/*
 * 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/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/prom.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)
{
	u64 retval;

	retval = kcpustat_cpu(cpu).cpustat[CPUTIME_IDLE] +
		 kcpustat_cpu(cpu).cpustat[CPUTIME_IOWAIT];

	if (rackmeter_ignore_nice)
		retval += kcpustat_cpu(cpu).cpustat[CPUTIME_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, 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 */
	while ((i2s = of_get_next_child(mdev->ofdev.dev.of_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) &&
		   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");
