benjamin Herrenschmidt, IBM Corp.
	* <benh@kernel.crashing.org>
	*
	* 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/slab.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 <linux/of_address.h>
	#include <linux/of_irq.h>

	#include <asm/io.h>
	#include <asm/machdep.h>
	#include <asm/pmac_feature.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 delayed_work sniffer;
	struct rackmeter *rm;
	u64 prev_wall;
	u64 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 u64 get_cpu_idle_time(unsigned int cpu)
	{
	struct kernel_cpustat *kcpustat = &kcpustat_cpu(cpu);
	u64 retval;

	retval = kcpustat->cpustat[CPUTIME_IDLE] +
	kcpustat->cpustat[CPUTIME_IOWAIT];

	if (rackmeter_ignore_nice)
	retval += kcpustat_field(kcpustat, CPUTIME_NICE, cpu);

	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, sizeof(rdma->buf1));
	memset(rdma->buf2, 0, sizeof(rdma->buf2));

	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%zx\n",
	offsetof(struct rackmeter_dma, mark));
	pr_debug("rackmeter: buf1 offset=0x%zx\n",
	offsetof(struct rackmeter_dma, buf1));
	pr_debug("rackmeter: buf2 offset=0x%zx\n",
	offsetof(struct rackmeter_dma, buf2));

	/* Prepare 4 dbdma commands for the 2 buffers */
	memset(cmd, 0, 4 * sizeof(struct dbdma_cmd));
	cmd->req_count = cpu_to_le16(4);
	cmd->command = cpu_to_le16(STORE_WORD \| INTR_ALWAYS \| KEY_SYSTEM);
	cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
	offsetof(struct rackmeter_dma, mark));
	cmd->cmd_dep = cpu_to_le32(0x02000000);
	cmd++;

	cmd->req_count = cpu_to_le16(SAMPLE_COUNT * 4);
	cmd->command = cpu_to_le16(OUTPUT_MORE);
	cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
	offsetof(struct rackmeter_dma, buf1));
	cmd++;

	cmd->req_count = cpu_to_le16(4);
	cmd->command = cpu_to_le16(STORE_WORD \| INTR_ALWAYS \| KEY_SYSTEM);
	cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
	offsetof(struct rackmeter_dma, mark));
	cmd->cmd_dep = cpu_to_le32(0x01000000);
	cmd++;

	cmd->req_count = cpu_to_le16(SAMPLE_COUNT * 4);
	cmd->command = cpu_to_le16(OUTPUT_MORE \| BR_ALWAYS);
	cmd->phy_addr = cpu_to_le32(rm->dma_buf_p +
	offsetof(struct rackmeter_dma, buf2));
	cmd->cmd_dep = cpu_to_le32(rm->dma_buf_p);

	rackmeter_do_pause(rm, 0);
	}

	static void rackmeter_do_timer(struct work_struct *work)
	{
	struct rackmeter_cpu *rcpu =
	container_of(work, struct rackmeter_cpu, sniffer.work);
	struct rackmeter *rm = rcpu->rm;
	unsigned int cpu = smp_processor_id();
	u64 cur_nsecs, total_idle_nsecs;
	u64 total_nsecs, idle_nsecs;
	int i, offset, load, cumm, pause;

	cur_nsecs = jiffies64_to_nsecs(get_jiffies_64());
	total_nsecs = cur_nsecs - rcpu->prev_wall;
	rcpu->prev_wall = cur_nsecs;

	total_idle_nsecs = get_cpu_idle_time(cpu);
	idle_nsecs = total_idle_nsecs - rcpu->prev_idle;
	idle_nsecs = min(idle_nsecs, total_nsecs);
	rcpu->prev_idle = total_idle_nsecs;

	/* We do a very dumb calculation to update the LEDs for now,
	* we'll do better once we have actual PWM implemented
	*/
	load = div64_u64(9 * (total_nsecs - idle_nsecs), total_nsecs);

	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 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
	*/

	rm->cpu[0].rm = rm;
	INIT_DELAYED_WORK(&rm->cpu[0].sniffer, rackmeter_do_timer);
	rm->cpu[1].rm = rm;
	INIT_DELAYED_WORK(&rm->cpu[1].sniffer, rackmeter_do_timer);

	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_nsecs(get_jiffies_64());
	schedule_delayed_work_on(cpu, &rm->cpu[cpu].sniffer,
	msecs_to_jiffies(CPU_SAMPLING_RATE));
	}
	}

	static void rackmeter_stop_cpu_sniffer(struct rackmeter *rm)
	{
	cancel_delayed_work_sync(&rm->cpu[0].sniffer);
	cancel_delayed_work_sync(&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 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 */
	for_each_child_of_node(mdev->ofdev.dev.of_node, i2s)
	if (of_node_name_eq(i2s, "i2s-a"))
	break;

	if (i2s == NULL) {
	pr_debug(" i2s-a child not found\n");
	goto bail;
	}
	/* Get lightshow or virtual sound */
	for_each_child_of_node(i2s, np) {
	if (of_node_name_eq(np, "lightshow"))
	break;
	if (of_node_name_eq(np, "sound") &&
	of_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(*rm), 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: %pOF"
	" (%d resources, %d interrupts)\n",
	mdev->ofdev.dev.of_node);
	rc = -ENXIO;
	goto bail_free;
	}
	if (macio_request_resources(mdev, "rackmeter")) {
	printk(KERN_ERR
	"rackmeter: failed to request resources: %pOF\n",
	mdev->ofdev.dev.of_node);
	rc = -EBUSY;
	goto bail_free;
	}
	rm->irq = macio_irq(mdev, 1);
	#else
	rm->irq = irq_of_parse_and_map(i2s, 1);
	if (!rm->irq \|\|
	of_address_to_resource(i2s, 0, &ri2s) \|\|
	of_address_to_resource(i2s, 1, &rdma)) {
	printk(KERN_ERR
	"rackmeter: found match but lacks resources: %pOF",
	mdev->ofdev.dev.of_node);
	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);

	/* 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 const struct of_device_id rackmeter_match[] = {
	{ .name = "i2s" },
	{ }
	};
	MODULE_DEVICE_TABLE(of, rackmeter_match);

	static struct macio_driver rackmeter_driver = {
	.driver = {
	.name = "rackmeter",
	.owner = THIS_MODULE,
	.of_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_driver);
	}

	static void __exit rackmeter_exit(void)
	{
	pr_debug("rackmeter_exit()\n");

	macio_unregister_driver(&rackmeter_driver);
	}

	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");