/*
 * 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;
        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)
{
        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, ARRAY_SIZE(rdma->buf1));
        memset(rdma->buf2, 0, ARRAY_SIZE(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();
        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) (cur_jiffies - rcpu->prev_wall);
        rcpu->prev_wall = cur_jiffies;

        total_idle_ticks = get_cpu_idle_time(cpu);
        idle_ticks = (unsigned int) (total_idle_ticks - rcpu->prev_idle);
        idle_ticks = min(idle_ticks, total_ticks);
        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 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_cputime64(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(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 ||
            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.dev.of_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);

        /* 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" },
        { }
};
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");