// SPDX-License-Identifier: GPL-2.0
#define pr_fmt(fmt) "zpci: " fmt

#include <linux/kernel.h>
#include <linux/irq.h>
#include <linux/kernel_stat.h>
#include <linux/pci.h>
#include <linux/msi.h>
#include <linux/irqchip/irq-msi-lib.h>
#include <linux/smp.h>

#include <asm/isc.h>
#include <asm/airq.h>
#include <asm/tpi.h>

static enum {FLOATING, DIRECTED} irq_delivery;

/*
 * summary bit vector
 * FLOATING - summary bit per function
 * DIRECTED - summary bit per cpu (only used in fallback path)
 */
static struct airq_iv *zpci_sbv;

/*
 * interrupt bit vectors
 * FLOATING - interrupt bit vector per function
 * DIRECTED - interrupt bit vector per cpu
 */
static struct airq_iv **zpci_ibv;

/* Modify PCI: Register floating adapter interruptions */
static int zpci_set_airq(struct zpci_dev *zdev)
{
	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_REG_INT);
	struct zpci_fib fib = {0};
	u8 status;

	fib.fmt0.isc = PCI_ISC;
	fib.fmt0.sum = 1;	/* enable summary notifications */
	fib.fmt0.noi = airq_iv_end(zdev->aibv);
	fib.fmt0.aibv = virt_to_phys(zdev->aibv->vector);
	fib.fmt0.aibvo = 0;	/* each zdev has its own interrupt vector */
	fib.fmt0.aisb = virt_to_phys(zpci_sbv->vector) + (zdev->aisb / 64) * 8;
	fib.fmt0.aisbo = zdev->aisb & 63;
	fib.gd = zdev->gisa;

	return zpci_mod_fc(req, &fib, &status) ? -EIO : 0;
}

/* Modify PCI: Unregister floating adapter interruptions */
static int zpci_clear_airq(struct zpci_dev *zdev)
{
	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_DEREG_INT);
	struct zpci_fib fib = {0};
	u8 cc, status;

	fib.gd = zdev->gisa;

	cc = zpci_mod_fc(req, &fib, &status);
	if (cc == 3 || (cc == 1 && status == 24))
		/* Function already gone or IRQs already deregistered. */
		cc = 0;

	return cc ? -EIO : 0;
}

/* Modify PCI: Register CPU directed interruptions */
static int zpci_set_directed_irq(struct zpci_dev *zdev)
{
	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_REG_INT_D);
	struct zpci_fib fib = {0};
	u8 status;

	fib.fmt = 1;
	fib.fmt1.noi = zdev->msi_nr_irqs;
	fib.fmt1.dibvo = zdev->msi_first_bit;
	fib.gd = zdev->gisa;

	return zpci_mod_fc(req, &fib, &status) ? -EIO : 0;
}

/* Modify PCI: Unregister CPU directed interruptions */
static int zpci_clear_directed_irq(struct zpci_dev *zdev)
{
	u64 req = ZPCI_CREATE_REQ(zdev->fh, 0, ZPCI_MOD_FC_DEREG_INT_D);
	struct zpci_fib fib = {0};
	u8 cc, status;

	fib.fmt = 1;
	fib.gd = zdev->gisa;
	cc = zpci_mod_fc(req, &fib, &status);
	if (cc == 3 || (cc == 1 && status == 24))
		/* Function already gone or IRQs already deregistered. */
		cc = 0;

	return cc ? -EIO : 0;
}

/* Register adapter interruptions */
int zpci_set_irq(struct zpci_dev *zdev)
{
	int rc;

	if (irq_delivery == DIRECTED)
		rc = zpci_set_directed_irq(zdev);
	else
		rc = zpci_set_airq(zdev);

	return rc;
}

/* Clear adapter interruptions */
static int zpci_clear_irq(struct zpci_dev *zdev)
{
	int rc;

	if (irq_delivery == DIRECTED)
		rc = zpci_clear_directed_irq(zdev);
	else
		rc = zpci_clear_airq(zdev);

	return rc;
}

static int zpci_set_irq_affinity(struct irq_data *data, const struct cpumask *dest,
				 bool force)
{
	irq_data_update_affinity(data, dest);
	return IRQ_SET_MASK_OK;
}

/*
 * Encode the hwirq number for the parent domain. The encoding must be unique
 * for each IRQ of each device in the parent domain, so it uses the devfn to
 * identify the device and the msi_index to identify the IRQ within that device.
 */
static inline u32 zpci_encode_hwirq(u8 devfn, u16 msi_index)
{
	return (devfn << 16) | msi_index;
}

static inline u16 zpci_decode_hwirq_msi_index(irq_hw_number_t hwirq)
{
	return hwirq & 0xffff;
}

static void zpci_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
{
	struct msi_desc *desc = irq_data_get_msi_desc(data);
	struct zpci_dev *zdev = to_zpci_dev(desc->dev);

	if (irq_delivery == DIRECTED) {
		int cpu = cpumask_first(irq_data_get_affinity_mask(data));

		msg->address_lo = zdev->msi_addr & 0xff0000ff;
		msg->address_lo |= (smp_cpu_get_cpu_address(cpu) << 8);
	} else {
		msg->address_lo = zdev->msi_addr & 0xffffffff;
	}
	msg->address_hi = zdev->msi_addr >> 32;
	msg->data = zpci_decode_hwirq_msi_index(data->hwirq);
}

static struct irq_chip zpci_irq_chip = {
	.name = "PCI-MSI",
	.irq_compose_msi_msg = zpci_compose_msi_msg,
};

static void zpci_handle_cpu_local_irq(bool rescan)
{
	struct airq_iv *dibv = zpci_ibv[smp_processor_id()];
	union zpci_sic_iib iib = {{0}};
	struct irq_domain *msi_domain;
	irq_hw_number_t hwirq;
	unsigned long bit;
	int irqs_on = 0;

	for (bit = 0;;) {
		/* Scan the directed IRQ bit vector */
		bit = airq_iv_scan(dibv, bit, airq_iv_end(dibv));
		if (bit == -1UL) {
			if (!rescan || irqs_on++)
				/* End of second scan with interrupts on. */
				break;
			/* First scan complete, re-enable interrupts. */
			if (zpci_set_irq_ctrl(SIC_IRQ_MODE_D_SINGLE, PCI_ISC, &iib))
				break;
			bit = 0;
			continue;
		}
		inc_irq_stat(IRQIO_MSI);
		hwirq = airq_iv_get_data(dibv, bit);
		msi_domain = (struct irq_domain *)airq_iv_get_ptr(dibv, bit);
		generic_handle_domain_irq(msi_domain, hwirq);
	}
}

struct cpu_irq_data {
	call_single_data_t csd;
	atomic_t scheduled;
};
static DEFINE_PER_CPU_SHARED_ALIGNED(struct cpu_irq_data, irq_data);

static void zpci_handle_remote_irq(void *data)
{
	atomic_t *scheduled = data;

	do {
		zpci_handle_cpu_local_irq(false);
	} while (atomic_dec_return(scheduled));
}

static void zpci_handle_fallback_irq(void)
{
	struct cpu_irq_data *cpu_data;
	union zpci_sic_iib iib = {{0}};
	unsigned long cpu;
	int irqs_on = 0;

	for (cpu = 0;;) {
		cpu = airq_iv_scan(zpci_sbv, cpu, airq_iv_end(zpci_sbv));
		if (cpu == -1UL) {
			if (irqs_on++)
				/* End of second scan with interrupts on. */
				break;
			/* First scan complete, re-enable interrupts. */
			if (zpci_set_irq_ctrl(SIC_IRQ_MODE_SINGLE, PCI_ISC, &iib))
				break;
			cpu = 0;
			continue;
		}
		cpu_data = &per_cpu(irq_data, cpu);
		if (atomic_inc_return(&cpu_data->scheduled) > 1)
			continue;

		INIT_CSD(&cpu_data->csd, zpci_handle_remote_irq, &cpu_data->scheduled);
		smp_call_function_single_async(cpu, &cpu_data->csd);
	}
}

static void zpci_directed_irq_handler(struct airq_struct *airq,
				      struct tpi_info *tpi_info)
{
	bool floating = !tpi_info->directed_irq;

	if (floating) {
		inc_irq_stat(IRQIO_PCF);
		zpci_handle_fallback_irq();
	} else {
		inc_irq_stat(IRQIO_PCD);
		zpci_handle_cpu_local_irq(true);
	}
}

static void zpci_floating_irq_handler(struct airq_struct *airq,
				      struct tpi_info *tpi_info)
{
	union zpci_sic_iib iib = {{0}};
	struct irq_domain *msi_domain;
	irq_hw_number_t hwirq;
	unsigned long si, ai;
	struct airq_iv *aibv;
	int irqs_on = 0;

	inc_irq_stat(IRQIO_PCF);
	for (si = 0;;) {
		/* Scan adapter summary indicator bit vector */
		si = airq_iv_scan(zpci_sbv, si, airq_iv_end(zpci_sbv));
		if (si == -1UL) {
			if (irqs_on++)
				/* End of second scan with interrupts on. */
				break;
			/* First scan complete, re-enable interrupts. */
			if (zpci_set_irq_ctrl(SIC_IRQ_MODE_SINGLE, PCI_ISC, &iib))
				break;
			si = 0;
			continue;
		}

		/* Scan the adapter interrupt vector for this device. */
		aibv = zpci_ibv[si];
		for (ai = 0;;) {
			ai = airq_iv_scan(aibv, ai, airq_iv_end(aibv));
			if (ai == -1UL)
				break;
			inc_irq_stat(IRQIO_MSI);
			airq_iv_lock(aibv, ai);
			hwirq = airq_iv_get_data(aibv, ai);
			msi_domain = (struct irq_domain *)airq_iv_get_ptr(aibv, ai);
			generic_handle_domain_irq(msi_domain, hwirq);
			airq_iv_unlock(aibv, ai);
		}
	}
}

static int __alloc_airq(struct zpci_dev *zdev, int msi_vecs,
			unsigned long *bit)
{
	if (irq_delivery == DIRECTED) {
		/* Allocate cpu vector bits */
		*bit = airq_iv_alloc(zpci_ibv[0], msi_vecs);
		if (*bit == -1UL)
			return -EIO;
	} else {
		/* Allocate adapter summary indicator bit */
		*bit = airq_iv_alloc_bit(zpci_sbv);
		if (*bit == -1UL)
			return -EIO;
		zdev->aisb = *bit;

		/* Create adapter interrupt vector */
		zdev->aibv = airq_iv_create(msi_vecs,
					    AIRQ_IV_PTR | AIRQ_IV_DATA | AIRQ_IV_BITLOCK,
					    NULL);
		if (!zdev->aibv)
			return -ENOMEM;

		/* Wire up shortcut pointer */
		zpci_ibv[*bit] = zdev->aibv;
		/* Each function has its own interrupt vector */
		*bit = 0;
	}
	return 0;
}

bool arch_restore_msi_irqs(struct pci_dev *pdev)
{
	struct zpci_dev *zdev = to_zpci(pdev);

	zpci_set_irq(zdev);
	return true;
}

static struct airq_struct zpci_airq = {
	.handler = zpci_floating_irq_handler,
	.isc = PCI_ISC,
};

static void zpci_msi_teardown_directed(struct zpci_dev *zdev)
{
	airq_iv_free(zpci_ibv[0], zdev->msi_first_bit, zdev->max_msi);
	zdev->msi_first_bit = -1U;
	zdev->msi_nr_irqs = 0;
}

static void zpci_msi_teardown_floating(struct zpci_dev *zdev)
{
	airq_iv_release(zdev->aibv);
	zdev->aibv = NULL;
	airq_iv_free_bit(zpci_sbv, zdev->aisb);
	zdev->aisb = -1UL;
	zdev->msi_first_bit = -1U;
	zdev->msi_nr_irqs = 0;
}

static void zpci_msi_teardown(struct irq_domain *domain, msi_alloc_info_t *arg)
{
	struct zpci_dev *zdev = to_zpci_dev(domain->dev);

	zpci_clear_irq(zdev);
	if (irq_delivery == DIRECTED)
		zpci_msi_teardown_directed(zdev);
	else
		zpci_msi_teardown_floating(zdev);
}

static int zpci_msi_prepare(struct irq_domain *domain,
			    struct device *dev, int nvec,
			    msi_alloc_info_t *info)
{
	struct zpci_dev *zdev = to_zpci_dev(dev);
	struct pci_dev *pdev = to_pci_dev(dev);
	unsigned long bit;
	int msi_vecs, rc;

	msi_vecs = min_t(unsigned int, nvec, zdev->max_msi);
	if (msi_vecs < nvec) {
		pr_info("%s requested %d IRQs, allocate system limit of %d\n",
			pci_name(pdev), nvec, zdev->max_msi);
	}

	rc = __alloc_airq(zdev, msi_vecs, &bit);
	if (rc) {
		pr_err("Allocating adapter IRQs for %s failed\n", pci_name(pdev));
		return rc;
	}

	zdev->msi_first_bit = bit;
	zdev->msi_nr_irqs = msi_vecs;
	rc = zpci_set_irq(zdev);
	if (rc) {
		pr_err("Registering adapter IRQs for %s failed\n",
		       pci_name(pdev));

		if (irq_delivery == DIRECTED)
			zpci_msi_teardown_directed(zdev);
		else
			zpci_msi_teardown_floating(zdev);
		return rc;
	}
	return 0;
}

static int zpci_msi_domain_alloc(struct irq_domain *domain, unsigned int virq,
				 unsigned int nr_irqs, void *args)
{
	struct msi_desc *desc = ((msi_alloc_info_t *)args)->desc;
	struct zpci_dev *zdev = to_zpci_dev(desc->dev);
	struct zpci_bus *zbus = zdev->zbus;
	unsigned int cpu, hwirq;
	unsigned long bit;
	int i;

	bit = zdev->msi_first_bit + desc->msi_index;
	hwirq = zpci_encode_hwirq(zdev->devfn, desc->msi_index);

	if (desc->msi_index + nr_irqs > zdev->max_msi)
		return -EINVAL;

	for (i = 0; i < nr_irqs; i++) {
		irq_domain_set_info(domain, virq + i, hwirq + i,
				    &zpci_irq_chip, zdev,
				    handle_percpu_irq, NULL, NULL);

		if (irq_delivery == DIRECTED) {
			for_each_possible_cpu(cpu) {
				airq_iv_set_ptr(zpci_ibv[cpu], bit + i,
						(unsigned long)zbus->msi_parent_domain);
				airq_iv_set_data(zpci_ibv[cpu], bit + i, hwirq + i);
			}
		} else {
			airq_iv_set_ptr(zdev->aibv, bit + i,
					(unsigned long)zbus->msi_parent_domain);
			airq_iv_set_data(zdev->aibv, bit + i, hwirq + i);
		}
	}

	return 0;
}

static void zpci_msi_clear_airq(struct irq_data *d, int i)
{
	struct msi_desc *desc = irq_data_get_msi_desc(d);
	struct zpci_dev *zdev = to_zpci_dev(desc->dev);
	unsigned long bit;
	unsigned int cpu;
	u16 msi_index;

	msi_index = zpci_decode_hwirq_msi_index(d->hwirq);
	bit = zdev->msi_first_bit + msi_index;

	if (irq_delivery == DIRECTED) {
		for_each_possible_cpu(cpu) {
			airq_iv_set_ptr(zpci_ibv[cpu], bit + i, 0);
			airq_iv_set_data(zpci_ibv[cpu], bit + i, 0);
		}
	} else {
		airq_iv_set_ptr(zdev->aibv, bit + i, 0);
		airq_iv_set_data(zdev->aibv, bit + i, 0);
	}
}

static void zpci_msi_domain_free(struct irq_domain *domain, unsigned int virq,
				 unsigned int nr_irqs)
{
	struct irq_data *d;
	int i;

	for (i = 0; i < nr_irqs; i++) {
		d = irq_domain_get_irq_data(domain, virq + i);
		zpci_msi_clear_airq(d, i);
		irq_domain_reset_irq_data(d);
	}
}

static const struct irq_domain_ops zpci_msi_domain_ops = {
	.alloc = zpci_msi_domain_alloc,
	.free  = zpci_msi_domain_free,
};

static bool zpci_init_dev_msi_info(struct device *dev, struct irq_domain *domain,
				   struct irq_domain *real_parent,
				   struct msi_domain_info *info)
{
	if (!msi_lib_init_dev_msi_info(dev, domain, real_parent, info))
		return false;

	info->ops->msi_prepare = zpci_msi_prepare;
	info->ops->msi_teardown = zpci_msi_teardown;

	return true;
}

static struct msi_parent_ops zpci_msi_parent_ops = {
	.supported_flags   = MSI_GENERIC_FLAGS_MASK	|
			     MSI_FLAG_PCI_MSIX		|
			     MSI_FLAG_MULTI_PCI_MSI,
	.required_flags	   = MSI_FLAG_USE_DEF_DOM_OPS  |
			     MSI_FLAG_USE_DEF_CHIP_OPS,
	.init_dev_msi_info = zpci_init_dev_msi_info,
};

int zpci_create_parent_msi_domain(struct zpci_bus *zbus)
{
	char fwnode_name[18];

	snprintf(fwnode_name, sizeof(fwnode_name), "ZPCI_MSI_DOM_%04x", zbus->domain_nr);
	struct irq_domain_info info = {
		.fwnode		= irq_domain_alloc_named_fwnode(fwnode_name),
		.ops		= &zpci_msi_domain_ops,
	};

	if (!info.fwnode) {
		pr_err("Failed to allocate fwnode for MSI IRQ domain\n");
		return -ENOMEM;
	}

	if (irq_delivery == FLOATING)
		zpci_msi_parent_ops.required_flags |= MSI_FLAG_NO_AFFINITY;

	zbus->msi_parent_domain = msi_create_parent_irq_domain(&info, &zpci_msi_parent_ops);
	if (!zbus->msi_parent_domain) {
		irq_domain_free_fwnode(info.fwnode);
		pr_err("Failed to create MSI IRQ domain\n");
		return -ENOMEM;
	}

	return 0;
}

void zpci_remove_parent_msi_domain(struct zpci_bus *zbus)
{
	struct fwnode_handle *fn;

	fn = zbus->msi_parent_domain->fwnode;
	irq_domain_remove(zbus->msi_parent_domain);
	irq_domain_free_fwnode(fn);
}

static void __init cpu_enable_directed_irq(void *unused)
{
	union zpci_sic_iib iib = {{0}};
	union zpci_sic_iib ziib = {{0}};

	iib.cdiib.dibv_addr = virt_to_phys(zpci_ibv[smp_processor_id()]->vector);

	zpci_set_irq_ctrl(SIC_IRQ_MODE_SET_CPU, 0, &iib);
	zpci_set_irq_ctrl(SIC_IRQ_MODE_D_SINGLE, PCI_ISC, &ziib);
}

static int __init zpci_directed_irq_init(void)
{
	union zpci_sic_iib iib = {{0}};
	unsigned int cpu;

	zpci_sbv = airq_iv_create(num_possible_cpus(), 0, NULL);
	if (!zpci_sbv)
		return -ENOMEM;

	iib.diib.isc = PCI_ISC;
	iib.diib.nr_cpus = num_possible_cpus();
	iib.diib.disb_addr = virt_to_phys(zpci_sbv->vector);
	zpci_set_irq_ctrl(SIC_IRQ_MODE_DIRECT, 0, &iib);

	zpci_ibv = kcalloc(num_possible_cpus(), sizeof(*zpci_ibv),
			   GFP_KERNEL);
	if (!zpci_ibv)
		return -ENOMEM;

	for_each_possible_cpu(cpu) {
		/*
		 * Per CPU IRQ vectors look the same but bit-allocation
		 * is only done on the first vector.
		 */
		zpci_ibv[cpu] = airq_iv_create(cache_line_size() * BITS_PER_BYTE,
					       AIRQ_IV_PTR |
					       AIRQ_IV_DATA |
					       AIRQ_IV_CACHELINE |
					       (!cpu ? AIRQ_IV_ALLOC : 0), NULL);
		if (!zpci_ibv[cpu])
			return -ENOMEM;
	}
	on_each_cpu(cpu_enable_directed_irq, NULL, 1);

	zpci_irq_chip.irq_set_affinity = zpci_set_irq_affinity;

	return 0;
}

static int __init zpci_floating_irq_init(void)
{
	zpci_ibv = kcalloc(ZPCI_NR_DEVICES, sizeof(*zpci_ibv), GFP_KERNEL);
	if (!zpci_ibv)
		return -ENOMEM;

	zpci_sbv = airq_iv_create(ZPCI_NR_DEVICES, AIRQ_IV_ALLOC, NULL);
	if (!zpci_sbv)
		goto out_free;

	return 0;

out_free:
	kfree(zpci_ibv);
	return -ENOMEM;
}

int __init zpci_irq_init(void)
{
	union zpci_sic_iib iib = {{0}};
	int rc;

	irq_delivery = sclp.has_dirq ? DIRECTED : FLOATING;
	if (s390_pci_force_floating)
		irq_delivery = FLOATING;

	if (irq_delivery == DIRECTED)
		zpci_airq.handler = zpci_directed_irq_handler;

	rc = register_adapter_interrupt(&zpci_airq);
	if (rc)
		goto out;
	/* Set summary to 1 to be called every time for the ISC. */
	*zpci_airq.lsi_ptr = 1;

	switch (irq_delivery) {
	case FLOATING:
		rc = zpci_floating_irq_init();
		break;
	case DIRECTED:
		rc = zpci_directed_irq_init();
		break;
	}

	if (rc)
		goto out_airq;

	/*
	 * Enable floating IRQs (with suppression after one IRQ). When using
	 * directed IRQs this enables the fallback path.
	 */
	zpci_set_irq_ctrl(SIC_IRQ_MODE_SINGLE, PCI_ISC, &iib);

	return 0;
out_airq:
	unregister_adapter_interrupt(&zpci_airq);
out:
	return rc;
}

void __init zpci_irq_exit(void)
{
	unsigned int cpu;

	if (irq_delivery == DIRECTED) {
		for_each_possible_cpu(cpu) {
			airq_iv_release(zpci_ibv[cpu]);
		}
	}
	kfree(zpci_ibv);
	if (zpci_sbv)
		airq_iv_release(zpci_sbv);
	unregister_adapter_interrupt(&zpci_airq);
}